1893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 2893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#if 0 /* in case someone actually tries to compile this */ 3893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 4893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project/* example.c - an example of using libpng 5ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * Last changed in libpng 1.6.3 [July 18, 2013] 6ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * Maintained 1998-2013 Glenn Randers-Pehrson 7893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * Maintained 1996, 1997 Andreas Dilger) 8893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) 9ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * To the extent possible under law, the authors have waived 10ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * all copyright and related or neighboring rights to this file. 11ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * This work is published from: United States. 12893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 13893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 14893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project/* This is an example of how to use libpng to read and write PNG files. 15ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * The file libpng-manual.txt is much more verbose then this. If you have not 16893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * read it, do so first. This was designed to be a starting point of an 17893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * implementation. This is not officially part of libpng, is hereby placed 18893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * in the public domain, and therefore does not require a copyright notice. 19893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 20893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * This file does not currently compile, because it is missing certain 21893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * parts, like allocating memory to hold an image. You will have to 22893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * supply these parts to get it to compile. For an example of a minimal 23893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * working PNG reader/writer, see pngtest.c, included in this distribution; 24893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * see also the programs in the contrib directory. 25893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 26893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 27ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik/* The simple, but restricted, approach to reading a PNG file or data stream 28ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * just requires two function calls, as in the following complete program. 29ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * Writing a file just needs one function call, so long as the data has an 30ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * appropriate layout. 31ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 32ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * The following code reads PNG image data from a file and writes it, in a 33ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * potentially new format, to a new file. While this code will compile there is 34ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * minimal (insufficient) error checking; for a more realistic version look at 35ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * contrib/examples/pngtopng.c 36ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik */ 37ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#include <stddef.h> 38ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#include <stdlib.h> 39ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#include <string.h> 40ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#include <stdio.h> 41ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#include <png.h> 42ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#include <zlib.h> 43ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 44ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craikint main(int argc, const char **argv) 45ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik{ 46ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik if (argc == 3) 47ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik { 48ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_image image; /* The control structure used by libpng */ 49ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 50ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* Initialize the 'png_image' structure. */ 51ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik memset(&image, 0, (sizeof image)); 52ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik image.version = PNG_IMAGE_VERSION; 53ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 54ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* The first argument is the file to read: */ 55ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik if (png_image_begin_read_from_file(&image, argv[1])) 56ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik { 57ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_bytep buffer; 58ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 59ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* Set the format in which to read the PNG file; this code chooses a 60ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * simple sRGB format with a non-associated alpha channel, adequate to 61ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * store most images. 62ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik */ 63ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik image.format = PNG_FORMAT_RGBA; 64ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 65ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* Now allocate enough memory to hold the image in this format; the 66ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * PNG_IMAGE_SIZE macro uses the information about the image (width, 67ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * height and format) stored in 'image'. 68ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik */ 69ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik buffer = malloc(PNG_IMAGE_SIZE(image)); 70ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 71ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* If enough memory was available read the image in the desired format 72ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * then write the result out to the new file. 'background' is not 73ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * necessary when reading the image because the alpha channel is 74ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * preserved; if it were to be removed, for example if we requested 75ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * PNG_FORMAT_RGB, then either a solid background color would have to 76ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * be supplied or the output buffer would have to be initialized to the 77ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * actual background of the image. 78ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 79ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * The fourth argument to png_image_finish_read is the 'row_stride' - 80ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * this is the number of components allocated for the image in each 81ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * row. It has to be at least as big as the value returned by 82ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * PNG_IMAGE_ROW_STRIDE, but if you just allocate space for the 83ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * default, minimum, size using PNG_IMAGE_SIZE as above you can pass 84ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * zero. 85ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 86ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * The final argument is a pointer to a buffer for the colormap; 87ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * colormaps have exactly the same format as a row of image pixels (so 88ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * you choose what format to make the colormap by setting 89ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * image.format). A colormap is only returned if 90ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * PNG_FORMAT_FLAG_COLORMAP is also set in image.format, so in this 91ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * case NULL is passed as the final argument. If you do want to force 92ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * all images into an index/color-mapped format then you can use: 93ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 94ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * PNG_IMAGE_COLORMAP_SIZE(image) 95ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 96ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * to find the maximum size of the colormap in bytes. 97ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik */ 98ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik if (buffer != NULL && 99ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_image_finish_read(&image, NULL/*background*/, buffer, 100ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 0/*row_stride*/, NULL/*colormap*/)) 101ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik { 102ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* Now write the image out to the second argument. In the write 103ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * call 'convert_to_8bit' allows 16-bit data to be squashed down to 104ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 8 bits; this isn't necessary here because the original read was 105ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * to the 8-bit format. 106ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik */ 107ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik if (png_image_write_to_file(&image, argv[2], 0/*convert_to_8bit*/, 108ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik buffer, 0/*row_stride*/, NULL/*colormap*/)) 109ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik { 110ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* The image has been written successfully. */ 111ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik exit(0); 112ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik } 113ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik } 114ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 115ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik else 116ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik { 117ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* Calling png_free_image is optional unless the simplified API was 118ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * not run to completion. In this case if there wasn't enough 119ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * memory for 'buffer' we didn't complete the read, so we must free 120ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * the image: 121ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik */ 122ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik if (buffer == NULL) 123ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_free_image(&image); 124ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 125ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik else 126ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik free(buffer); 127ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik } 128ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 129ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* Something went wrong reading or writing the image. libpng stores a 130ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * textual message in the 'png_image' structure: 131ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik */ 132ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik fprintf(stderr, "pngtopng: error: %s\n", image.message); 133ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik exit (1); 134ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik } 135ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 136ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n"); 137ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik exit(1); 138ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik} 139ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 140ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik/* That's it ;-) Of course you probably want to do more with PNG files than 141ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * just converting them all to 32-bit RGBA PNG files; you can do that between 142ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * the call to png_image_finish_read and png_image_write_to_file. You can also 143ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * ask for the image data to be presented in a number of different formats. You 144ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * do this by simply changing the 'format' parameter set before allocating the 145ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * buffer. 146ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 147ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * The format parameter consists of five flags that define various aspects of 148ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * the image, you can simply add these together to get the format or you can use 149ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * one of the predefined macros from png.h (as above): 150ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 151ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * PNG_FORMAT_FLAG_COLOR: if set the image will have three color components per 152ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * pixel (red, green and blue), if not set the image will just have one 153ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * luminance (grayscale) component. 154ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 155ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * PNG_FORMAT_FLAG_ALPHA: if set each pixel in the image will have an additional 156ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * alpha value; a linear value that describes the degree the image pixel 157ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * covers (overwrites) the contents of the existing pixel on the display. 158ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 159ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * PNG_FORMAT_FLAG_LINEAR: if set the components of each pixel will be returned 160ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * as a series of 16-bit linear values, if not set the components will be 161ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * returned as a series of 8-bit values encoded according to the 'sRGB' 162ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * standard. The 8-bit format is the normal format for images intended for 163ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * direct display, because almost all display devices do the inverse of the 164ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * sRGB transformation to the data they receive. The 16-bit format is more 165ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * common for scientific data and image data that must be further processed; 166ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * because it is linear simple math can be done on the component values. 167ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * Regardless of the setting of this flag the alpha channel is always linear, 168ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * although it will be 8 bits or 16 bits wide as specified by the flag. 169ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 170ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * PNG_FORMAT_FLAG_BGR: if set the components of a color pixel will be returned 171ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * in the order blue, then green, then red. If not set the pixel components 172ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * are in the order red, then green, then blue. 173ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 174ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * PNG_FORMAT_FLAG_AFIRST: if set the alpha channel (if present) precedes the 175ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * color or grayscale components. If not set the alpha channel follows the 176ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * components. 177ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 178ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * You do not have to read directly from a file. You can read from memory or, 179ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * on systems that support it, from a <stdio.h> FILE*. This is controlled by 180ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * the particular png_image_read_from_ function you call at the start. Likewise 181ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * on write you can write to a FILE* if your system supports it. Check the 182ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * macro PNG_STDIO_SUPPORTED to see if stdio support has been included in your 183ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * libpng build. 184ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 185ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * If you read 16-bit (PNG_FORMAT_FLAG_LINEAR) data you may need to write it in 186ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * the 8-bit format for display. You do this by setting the convert_to_8bit 187ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * flag to 'true'. 188ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 189ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * Don't repeatedly convert between the 8-bit and 16-bit forms. There is 190ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * significant data loss when 16-bit data is converted to the 8-bit encoding and 191ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * the current libpng implementation of convertion to 16-bit is also 192ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * significantly lossy. The latter will be fixed in the future, but the former 193ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * is unavoidable - the 8-bit format just doesn't have enough resolution. 194ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik */ 195ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 196ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik/* If your program needs more information from the PNG data it reads, or if you 197ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * need to do more complex transformations, or minimise transformations, on the 198ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * data you read, then you must use one of the several lower level libpng 199ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * interfaces. 200ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 201ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * All these interfaces require that you do your own error handling - your 202ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * program must be able to arrange for control to return to your own code any 203ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * time libpng encounters a problem. There are several ways to do this, but the 204ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * standard way is to use the ANSI-C (C90) <setjmp.h> interface to establish a 205ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * return point within your own code. You must do this if you do not use the 206ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * simplified interface (above). 207ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * 208ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * The first step is to include the header files you need, including the libpng 209ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * header file. Include any standard headers and feature test macros your 210ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * program requires before including png.h: 211ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik */ 212ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#include <png.h> 213893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 214893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The png_jmpbuf() macro, used in error handling, became available in 215893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * libpng version 1.0.6. If you want to be able to run your code with older 216893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * versions of libpng, you must define the macro yourself (but only if it 217893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * is not already defined by libpng!). 218893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 219893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 220893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifndef png_jmpbuf 221ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik# define png_jmpbuf(png_ptr) ((png_ptr)->png_jmpbuf) 222893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif 223893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 224893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project/* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp() 225893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * returns zero if the image is a PNG and nonzero if it isn't a PNG. 226893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 227893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * The function check_if_png() shown here, but not used, returns nonzero (true) 228893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * if the file can be opened and is a PNG, 0 (false) otherwise. 229893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 230893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * If this call is successful, and you are going to keep the file open, 231893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once 232893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you have created the png_ptr, so that libpng knows your application 233893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * has read that many bytes from the start of the file. Make sure you 234893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * don't call png_set_sig_bytes() with more than 8 bytes read or give it 235893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * an incorrect number of bytes read, or you will either have read too 236893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * many bytes (your fault), or you are telling libpng to read the wrong 237893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * number of magic bytes (also your fault). 238893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 239893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * Many applications already read the first 2 or 4 bytes from the start 240893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * of the image to determine the file type, so it would be easiest just 241893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * to pass the bytes to png_sig_cmp() or even skip that if you know 242893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you have a PNG file, and call png_set_sig_bytes(). 243893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 244893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#define PNG_BYTES_TO_CHECK 4 245893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectint check_if_png(char *file_name, FILE **fp) 246893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 247893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project char buf[PNG_BYTES_TO_CHECK]; 248893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 249893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Open the prospective PNG file. */ 250893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if ((*fp = fopen(file_name, "rb")) == NULL) 251893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return 0; 252893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 253893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Read in some of the signature bytes */ 254893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK) 255893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return 0; 256893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 257893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature. 258893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project Return nonzero (true) if they match */ 259893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 260893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK)); 261893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 262893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 263893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project/* Read a PNG file. You may want to return an error code if the read 264893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * fails (depending upon the failure). There are two "prototypes" given 265893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * here - one where we are given the filename, and we need to open the 266893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * file, and the other where we are given an open file (possibly with 267893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * some or all of the magic bytes read - see comments above). 268893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 269893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef open_file /* prototype 1 */ 270893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectvoid read_png(char *file_name) /* We need to open the file */ 271893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 272893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_structp png_ptr; 273893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_infop info_ptr; 274893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project unsigned int sig_read = 0; 275893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_uint_32 width, height; 276893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project int bit_depth, color_type, interlace_type; 277893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project FILE *fp; 278893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 279893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if ((fp = fopen(file_name, "rb")) == NULL) 280893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 281a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 282893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_open_file /* prototype 2 */ 283a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scottvoid read_png(FILE *fp, unsigned int sig_read) /* File is already open */ 284893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 285893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_structp png_ptr; 286893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_infop info_ptr; 287893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_uint_32 width, height; 288893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project int bit_depth, color_type, interlace_type; 289a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_open_file /* Only use one prototype! */ 290893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 291893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Create and initialize the png_struct with the desired error handler 292893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * functions. If you want to use the default stderr and longjump method, 293893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you can supply NULL for the last three parameters. We also supply the 294893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the compiler header file version, so that we know if the application 295893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * was compiled with a compatible version of the library. REQUIRED 296893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 297893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 298893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_voidp user_error_ptr, user_error_fn, user_warning_fn); 299893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 300893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_ptr == NULL) 301893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 302893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 303893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 304893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 305893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 306893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Allocate/initialize the memory for image information. REQUIRED. */ 307893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project info_ptr = png_create_info_struct(png_ptr); 308893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (info_ptr == NULL) 309893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 310893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 311ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_destroy_read_struct(&png_ptr, NULL, NULL); 312893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 313893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 314893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 315893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Set error handling if you are using the setjmp/longjmp method (this is 316893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the normal method of doing things with libpng). REQUIRED unless you 317893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * set up your own error handlers in the png_create_read_struct() earlier. 318893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 319893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 320893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (setjmp(png_jmpbuf(png_ptr))) 321893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 322893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Free all of the memory associated with the png_ptr and info_ptr */ 323ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_destroy_read_struct(&png_ptr, &info_ptr, NULL); 324893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 325893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If we get here, we had a problem reading the file */ 326893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 327893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 328893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 329893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* One of the following I/O initialization methods is REQUIRED */ 330893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef streams /* PNG file I/O method 1 */ 331893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Set up the input control if you are using standard C streams */ 332893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_init_io(png_ptr, fp); 333893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 334893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_streams /* PNG file I/O method 2 */ 335893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If you are using replacement read functions, instead of calling 336893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * png_init_io() here you would call: 337893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 338893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn); 339893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* where user_io_ptr is a structure you want available to the callbacks */ 340893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif no_streams /* Use only one I/O method! */ 341893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 342893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If we have already read some of the signature */ 343893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_sig_bytes(png_ptr, sig_read); 344893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 345893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef hilevel 346893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* 347893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * If you have enough memory to read in the entire image at once, 348893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * and you need to specify only transforms that can be controlled 349893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * with one of the PNG_TRANSFORM_* bits (this presently excludes 350ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * quantizing, filling, setting background, and doing gamma 351893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * adjustment), then you can read the entire image (including 352893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * pixels) into the info structure with this call: 353893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 354ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_read_png(png_ptr, info_ptr, png_transforms, NULL); 355a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 356893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else 357893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* OK, you're doing it the hard way, with the lower-level functions */ 358893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 359893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The call to png_read_info() gives us all of the information from the 360893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * PNG file before the first IDAT (image data chunk). REQUIRED 361893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 362893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_info(png_ptr, info_ptr); 363893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 364893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, 365ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik &interlace_type, NULL, NULL); 366893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 367a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Set up the data transformations you want. Note that these are all 368a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * optional. Only call them if you want/need them. Many of the 369a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * transformations only work on specific types of images, and many 370a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * are mutually exclusive. 371a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 372893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 373ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* Tell libpng to strip 16 bit/color files down to 8 bits/color. 374ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * Use accurate scaling if it's available, otherwise just chop off the 375ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * low byte. 376ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik */ 377ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED 378ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_set_scale_16(png_ptr); 379ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#else 380893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_strip_16(png_ptr); 381ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#endif 382893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 383893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Strip alpha bytes from the input data without combining with the 384893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * background (not recommended). 385893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 386893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_strip_alpha(png_ptr); 387893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 388893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single 389893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * byte into separate bytes (useful for paletted and grayscale images). 390893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 391893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_packing(png_ptr); 392893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 393893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Change the order of packed pixels to least significant bit first 394893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * (not useful if you are using png_set_packing). */ 395893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_packswap(png_ptr); 396893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 397893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Expand paletted colors into true RGB triplets */ 398893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (color_type == PNG_COLOR_TYPE_PALETTE) 399893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_palette_to_rgb(png_ptr); 400893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 401893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */ 402893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) 4034215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project png_set_expand_gray_1_2_4_to_8(png_ptr); 404893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 405893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Expand paletted or RGB images with transparency to full alpha channels 406893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * so the data will be available as RGBA quartets. 407893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 408893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) 409893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_tRNS_to_alpha(png_ptr); 410893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 411893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Set the background color to draw transparent and alpha images over. 412893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * It is possible to set the red, green, and blue components directly 413893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * for paletted images instead of supplying a palette index. Note that 414893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * even if the PNG file supplies a background, you are not required to 415893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * use it - you should use the (solid) application background if it has one. 416893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 417893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 418893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_color_16 my_background, *image_background; 419893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 420893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_get_bKGD(png_ptr, info_ptr, &image_background)) 421893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_background(png_ptr, image_background, 422893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project PNG_BACKGROUND_GAMMA_FILE, 1, 1.0); 423893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else 424893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_background(png_ptr, &my_background, 425893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0); 426893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 427a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Some suggestions as to how to get a screen gamma value 428a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 429a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * Note that screen gamma is the display_exponent, which includes 430a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the CRT_exponent and any correction for viewing conditions 431a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 432893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (/* We have a user-defined screen gamma value */) 433893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 434893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project screen_gamma = user-defined screen_gamma; 435893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 436893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This is one way that applications share the same screen gamma value */ 437893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL) 438893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 439893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project screen_gamma = atof(gamma_str); 440893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 441893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If we don't have another value */ 442893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else 443893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 444ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik screen_gamma = PNG_DEFAULT_sRGB; /* A good guess for a PC monitor 445ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik in a dimly lit room */ 446ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik screen_gamma = PNG_GAMMA_MAC_18 or 1.0; /* Good guesses for Mac systems */ 447893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 448893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 449893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Tell libpng to handle the gamma conversion for you. The final call 450893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * is a good guess for PC generated images, but it should be configurable 451893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * by the user at run time by the user. It is strongly suggested that 452893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * your application support gamma correction. 453893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 454893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 455893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project int intent; 456893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 457893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_get_sRGB(png_ptr, info_ptr, &intent)) 458ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_set_gamma(png_ptr, screen_gamma, PNG_DEFAULT_sRGB); 459893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else 460893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 461893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project double image_gamma; 462893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_get_gAMA(png_ptr, info_ptr, &image_gamma)) 463893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_gamma(png_ptr, screen_gamma, image_gamma); 464893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else 465893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_gamma(png_ptr, screen_gamma, 0.45455); 466893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 467893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 468ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#ifdef PNG_READ_QUANTIZE_SUPPORTED 469ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* Quantize RGB files down to 8 bit palette or reduce palettes 470893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * to the number of colors available on your screen. 471893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 472893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (color_type & PNG_COLOR_MASK_COLOR) 473893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 474893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project int num_palette; 475893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_colorp palette; 476893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 477893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This reduces the image to the application supplied palette */ 478a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott if (/* We have our own palette */) 479893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 480ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* An array of colors to which the image should be quantized */ 481893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_color std_color_cube[MAX_SCREEN_COLORS]; 482893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 483ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_set_quantize(png_ptr, std_color_cube, MAX_SCREEN_COLORS, 484ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik MAX_SCREEN_COLORS, NULL, 0); 485893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 486893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This reduces the image to the palette supplied in the file */ 487893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette)) 488893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 489893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_uint_16p histogram = NULL; 490893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 491893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_get_hIST(png_ptr, info_ptr, &histogram); 492893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 493ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_set_quantize(png_ptr, palette, num_palette, 494893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project max_screen_colors, histogram, 0); 495893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 496893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 497ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#endif /* PNG_READ_QUANTIZE_SUPPORTED */ 498893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 499a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Invert monochrome files to have 0 as white and 1 as black */ 500893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_invert_mono(png_ptr); 501893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 502893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If you want to shift the pixel values from the range [0,255] or 503893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * [0,65535] to the original [0,7] or [0,31], or whatever range the 504893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * colors were originally in: 505893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 506893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT)) 507893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 508a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott png_color_8p sig_bit_p; 509893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 510a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott png_get_sBIT(png_ptr, info_ptr, &sig_bit_p); 511a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott png_set_shift(png_ptr, sig_bit_p); 512893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 513893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 514a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Flip the RGB pixels to BGR (or RGBA to BGRA) */ 515893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (color_type & PNG_COLOR_MASK_COLOR) 516893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_bgr(png_ptr); 517893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 518a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */ 519893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_swap_alpha(png_ptr); 520893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 521a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Swap bytes of 16 bit files to least significant byte first */ 522893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_swap(png_ptr); 523893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 524893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Add filler (or alpha) byte (before/after each RGB triplet) */ 525893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER); 526893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 527ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#ifdef PNG_READ_INTERLACING_SUPPORTED 528893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Turn on interlace handling. REQUIRED if you are not using 529893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * png_read_image(). To see how to handle interlacing passes, 530893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * see the png_read_row() method below: 531893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 532893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project number_passes = png_set_interlace_handling(png_ptr); 533ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#else 534ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik number_passes = 1; 535ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#endif /* PNG_READ_INTERLACING_SUPPORTED */ 536ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 537893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 538893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Optional call to gamma correct and add the background to the palette 539893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * and update info structure. REQUIRED if you are expecting libpng to 540893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * update the palette for you (ie you selected such a transform above). 541893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 542893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_update_info(png_ptr, info_ptr); 543893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 544893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Allocate the memory to hold the image using the fields of info_ptr. */ 545893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 546893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The easiest way to read the image: */ 547893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_bytep row_pointers[height]; 548893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 5494215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project /* Clear the pointer array */ 5504215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project for (row = 0; row < height; row++) 5514215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project row_pointers[row] = NULL; 5524215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project 553893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (row = 0; row < height; row++) 554893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr, 555893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project info_ptr)); 556893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 557893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Now it's time to read the image. One of these methods is REQUIRED */ 558893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef entire /* Read the entire image in one go */ 559893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_image(png_ptr, row_pointers); 560893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 561893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_entire /* Read the image one or more scanlines at a time */ 562893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The other way to read images - deal with interlacing: */ 563893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 564893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (pass = 0; pass < number_passes; pass++) 565893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 566893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef single /* Read the image a single row at a time */ 567893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (y = 0; y < height; y++) 568893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 569ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_read_rows(png_ptr, &row_pointers[y], NULL, 1); 570893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 571893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 572893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_single /* Read the image several rows at a time */ 573893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (y = 0; y < height; y += number_of_rows) 574893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 575893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef sparkle /* Read the image using the "sparkle" effect. */ 576ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_read_rows(png_ptr, &row_pointers[y], NULL, 577893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project number_of_rows); 578893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_sparkle /* Read the image using the "rectangle" effect */ 579ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_read_rows(png_ptr, NULL, &row_pointers[y], 580893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project number_of_rows); 581a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_sparkle /* Use only one of these two methods */ 582893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 583893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 584a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* If you want to display the image after every pass, do so here */ 585a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_single /* Use only one of these two methods */ 586893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 587a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_entire /* Use only one of these two methods */ 588893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 589a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */ 590893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_end(png_ptr, info_ptr); 591893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif hilevel 592893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 593893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* At this point you have read the entire image */ 594893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 595a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Clean up after the read, and free any memory allocated - REQUIRED */ 596ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_destroy_read_struct(&png_ptr, &info_ptr, NULL); 597893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 598a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Close the file */ 599893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 600893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 601a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* That's it */ 602893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (OK); 603893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 604893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 605a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott/* Progressively read a file */ 606893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 607893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectint 608893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectinitialize_png_reader(png_structp *png_ptr, png_infop *info_ptr) 609893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 610893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Create and initialize the png_struct with the desired error handler 611893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * functions. If you want to use the default stderr and longjump method, 612893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you can supply NULL for the last three parameters. We also check that 613893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the library version is compatible in case we are using dynamically 614893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * linked libraries. 615893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 616893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 617893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_voidp user_error_ptr, user_error_fn, user_warning_fn); 618893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 619893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (*png_ptr == NULL) 620893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 621893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project *info_ptr = NULL; 622893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 623893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 624893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 625893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project *info_ptr = png_create_info_struct(png_ptr); 626893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 627893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (*info_ptr == NULL) 628893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 629ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_destroy_read_struct(png_ptr, info_ptr, NULL); 630893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 631893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 632893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 633893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (setjmp(png_jmpbuf((*png_ptr)))) 634893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 635ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_destroy_read_struct(png_ptr, info_ptr, NULL); 636893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 637893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 638893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 639893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This one's new. You will need to provide all three 640893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * function callbacks, even if you aren't using them all. 641893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * If you aren't using all functions, you can specify NULL 642893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * parameters. Even when all three functions are NULL, 643893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you need to call png_set_progressive_read_fn(). 644893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * These functions shouldn't be dependent on global or 645893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * static variables if you are decoding several images 646893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * simultaneously. You should store stream specific data 647893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * in a separate struct, given as the second parameter, 648893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * and retrieve the pointer from inside the callbacks using 649893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the function png_get_progressive_ptr(png_ptr). 650893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 651893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_progressive_read_fn(*png_ptr, (void *)stream_data, 652893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project info_callback, row_callback, end_callback); 653893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 654893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (OK); 655893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 656893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 657893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectint 658893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectprocess_data(png_structp *png_ptr, png_infop *info_ptr, 659893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_bytep buffer, png_uint_32 length) 660893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 661893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (setjmp(png_jmpbuf((*png_ptr)))) 662893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 663893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Free the png_ptr and info_ptr memory on error */ 664ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_destroy_read_struct(png_ptr, info_ptr, NULL); 665893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 666893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 667893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 668893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This one's new also. Simply give it chunks of data as 669893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * they arrive from the data stream (in order, of course). 670a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * On segmented machines, don't give it any more than 64K. 671893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * The library seems to run fine with sizes of 4K, although 672893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you can give it much less if necessary (I assume you can 673893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * give it chunks of 1 byte, but I haven't tried with less 674893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * than 256 bytes yet). When this function returns, you may 675893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * want to display any rows that were generated in the row 676893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * callback, if you aren't already displaying them there. 677893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 678893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_process_data(*png_ptr, *info_ptr, buffer, length); 679893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (OK); 680893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 681893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 682893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectinfo_callback(png_structp png_ptr, png_infop info) 683893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 684a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Do any setup here, including setting any of the transformations 685a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * mentioned in the Reading PNG files section. For now, you _must_ 686a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * call either png_start_read_image() or png_read_update_info() 687a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * after all the transformations are set (even if you don't set 688a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * any). You may start getting rows before png_process_data() 689a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * returns, so this is your last chance to prepare for that. 690a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 691893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 692893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 693893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectrow_callback(png_structp png_ptr, png_bytep new_row, 694893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_uint_32 row_num, int pass) 695893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 696a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* 697a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * This function is called for every row in the image. If the 698a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * image is interlaced, and you turned on the interlace handler, 699a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * this function will be called for every row in every pass. 700a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 701a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * In this function you will receive a pointer to new row data from 702a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * libpng called new_row that is to replace a corresponding row (of 703a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the same data format) in a buffer allocated by your application. 704a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 705a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * The new row data pointer "new_row" may be NULL, indicating there is 706a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * no new data to be replaced (in cases of interlace loading). 707a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 708a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * If new_row is not NULL then you need to call 709a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * png_progressive_combine_row() to replace the corresponding row as 710a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * shown below: 711a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 712a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 7135f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott /* Get pointer to corresponding row in our 7145f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott * PNG read buffer. 7155f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott */ 7165f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott png_bytep old_row = ((png_bytep *)our_data)[row_num]; 7175f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott 718ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#ifdef PNG_READ_INTERLACING_SUPPORTED 7195f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott /* If both rows are allocated then copy the new row 7205f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott * data to the corresponding row data. 7215f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott */ 7225f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott if ((old_row != NULL) && (new_row != NULL)) 7235f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott png_progressive_combine_row(png_ptr, old_row, new_row); 7245f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott 725a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* 726a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * The rows and passes are called in order, so you don't really 727a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * need the row_num and pass, but I'm supplying them because it 728a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * may make your life easier. 729a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 730a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * For the non-NULL rows of interlaced images, you must call 731a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * png_progressive_combine_row() passing in the new row and the 732a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * old row, as demonstrated above. You can call this function for 733a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * NULL rows (it will just return) and for non-interlaced images 734ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * (it just does the memcpy for you) if it will make the code 735a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * easier. Thus, you can just do this for all cases: 736a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 737893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 738893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_progressive_combine_row(png_ptr, old_row, new_row); 739893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 740a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* where old_row is what was displayed for previous rows. Note 741a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * that the first pass (pass == 0 really) will completely cover 742a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the old row, so the rows do not have to be initialized. After 743a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the first pass (and only for interlaced images), you will have 744a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * to pass the current row as new_row, and the function will combine 745a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the old row and the new row. 746a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 747ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik#endif /* PNG_READ_INTERLACING_SUPPORTED */ 748893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 749893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 750893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectend_callback(png_structp png_ptr, png_infop info) 751893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 752a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* This function is called when the whole image has been read, 753a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * including any chunks after the image (up to and including 754a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the IEND). You will usually have the same info chunk as you 755a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * had in the header, although some data may have been added 756a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * to the comments and time fields. 757a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 758a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * Most people won't do much here, perhaps setting a flag that 759a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * marks the image as finished. 760a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 761893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 762893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 763a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott/* Write a png file */ 764893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectvoid write_png(char *file_name /* , ... other image information ... */) 765893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 766893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project FILE *fp; 767893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_structp png_ptr; 768893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_infop info_ptr; 769893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_colorp palette; 770893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 771a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Open the file */ 772893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fp = fopen(file_name, "wb"); 773893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (fp == NULL) 774893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 775893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 776893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Create and initialize the png_struct with the desired error handler 777893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * functions. If you want to use the default stderr and longjump method, 778893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you can supply NULL for the last three parameters. We also check that 779893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the library version is compatible with the one used at compile time, 780893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * in case we are using dynamically linked libraries. REQUIRED. 781893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 782893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, 783893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_voidp user_error_ptr, user_error_fn, user_warning_fn); 784893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 785893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_ptr == NULL) 786893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 787893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 788893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 789893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 790893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 791893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Allocate/initialize the image information data. REQUIRED */ 792893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project info_ptr = png_create_info_struct(png_ptr); 793893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (info_ptr == NULL) 794893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 795893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 796ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_destroy_write_struct(&png_ptr, NULL); 797893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 798893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 799893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 800893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Set error handling. REQUIRED if you aren't supplying your own 801893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * error handling functions in the png_create_write_struct() call. 802893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 803893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (setjmp(png_jmpbuf(png_ptr))) 804893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 805a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* If we get here, we had a problem writing the file */ 806893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 807893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_write_struct(&png_ptr, &info_ptr); 808893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 809893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 810893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 811893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* One of the following I/O initialization functions is REQUIRED */ 812a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 813893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef streams /* I/O initialization method 1 */ 814a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Set up the output control if you are using standard C streams */ 815893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_init_io(png_ptr, fp); 816a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 817893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_streams /* I/O initialization method 2 */ 8184215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project /* If you are using replacement write functions, instead of calling 819a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * png_init_io() here you would call 820a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 821893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn, 822893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project user_IO_flush_function); 823893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* where user_io_ptr is a structure you want available to the callbacks */ 824a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_streams /* Only use one initialization method */ 825893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 826893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef hilevel 827893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This is the easy way. Use it if you already have all the 828a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * image info living in the structure. You could "|" many 829893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * PNG_TRANSFORM flags into the png_transforms integer here. 830893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 831ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_write_png(png_ptr, info_ptr, png_transforms, NULL); 832a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 833893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else 834893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This is the hard way */ 835893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 836893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Set the image information here. Width and height are up to 2^31, 837893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on 838893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY, 839893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB, 840893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * or PNG_COLOR_TYPE_RGB_ALPHA. interlace is either PNG_INTERLACE_NONE or 841893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST 842893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED 843893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 844893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???, 845893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE); 846893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 847a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Set the palette if there is one. REQUIRED for indexed-color images */ 848893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH 849ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik * (sizeof (png_color))); 850a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* ... Set palette colors ... */ 851893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH); 852893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* You must not free palette here, because png_set_PLTE only makes a link to 853a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the palette that you malloced. Wait until you are about to destroy 854a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the png structure. 855a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 856893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 857a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Optional significant bit (sBIT) chunk */ 858a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott png_color_8 sig_bit; 859ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 860a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* If we are dealing with a grayscale image then */ 861893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project sig_bit.gray = true_bit_depth; 862ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 863a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Otherwise, if we are dealing with a color image then */ 864893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project sig_bit.red = true_red_bit_depth; 865893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project sig_bit.green = true_green_bit_depth; 866893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project sig_bit.blue = true_blue_bit_depth; 867ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 868a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* If the image has an alpha channel then */ 869893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project sig_bit.alpha = true_alpha_bit_depth; 870ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 871a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott png_set_sBIT(png_ptr, info_ptr, &sig_bit); 872893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 873893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 874893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Optional gamma chunk is strongly suggested if you have any guess 875893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * as to the correct gamma of the image. 876893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 877893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_gAMA(png_ptr, info_ptr, gamma); 878893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 879893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Optionally write comments into the image */ 880ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik { 881ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_text text_ptr[3]; 882ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 883ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik char key0[]="Title"; 884ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik char text0[]="Mona Lisa"; 885ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[0].key = key0; 886ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[0].text = text0; 887ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE; 888ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[0].itxt_length = 0; 889ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[0].lang = NULL; 890ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[0].lang_key = NULL; 891ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 892ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik char key1[]="Author"; 893ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik char text1[]="Leonardo DaVinci"; 894ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[1].key = key1; 895ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[1].text = text1; 896ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE; 897ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[1].itxt_length = 0; 898ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[1].lang = NULL; 899ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[1].lang_key = NULL; 900ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 901ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik char key2[]="Description"; 902ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik char text2[]="<long text>"; 903ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[2].key = key2; 904ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[2].text = text2; 905ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt; 906ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[2].itxt_length = 0; 907ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[2].lang = NULL; 908ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik text_ptr[2].lang_key = NULL; 909ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 910ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_set_text(write_ptr, write_info_ptr, text_ptr, 3); 911ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik } 912893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 913a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */ 914a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 915a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Note that if sRGB is present the gAMA and cHRM chunks must be ignored 916a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * on read and, if your application chooses to write them, they must 917a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * be written in accordance with the sRGB profile 918a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 919893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 920893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Write the file header information. REQUIRED */ 921893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_info(png_ptr, info_ptr); 922893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 923893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If you want, you can write the info in two steps, in case you need to 924893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * write your private chunk ahead of PLTE: 925893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 926893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * png_write_info_before_PLTE(write_ptr, write_info_ptr); 927893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * write_my_chunk(); 928893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * png_write_info(png_ptr, info_ptr); 929893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 930a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * However, given the level of known- and unknown-chunk support in 1.2.0 931893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * and up, this should no longer be necessary. 932893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 933893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 934893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Once we write out the header, the compression type on the text 935893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * chunks gets changed to PNG_TEXT_COMPRESSION_NONE_WR or 936893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again 937893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * at the end. 938893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 939893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 940a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Set up the transformations you want. Note that these are 941893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * all optional. Only call them if you want them. 942893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 943893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 944a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Invert monochrome pixels */ 945893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_invert_mono(png_ptr); 946893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 947893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Shift the pixels up to a legal bit depth and fill in 948893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * as appropriate to correctly scale the image. 949893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 950893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_shift(png_ptr, &sig_bit); 951893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 952a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Pack pixels into bytes */ 953893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_packing(png_ptr); 954893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 955a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Swap location of alpha bytes from ARGB to RGBA */ 956893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_swap_alpha(png_ptr); 957893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 958893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into 959893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * RGB (4 channels -> 3 channels). The second parameter is not used. 960893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 961893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE); 962893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 963a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Flip BGR pixels to RGB */ 964893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_bgr(png_ptr); 965893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 966a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Swap bytes of 16-bit files to most significant byte first */ 967893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_swap(png_ptr); 968893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 969a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Swap bits of 1, 2, 4 bit packed pixel formats */ 970893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_packswap(png_ptr); 971893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 972a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Turn on interlace handling if you are not using png_write_image() */ 973893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (interlacing) 974893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project number_passes = png_set_interlace_handling(png_ptr); 975ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 976893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else 977893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project number_passes = 1; 978893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 979893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The easiest way to write the image (you may have a different memory 980893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * layout, however, so choose what fits your needs best). You need to 981893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * use the first method if you aren't handling interlacing yourself. 982893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 983893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_uint_32 k, height, width; 984ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 985ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* In this example, "image" is a one-dimensional array of bytes */ 986ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik png_byte image[height*width*bytes_per_pixel]; 987ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik 988893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_bytep row_pointers[height]; 989893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 990ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik if (height > PNG_UINT_32_MAX/(sizeof (png_bytep))) 991893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_error (png_ptr, "Image is too tall to process in memory"); 992893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 993ca2bf81b02c99afa2e76b3b2c6eb232c239221e0Chris Craik /* Set up pointers into your "image" byte array */ 994893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (k = 0; k < height; k++) 995893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project row_pointers[k] = image + k*width*bytes_per_pixel; 996893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 997893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* One of the following output methods is REQUIRED */ 998a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 999a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#ifdef entire /* Write out the entire image data in one call */ 1000893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_image(png_ptr, row_pointers); 1001893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1002a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* The other way to write the image - deal with interlacing */ 1003a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 1004a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#else no_entire /* Write out the image data by one or more scanlines */ 1005893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1006893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The number of passes is either 1 for non-interlaced images, 1007893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * or 7 for interlaced images. 1008893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 1009893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (pass = 0; pass < number_passes; pass++) 1010893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 1011893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Write a few rows at a time. */ 1012893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows); 1013893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1014893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If you are only writing one row at a time, this works */ 1015893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (y = 0; y < height; y++) 1016893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_rows(png_ptr, &row_pointers[y], 1); 1017893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 1018a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_entire /* Use only one output method */ 1019893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1020893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* You can write optional chunks like tEXt, zTXt, and tIME at the end 1021a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * as well. Shouldn't be necessary in 1.2.0 and up as all the public 1022893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * chunks are supported and you can use png_set_unknown_chunks() to 1023893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * register unknown chunks into the info structure to be written out. 1024893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 1025893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1026893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* It is REQUIRED to call this to finish writing the rest of the file */ 1027893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_end(png_ptr, info_ptr); 1028893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif hilevel 1029893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1030893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If you png_malloced a palette, free it here (don't free info_ptr->palette, 1031a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * as recommended in versions 1.0.5m and earlier of this example; if 1032a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * libpng mallocs info_ptr->palette, libpng will free it). If you 1033a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * allocated it with malloc() instead of png_malloc(), use free() instead 1034a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * of png_free(). 1035a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 1036893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_free(png_ptr, palette); 10374215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project palette = NULL; 1038893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1039893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Similarly, if you png_malloced any data that you passed in with 1040a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * png_set_something(), such as a hist or trans array, free it here, 1041a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * when you can be sure that libpng is through with it. 1042a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 1043893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_free(png_ptr, trans); 10444215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project trans = NULL; 1045a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Whenever you use png_free() it is a good idea to set the pointer to 1046a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * NULL in case your application inadvertently tries to png_free() it 1047a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * again. When png_free() sees a NULL it returns without action, thus 1048a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * avoiding the double-free security problem. 1049a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 1050893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1051a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Clean up after the write, and free any memory allocated */ 1052893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_write_struct(&png_ptr, &info_ptr); 1053893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1054a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Close the file */ 1055893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 1056893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1057a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* That's it */ 1058893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (OK); 1059893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 1060893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 1061893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif /* if 0 */ 1062