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 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;
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.
WebPDemux(const WebPData * data)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.
WebPDemuxPartial(const WebPData * data,WebPDemuxState * state)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 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'.
153 WEBP_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.
159 WEBP_EXTERN(int) WebPDemuxNextFrame(WebPIterator* iter);
160 WEBP_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.
164 WEBP_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().
170 WEBP_EXTERN(void) WebPDemuxReleaseIterator(WebPIterator* iter);
171
172 //------------------------------------------------------------------------------
173 // Chunk iteration.
174
175 struct 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.
195 WEBP_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.
202 WEBP_EXTERN(int) WebPDemuxNextChunk(WebPChunkIterator* iter);
203 WEBP_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().
208 WEBP_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