WebP Container API 文档

int copy_data = 0;
WebPMux* mux = WebPMuxNew();
// ... (Prepare image data).
WebPMuxSetImage(mux, &image, copy_data);
// ... (Prepare ICCP color profile data).
WebPMuxSetChunk(mux, "ICCP", &icc_profile, copy_data);
// ... (Prepare XMP metadata).
WebPMuxSetChunk(mux, "XMP ", &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);

int copy_data = 0;
// ... (Read data from file).
WebPMux* mux = WebPMuxCreate(&data, copy_data);
WebPMuxGetFrame(mux, 1, &image);
// ... (Consume image; e.g. call WebPDecode() to decode the data).
WebPMuxGetChunk(mux, "ICCP", &icc_profile);
// ... (Consume icc_data).
WebPMuxDelete(mux);
free(data);

// Error codes
typedef enum WebPMuxError {
  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;

// IDs for different types of chunks.
typedef enum WebPChunkId {
  WEBP_CHUNK_VP8X,     // VP8X
  WEBP_CHUNK_ICCP,     // ICCP
  WEBP_CHUNK_ANIM,     // ANIM
  WEBP_CHUNK_ANMF,     // ANMF
  WEBP_CHUNK_ALPHA,    // ALPH
  WEBP_CHUNK_IMAGE,    // VP8/VP8L
  WEBP_CHUNK_EXIF,     // EXIF
  WEBP_CHUNK_XMP,      // XMP
  WEBP_CHUNK_UNKNOWN,  // Other chunks.
  WEBP_CHUNK_NIL
} WebPChunkId;

int WebPGetMuxVersion(void);

WebPMux* WebPMuxNew(void);

void WebPMuxDelete(WebPMux* mux);

WebPMux* WebPMuxCreate(const WebPData* bitstream, int copy_data);

WebPMuxError WebPMuxSetChunk(WebPMux* mux,
                             const char fourcc[4],
                             const WebPData* chunk_data,
                             int copy_data);

WebPMuxError WebPMuxGetChunk(const WebPMux* mux,
                             const char fourcc[4],
                             WebPData* chunk_data);

WebPMuxError WebPMuxDeleteChunk(WebPMux* mux, const char fourcc[4]);

struct WebPMuxFrameInfo {
  WebPData    bitstream;  // image data: can be a raw VP8/VP8L bitstream
                          // or a single-image WebP file.
  int         x_offset;   // x-offset of the frame.
  int         y_offset;   // y-offset of the frame.
  int         duration;   // duration of the frame (in milliseconds).

  WebPChunkId id;         // frame type: should be one of WEBP_CHUNK_ANMF,
                          // WEBP_CHUNK_FRGM or WEBP_CHUNK_IMAGE
  WebPMuxAnimDispose dispose_method;  // Disposal method for the frame.
  WebPMuxAnimBlend   blend_method;    // Blend operation for the frame.
};

WebPMuxError WebPMuxSetImage(WebPMux* mux,
                             const WebPData* bitstream,
                             int copy_data);

WebPMuxError WebPMuxPushFrame(WebPMux* mux,
                              const WebPMuxFrameInfo* frame,
                              int copy_data);

WebPMuxError WebPMuxGetFrame(const WebPMux* mux,
                             uint32_t nth,
                             WebPMuxFrameInfo* frame);

WebPMuxError WebPMuxDeleteFrame(WebPMux* mux, uint32_t nth);

struct WebPMuxAnimParams {
  uint32_t bgcolor;  // Background color of the canvas stored (in MSB order) as:
                     // Bits 00 to 07: Alpha.
                     // Bits 08 to 15: Red.
                     // Bits 16 to 23: Green.
                     // Bits 24 to 31: Blue.
  int loop_count;    // Number of times to repeat the animation [0 = infinite].
};

WebPMuxError WebPMuxSetAnimationParams(WebPMux* mux,
                                       const WebPMuxAnimParams* params);

WebPMuxError WebPMuxGetAnimationParams(const WebPMux* mux,
                                       WebPMuxAnimParams* params);

WebPMuxError WebPMuxGetCanvasSize(const WebPMux* mux,
                                  int* width,
                                  int* height);

WebPMuxError WebPMuxGetFeatures(const WebPMux* mux, uint32_t* flags);

WebPMuxError WebPMuxNumChunks(const WebPMux* mux,
                              WebPChunkId id,
                              int* num_elements);

WebPMuxError WebPMuxAssemble(WebPMux* mux, WebPData* assembled_data);

WebPAnimEncoderOptions enc_options;
WebPAnimEncoderOptionsInit(&enc_options);
// Tune 'enc_options' as needed.
WebPAnimEncoder* enc = WebPAnimEncoderNew(width, height, &enc_options);
while(<there are more frames>) {
  WebPConfig config;
  WebPConfigInit(&config);
  // Tune 'config' as needed.
  WebPAnimEncoderAdd(enc, frame, timestamp_ms, &config);
}
WebPAnimEncoderAdd(enc, NULL, timestamp_ms, NULL);
WebPAnimEncoderAssemble(enc, webp_data);
WebPAnimEncoderDelete(enc);
// Write the 'webp_data' to a file, or re-mux it further.

typedef struct WebPAnimEncoder WebPAnimEncoder;  // Main opaque object.

struct WebPAnimEncoderOptions {
  WebPMuxAnimParams anim_params;  // Animation parameters.
  int minimize_size;    // If true, minimize the output size (slow). Implicitly
                        // disables key-frame insertion.
  int kmin;
  int kmax;             // Minimum and maximum distance between consecutive key
                        // frames in the output. The library may insert some key
                        // frames as needed to satisfy this criteria.
                        // Note that these conditions should hold: kmax > kmin
                        // and kmin >= kmax / 2 + 1. Also, if kmax <= 0, then
                        // key-frame insertion is disabled; and if kmax == 1,
                        // then all frames will be key-frames (kmin value does
                        // not matter for these special cases).
  int allow_mixed;      // If true, use mixed compression mode; may choose
                        // either lossy and lossless for each frame.
  int verbose;          // If true, print info and warning messages to stderr.
};

int WebPAnimEncoderOptionsInit(
    WebPAnimEncoderOptions* enc_options);

WebPAnimEncoder* WebPAnimEncoderNew(
    int width, int height, const WebPAnimEncoderOptions* enc_options);

int WebPAnimEncoderAdd(
    WebPAnimEncoder* enc, struct WebPPicture* frame, int timestamp_ms,
    const struct WebPConfig* config);

int WebPAnimEncoderAssemble(WebPAnimEncoder* enc, WebPData* webp_data);

const char* WebPAnimEncoderGetError(WebPAnimEncoder* enc);

void WebPAnimEncoderDelete(WebPAnimEncoder* enc);

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);

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;

int WebPGetDemuxVersion(void);

WebPDemuxer WebPDemux(const WebPData* data);

WebPDemuxer WebPDemuxPartial(const WebPData* data, WebPDemuxState* state);

void WebPDemuxDelete(WebPDemuxer* dmux);

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;

uint32_t WebPDemuxGetI(const WebPDemuxer* dmux, WebPFormatFeature feature);

struct WebPIterator {
  int frame_num;
  int num_frames;          // equivalent to WEBP_FF_FRAME_COUNT.
  int fragment_num;
  int num_fragments;
  int x_offset, y_offset;  // offset relative to the canvas.
  int width, height;       // dimensions of this frame or fragment.
  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 or fragment given by 'frame_num' and
                      // 'fragment_num'.
  int has_alpha;      // True if the frame or fragment contains transparency.
  WebPMuxAnimBlend blend_method;  // Blend operation for the frame.
};

int WebPDemuxGetFrame(const WebPDemuxer* dmux,
                      int frame_number,
                      WebPIterator* iter);

int WebPDemuxNextFrame(WebPIterator* iter);
int WebPDemuxPrevFrame(WebPIterator* iter);

int WebPDemuxSelectFragment(WebPIterator* iter, int fragment_num);

void WebPDemuxReleaseIterator(WebPIterator* iter);

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.
};

int WebPDemuxGetChunk(const WebPDemuxer* dmux,
                      const char fourcc[4], int chunk_number,
                      WebPChunkIterator* iter);

int WebPDemuxNextChunk(WebPChunkIterator* iter);
int WebPDemuxPrevChunk(WebPChunkIterator* iter);

void WebPDemuxReleaseChunkIterator(WebPChunkIterator* iter);

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.

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.
};

int WebPAnimDecoderOptionsInit(
    WebPAnimDecoderOptions* dec_options);

WebPAnimDecoder* WebPAnimDecoderNew(
    const WebPData* webp_data, const WebPAnimDecoderOptions* dec_options);

struct WebPAnimInfo {
  uint32_t canvas_width;
  uint32_t canvas_height;
  uint32_t loop_count;
  uint32_t bgcolor;
  uint32_t frame_count;
};

int WebPAnimDecoderGetInfo(const WebPAnimDecoder* dec,
                           WebPAnimInfo* info);

int WebPAnimDecoderGetNext(WebPAnimDecoder* dec,
                           uint8_t** buf, int* timestamp);

int WebPAnimDecoderHasMoreFrames(const WebPAnimDecoder* dec);

void WebPAnimDecoderReset(WebPAnimDecoder* dec);

const WebPDemuxer* WebPAnimDecoderGetDemuxer(const WebPAnimDecoder* dec);

void WebPAnimDecoderDelete(WebPAnimDecoder* dec);

typedef enum WebPFeatureFlags {
  FRAGMENTS_FLAG  = 0x00000001,
  ANIMATION_FLAG  = 0x00000002,
  XMP_FLAG        = 0x00000004,
  EXIF_FLAG       = 0x00000008,
  ALPHA_FLAG      = 0x00000010,
  ICCP_FLAG       = 0x00000020
} WebPFeatureFlags;

// Dispose method (animation only). Indicates how the area used by the current
// frame is to be treated before rendering the next frame on the canvas.
typedef enum WebPMuxAnimDispose {
  WEBP_MUX_DISPOSE_NONE,       // Do not dispose.
  WEBP_MUX_DISPOSE_BACKGROUND  // Dispose to background color.
} WebPMuxAnimDispose;

// Blend operation (animation only). Indicates how transparent pixels of the
// current frame are blended with those of the previous canvas.
typedef enum WebPMuxAnimBlend {
  WEBP_MUX_BLEND,              // Blend.
  WEBP_MUX_NO_BLEND            // Do not blend.
} WebPMuxAnimBlend;

void WebPDataInit(WebPData* webp_data);

void WebPDataClear(WebPData* webp_data);

int WebPDataCopy(const WebPData* src, WebPData* dst);