1// Copyright 2011 Google Inc. All Rights Reserved. 2// 3// Use of this source code is governed by a BSD-style license 4// that can be found in the COPYING file in the root of the source 5// tree. An additional intellectual property rights grant can be found 6// in the file PATENTS. All contributing project authors may 7// be found in the AUTHORS file in the root of the source tree. 8// ----------------------------------------------------------------------------- 9// 10// Internal header: WebP decoding parameters and custom IO on buffer 11// 12// Author: somnath@google.com (Somnath Banerjee) 13 14#ifndef WEBP_DEC_WEBPI_H_ 15#define WEBP_DEC_WEBPI_H_ 16 17#ifdef __cplusplus 18extern "C" { 19#endif 20 21#include "../utils/rescaler.h" 22#include "./decode_vp8.h" 23 24//------------------------------------------------------------------------------ 25// WebPDecParams: Decoding output parameters. Transient internal object. 26 27typedef struct WebPDecParams WebPDecParams; 28typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p); 29typedef int (*OutputRowFunc)(WebPDecParams* const p, int y_pos); 30 31struct WebPDecParams { 32 WebPDecBuffer* output; // output buffer. 33 uint8_t* tmp_y, *tmp_u, *tmp_v; // cache for the fancy upsampler 34 // or used for tmp rescaling 35 36 int last_y; // coordinate of the line that was last output 37 const WebPDecoderOptions* options; // if not NULL, use alt decoding features 38 // rescalers 39 WebPRescaler scaler_y, scaler_u, scaler_v, scaler_a; 40 void* memory; // overall scratch memory for the output work. 41 42 OutputFunc emit; // output RGB or YUV samples 43 OutputFunc emit_alpha; // output alpha channel 44 OutputRowFunc emit_alpha_row; // output one line of rescaled alpha values 45}; 46 47// Should be called first, before any use of the WebPDecParams object. 48void WebPResetDecParams(WebPDecParams* const params); 49 50//------------------------------------------------------------------------------ 51// Header parsing helpers 52 53// Structure storing a description of the RIFF headers. 54typedef struct { 55 const uint8_t* data; // input buffer 56 size_t data_size; // input buffer size 57 int have_all_data; // true if all data is known to be available 58 size_t offset; // offset to main data chunk (VP8 or VP8L) 59 const uint8_t* alpha_data; // points to alpha chunk (if present) 60 size_t alpha_data_size; // alpha chunk size 61 size_t compressed_size; // VP8/VP8L compressed data size 62 size_t riff_size; // size of the riff payload (or 0 if absent) 63 int is_lossless; // true if a VP8L chunk is present 64} WebPHeaderStructure; 65 66// Skips over all valid chunks prior to the first VP8/VP8L frame header. 67// Returns: VP8_STATUS_OK, VP8_STATUS_BITSTREAM_ERROR (invalid header/chunk), 68// VP8_STATUS_NOT_ENOUGH_DATA (partial input) or VP8_STATUS_UNSUPPORTED_FEATURE 69// in the case of non-decodable features (animation for instance). 70// In 'headers', compressed_size, offset, alpha_data, alpha_size, and lossless 71// fields are updated appropriately upon success. 72VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers); 73 74//------------------------------------------------------------------------------ 75// Misc utils 76 77// Initializes VP8Io with custom setup, io and teardown functions. The default 78// hooks will use the supplied 'params' as io->opaque handle. 79void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io); 80 81// Setup crop_xxx fields, mb_w and mb_h in io. 'src_colorspace' refers 82// to the *compressed* format, not the output one. 83int WebPIoInitFromOptions(const WebPDecoderOptions* const options, 84 VP8Io* const io, WEBP_CSP_MODE src_colorspace); 85 86//------------------------------------------------------------------------------ 87// Internal functions regarding WebPDecBuffer memory (in buffer.c). 88// Don't really need to be externally visible for now. 89 90// Prepare 'buffer' with the requested initial dimensions width/height. 91// If no external storage is supplied, initializes buffer by allocating output 92// memory and setting up the stride information. Validate the parameters. Return 93// an error code in case of problem (no memory, or invalid stride / size / 94// dimension / etc.). If *options is not NULL, also verify that the options' 95// parameters are valid and apply them to the width/height dimensions of the 96// output buffer. This takes cropping / scaling / rotation into account. 97// Also incorporates the options->flip flag to flip the buffer parameters if 98// needed. 99VP8StatusCode WebPAllocateDecBuffer(int width, int height, 100 const WebPDecoderOptions* const options, 101 WebPDecBuffer* const buffer); 102 103// Flip buffer vertically by negating the various strides. 104VP8StatusCode WebPFlipBuffer(WebPDecBuffer* const buffer); 105 106// Copy 'src' into 'dst' buffer, making sure 'dst' is not marked as owner of the 107// memory (still held by 'src'). 108void WebPCopyDecBuffer(const WebPDecBuffer* const src, 109 WebPDecBuffer* const dst); 110 111// Copy and transfer ownership from src to dst (beware of parameter order!) 112void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst); 113 114//------------------------------------------------------------------------------ 115 116#ifdef __cplusplus 117} // extern "C" 118#endif 119 120#endif /* WEBP_DEC_WEBPI_H_ */ 121