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Diffstat (limited to 'drivers/webpold/mux.h')
| -rw-r--r-- | drivers/webpold/mux.h | 604 |
1 files changed, 604 insertions, 0 deletions
diff --git a/drivers/webpold/mux.h b/drivers/webpold/mux.h new file mode 100644 index 0000000000..5139af80fa --- /dev/null +++ b/drivers/webpold/mux.h @@ -0,0 +1,604 @@ +// Copyright 2011 Google Inc. All Rights Reserved. +// +// This code is licensed under the same terms as WebM: +// Software License Agreement: http://www.webmproject.org/license/software/ +// Additional IP Rights Grant: http://www.webmproject.org/license/additional/ +// ----------------------------------------------------------------------------- +// +// RIFF container manipulation for WEBP images. +// +// Authors: Urvang (urvang@google.com) +// Vikas (vikasa@google.com) + +// This API allows manipulation of WebP container images containing features +// like Color profile, XMP metadata, Animation and Tiling. +// +// Code Example#1: Creating a MUX with image data, color profile and XMP +// metadata. +// +// int copy_data = 0; +// WebPMux* mux = WebPMuxNew(); +// // ... (Prepare image data). +// WebPMuxSetImage(mux, &image, copy_data); +// // ... (Prepare ICCP color profile data). +// WebPMuxSetColorProfile(mux, &icc_profile, copy_data); +// // ... (Prepare XMP metadata). +// WebPMuxSetMetadata(mux, &xmp, copy_data); +// // Get data from mux in WebP RIFF format. +// WebPMuxAssemble(mux, &output_data); +// WebPMuxDelete(mux); +// // ... (Consume output_data; e.g. write output_data.bytes_ to file). +// WebPDataClear(&output_data); +// +// Code Example#2: Get image and color profile data from a WebP file. +// +// int copy_data = 0; +// // ... (Read data from file). +// WebPMux* mux = WebPMuxCreate(&data, copy_data); +// WebPMuxGetImage(mux, &image); +// // ... (Consume image; e.g. call WebPDecode() to decode the data). +// WebPMuxGetColorProfile(mux, &icc_profile); +// // ... (Consume icc_data). +// WebPMuxDelete(mux); +// free(data); + +#ifndef WEBP_WEBP_MUX_H_ +#define WEBP_WEBP_MUX_H_ + +#include "./types.h" + +#if defined(__cplusplus) || defined(c_plusplus) +extern "C" { +#endif + +#define WEBP_MUX_ABI_VERSION 0x0100 // MAJOR(8b) + MINOR(8b) + +// Error codes +typedef enum { + WEBP_MUX_OK = 1, + WEBP_MUX_NOT_FOUND = 0, + WEBP_MUX_INVALID_ARGUMENT = -1, + WEBP_MUX_BAD_DATA = -2, + WEBP_MUX_MEMORY_ERROR = -3, + WEBP_MUX_NOT_ENOUGH_DATA = -4 +} WebPMuxError; + +// Flag values for different features used in VP8X chunk. +typedef enum { + TILE_FLAG = 0x00000001, + ANIMATION_FLAG = 0x00000002, + ICCP_FLAG = 0x00000004, + META_FLAG = 0x00000008, + ALPHA_FLAG = 0x00000010 +} WebPFeatureFlags; + +// IDs for different types of chunks. +typedef enum { + WEBP_CHUNK_VP8X, // VP8X + WEBP_CHUNK_ICCP, // ICCP + WEBP_CHUNK_LOOP, // LOOP + WEBP_CHUNK_FRAME, // FRM + WEBP_CHUNK_TILE, // TILE + WEBP_CHUNK_ALPHA, // ALPH + WEBP_CHUNK_IMAGE, // VP8/VP8L + WEBP_CHUNK_META, // META + WEBP_CHUNK_UNKNOWN, // Other chunks. + WEBP_CHUNK_NIL +} WebPChunkId; + +typedef struct WebPMux WebPMux; // main opaque object. + +// Data type used to describe 'raw' data, e.g., chunk data +// (ICC profile, metadata) and WebP compressed image data. +typedef struct { + const uint8_t* bytes_; + size_t size_; +} WebPData; + +//------------------------------------------------------------------------------ +// Manipulation of a WebPData object. + +// Initializes the contents of the 'webp_data' object with default values. +WEBP_EXTERN(void) WebPDataInit(WebPData* webp_data); + +// Clears the contents of the 'webp_data' object by calling free(). Does not +// deallocate the object itself. +WEBP_EXTERN(void) WebPDataClear(WebPData* webp_data); + +// Allocates necessary storage for 'dst' and copies the contents of 'src'. +// Returns true on success. +WEBP_EXTERN(int) WebPDataCopy(const WebPData* src, WebPData* dst); + +//------------------------------------------------------------------------------ +// Life of a Mux object + +// Internal, version-checked, entry point +WEBP_EXTERN(WebPMux*) WebPNewInternal(int); + +// Creates an empty mux object. +// Returns: +// A pointer to the newly created empty mux object. +static WEBP_INLINE WebPMux* WebPMuxNew(void) { + return WebPNewInternal(WEBP_MUX_ABI_VERSION); +} + +// Deletes the mux object. +// Parameters: +// mux - (in/out) object to be deleted +WEBP_EXTERN(void) WebPMuxDelete(WebPMux* mux); + +//------------------------------------------------------------------------------ +// Mux creation. + +// Internal, version-checked, entry point +WEBP_EXTERN(WebPMux*) WebPMuxCreateInternal(const WebPData*, int, int); + +// Creates a mux object from raw data given in WebP RIFF format. +// Parameters: +// bitstream - (in) the bitstream data in WebP RIFF format +// copy_data - (in) value 1 indicates given data WILL copied to the mux, and +// value 0 indicates data will NOT be copied. +// Returns: +// A pointer to the mux object created from given data - on success. +// NULL - In case of invalid data or memory error. +static WEBP_INLINE WebPMux* WebPMuxCreate(const WebPData* bitstream, + int copy_data) { + return WebPMuxCreateInternal(bitstream, copy_data, WEBP_MUX_ABI_VERSION); +} + +//------------------------------------------------------------------------------ +// Single Image. + +// Sets the image in the mux object. Any existing images (including frame/tile) +// will be removed. +// Parameters: +// mux - (in/out) object in which the image is to be set +// bitstream - (in) can either be a raw VP8/VP8L bitstream or a single-image +// WebP file (non-animated and non-tiled) +// copy_data - (in) value 1 indicates given data WILL copied to the mux, and +// value 0 indicates data will NOT be copied. +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux is NULL or bitstream is NULL. +// WEBP_MUX_MEMORY_ERROR - on memory allocation error. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxSetImage(WebPMux* mux, + const WebPData* bitstream, + int copy_data); + +// Gets image data from the mux object. +// The content of 'bitstream' is allocated using malloc(), and NOT +// owned by the 'mux' object. It MUST be deallocated by the caller by calling +// WebPDataClear(). +// Parameters: +// mux - (in) object from which the image is to be fetched +// bitstream - (out) the image data +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if either mux or bitstream is NULL +// OR mux contains animation/tiling. +// WEBP_MUX_NOT_FOUND - if image is not present in mux object. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxGetImage(const WebPMux* mux, + WebPData* bitstream); + +// Deletes the image in the mux object. +// Parameters: +// mux - (in/out) object from which the image is to be deleted +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux is NULL +// OR if mux contains animation/tiling. +// WEBP_MUX_NOT_FOUND - if image is not present in mux object. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxDeleteImage(WebPMux* mux); + +//------------------------------------------------------------------------------ +// XMP Metadata. + +// Sets the XMP metadata in the mux object. Any existing metadata chunk(s) will +// be removed. +// Parameters: +// mux - (in/out) object to which the XMP metadata is to be added +// metadata - (in) the XMP metadata data to be added +// copy_data - (in) value 1 indicates given data WILL copied to the mux, and +// value 0 indicates data will NOT be copied. +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux or metadata is NULL. +// WEBP_MUX_MEMORY_ERROR - on memory allocation error. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxSetMetadata(WebPMux* mux, + const WebPData* metadata, + int copy_data); + +// Gets a reference to the XMP metadata in the mux object. +// The caller should NOT free the returned data. +// Parameters: +// mux - (in) object from which the XMP metadata is to be fetched +// metadata - (out) XMP metadata +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if either mux or metadata is NULL. +// WEBP_MUX_NOT_FOUND - if metadata is not present in mux object. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxGetMetadata(const WebPMux* mux, + WebPData* metadata); + +// Deletes the XMP metadata in the mux object. +// Parameters: +// mux - (in/out) object from which XMP metadata is to be deleted +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux is NULL +// WEBP_MUX_NOT_FOUND - If mux does not contain metadata. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxDeleteMetadata(WebPMux* mux); + +//------------------------------------------------------------------------------ +// ICC Color Profile. + +// Sets the color profile in the mux object. Any existing color profile chunk(s) +// will be removed. +// Parameters: +// mux - (in/out) object to which the color profile is to be added +// color_profile - (in) the color profile data to be added +// copy_data - (in) value 1 indicates given data WILL copied to the mux, and +// value 0 indicates data will NOT be copied. +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux or color_profile is NULL +// WEBP_MUX_MEMORY_ERROR - on memory allocation error +// WEBP_MUX_OK - on success +WEBP_EXTERN(WebPMuxError) WebPMuxSetColorProfile(WebPMux* mux, + const WebPData* color_profile, + int copy_data); + +// Gets a reference to the color profile in the mux object. +// The caller should NOT free the returned data. +// Parameters: +// mux - (in) object from which the color profile data is to be fetched +// color_profile - (out) color profile data +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if either mux or color_profile is NULL. +// WEBP_MUX_NOT_FOUND - if color profile is not present in mux object. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxGetColorProfile(const WebPMux* mux, + WebPData* color_profile); + +// Deletes the color profile in the mux object. +// Parameters: +// mux - (in/out) object from which color profile is to be deleted +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux is NULL +// WEBP_MUX_NOT_FOUND - If mux does not contain color profile. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxDeleteColorProfile(WebPMux* mux); + +//------------------------------------------------------------------------------ +// Animation. + +// Adds an animation frame at the end of the mux object. +// Note: as WebP only supports even offsets, any odd offset will be snapped to +// an even location using: offset &= ~1 +// Parameters: +// mux - (in/out) object to which an animation frame is to be added +// bitstream - (in) the image data corresponding to the frame. It can either +// be a raw VP8/VP8L bitstream or a single-image WebP file +// (non-animated and non-tiled) +// x_offset - (in) x-offset of the frame to be added +// y_offset - (in) y-offset of the frame to be added +// duration - (in) duration of the frame to be added (in milliseconds) +// copy_data - (in) value 1 indicates given data WILL copied to the mux, and +// value 0 indicates data will NOT be copied. +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux is NULL or bitstream is NULL +// WEBP_MUX_MEMORY_ERROR - on memory allocation error. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxPushFrame( + WebPMux* mux, const WebPData* bitstream, + int x_offset, int y_offset, int duration, int copy_data); + +// TODO(urvang): Create a struct as follows to reduce argument list size: +// typedef struct { +// WebPData bitstream; +// int x_offset, y_offset; +// int duration; +// } FrameInfo; + +// Gets the nth animation frame from the mux object. +// The content of 'bitstream' is allocated using malloc(), and NOT +// owned by the 'mux' object. It MUST be deallocated by the caller by calling +// WebPDataClear(). +// nth=0 has a special meaning - last position. +// Parameters: +// mux - (in) object from which the info is to be fetched +// nth - (in) index of the frame in the mux object +// bitstream - (out) the image data +// x_offset - (out) x-offset of the returned frame +// y_offset - (out) y-offset of the returned frame +// duration - (out) duration of the returned frame (in milliseconds) +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if either mux, bitstream, x_offset, +// y_offset, or duration is NULL +// WEBP_MUX_NOT_FOUND - if there are less than nth frames in the mux object. +// WEBP_MUX_BAD_DATA - if nth frame chunk in mux is invalid. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxGetFrame( + const WebPMux* mux, uint32_t nth, WebPData* bitstream, + int* x_offset, int* y_offset, int* duration); + +// Deletes an animation frame from the mux object. +// nth=0 has a special meaning - last position. +// Parameters: +// mux - (in/out) object from which a frame is to be deleted +// nth - (in) The position from which the frame is to be deleted +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux is NULL +// WEBP_MUX_NOT_FOUND - If there are less than nth frames in the mux object +// before deletion. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxDeleteFrame(WebPMux* mux, uint32_t nth); + +// Sets the animation loop count in the mux object. Any existing loop count +// value(s) will be removed. +// Parameters: +// mux - (in/out) object in which loop chunk is to be set/added +// loop_count - (in) animation loop count value. +// Note that loop_count of zero denotes infinite loop. +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux is NULL +// WEBP_MUX_MEMORY_ERROR - on memory allocation error. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxSetLoopCount(WebPMux* mux, int loop_count); + +// Gets the animation loop count from the mux object. +// Parameters: +// mux - (in) object from which the loop count is to be fetched +// loop_count - (out) the loop_count value present in the LOOP chunk +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if either of mux or loop_count is NULL +// WEBP_MUX_NOT_FOUND - if loop chunk is not present in mux object. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxGetLoopCount(const WebPMux* mux, + int* loop_count); + +//------------------------------------------------------------------------------ +// Tiling. + +// Adds a tile at the end of the mux object. +// Note: as WebP only supports even offsets, any odd offset will be snapped to +// an even location using: offset &= ~1 +// Parameters: +// mux - (in/out) object to which a tile is to be added. +// bitstream - (in) the image data corresponding to the frame. It can either +// be a raw VP8/VP8L bitstream or a single-image WebP file +// (non-animated and non-tiled) +// x_offset - (in) x-offset of the tile to be added +// y_offset - (in) y-offset of the tile to be added +// copy_data - (in) value 1 indicates given data WILL copied to the mux, and +// value 0 indicates data will NOT be copied. +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux is NULL or bitstream is NULL +// WEBP_MUX_MEMORY_ERROR - on memory allocation error. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxPushTile( + WebPMux* mux, const WebPData* bitstream, + int x_offset, int y_offset, int copy_data); + +// Gets the nth tile from the mux object. +// The content of 'bitstream' is allocated using malloc(), and NOT +// owned by the 'mux' object. It MUST be deallocated by the caller by calling +// WebPDataClear(). +// nth=0 has a special meaning - last position. +// Parameters: +// mux - (in) object from which the info is to be fetched +// nth - (in) index of the tile in the mux object +// bitstream - (out) the image data +// x_offset - (out) x-offset of the returned tile +// y_offset - (out) y-offset of the returned tile +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if either mux, bitstream, x_offset or +// y_offset is NULL +// WEBP_MUX_NOT_FOUND - if there are less than nth tiles in the mux object. +// WEBP_MUX_BAD_DATA - if nth tile chunk in mux is invalid. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxGetTile( + const WebPMux* mux, uint32_t nth, WebPData* bitstream, + int* x_offset, int* y_offset); + +// Deletes a tile from the mux object. +// nth=0 has a special meaning - last position +// Parameters: +// mux - (in/out) object from which a tile is to be deleted +// nth - (in) The position from which the tile is to be deleted +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux is NULL +// WEBP_MUX_NOT_FOUND - If there are less than nth tiles in the mux object +// before deletion. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxDeleteTile(WebPMux* mux, uint32_t nth); + +//------------------------------------------------------------------------------ +// Misc Utilities. + +// Gets the feature flags from the mux object. +// Parameters: +// mux - (in) object from which the features are to be fetched +// flags - (out) the flags specifying which features are present in the +// mux object. This will be an OR of various flag values. +// Enum 'WebPFeatureFlags' can be used to test individual flag values. +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if mux or flags is NULL +// WEBP_MUX_NOT_FOUND - if VP8X chunk is not present in mux object. +// WEBP_MUX_BAD_DATA - if VP8X chunk in mux is invalid. +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxGetFeatures(const WebPMux* mux, + uint32_t* flags); + +// Gets number of chunks having tag value tag in the mux object. +// Parameters: +// mux - (in) object from which the info is to be fetched +// id - (in) chunk id specifying the type of chunk +// num_elements - (out) number of chunks with the given chunk id +// Returns: +// WEBP_MUX_INVALID_ARGUMENT - if either mux, or num_elements is NULL +// WEBP_MUX_OK - on success. +WEBP_EXTERN(WebPMuxError) WebPMuxNumChunks(const WebPMux* mux, + WebPChunkId id, int* num_elements); + +// Assembles all chunks in WebP RIFF format and returns in 'assembled_data'. +// This function also validates the mux object. +// Note: The content of 'assembled_data' will be ignored and overwritten. +// Also, the content of 'assembled_data' is allocated using malloc(), and NOT +// owned by the 'mux' object. It MUST be deallocated by the caller by calling +// WebPDataClear(). +// Parameters: +// mux - (in/out) object whose chunks are to be assembled +// assembled_data - (out) assembled WebP data +// Returns: +// WEBP_MUX_BAD_DATA - if mux object is invalid. +// WEBP_MUX_INVALID_ARGUMENT - if either mux, output_data or output_size is +// NULL. +// WEBP_MUX_MEMORY_ERROR - on memory allocation error. +// WEBP_MUX_OK - on success +WEBP_EXTERN(WebPMuxError) WebPMuxAssemble(WebPMux* mux, + WebPData* assembled_data); + +//------------------------------------------------------------------------------ +// Demux API. +// Enables extraction of image and extended format data from WebP files. + +#define WEBP_DEMUX_ABI_VERSION 0x0100 // MAJOR(8b) + MINOR(8b) + +typedef struct WebPDemuxer WebPDemuxer; + +typedef enum { + WEBP_DEMUX_PARSING_HEADER, // Not enough data to parse full header. + WEBP_DEMUX_PARSED_HEADER, // Header parsing complete, data may be available. + WEBP_DEMUX_DONE // Entire file has been parsed. +} WebPDemuxState; + +//------------------------------------------------------------------------------ +// Life of a Demux object + +// Internal, version-checked, entry point +WEBP_EXTERN(WebPDemuxer*) WebPDemuxInternal( + const WebPData*, int, WebPDemuxState*, int); + +// Parses the WebP file given by 'data'. +// A complete WebP file must be present in 'data' for the function to succeed. +// Returns a WebPDemuxer object on successful parse, NULL otherwise. +static WEBP_INLINE WebPDemuxer* WebPDemux(const WebPData* data) { + return WebPDemuxInternal(data, 0, NULL, WEBP_DEMUX_ABI_VERSION); +} + +// Parses the WebP file given by 'data'. +// If 'state' is non-NULL it will be set to indicate the status of the demuxer. +// Returns a WebPDemuxer object on successful parse, NULL otherwise. +static WEBP_INLINE WebPDemuxer* WebPDemuxPartial( + const WebPData* data, WebPDemuxState* state) { + return WebPDemuxInternal(data, 1, state, WEBP_DEMUX_ABI_VERSION); +} + +// Frees memory associated with 'dmux'. +WEBP_EXTERN(void) WebPDemuxDelete(WebPDemuxer* dmux); + +//------------------------------------------------------------------------------ +// Data/information extraction. + +typedef enum { + WEBP_FF_FORMAT_FLAGS, // Extended format flags present in the 'VP8X' chunk. + WEBP_FF_CANVAS_WIDTH, + WEBP_FF_CANVAS_HEIGHT, + WEBP_FF_LOOP_COUNT +} WebPFormatFeature; + +// Get the 'feature' value from the 'dmux'. +// NOTE: values are only valid if WebPDemux() was used or WebPDemuxPartial() +// returned a state > WEBP_DEMUX_PARSING_HEADER. +WEBP_EXTERN(uint32_t) WebPDemuxGetI( + const WebPDemuxer* dmux, WebPFormatFeature feature); + +//------------------------------------------------------------------------------ +// Frame iteration. + +typedef struct { + int frame_num_; + int num_frames_; + int tile_num_; + int num_tiles_; + int x_offset_, y_offset_; // offset relative to the canvas. + int width_, height_; // dimensions of this frame or tile. + int duration_; // display duration in milliseconds. + int complete_; // true if 'tile_' contains a full frame. partial images may + // still be decoded with the WebP incremental decoder. + WebPData tile_; // The frame or tile given by 'frame_num_' and 'tile_num_'. + + uint32_t pad[4]; // padding for later use + void* private_; +} WebPIterator; + +// Retrieves frame 'frame_number' from 'dmux'. +// 'iter->tile_' points to the first tile on return from this function. +// Individual tiles may be extracted using WebPDemuxSetTile(). +// Setting 'frame_number' equal to 0 will return the last frame of the image. +// Returns false if 'dmux' is NULL or frame 'frame_number' is not present. +// Call WebPDemuxReleaseIterator() when use of the iterator is complete. +// NOTE: 'dmux' must persist for the lifetime of 'iter'. +WEBP_EXTERN(int) WebPDemuxGetFrame( + const WebPDemuxer* dmux, int frame_number, WebPIterator* iter); + +// Sets 'iter->tile_' to point to the next ('iter->frame_num_' + 1) or previous +// ('iter->frame_num_' - 1) frame. These functions do not loop. +// Returns true on success, false otherwise. +WEBP_EXTERN(int) WebPDemuxNextFrame(WebPIterator* iter); +WEBP_EXTERN(int) WebPDemuxPrevFrame(WebPIterator* iter); + +// Sets 'iter->tile_' to reflect tile number 'tile_number'. +// Returns true if tile 'tile_number' is present, false otherwise. +WEBP_EXTERN(int) WebPDemuxSelectTile(WebPIterator* iter, int tile_number); + +// Releases any memory associated with 'iter'. +// Must be called before destroying the associated WebPDemuxer with +// WebPDemuxDelete(). +WEBP_EXTERN(void) WebPDemuxReleaseIterator(WebPIterator* iter); + +//------------------------------------------------------------------------------ +// Chunk iteration. + +typedef struct { + // The current and total number of chunks with the fourcc given to + // WebPDemuxGetChunk(). + int chunk_num_; + int num_chunks_; + WebPData chunk_; // The payload of the chunk. + + uint32_t pad[6]; // padding for later use + void* private_; +} WebPChunkIterator; + +// Retrieves the 'chunk_number' instance of the chunk with id 'fourcc' from +// 'dmux'. +// 'fourcc' is a character array containing the fourcc of the chunk to return, +// e.g., "ICCP", "META", "EXIF", etc. +// Setting 'chunk_number' equal to 0 will return the last chunk in a set. +// Returns true if the chunk is found, false otherwise. Image related chunk +// payloads are accessed through WebPDemuxGetFrame() and related functions. +// Call WebPDemuxReleaseChunkIterator() when use of the iterator is complete. +// NOTE: 'dmux' must persist for the lifetime of the iterator. +WEBP_EXTERN(int) WebPDemuxGetChunk(const WebPDemuxer* dmux, + const char fourcc[4], int chunk_number, + WebPChunkIterator* iter); + +// Sets 'iter->chunk_' to point to the next ('iter->chunk_num_' + 1) or previous +// ('iter->chunk_num_' - 1) chunk. These functions do not loop. +// Returns true on success, false otherwise. +WEBP_EXTERN(int) WebPDemuxNextChunk(WebPChunkIterator* iter); +WEBP_EXTERN(int) WebPDemuxPrevChunk(WebPChunkIterator* iter); + +// Releases any memory associated with 'iter'. +// Must be called before destroying the associated WebPDemuxer with +// WebPDemuxDelete(). +WEBP_EXTERN(void) WebPDemuxReleaseChunkIterator(WebPChunkIterator* iter); + +//------------------------------------------------------------------------------ + +#if defined(__cplusplus) || defined(c_plusplus) +} // extern "C" +#endif + +#endif /* WEBP_WEBP_MUX_H_ */ |