example.c revision 5f6bd84e375226bf228fc8ac90318957ec9e1e7f
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 5a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * Last changed in libpng 1.2.37 [June 4, 2009] 6893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * This file has been placed in the public domain by the authors. 75f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott * Maintained 1998-2010 Glenn Randers-Pehrson 8893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * Maintained 1996, 1997 Andreas Dilger) 9893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) 10893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 11893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 12893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project/* This is an example of how to use libpng to read and write PNG files. 13893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * The file libpng.txt is much more verbose then this. If you have not 14893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * read it, do so first. This was designed to be a starting point of an 15893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * implementation. This is not officially part of libpng, is hereby placed 16893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * in the public domain, and therefore does not require a copyright notice. 17893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 18893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * This file does not currently compile, because it is missing certain 19893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * parts, like allocating memory to hold an image. You will have to 20893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * supply these parts to get it to compile. For an example of a minimal 21893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * working PNG reader/writer, see pngtest.c, included in this distribution; 22893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * see also the programs in the contrib directory. 23893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 24893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 25893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#include "png.h" 26893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 27893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The png_jmpbuf() macro, used in error handling, became available in 28893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * libpng version 1.0.6. If you want to be able to run your code with older 29893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * versions of libpng, you must define the macro yourself (but only if it 30893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * is not already defined by libpng!). 31893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 32893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 33893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifndef png_jmpbuf 34893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project# define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf) 35893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif 36893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 37893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project/* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp() 38893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * returns zero if the image is a PNG and nonzero if it isn't a PNG. 39893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 40893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * The function check_if_png() shown here, but not used, returns nonzero (true) 41893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * if the file can be opened and is a PNG, 0 (false) otherwise. 42893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 43893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * If this call is successful, and you are going to keep the file open, 44893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once 45893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you have created the png_ptr, so that libpng knows your application 46893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * has read that many bytes from the start of the file. Make sure you 47893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * don't call png_set_sig_bytes() with more than 8 bytes read or give it 48893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * an incorrect number of bytes read, or you will either have read too 49893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * many bytes (your fault), or you are telling libpng to read the wrong 50893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * number of magic bytes (also your fault). 51893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 52893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * Many applications already read the first 2 or 4 bytes from the start 53893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * of the image to determine the file type, so it would be easiest just 54893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * to pass the bytes to png_sig_cmp() or even skip that if you know 55893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you have a PNG file, and call png_set_sig_bytes(). 56893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 57893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#define PNG_BYTES_TO_CHECK 4 58893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectint check_if_png(char *file_name, FILE **fp) 59893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 60893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project char buf[PNG_BYTES_TO_CHECK]; 61893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 62893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Open the prospective PNG file. */ 63893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if ((*fp = fopen(file_name, "rb")) == NULL) 64893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return 0; 65893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 66893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Read in some of the signature bytes */ 67893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK) 68893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return 0; 69893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 70893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature. 71893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project Return nonzero (true) if they match */ 72893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 73893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK)); 74893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 75893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 76893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project/* Read a PNG file. You may want to return an error code if the read 77893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * fails (depending upon the failure). There are two "prototypes" given 78893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * here - one where we are given the filename, and we need to open the 79893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * file, and the other where we are given an open file (possibly with 80893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * some or all of the magic bytes read - see comments above). 81893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 82893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef open_file /* prototype 1 */ 83893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectvoid read_png(char *file_name) /* We need to open the file */ 84893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 85893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_structp png_ptr; 86893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_infop info_ptr; 87893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project unsigned int sig_read = 0; 88893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_uint_32 width, height; 89893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project int bit_depth, color_type, interlace_type; 90893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project FILE *fp; 91893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 92893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if ((fp = fopen(file_name, "rb")) == NULL) 93893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 94a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 95893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_open_file /* prototype 2 */ 96a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scottvoid read_png(FILE *fp, unsigned int sig_read) /* File is already open */ 97893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 98893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_structp png_ptr; 99893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_infop info_ptr; 100893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_uint_32 width, height; 101893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project int bit_depth, color_type, interlace_type; 102a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_open_file /* Only use one prototype! */ 103893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 104893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Create and initialize the png_struct with the desired error handler 105893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * functions. If you want to use the default stderr and longjump method, 106893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you can supply NULL for the last three parameters. We also supply the 107893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the compiler header file version, so that we know if the application 108893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * was compiled with a compatible version of the library. REQUIRED 109893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 110893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 111893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_voidp user_error_ptr, user_error_fn, user_warning_fn); 112893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 113893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_ptr == NULL) 114893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 115893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 116893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 117893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 118893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 119893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Allocate/initialize the memory for image information. REQUIRED. */ 120893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project info_ptr = png_create_info_struct(png_ptr); 121893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (info_ptr == NULL) 122893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 123893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 124893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_read_struct(&png_ptr, png_infopp_NULL, png_infopp_NULL); 125893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 126893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 127893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 128893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Set error handling if you are using the setjmp/longjmp method (this is 129893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the normal method of doing things with libpng). REQUIRED unless you 130893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * set up your own error handlers in the png_create_read_struct() earlier. 131893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 132893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 133893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (setjmp(png_jmpbuf(png_ptr))) 134893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 135893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Free all of the memory associated with the png_ptr and info_ptr */ 136893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL); 137893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 138893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If we get here, we had a problem reading the file */ 139893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 140893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 141893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 142893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* One of the following I/O initialization methods is REQUIRED */ 143893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef streams /* PNG file I/O method 1 */ 144893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Set up the input control if you are using standard C streams */ 145893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_init_io(png_ptr, fp); 146893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 147893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_streams /* PNG file I/O method 2 */ 148893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If you are using replacement read functions, instead of calling 149893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * png_init_io() here you would call: 150893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 151893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn); 152893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* where user_io_ptr is a structure you want available to the callbacks */ 153893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif no_streams /* Use only one I/O method! */ 154893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 155893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If we have already read some of the signature */ 156893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_sig_bytes(png_ptr, sig_read); 157893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 158893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef hilevel 159893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* 160893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * If you have enough memory to read in the entire image at once, 161893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * and you need to specify only transforms that can be controlled 162893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * with one of the PNG_TRANSFORM_* bits (this presently excludes 163893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * dithering, filling, setting background, and doing gamma 164893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * adjustment), then you can read the entire image (including 165893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * pixels) into the info structure with this call: 166893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 167893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_png(png_ptr, info_ptr, png_transforms, png_voidp_NULL); 168a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 169893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else 170893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* OK, you're doing it the hard way, with the lower-level functions */ 171893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 172893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The call to png_read_info() gives us all of the information from the 173893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * PNG file before the first IDAT (image data chunk). REQUIRED 174893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 175893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_info(png_ptr, info_ptr); 176893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 177893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, 178893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project &interlace_type, int_p_NULL, int_p_NULL); 179893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 180a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Set up the data transformations you want. Note that these are all 181a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * optional. Only call them if you want/need them. Many of the 182a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * transformations only work on specific types of images, and many 183a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * are mutually exclusive. 184a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 185893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 186a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Tell libpng to strip 16 bit/color files down to 8 bits/color */ 187893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_strip_16(png_ptr); 188893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 189893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Strip alpha bytes from the input data without combining with the 190893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * background (not recommended). 191893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 192893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_strip_alpha(png_ptr); 193893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 194893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single 195893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * byte into separate bytes (useful for paletted and grayscale images). 196893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 197893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_packing(png_ptr); 198893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 199893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Change the order of packed pixels to least significant bit first 200893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * (not useful if you are using png_set_packing). */ 201893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_packswap(png_ptr); 202893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 203893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Expand paletted colors into true RGB triplets */ 204893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (color_type == PNG_COLOR_TYPE_PALETTE) 205893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_palette_to_rgb(png_ptr); 206893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 207893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */ 208893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) 2094215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project png_set_expand_gray_1_2_4_to_8(png_ptr); 210893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 211893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Expand paletted or RGB images with transparency to full alpha channels 212893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * so the data will be available as RGBA quartets. 213893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 214893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) 215893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_tRNS_to_alpha(png_ptr); 216893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 217893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Set the background color to draw transparent and alpha images over. 218893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * It is possible to set the red, green, and blue components directly 219893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * for paletted images instead of supplying a palette index. Note that 220893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * even if the PNG file supplies a background, you are not required to 221893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * use it - you should use the (solid) application background if it has one. 222893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 223893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 224893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_color_16 my_background, *image_background; 225893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 226893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_get_bKGD(png_ptr, info_ptr, &image_background)) 227893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_background(png_ptr, image_background, 228893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project PNG_BACKGROUND_GAMMA_FILE, 1, 1.0); 229893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else 230893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_background(png_ptr, &my_background, 231893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0); 232893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 233a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Some suggestions as to how to get a screen gamma value 234a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 235a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * Note that screen gamma is the display_exponent, which includes 236a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the CRT_exponent and any correction for viewing conditions 237a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 238893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (/* We have a user-defined screen gamma value */) 239893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 240893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project screen_gamma = user-defined screen_gamma; 241893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 242893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This is one way that applications share the same screen gamma value */ 243893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL) 244893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 245893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project screen_gamma = atof(gamma_str); 246893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 247893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If we don't have another value */ 248893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else 249893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 250a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott screen_gamma = 2.2; /* A good guess for a PC monitor in a dimly 251893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project lit room */ 252893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project screen_gamma = 1.7 or 1.0; /* A good guess for Mac systems */ 253893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 254893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 255893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Tell libpng to handle the gamma conversion for you. The final call 256893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * is a good guess for PC generated images, but it should be configurable 257893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * by the user at run time by the user. It is strongly suggested that 258893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * your application support gamma correction. 259893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 260893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 261893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project int intent; 262893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 263893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_get_sRGB(png_ptr, info_ptr, &intent)) 264893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_gamma(png_ptr, screen_gamma, 0.45455); 265893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else 266893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 267893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project double image_gamma; 268893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_get_gAMA(png_ptr, info_ptr, &image_gamma)) 269893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_gamma(png_ptr, screen_gamma, image_gamma); 270893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else 271893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_gamma(png_ptr, screen_gamma, 0.45455); 272893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 273893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 274893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Dither RGB files down to 8 bit palette or reduce palettes 275893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * to the number of colors available on your screen. 276893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 277893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (color_type & PNG_COLOR_MASK_COLOR) 278893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 279893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project int num_palette; 280893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_colorp palette; 281893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 282893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This reduces the image to the application supplied palette */ 283a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott if (/* We have our own palette */) 284893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 285893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* An array of colors to which the image should be dithered */ 286893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_color std_color_cube[MAX_SCREEN_COLORS]; 287893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 288893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_dither(png_ptr, std_color_cube, MAX_SCREEN_COLORS, 289893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project MAX_SCREEN_COLORS, png_uint_16p_NULL, 0); 290893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 291893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This reduces the image to the palette supplied in the file */ 292893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette)) 293893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 294893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_uint_16p histogram = NULL; 295893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 296893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_get_hIST(png_ptr, info_ptr, &histogram); 297893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 298893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_dither(png_ptr, palette, num_palette, 299893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project max_screen_colors, histogram, 0); 300893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 301893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 302893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 303a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Invert monochrome files to have 0 as white and 1 as black */ 304893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_invert_mono(png_ptr); 305893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 306893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If you want to shift the pixel values from the range [0,255] or 307893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * [0,65535] to the original [0,7] or [0,31], or whatever range the 308893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * colors were originally in: 309893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 310893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT)) 311893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 312a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott png_color_8p sig_bit_p; 313893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 314a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott png_get_sBIT(png_ptr, info_ptr, &sig_bit_p); 315a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott png_set_shift(png_ptr, sig_bit_p); 316893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 317893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 318a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Flip the RGB pixels to BGR (or RGBA to BGRA) */ 319893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (color_type & PNG_COLOR_MASK_COLOR) 320893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_bgr(png_ptr); 321893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 322a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */ 323893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_swap_alpha(png_ptr); 324893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 325a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Swap bytes of 16 bit files to least significant byte first */ 326893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_swap(png_ptr); 327893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 328893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Add filler (or alpha) byte (before/after each RGB triplet) */ 329893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER); 330893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 331893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Turn on interlace handling. REQUIRED if you are not using 332893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * png_read_image(). To see how to handle interlacing passes, 333893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * see the png_read_row() method below: 334893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 335893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project number_passes = png_set_interlace_handling(png_ptr); 336893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 337893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Optional call to gamma correct and add the background to the palette 338893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * and update info structure. REQUIRED if you are expecting libpng to 339893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * update the palette for you (ie you selected such a transform above). 340893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 341893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_update_info(png_ptr, info_ptr); 342893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 343893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Allocate the memory to hold the image using the fields of info_ptr. */ 344893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 345893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The easiest way to read the image: */ 346893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_bytep row_pointers[height]; 347893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 3484215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project /* Clear the pointer array */ 3494215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project for (row = 0; row < height; row++) 3504215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project row_pointers[row] = NULL; 3514215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project 352893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (row = 0; row < height; row++) 353893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr, 354893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project info_ptr)); 355893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 356893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Now it's time to read the image. One of these methods is REQUIRED */ 357893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef entire /* Read the entire image in one go */ 358893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_image(png_ptr, row_pointers); 359893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 360893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_entire /* Read the image one or more scanlines at a time */ 361893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The other way to read images - deal with interlacing: */ 362893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 363893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (pass = 0; pass < number_passes; pass++) 364893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 365893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef single /* Read the image a single row at a time */ 366893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (y = 0; y < height; y++) 367893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 368893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_rows(png_ptr, &row_pointers[y], png_bytepp_NULL, 1); 369893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 370893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 371893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_single /* Read the image several rows at a time */ 372893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (y = 0; y < height; y += number_of_rows) 373893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 374893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef sparkle /* Read the image using the "sparkle" effect. */ 375893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_rows(png_ptr, &row_pointers[y], png_bytepp_NULL, 376893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project number_of_rows); 377893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_sparkle /* Read the image using the "rectangle" effect */ 378893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_rows(png_ptr, png_bytepp_NULL, &row_pointers[y], 379893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project number_of_rows); 380a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_sparkle /* Use only one of these two methods */ 381893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 382893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 383a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* If you want to display the image after every pass, do so here */ 384a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_single /* Use only one of these two methods */ 385893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 386a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_entire /* Use only one of these two methods */ 387893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 388a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */ 389893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_read_end(png_ptr, info_ptr); 390893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif hilevel 391893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 392893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* At this point you have read the entire image */ 393893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 394a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Clean up after the read, and free any memory allocated - REQUIRED */ 395893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL); 396893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 397a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Close the file */ 398893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 399893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 400a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* That's it */ 401893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (OK); 402893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 403893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 404a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott/* Progressively read a file */ 405893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 406893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectint 407893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectinitialize_png_reader(png_structp *png_ptr, png_infop *info_ptr) 408893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 409893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Create and initialize the png_struct with the desired error handler 410893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * functions. If you want to use the default stderr and longjump method, 411893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you can supply NULL for the last three parameters. We also check that 412893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the library version is compatible in case we are using dynamically 413893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * linked libraries. 414893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 415893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 416893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_voidp user_error_ptr, user_error_fn, user_warning_fn); 417893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 418893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (*png_ptr == NULL) 419893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 420893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project *info_ptr = NULL; 421893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 422893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 423893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 424893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project *info_ptr = png_create_info_struct(png_ptr); 425893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 426893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (*info_ptr == NULL) 427893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 428893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL); 429893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 430893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 431893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 432893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (setjmp(png_jmpbuf((*png_ptr)))) 433893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 434893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL); 435893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 436893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 437893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 438893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This one's new. You will need to provide all three 439893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * function callbacks, even if you aren't using them all. 440893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * If you aren't using all functions, you can specify NULL 441893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * parameters. Even when all three functions are NULL, 442893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you need to call png_set_progressive_read_fn(). 443893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * These functions shouldn't be dependent on global or 444893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * static variables if you are decoding several images 445893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * simultaneously. You should store stream specific data 446893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * in a separate struct, given as the second parameter, 447893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * and retrieve the pointer from inside the callbacks using 448893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the function png_get_progressive_ptr(png_ptr). 449893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 450893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_progressive_read_fn(*png_ptr, (void *)stream_data, 451893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project info_callback, row_callback, end_callback); 452893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 453893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (OK); 454893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 455893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 456893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectint 457893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectprocess_data(png_structp *png_ptr, png_infop *info_ptr, 458893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_bytep buffer, png_uint_32 length) 459893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 460893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (setjmp(png_jmpbuf((*png_ptr)))) 461893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 462893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Free the png_ptr and info_ptr memory on error */ 463893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL); 464893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 465893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 466893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 467893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This one's new also. Simply give it chunks of data as 468893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * they arrive from the data stream (in order, of course). 469a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * On segmented machines, don't give it any more than 64K. 470893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * The library seems to run fine with sizes of 4K, although 471893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you can give it much less if necessary (I assume you can 472893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * give it chunks of 1 byte, but I haven't tried with less 473893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * than 256 bytes yet). When this function returns, you may 474893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * want to display any rows that were generated in the row 475893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * callback, if you aren't already displaying them there. 476893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 477893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_process_data(*png_ptr, *info_ptr, buffer, length); 478893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (OK); 479893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 480893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 481893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectinfo_callback(png_structp png_ptr, png_infop info) 482893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 483a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Do any setup here, including setting any of the transformations 484a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * mentioned in the Reading PNG files section. For now, you _must_ 485a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * call either png_start_read_image() or png_read_update_info() 486a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * after all the transformations are set (even if you don't set 487a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * any). You may start getting rows before png_process_data() 488a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * returns, so this is your last chance to prepare for that. 489a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 490893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 491893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 492893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectrow_callback(png_structp png_ptr, png_bytep new_row, 493893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_uint_32 row_num, int pass) 494893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 495a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* 496a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * This function is called for every row in the image. If the 497a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * image is interlaced, and you turned on the interlace handler, 498a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * this function will be called for every row in every pass. 499a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 500a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * In this function you will receive a pointer to new row data from 501a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * libpng called new_row that is to replace a corresponding row (of 502a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the same data format) in a buffer allocated by your application. 503a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 504a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * The new row data pointer "new_row" may be NULL, indicating there is 505a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * no new data to be replaced (in cases of interlace loading). 506a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 507a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * If new_row is not NULL then you need to call 508a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * png_progressive_combine_row() to replace the corresponding row as 509a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * shown below: 510a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 511a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 5125f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott /* Get pointer to corresponding row in our 5135f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott * PNG read buffer. 5145f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott */ 5155f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott png_bytep old_row = ((png_bytep *)our_data)[row_num]; 5165f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott 5175f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott /* If both rows are allocated then copy the new row 5185f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott * data to the corresponding row data. 5195f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott */ 5205f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott if ((old_row != NULL) && (new_row != NULL)) 5215f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott png_progressive_combine_row(png_ptr, old_row, new_row); 5225f6bd84e375226bf228fc8ac90318957ec9e1e7fPatrick Scott 523a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* 524a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * The rows and passes are called in order, so you don't really 525a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * need the row_num and pass, but I'm supplying them because it 526a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * may make your life easier. 527a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 528a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * For the non-NULL rows of interlaced images, you must call 529a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * png_progressive_combine_row() passing in the new row and the 530a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * old row, as demonstrated above. You can call this function for 531a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * NULL rows (it will just return) and for non-interlaced images 532a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * (it just does the png_memcpy for you) if it will make the code 533a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * easier. Thus, you can just do this for all cases: 534a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 535893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 536893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_progressive_combine_row(png_ptr, old_row, new_row); 537893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 538a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* where old_row is what was displayed for previous rows. Note 539a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * that the first pass (pass == 0 really) will completely cover 540a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the old row, so the rows do not have to be initialized. After 541a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the first pass (and only for interlaced images), you will have 542a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * to pass the current row as new_row, and the function will combine 543a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the old row and the new row. 544a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 545893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 546893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 547893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectend_callback(png_structp png_ptr, png_infop info) 548893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 549a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* This function is called when the whole image has been read, 550a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * including any chunks after the image (up to and including 551a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the IEND). You will usually have the same info chunk as you 552a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * had in the header, although some data may have been added 553a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * to the comments and time fields. 554a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * 555a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * Most people won't do much here, perhaps setting a flag that 556a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * marks the image as finished. 557a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 558893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 559893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 560a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott/* Write a png file */ 561893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Projectvoid write_png(char *file_name /* , ... other image information ... */) 562893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project{ 563893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project FILE *fp; 564893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_structp png_ptr; 565893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_infop info_ptr; 566893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_colorp palette; 567893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 568a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Open the file */ 569893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fp = fopen(file_name, "wb"); 570893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (fp == NULL) 571893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 572893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 573893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Create and initialize the png_struct with the desired error handler 574893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * functions. If you want to use the default stderr and longjump method, 575893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * you can supply NULL for the last three parameters. We also check that 576893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the library version is compatible with the one used at compile time, 577893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * in case we are using dynamically linked libraries. REQUIRED. 578893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 579893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, 580893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_voidp user_error_ptr, user_error_fn, user_warning_fn); 581893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 582893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (png_ptr == NULL) 583893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 584893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 585893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 586893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 587893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 588893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Allocate/initialize the image information data. REQUIRED */ 589893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project info_ptr = png_create_info_struct(png_ptr); 590893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (info_ptr == NULL) 591893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 592893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 593893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_write_struct(&png_ptr, png_infopp_NULL); 594893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 595893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 596893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 597893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Set error handling. REQUIRED if you aren't supplying your own 598893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * error handling functions in the png_create_write_struct() call. 599893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 600893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (setjmp(png_jmpbuf(png_ptr))) 601893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 602a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* If we get here, we had a problem writing the file */ 603893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 604893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_write_struct(&png_ptr, &info_ptr); 605893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (ERROR); 606893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 607893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 608893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* One of the following I/O initialization functions is REQUIRED */ 609a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 610893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef streams /* I/O initialization method 1 */ 611a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Set up the output control if you are using standard C streams */ 612893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_init_io(png_ptr, fp); 613a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 614893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else no_streams /* I/O initialization method 2 */ 6154215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project /* If you are using replacement write functions, instead of calling 616a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * png_init_io() here you would call 617a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 618893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn, 619893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project user_IO_flush_function); 620893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* where user_io_ptr is a structure you want available to the callbacks */ 621a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_streams /* Only use one initialization method */ 622893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 623893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef hilevel 624893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This is the easy way. Use it if you already have all the 625a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * image info living in the structure. You could "|" many 626893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * PNG_TRANSFORM flags into the png_transforms integer here. 627893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 628893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_png(png_ptr, info_ptr, png_transforms, png_voidp_NULL); 629a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 630893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#else 631893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* This is the hard way */ 632893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 633893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Set the image information here. Width and height are up to 2^31, 634893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on 635893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY, 636893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB, 637893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * or PNG_COLOR_TYPE_RGB_ALPHA. interlace is either PNG_INTERLACE_NONE or 638893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST 639893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED 640893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 641893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???, 642893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE); 643893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 644a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Set the palette if there is one. REQUIRED for indexed-color images */ 645893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH 6464215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project * png_sizeof(png_color)); 647a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* ... Set palette colors ... */ 648893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH); 649893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* You must not free palette here, because png_set_PLTE only makes a link to 650a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the palette that you malloced. Wait until you are about to destroy 651a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * the png structure. 652a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 653893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 654a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Optional significant bit (sBIT) chunk */ 655a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott png_color_8 sig_bit; 656a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* If we are dealing with a grayscale image then */ 657893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project sig_bit.gray = true_bit_depth; 658a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Otherwise, if we are dealing with a color image then */ 659893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project sig_bit.red = true_red_bit_depth; 660893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project sig_bit.green = true_green_bit_depth; 661893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project sig_bit.blue = true_blue_bit_depth; 662a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* If the image has an alpha channel then */ 663893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project sig_bit.alpha = true_alpha_bit_depth; 664a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott png_set_sBIT(png_ptr, info_ptr, &sig_bit); 665893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 666893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 667893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Optional gamma chunk is strongly suggested if you have any guess 668893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * as to the correct gamma of the image. 669893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 670893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_gAMA(png_ptr, info_ptr, gamma); 671893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 672893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Optionally write comments into the image */ 673893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[0].key = "Title"; 674893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[0].text = "Mona Lisa"; 675893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE; 676893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[1].key = "Author"; 677893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[1].text = "Leonardo DaVinci"; 678893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE; 679893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[2].key = "Description"; 680893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[2].text = "<long text>"; 681893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt; 682893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#ifdef PNG_iTXt_SUPPORTED 683893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[0].lang = NULL; 684893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[1].lang = NULL; 685893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project text_ptr[2].lang = NULL; 686893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif 687893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_text(png_ptr, info_ptr, text_ptr, 3); 688893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 689a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */ 690a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 691a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Note that if sRGB is present the gAMA and cHRM chunks must be ignored 692a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * on read and, if your application chooses to write them, they must 693a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * be written in accordance with the sRGB profile 694a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 695893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 696893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Write the file header information. REQUIRED */ 697893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_info(png_ptr, info_ptr); 698893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 699893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If you want, you can write the info in two steps, in case you need to 700893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * write your private chunk ahead of PLTE: 701893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 702893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * png_write_info_before_PLTE(write_ptr, write_info_ptr); 703893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * write_my_chunk(); 704893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * png_write_info(png_ptr, info_ptr); 705893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * 706a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * However, given the level of known- and unknown-chunk support in 1.2.0 707893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * and up, this should no longer be necessary. 708893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 709893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 710893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Once we write out the header, the compression type on the text 711893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * chunks gets changed to PNG_TEXT_COMPRESSION_NONE_WR or 712893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again 713893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * at the end. 714893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 715893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 716a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Set up the transformations you want. Note that these are 717893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * all optional. Only call them if you want them. 718893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 719893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 720a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Invert monochrome pixels */ 721893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_invert_mono(png_ptr); 722893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 723893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Shift the pixels up to a legal bit depth and fill in 724893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * as appropriate to correctly scale the image. 725893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 726893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_shift(png_ptr, &sig_bit); 727893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 728a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Pack pixels into bytes */ 729893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_packing(png_ptr); 730893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 731a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Swap location of alpha bytes from ARGB to RGBA */ 732893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_swap_alpha(png_ptr); 733893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 734893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into 735893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * RGB (4 channels -> 3 channels). The second parameter is not used. 736893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 737893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE); 738893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 739a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Flip BGR pixels to RGB */ 740893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_bgr(png_ptr); 741893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 742a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Swap bytes of 16-bit files to most significant byte first */ 743893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_swap(png_ptr); 744893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 745a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Swap bits of 1, 2, 4 bit packed pixel formats */ 746893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_set_packswap(png_ptr); 747893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 748a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Turn on interlace handling if you are not using png_write_image() */ 749893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (interlacing) 750893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project number_passes = png_set_interlace_handling(png_ptr); 751893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project else 752893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project number_passes = 1; 753893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 754893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The easiest way to write the image (you may have a different memory 755893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * layout, however, so choose what fits your needs best). You need to 756893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * use the first method if you aren't handling interlacing yourself. 757893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 758893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_uint_32 k, height, width; 759893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_byte image[height][width*bytes_per_pixel]; 760893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_bytep row_pointers[height]; 761893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 762893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project if (height > PNG_UINT_32_MAX/png_sizeof(png_bytep)) 763893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_error (png_ptr, "Image is too tall to process in memory"); 764893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 765893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (k = 0; k < height; k++) 766893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project row_pointers[k] = image + k*width*bytes_per_pixel; 767893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 768893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* One of the following output methods is REQUIRED */ 769a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 770a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#ifdef entire /* Write out the entire image data in one call */ 771893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_image(png_ptr, row_pointers); 772893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 773a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* The other way to write the image - deal with interlacing */ 774a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott 775a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#else no_entire /* Write out the image data by one or more scanlines */ 776893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 777893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* The number of passes is either 1 for non-interlaced images, 778893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * or 7 for interlaced images. 779893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 780893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (pass = 0; pass < number_passes; pass++) 781893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project { 782893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Write a few rows at a time. */ 783893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows); 784893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 785893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If you are only writing one row at a time, this works */ 786893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project for (y = 0; y < height; y++) 787893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_rows(png_ptr, &row_pointers[y], 1); 788893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project } 789a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott#endif no_entire /* Use only one output method */ 790893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 791893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* You can write optional chunks like tEXt, zTXt, and tIME at the end 792a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * as well. Shouldn't be necessary in 1.2.0 and up as all the public 793893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * chunks are supported and you can use png_set_unknown_chunks() to 794893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project * register unknown chunks into the info structure to be written out. 795893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project */ 796893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 797893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* It is REQUIRED to call this to finish writing the rest of the file */ 798893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_write_end(png_ptr, info_ptr); 799893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif hilevel 800893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 801893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* If you png_malloced a palette, free it here (don't free info_ptr->palette, 802a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * as recommended in versions 1.0.5m and earlier of this example; if 803a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * libpng mallocs info_ptr->palette, libpng will free it). If you 804a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * allocated it with malloc() instead of png_malloc(), use free() instead 805a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * of png_free(). 806a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 807893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_free(png_ptr, palette); 8084215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project palette = NULL; 809893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 810893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project /* Similarly, if you png_malloced any data that you passed in with 811a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * png_set_something(), such as a hist or trans array, free it here, 812a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * when you can be sure that libpng is through with it. 813a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 814893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_free(png_ptr, trans); 8154215dd1533c56e1a89ae6f1d6ea68677fac27fdaThe Android Open Source Project trans = NULL; 816a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Whenever you use png_free() it is a good idea to set the pointer to 817a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * NULL in case your application inadvertently tries to png_free() it 818a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * again. When png_free() sees a NULL it returns without action, thus 819a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott * avoiding the double-free security problem. 820a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott */ 821893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 822a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Clean up after the write, and free any memory allocated */ 823893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project png_destroy_write_struct(&png_ptr, &info_ptr); 824893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 825a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* Close the file */ 826893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project fclose(fp); 827893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 828a0bb96c34e65378853ee518bac502842d26c2d1aPatrick Scott /* That's it */ 829893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project return (OK); 830893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project} 831893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project 832893912bfc2683463dc3e2c445336752d012563d3The Android Open Source Project#endif /* if 0 */ 833