go-libwebp

demux.h (16019B)

---

 // Copyright 2012 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.
 // -----------------------------------------------------------------------------
 //
 // Demux API.
 // Enables extraction of image and extended format data from WebP files.
 
 // Code Example: Demuxing WebP data to extract all the frames, ICC profile
 // and EXIF/XMP metadata.
 /*
   WebPDemuxer* demux = WebPDemux(&webp_data);
 
   uint32_t width = WebPDemuxGetI(demux, WEBP_FF_CANVAS_WIDTH);
   uint32_t height = WebPDemuxGetI(demux, WEBP_FF_CANVAS_HEIGHT);
   // ... (Get information about the features present in the WebP file).
   uint32_t flags = WebPDemuxGetI(demux, WEBP_FF_FORMAT_FLAGS);
 
   // ... (Iterate over all frames).
   WebPIterator iter;
   if (WebPDemuxGetFrame(demux, 1, &iter)) {
     do {
       // ... (Consume 'iter'; e.g. Decode 'iter.fragment' with WebPDecode(),
       // ... and get other frame properties like width, height, offsets etc.
       // ... see 'struct WebPIterator' below for more info).
     } while (WebPDemuxNextFrame(&iter));
     WebPDemuxReleaseIterator(&iter);
   }
 
   // ... (Extract metadata).
   WebPChunkIterator chunk_iter;
   if (flags & ICCP_FLAG) WebPDemuxGetChunk(demux, "ICCP", 1, &chunk_iter);
   // ... (Consume the ICC profile in 'chunk_iter.chunk').
   WebPDemuxReleaseChunkIterator(&chunk_iter);
   if (flags & EXIF_FLAG) WebPDemuxGetChunk(demux, "EXIF", 1, &chunk_iter);
   // ... (Consume the EXIF metadata in 'chunk_iter.chunk').
   WebPDemuxReleaseChunkIterator(&chunk_iter);
   if (flags & XMP_FLAG) WebPDemuxGetChunk(demux, "XMP ", 1, &chunk_iter);
   // ... (Consume the XMP metadata in 'chunk_iter.chunk').
   WebPDemuxReleaseChunkIterator(&chunk_iter);
   WebPDemuxDelete(demux);
 */
 
 #ifndef WEBP_WEBP_DEMUX_H_
 #define WEBP_WEBP_DEMUX_H_
 
 #include <stddef.h>
 
 #include "./decode.h"     // for WEBP_CSP_MODE
 #include "./mux_types.h"
 #include "./types.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 #define WEBP_DEMUX_ABI_VERSION 0x0107    // MAJOR(8b) + MINOR(8b)
 
 // Note: forward declaring enumerations is not allowed in (strict) C and C++,
 // the types are left here for reference.
 // typedef enum WebPDemuxState WebPDemuxState;
 // typedef enum WebPFormatFeature WebPFormatFeature;
 typedef struct WebPDemuxer WebPDemuxer;
 typedef struct WebPIterator WebPIterator;
 typedef struct WebPChunkIterator WebPChunkIterator;
 typedef struct WebPAnimInfo WebPAnimInfo;
 typedef struct WebPAnimDecoderOptions WebPAnimDecoderOptions;
 
 //------------------------------------------------------------------------------
 
 // Returns the version number of the demux library, packed in hexadecimal using
 // 8bits for each of major/minor/revision. E.g: v2.5.7 is 0x020507.
 WEBP_EXTERN int WebPGetDemuxVersion(void);
 
 //------------------------------------------------------------------------------
 // Life of a Demux object
 
 typedef enum WebPDemuxState {
   WEBP_DEMUX_PARSE_ERROR    = -1,  // An error occurred while parsing.
   WEBP_DEMUX_PARSING_HEADER =  0,  // Not enough data to parse full header.
   WEBP_DEMUX_PARSED_HEADER  =  1,  // Header parsing complete,
                                    // data may be available.
   WEBP_DEMUX_DONE           =  2   // Entire file has been parsed.
 } WebPDemuxState;
 
 // Internal, version-checked, entry point
 WEBP_NODISCARD WEBP_EXTERN WebPDemuxer* WebPDemuxInternal(
     const WebPData*, int, WebPDemuxState*, int);
 
 // Parses the full WebP file given by 'data'. For single images the WebP file
 // header alone or the file header and the chunk header may be absent.
 // Returns a WebPDemuxer object on successful parse, NULL otherwise.
 WEBP_NODISCARD static WEBP_INLINE WebPDemuxer* WebPDemux(const WebPData* data) {
   return WebPDemuxInternal(data, 0, NULL, WEBP_DEMUX_ABI_VERSION);
 }
 
 // Parses the possibly incomplete WebP file given by 'data'.
 // If 'state' is non-NULL it will be set to indicate the status of the demuxer.
 // Returns NULL in case of error or if there isn't enough data to start parsing;
 // and a WebPDemuxer object on successful parse.
 // Note that WebPDemuxer keeps internal pointers to 'data' memory segment.
 // If this data is volatile, the demuxer object should be deleted (by calling
 // WebPDemuxDelete()) and WebPDemuxPartial() called again on the new data.
 // This is usually an inexpensive operation.
 WEBP_NODISCARD 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 WebPFormatFeature {
   WEBP_FF_FORMAT_FLAGS,      // bit-wise combination of WebPFeatureFlags
                              // corresponding to the 'VP8X' chunk (if present).
   WEBP_FF_CANVAS_WIDTH,
   WEBP_FF_CANVAS_HEIGHT,
   WEBP_FF_LOOP_COUNT,        // only relevant for animated file
   WEBP_FF_BACKGROUND_COLOR,  // idem.
   WEBP_FF_FRAME_COUNT        // Number of frames present in the demux object.
                              // In case of a partial demux, this is the number
                              // of frames seen so far, with the last frame
                              // possibly being partial.
 } 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.
 // If 'feature' is WEBP_FF_FORMAT_FLAGS, the returned value is a bit-wise
 // combination of WebPFeatureFlags values.
 // If 'feature' is WEBP_FF_LOOP_COUNT, WEBP_FF_BACKGROUND_COLOR, the returned
 // value is only meaningful if the bitstream is animated.
 WEBP_EXTERN uint32_t WebPDemuxGetI(
     const WebPDemuxer* dmux, WebPFormatFeature feature);
 
 //------------------------------------------------------------------------------
 // Frame iteration.
 
 struct WebPIterator {
   int frame_num;
   int num_frames;          // equivalent to WEBP_FF_FRAME_COUNT.
   int x_offset, y_offset;  // offset relative to the canvas.
   int width, height;       // dimensions of this frame.
   int duration;            // display duration in milliseconds.
   WebPMuxAnimDispose dispose_method;  // dispose method for the frame.
   int complete;   // true if 'fragment' contains a full frame. partial images
                   // may still be decoded with the WebP incremental decoder.
   WebPData fragment;  // The frame given by 'frame_num'. Note for historical
                       // reasons this is called a fragment.
   int has_alpha;      // True if the frame contains transparency.
   WebPMuxAnimBlend blend_method;  // Blend operation for the frame.
 
   uint32_t pad[2];         // padding for later use.
   void* private_;          // for internal use only.
 };
 
 // Retrieves frame 'frame_number' from 'dmux'.
 // 'iter->fragment' points to the frame on return from this function.
 // 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_NODISCARD WEBP_EXTERN int WebPDemuxGetFrame(
     const WebPDemuxer* dmux, int frame_number, WebPIterator* iter);
 
 // Sets 'iter->fragment' 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_NODISCARD WEBP_EXTERN int WebPDemuxNextFrame(WebPIterator* iter);
 WEBP_NODISCARD WEBP_EXTERN int WebPDemuxPrevFrame(WebPIterator* iter);
 
 // Releases any memory associated with 'iter'.
 // Must be called before any subsequent calls to WebPDemuxGetChunk() on the same
 // iter. Also, must be called before destroying the associated WebPDemuxer with
 // WebPDemuxDelete().
 WEBP_EXTERN void WebPDemuxReleaseIterator(WebPIterator* iter);
 
 //------------------------------------------------------------------------------
 // Chunk iteration.
 
 struct WebPChunkIterator {
   // 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_;
 };
 
 // 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", "XMP ", "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_NODISCARD 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_NODISCARD WEBP_EXTERN int WebPDemuxNextChunk(WebPChunkIterator* iter);
 WEBP_NODISCARD 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);
 
 //------------------------------------------------------------------------------
 // WebPAnimDecoder API
 //
 // This API allows decoding (possibly) animated WebP images.
 //
 // Code Example:
 /*
   WebPAnimDecoderOptions dec_options;
   WebPAnimDecoderOptionsInit(&dec_options);
   // Tune 'dec_options' as needed.
   WebPAnimDecoder* dec = WebPAnimDecoderNew(webp_data, &dec_options);
   WebPAnimInfo anim_info;
   WebPAnimDecoderGetInfo(dec, &anim_info);
   for (uint32_t i = 0; i < anim_info.loop_count; ++i) {
     while (WebPAnimDecoderHasMoreFrames(dec)) {
       uint8_t* buf;
       int timestamp;
       WebPAnimDecoderGetNext(dec, &buf, &timestamp);
       // ... (Render 'buf' based on 'timestamp').
       // ... (Do NOT free 'buf', as it is owned by 'dec').
     }
     WebPAnimDecoderReset(dec);
   }
   const WebPDemuxer* demuxer = WebPAnimDecoderGetDemuxer(dec);
   // ... (Do something using 'demuxer'; e.g. get EXIF/XMP/ICC data).
   WebPAnimDecoderDelete(dec);
 */
 
 typedef struct WebPAnimDecoder WebPAnimDecoder;  // Main opaque object.
 
 // Global options.
 struct WebPAnimDecoderOptions {
   // Output colorspace. Only the following modes are supported:
   // MODE_RGBA, MODE_BGRA, MODE_rgbA and MODE_bgrA.
   WEBP_CSP_MODE color_mode;
   int use_threads;           // If true, use multi-threaded decoding.
   uint32_t padding[7];       // Padding for later use.
 };
 
 // Internal, version-checked, entry point.
 WEBP_NODISCARD WEBP_EXTERN int WebPAnimDecoderOptionsInitInternal(
     WebPAnimDecoderOptions*, int);
 
 // Should always be called, to initialize a fresh WebPAnimDecoderOptions
 // structure before modification. Returns false in case of version mismatch.
 // WebPAnimDecoderOptionsInit() must have succeeded before using the
 // 'dec_options' object.
 WEBP_NODISCARD static WEBP_INLINE int WebPAnimDecoderOptionsInit(
     WebPAnimDecoderOptions* dec_options) {
   return WebPAnimDecoderOptionsInitInternal(dec_options,
                                             WEBP_DEMUX_ABI_VERSION);
 }
 
 // Internal, version-checked, entry point.
 WEBP_NODISCARD WEBP_EXTERN WebPAnimDecoder* WebPAnimDecoderNewInternal(
     const WebPData*, const WebPAnimDecoderOptions*, int);
 
 // Creates and initializes a WebPAnimDecoder object.
 // Parameters:
 //   webp_data - (in) WebP bitstream. This should remain unchanged during the
 //                    lifetime of the output WebPAnimDecoder object.
 //   dec_options - (in) decoding options. Can be passed NULL to choose
 //                      reasonable defaults (in particular, color mode MODE_RGBA
 //                      will be picked).
 // Returns:
 //   A pointer to the newly created WebPAnimDecoder object, or NULL in case of
 //   parsing error, invalid option or memory error.
 WEBP_NODISCARD static WEBP_INLINE WebPAnimDecoder* WebPAnimDecoderNew(
     const WebPData* webp_data, const WebPAnimDecoderOptions* dec_options) {
   return WebPAnimDecoderNewInternal(webp_data, dec_options,
                                     WEBP_DEMUX_ABI_VERSION);
 }
 
 // Global information about the animation..
 struct WebPAnimInfo {
   uint32_t canvas_width;
   uint32_t canvas_height;
   uint32_t loop_count;
   uint32_t bgcolor;
   uint32_t frame_count;
   uint32_t pad[4];   // padding for later use
 };
 
 // Get global information about the animation.
 // Parameters:
 //   dec - (in) decoder instance to get information from.
 //   info - (out) global information fetched from the animation.
 // Returns:
 //   True on success.
 WEBP_NODISCARD WEBP_EXTERN int WebPAnimDecoderGetInfo(
     const WebPAnimDecoder* dec, WebPAnimInfo* info);
 
 // Fetch the next frame from 'dec' based on options supplied to
 // WebPAnimDecoderNew(). This will be a fully reconstructed canvas of size
 // 'canvas_width * 4 * canvas_height', and not just the frame sub-rectangle. The
 // returned buffer 'buf' is valid only until the next call to
 // WebPAnimDecoderGetNext(), WebPAnimDecoderReset() or WebPAnimDecoderDelete().
 // Parameters:
 //   dec - (in/out) decoder instance from which the next frame is to be fetched.
 //   buf - (out) decoded frame.
 //   timestamp - (out) timestamp of the frame in milliseconds.
 // Returns:
 //   False if any of the arguments are NULL, or if there is a parsing or
 //   decoding error, or if there are no more frames. Otherwise, returns true.
 WEBP_NODISCARD WEBP_EXTERN int WebPAnimDecoderGetNext(WebPAnimDecoder* dec,
                                                       uint8_t** buf,
                                                       int* timestamp);
 
 // Check if there are more frames left to decode.
 // Parameters:
 //   dec - (in) decoder instance to be checked.
 // Returns:
 //   True if 'dec' is not NULL and some frames are yet to be decoded.
 //   Otherwise, returns false.
 WEBP_NODISCARD WEBP_EXTERN int WebPAnimDecoderHasMoreFrames(
     const WebPAnimDecoder* dec);
 
 // Resets the WebPAnimDecoder object, so that next call to
 // WebPAnimDecoderGetNext() will restart decoding from 1st frame. This would be
 // helpful when all frames need to be decoded multiple times (e.g.
 // info.loop_count times) without destroying and recreating the 'dec' object.
 // Parameters:
 //   dec - (in/out) decoder instance to be reset
 WEBP_EXTERN void WebPAnimDecoderReset(WebPAnimDecoder* dec);
 
 // Grab the internal demuxer object.
 // Getting the demuxer object can be useful if one wants to use operations only
 // available through demuxer; e.g. to get XMP/EXIF/ICC metadata. The returned
 // demuxer object is owned by 'dec' and is valid only until the next call to
 // WebPAnimDecoderDelete().
 //
 // Parameters:
 //   dec - (in) decoder instance from which the demuxer object is to be fetched.
 WEBP_NODISCARD WEBP_EXTERN const WebPDemuxer* WebPAnimDecoderGetDemuxer(
     const WebPAnimDecoder* dec);
 
 // Deletes the WebPAnimDecoder object.
 // Parameters:
 //   dec - (in/out) decoder instance to be deleted
 WEBP_EXTERN void WebPAnimDecoderDelete(WebPAnimDecoder* dec);
 
 #ifdef __cplusplus
 }    // extern "C"
 #endif
 
 #endif  // WEBP_WEBP_DEMUX_H_