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: [email protected] (Somnath Banerjee) 13 14 #ifndef WEBP_DEC_WEBPI_DEC_H_ 15 #define WEBP_DEC_WEBPI_DEC_H_ 16 17 #ifdef __cplusplus 18 extern "C" { 19 #endif 20 21 #include "src/utils/rescaler_utils.h" 22 #include "src/dec/vp8_dec.h" 23 #include "src/webp/decode.h" 24 25 //------------------------------------------------------------------------------ 26 // WebPDecParams: Decoding output parameters. Transient internal object. 27 28 typedef struct WebPDecParams WebPDecParams; 29 typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p); 30 typedef int (*OutputAlphaFunc)(const VP8Io* const io, WebPDecParams* const p, 31 int expected_num_out_lines); 32 typedef int (*OutputRowFunc)(WebPDecParams* const p, int y_pos, 33 int max_out_lines); 34 35 struct WebPDecParams { 36 WebPDecBuffer* output; // output buffer. 37 uint8_t* tmp_y, *tmp_u, *tmp_v; // cache for the fancy upsampler 38 // or used for tmp rescaling 39 40 int last_y; // coordinate of the line that was last output 41 const WebPDecoderOptions* options; // if not NULL, use alt decoding features 42 43 WebPRescaler* scaler_y, *scaler_u, *scaler_v, *scaler_a; // rescalers 44 void* memory; // overall scratch memory for the output work. 45 46 OutputFunc emit; // output RGB or YUV samples 47 OutputAlphaFunc emit_alpha; // output alpha channel 48 OutputRowFunc emit_alpha_row; // output one line of rescaled alpha values 49 }; 50 51 // Should be called first, before any use of the WebPDecParams object. 52 void WebPResetDecParams(WebPDecParams* const params); 53 54 //------------------------------------------------------------------------------ 55 // Header parsing helpers 56 57 // Structure storing a description of the RIFF headers. 58 typedef struct { 59 const uint8_t* data; // input buffer 60 size_t data_size; // input buffer size 61 int have_all_data; // true if all data is known to be available 62 size_t offset; // offset to main data chunk (VP8 or VP8L) 63 const uint8_t* alpha_data; // points to alpha chunk (if present) 64 size_t alpha_data_size; // alpha chunk size 65 size_t compressed_size; // VP8/VP8L compressed data size 66 size_t riff_size; // size of the riff payload (or 0 if absent) 67 int is_lossless; // true if a VP8L chunk is present 68 } WebPHeaderStructure; 69 70 // Skips over all valid chunks prior to the first VP8/VP8L frame header. 71 // Returns: VP8_STATUS_OK, VP8_STATUS_BITSTREAM_ERROR (invalid header/chunk), 72 // VP8_STATUS_NOT_ENOUGH_DATA (partial input) or VP8_STATUS_UNSUPPORTED_FEATURE 73 // in the case of non-decodable features (animation for instance). 74 // In 'headers', compressed_size, offset, alpha_data, alpha_size, and lossless 75 // fields are updated appropriately upon success. 76 VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers); 77 78 //------------------------------------------------------------------------------ 79 // Misc utils 80 81 // Returns true if crop dimensions are within image bounds. 82 int WebPCheckCropDimensions(int image_width, int image_height, 83 int x, int y, int w, int h); 84 85 // Initializes VP8Io with custom setup, io and teardown functions. The default 86 // hooks will use the supplied 'params' as io->opaque handle. 87 void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io); 88 89 // Setup crop_xxx fields, mb_w and mb_h in io. 'src_colorspace' refers 90 // to the *compressed* format, not the output one. 91 WEBP_NODISCARD int WebPIoInitFromOptions( 92 const WebPDecoderOptions* const options, VP8Io* const io, 93 WEBP_CSP_MODE src_colorspace); 94 95 //------------------------------------------------------------------------------ 96 // Internal functions regarding WebPDecBuffer memory (in buffer.c). 97 // Don't really need to be externally visible for now. 98 99 // Prepare 'buffer' with the requested initial dimensions width/height. 100 // If no external storage is supplied, initializes buffer by allocating output 101 // memory and setting up the stride information. Validate the parameters. Return 102 // an error code in case of problem (no memory, or invalid stride / size / 103 // dimension / etc.). If *options is not NULL, also verify that the options' 104 // parameters are valid and apply them to the width/height dimensions of the 105 // output buffer. This takes cropping / scaling / rotation into account. 106 // Also incorporates the options->flip flag to flip the buffer parameters if 107 // needed. 108 VP8StatusCode WebPAllocateDecBuffer(int width, int height, 109 const WebPDecoderOptions* const options, 110 WebPDecBuffer* const buffer); 111 112 // Flip buffer vertically by negating the various strides. 113 VP8StatusCode WebPFlipBuffer(WebPDecBuffer* const buffer); 114 115 // Copy 'src' into 'dst' buffer, making sure 'dst' is not marked as owner of the 116 // memory (still held by 'src'). No pixels are copied. 117 void WebPCopyDecBuffer(const WebPDecBuffer* const src, 118 WebPDecBuffer* const dst); 119 120 // Copy and transfer ownership from src to dst (beware of parameter order!) 121 void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst); 122 123 // Copy pixels from 'src' into a *preallocated* 'dst' buffer. Returns 124 // VP8_STATUS_INVALID_PARAM if the 'dst' is not set up correctly for the copy. 125 VP8StatusCode WebPCopyDecBufferPixels(const WebPDecBuffer* const src, 126 WebPDecBuffer* const dst); 127 128 // Returns true if decoding will be slow with the current configuration 129 // and bitstream features. 130 int WebPAvoidSlowMemory(const WebPDecBuffer* const output, 131 const WebPBitstreamFeatures* const features); 132 133 //------------------------------------------------------------------------------ 134 135 #ifdef __cplusplus 136 } // extern "C" 137 #endif 138 139 #endif // WEBP_DEC_WEBPI_DEC_H_ 140