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)
53extern "C" {
54#endif
55
56#define WEBP_DEMUX_ABI_VERSION 0x0101    // 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;
62typedef struct WebPDemuxer WebPDemuxer;
63typedef struct WebPIterator WebPIterator;
64typedef 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.
70WEBP_EXTERN(int) WebPGetDemuxVersion(void);
71
72//------------------------------------------------------------------------------
73// Life of a Demux object
74
75typedef 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
82WEBP_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.
87static 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.
94static 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'.
100WEBP_EXTERN(void) WebPDemuxDelete(WebPDemuxer* dmux);
101
102//------------------------------------------------------------------------------
103// Data/information extraction.
104
105typedef 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.
120WEBP_EXTERN(uint32_t) WebPDemuxGetI(
121    const WebPDemuxer* dmux, WebPFormatFeature feature);
122
123//------------------------------------------------------------------------------
124// Frame iteration.
125
126struct 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  int has_alpha;      // True if the frame or fragment contains transparency.
140  WebPMuxAnimBlend blend_method;  // Blend operation for the frame.
141
142  uint32_t pad[2];         // padding for later use.
143  void* private_;          // for internal use only.
144};
145
146// Retrieves frame 'frame_number' from 'dmux'.
147// 'iter->fragment' points to the first fragment on return from this function.
148// Individual fragments may be extracted using WebPDemuxSetFragment().
149// Setting 'frame_number' equal to 0 will return the last frame of the image.
150// Returns false if 'dmux' is NULL or frame 'frame_number' is not present.
151// Call WebPDemuxReleaseIterator() when use of the iterator is complete.
152// NOTE: 'dmux' must persist for the lifetime of 'iter'.
153WEBP_EXTERN(int) WebPDemuxGetFrame(
154    const WebPDemuxer* dmux, int frame_number, WebPIterator* iter);
155
156// Sets 'iter->fragment' to point to the next ('iter->frame_num' + 1) or
157// previous ('iter->frame_num' - 1) frame. These functions do not loop.
158// Returns true on success, false otherwise.
159WEBP_EXTERN(int) WebPDemuxNextFrame(WebPIterator* iter);
160WEBP_EXTERN(int) WebPDemuxPrevFrame(WebPIterator* iter);
161
162// Sets 'iter->fragment' to reflect fragment number 'fragment_num'.
163// Returns true if fragment 'fragment_num' is present, false otherwise.
164WEBP_EXTERN(int) WebPDemuxSelectFragment(WebPIterator* iter, int fragment_num);
165
166// Releases any memory associated with 'iter'.
167// Must be called before any subsequent calls to WebPDemuxGetChunk() on the same
168// iter. Also, must be called before destroying the associated WebPDemuxer with
169// WebPDemuxDelete().
170WEBP_EXTERN(void) WebPDemuxReleaseIterator(WebPIterator* iter);
171
172//------------------------------------------------------------------------------
173// Chunk iteration.
174
175struct WebPChunkIterator {
176  // The current and total number of chunks with the fourcc given to
177  // WebPDemuxGetChunk().
178  int chunk_num;
179  int num_chunks;
180  WebPData chunk;    // The payload of the chunk.
181
182  uint32_t pad[6];   // padding for later use
183  void* private_;
184};
185
186// Retrieves the 'chunk_number' instance of the chunk with id 'fourcc' from
187// 'dmux'.
188// 'fourcc' is a character array containing the fourcc of the chunk to return,
189// e.g., "ICCP", "XMP ", "EXIF", etc.
190// Setting 'chunk_number' equal to 0 will return the last chunk in a set.
191// Returns true if the chunk is found, false otherwise. Image related chunk
192// payloads are accessed through WebPDemuxGetFrame() and related functions.
193// Call WebPDemuxReleaseChunkIterator() when use of the iterator is complete.
194// NOTE: 'dmux' must persist for the lifetime of the iterator.
195WEBP_EXTERN(int) WebPDemuxGetChunk(const WebPDemuxer* dmux,
196                                   const char fourcc[4], int chunk_number,
197                                   WebPChunkIterator* iter);
198
199// Sets 'iter->chunk' to point to the next ('iter->chunk_num' + 1) or previous
200// ('iter->chunk_num' - 1) chunk. These functions do not loop.
201// Returns true on success, false otherwise.
202WEBP_EXTERN(int) WebPDemuxNextChunk(WebPChunkIterator* iter);
203WEBP_EXTERN(int) WebPDemuxPrevChunk(WebPChunkIterator* iter);
204
205// Releases any memory associated with 'iter'.
206// Must be called before destroying the associated WebPDemuxer with
207// WebPDemuxDelete().
208WEBP_EXTERN(void) WebPDemuxReleaseChunkIterator(WebPChunkIterator* iter);
209
210//------------------------------------------------------------------------------
211
212#if defined(__cplusplus) || defined(c_plusplus)
213}    // extern "C"
214#endif
215
216#endif  /* WEBP_WEBP_DEMUX_H_ */
217