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Diffstat (limited to 'media/libwebp/src/dec/webpi_dec.h')
| -rw-r--r-- | media/libwebp/src/dec/webpi_dec.h | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/media/libwebp/src/dec/webpi_dec.h b/media/libwebp/src/dec/webpi_dec.h new file mode 100644 index 0000000000..3b97388c71 --- /dev/null +++ b/media/libwebp/src/dec/webpi_dec.h @@ -0,0 +1,137 @@ +// Copyright 2011 Google Inc. All Rights Reserved. +// +// Use of this source code is governed by a BSD-style license +// that can be found in the COPYING file in the root of the source +// tree. An additional intellectual property rights grant can be found +// in the file PATENTS. All contributing project authors may +// be found in the AUTHORS file in the root of the source tree. +// ----------------------------------------------------------------------------- +// +// Internal header: WebP decoding parameters and custom IO on buffer +// +// Author: somnath@google.com (Somnath Banerjee) + +#ifndef WEBP_DEC_WEBPI_DEC_H_ +#define WEBP_DEC_WEBPI_DEC_H_ + +#ifdef __cplusplus +extern "C" { +#endif + +#include "src/utils/rescaler_utils.h" +#include "src/dec/vp8_dec.h" + +//------------------------------------------------------------------------------ +// WebPDecParams: Decoding output parameters. Transient internal object. + +typedef struct WebPDecParams WebPDecParams; +typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p); +typedef int (*OutputAlphaFunc)(const VP8Io* const io, WebPDecParams* const p, + int expected_num_out_lines); +typedef int (*OutputRowFunc)(WebPDecParams* const p, int y_pos, + int max_out_lines); + +struct WebPDecParams { + WebPDecBuffer* output; // output buffer. + uint8_t* tmp_y, *tmp_u, *tmp_v; // cache for the fancy upsampler + // or used for tmp rescaling + + int last_y; // coordinate of the line that was last output + const WebPDecoderOptions* options; // if not NULL, use alt decoding features + + WebPRescaler* scaler_y, *scaler_u, *scaler_v, *scaler_a; // rescalers + void* memory; // overall scratch memory for the output work. + + OutputFunc emit; // output RGB or YUV samples + OutputAlphaFunc emit_alpha; // output alpha channel + OutputRowFunc emit_alpha_row; // output one line of rescaled alpha values +}; + +// Should be called first, before any use of the WebPDecParams object. +void WebPResetDecParams(WebPDecParams* const params); + +//------------------------------------------------------------------------------ +// Header parsing helpers + +// Structure storing a description of the RIFF headers. +typedef struct { + const uint8_t* data; // input buffer + size_t data_size; // input buffer size + int have_all_data; // true if all data is known to be available + size_t offset; // offset to main data chunk (VP8 or VP8L) + const uint8_t* alpha_data; // points to alpha chunk (if present) + size_t alpha_data_size; // alpha chunk size + size_t compressed_size; // VP8/VP8L compressed data size + size_t riff_size; // size of the riff payload (or 0 if absent) + int is_lossless; // true if a VP8L chunk is present +} WebPHeaderStructure; + +// Skips over all valid chunks prior to the first VP8/VP8L frame header. +// Returns: VP8_STATUS_OK, VP8_STATUS_BITSTREAM_ERROR (invalid header/chunk), +// VP8_STATUS_NOT_ENOUGH_DATA (partial input) or VP8_STATUS_UNSUPPORTED_FEATURE +// in the case of non-decodable features (animation for instance). +// In 'headers', compressed_size, offset, alpha_data, alpha_size, and lossless +// fields are updated appropriately upon success. +VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers); + +//------------------------------------------------------------------------------ +// Misc utils + +// Returns true if crop dimensions are within image bounds. +int WebPCheckCropDimensions(int image_width, int image_height, + int x, int y, int w, int h); + +// Initializes VP8Io with custom setup, io and teardown functions. The default +// hooks will use the supplied 'params' as io->opaque handle. +void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io); + +// Setup crop_xxx fields, mb_w and mb_h in io. 'src_colorspace' refers +// to the *compressed* format, not the output one. +int WebPIoInitFromOptions(const WebPDecoderOptions* const options, + VP8Io* const io, WEBP_CSP_MODE src_colorspace); + +//------------------------------------------------------------------------------ +// Internal functions regarding WebPDecBuffer memory (in buffer.c). +// Don't really need to be externally visible for now. + +// Prepare 'buffer' with the requested initial dimensions width/height. +// If no external storage is supplied, initializes buffer by allocating output +// memory and setting up the stride information. Validate the parameters. Return +// an error code in case of problem (no memory, or invalid stride / size / +// dimension / etc.). If *options is not NULL, also verify that the options' +// parameters are valid and apply them to the width/height dimensions of the +// output buffer. This takes cropping / scaling / rotation into account. +// Also incorporates the options->flip flag to flip the buffer parameters if +// needed. +VP8StatusCode WebPAllocateDecBuffer(int width, int height, + const WebPDecoderOptions* const options, + WebPDecBuffer* const buffer); + +// Flip buffer vertically by negating the various strides. +VP8StatusCode WebPFlipBuffer(WebPDecBuffer* const buffer); + +// Copy 'src' into 'dst' buffer, making sure 'dst' is not marked as owner of the +// memory (still held by 'src'). No pixels are copied. +void WebPCopyDecBuffer(const WebPDecBuffer* const src, + WebPDecBuffer* const dst); + +// Copy and transfer ownership from src to dst (beware of parameter order!) +void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst); + +// Copy pixels from 'src' into a *preallocated* 'dst' buffer. Returns +// VP8_STATUS_INVALID_PARAM if the 'dst' is not set up correctly for the copy. +VP8StatusCode WebPCopyDecBufferPixels(const WebPDecBuffer* const src, + WebPDecBuffer* const dst); + +// Returns true if decoding will be slow with the current configuration +// and bitstream features. +int WebPAvoidSlowMemory(const WebPDecBuffer* const output, + const WebPBitstreamFeatures* const features); + +//------------------------------------------------------------------------------ + +#ifdef __cplusplus +} // extern "C" +#endif + +#endif // WEBP_DEC_WEBPI_DEC_H_ |