third_party/libwebp/webp/demux.h

   1 // Copyright 2012 Google Inc. All Rights Reserved.
   2 //
   3 // Use of this source code is governed by a BSD-style license
   4 // that can be found in the COPYING file in the root of the source
   5 // tree. An additional intellectual property rights grant can be found
   6 // in the file PATENTS. All contributing project authors may
   7 // be found in the AUTHORS file in the root of the source tree.
   8 // -----------------------------------------------------------------------------
   9 //
  10 // Demux API.
  11 // Enables extraction of image and extended format data from WebP files.
  12
  13 // Code Example: Demuxing WebP data to extract all the frames, ICC profile
  14 // and EXIF/XMP metadata.
  15 //
  16 //   WebPDemuxer* demux = WebPDemux(&webp_data);
  17 //
  18 //   uint32_t width = WebPDemuxGetI(demux, WEBP_FF_CANVAS_WIDTH);
  19 //   uint32_t height = WebPDemuxGetI(demux, WEBP_FF_CANVAS_HEIGHT);
  20 //   // ... (Get information about the features present in the WebP file).
  21 //   uint32_t flags = WebPDemuxGetI(demux, WEBP_FF_FORMAT_FLAGS);
  22 //
  23 //   // ... (Iterate over all frames).
  24 //   WebPIterator iter;
  25 //   if (WebPDemuxGetFrame(demux, 1, &iter)) {
  26 //     do {
  27 //       // ... (Consume 'iter'; e.g. Decode 'iter.fragment' with WebPDecode(),
  28 //       // ... and get other frame properties like width, height, offsets etc.
  29 //       // ... see 'struct WebPIterator' below for more info).
  30 //     } while (WebPDemuxNextFrame(&iter));
  31 //     WebPDemuxReleaseIterator(&iter);
  32 //   }
  33 //
  34 //   // ... (Extract metadata).
  35 //   WebPChunkIterator chunk_iter;
  36 //   if (flags & ICCP_FLAG) WebPDemuxGetChunk(demux, "ICCP", 1, &chunk_iter);
  37 //   // ... (Consume the ICC profile in 'chunk_iter.chunk').
  38 //   WebPDemuxReleaseChunkIterator(&chunk_iter);
  39 //   if (flags & EXIF_FLAG) WebPDemuxGetChunk(demux, "EXIF", 1, &chunk_iter);
  40 //   // ... (Consume the EXIF metadata in 'chunk_iter.chunk').
  41 //   WebPDemuxReleaseChunkIterator(&chunk_iter);
  42 //   if (flags & XMP_FLAG) WebPDemuxGetChunk(demux, "XMP ", 1, &chunk_iter);
  43 //   // ... (Consume the XMP metadata in 'chunk_iter.chunk').
  44 //   WebPDemuxReleaseChunkIterator(&chunk_iter);
  45 //   WebPDemuxDelete(demux);
  46
  47 #ifndef WEBP_WEBP_DEMUX_H_
  48 #define WEBP_WEBP_DEMUX_H_
  49
  50 #include "./mux_types.h"
  51
  52 #if defined(__cplusplus) || defined(c_plusplus)
  53 extern "C" {
  54 #endif
  55
  56 #define WEBP_DEMUX_ABI_VERSION 0x0100    // MAJOR(8b) + MINOR(8b)
  57
  58 // Note: forward declaring enumerations is not allowed in (strict) C and C++,
  59 // the types are left here for reference.
  60 // typedef enum WebPDemuxState WebPDemuxState;
  61 // typedef enum WebPFormatFeature WebPFormatFeature;
  62 typedef struct WebPDemuxer WebPDemuxer;
  63 typedef struct WebPIterator WebPIterator;
  64 typedef struct WebPChunkIterator WebPChunkIterator;
  65
  66 //------------------------------------------------------------------------------
  67
  68 // Returns the version number of the demux library, packed in hexadecimal using
  69 // 8bits for each of major/minor/revision. E.g: v2.5.7 is 0x020507.
  70 WEBP_EXTERN(int) WebPGetDemuxVersion(void);
  71
  72 //------------------------------------------------------------------------------
  73 // Life of a Demux object
  74
  75 typedef enum WebPDemuxState {
  76   WEBP_DEMUX_PARSING_HEADER,  // Not enough data to parse full header.
  77   WEBP_DEMUX_PARSED_HEADER,   // Header parsing complete, data may be available.
  78   WEBP_DEMUX_DONE             // Entire file has been parsed.
  79 } WebPDemuxState;
  80
  81 // Internal, version-checked, entry point
  82 WEBP_EXTERN(WebPDemuxer*) WebPDemuxInternal(
  83     const WebPData*, int, WebPDemuxState*, int);
  84
  85 // Parses the full WebP file given by 'data'.
  86 // Returns a WebPDemuxer object on successful parse, NULL otherwise.
  87 static WEBP_INLINE WebPDemuxer* WebPDemux(const WebPData* data) {
  88   return WebPDemuxInternal(data, 0, NULL, WEBP_DEMUX_ABI_VERSION);
  89 }
  90
  91 // Parses the possibly incomplete WebP file given by 'data'.
  92 // If 'state' is non-NULL it will be set to indicate the status of the demuxer.
  93 // Returns a WebPDemuxer object on successful parse, NULL otherwise.
  94 static WEBP_INLINE WebPDemuxer* WebPDemuxPartial(
  95     const WebPData* data, WebPDemuxState* state) {
  96   return WebPDemuxInternal(data, 1, state, WEBP_DEMUX_ABI_VERSION);
  97 }
  98
  99 // Frees memory associated with 'dmux'.
 100 WEBP_EXTERN(void) WebPDemuxDelete(WebPDemuxer* dmux);
 101
 102 //------------------------------------------------------------------------------
 103 // Data/information extraction.
 104
 105 typedef enum WebPFormatFeature {
 106   WEBP_FF_FORMAT_FLAGS,  // Extended format flags present in the 'VP8X' chunk.
 107   WEBP_FF_CANVAS_WIDTH,
 108   WEBP_FF_CANVAS_HEIGHT,
 109   WEBP_FF_LOOP_COUNT,
 110   WEBP_FF_BACKGROUND_COLOR,
 111   WEBP_FF_FRAME_COUNT    // Number of frames present in the demux object.
 112                          // In case of a partial demux, this is the number of
 113                          // frames seen so far, with the last frame possibly
 114                          // being partial.
 115 } WebPFormatFeature;
 116
 117 // Get the 'feature' value from the 'dmux'.
 118 // NOTE: values are only valid if WebPDemux() was used or WebPDemuxPartial()
 119 // returned a state > WEBP_DEMUX_PARSING_HEADER.
 120 WEBP_EXTERN(uint32_t) WebPDemuxGetI(
 121     const WebPDemuxer* dmux, WebPFormatFeature feature);
 122
 123 //------------------------------------------------------------------------------
 124 // Frame iteration.
 125
 126 struct WebPIterator {
 127   int frame_num;
 128   int num_frames;          // equivalent to WEBP_FF_FRAME_COUNT.
 129   int fragment_num;
 130   int num_fragments;
 131   int x_offset, y_offset;  // offset relative to the canvas.
 132   int width, height;       // dimensions of this frame or fragment.
 133   int duration;            // display duration in milliseconds.
 134   WebPMuxAnimDispose dispose_method;  // dispose method for the frame.
 135   int complete;   // true if 'fragment' contains a full frame. partial images
 136                   // may still be decoded with the WebP incremental decoder.
 137   WebPData fragment;  // The frame or fragment given by 'frame_num' and
 138                       // 'fragment_num'.
 139
 140   uint32_t pad[4];         // padding for later use.
 141   void* private_;          // for internal use only.
 142 };
 143
 144 // Retrieves frame 'frame_number' from 'dmux'.
 145 // 'iter->fragment' points to the first fragment on return from this function.
 146 // Individual fragments may be extracted using WebPDemuxSetFragment().
 147 // Setting 'frame_number' equal to 0 will return the last frame of the image.
 148 // Returns false if 'dmux' is NULL or frame 'frame_number' is not present.
 149 // Call WebPDemuxReleaseIterator() when use of the iterator is complete.
 150 // NOTE: 'dmux' must persist for the lifetime of 'iter'.
 151 WEBP_EXTERN(int) WebPDemuxGetFrame(
 152     const WebPDemuxer* dmux, int frame_number, WebPIterator* iter);
 153
 154 // Sets 'iter->fragment' to point to the next ('iter->frame_num' + 1) or
 155 // previous ('iter->frame_num' - 1) frame. These functions do not loop.
 156 // Returns true on success, false otherwise.
 157 WEBP_EXTERN(int) WebPDemuxNextFrame(WebPIterator* iter);
 158 WEBP_EXTERN(int) WebPDemuxPrevFrame(WebPIterator* iter);
 159
 160 // Sets 'iter->fragment' to reflect fragment number 'fragment_num'.
 161 // Returns true if fragment 'fragment_num' is present, false otherwise.
 162 WEBP_EXTERN(int) WebPDemuxSelectFragment(WebPIterator* iter, int fragment_num);
 163
 164 // Releases any memory associated with 'iter'.
 165 // Must be called before any subsequent calls to WebPDemuxGetChunk() on the same
 166 // iter. Also, must be called before destroying the associated WebPDemuxer with
 167 // WebPDemuxDelete().
 168 WEBP_EXTERN(void) WebPDemuxReleaseIterator(WebPIterator* iter);
 169
 170 //------------------------------------------------------------------------------
 171 // Chunk iteration.
 172
 173 struct WebPChunkIterator {
 174   // The current and total number of chunks with the fourcc given to
 175   // WebPDemuxGetChunk().
 176   int chunk_num;
 177   int num_chunks;
 178   WebPData chunk;    // The payload of the chunk.
 179
 180   uint32_t pad[6];   // padding for later use
 181   void* private_;
 182 };
 183
 184 // Retrieves the 'chunk_number' instance of the chunk with id 'fourcc' from
 185 // 'dmux'.
 186 // 'fourcc' is a character array containing the fourcc of the chunk to return,
 187 // e.g., "ICCP", "XMP ", "EXIF", etc.
 188 // Setting 'chunk_number' equal to 0 will return the last chunk in a set.
 189 // Returns true if the chunk is found, false otherwise. Image related chunk
 190 // payloads are accessed through WebPDemuxGetFrame() and related functions.
 191 // Call WebPDemuxReleaseChunkIterator() when use of the iterator is complete.
 192 // NOTE: 'dmux' must persist for the lifetime of the iterator.
 193 WEBP_EXTERN(int) WebPDemuxGetChunk(const WebPDemuxer* dmux,
 194                                    const char fourcc[4], int chunk_number,
 195                                    WebPChunkIterator* iter);
 196
 197 // Sets 'iter->chunk' to point to the next ('iter->chunk_num' + 1) or previous
 198 // ('iter->chunk_num' - 1) chunk. These functions do not loop.
 199 // Returns true on success, false otherwise.
 200 WEBP_EXTERN(int) WebPDemuxNextChunk(WebPChunkIterator* iter);
 201 WEBP_EXTERN(int) WebPDemuxPrevChunk(WebPChunkIterator* iter);
 202
 203 // Releases any memory associated with 'iter'.
 204 // Must be called before destroying the associated WebPDemuxer with
 205 // WebPDemuxDelete().
 206 WEBP_EXTERN(void) WebPDemuxReleaseChunkIterator(WebPChunkIterator* iter);
 207
 208 //------------------------------------------------------------------------------
 209
 210 #if defined(__cplusplus) || defined(c_plusplus)
 211 }    // extern "C"
 212 #endif
 213
 214 #endif  /* WEBP_WEBP_DEMUX_H_ */