godotengine
/
godot
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
godot/drivers/webp/mux.h

605 lines
25 KiB
C
Raw Blame History

// 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_ */
Reference in New Issue View Git Blame Copy Permalink