Mercurial > repos > rliterman > csp2
comparison CSP2/CSP2_env/env-d9b9114564458d9d-741b3de822f2aaca6c6caa4325c4afce/include/webp/decode.h @ 69:33d812a61356
planemo upload commit 2e9511a184a1ca667c7be0c6321a36dc4e3d116d
author | jpayne |
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date | Tue, 18 Mar 2025 17:55:14 -0400 |
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1 // Copyright 2010 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 // Main decoding functions for WebP images. | |
11 // | |
12 // Author: Skal (pascal.massimino@gmail.com) | |
13 | |
14 #ifndef WEBP_WEBP_DECODE_H_ | |
15 #define WEBP_WEBP_DECODE_H_ | |
16 | |
17 #include "./types.h" | |
18 | |
19 #ifdef __cplusplus | |
20 extern "C" { | |
21 #endif | |
22 | |
23 #define WEBP_DECODER_ABI_VERSION 0x0209 // MAJOR(8b) + MINOR(8b) | |
24 | |
25 // Note: forward declaring enumerations is not allowed in (strict) C and C++, | |
26 // the types are left here for reference. | |
27 // typedef enum VP8StatusCode VP8StatusCode; | |
28 // typedef enum WEBP_CSP_MODE WEBP_CSP_MODE; | |
29 typedef struct WebPRGBABuffer WebPRGBABuffer; | |
30 typedef struct WebPYUVABuffer WebPYUVABuffer; | |
31 typedef struct WebPDecBuffer WebPDecBuffer; | |
32 typedef struct WebPIDecoder WebPIDecoder; | |
33 typedef struct WebPBitstreamFeatures WebPBitstreamFeatures; | |
34 typedef struct WebPDecoderOptions WebPDecoderOptions; | |
35 typedef struct WebPDecoderConfig WebPDecoderConfig; | |
36 | |
37 // Return the decoder's version number, packed in hexadecimal using 8bits for | |
38 // each of major/minor/revision. E.g: v2.5.7 is 0x020507. | |
39 WEBP_EXTERN int WebPGetDecoderVersion(void); | |
40 | |
41 // Retrieve basic header information: width, height. | |
42 // This function will also validate the header, returning true on success, | |
43 // false otherwise. '*width' and '*height' are only valid on successful return. | |
44 // Pointers 'width' and 'height' can be passed NULL if deemed irrelevant. | |
45 // Note: The following chunk sequences (before the raw VP8/VP8L data) are | |
46 // considered valid by this function: | |
47 // RIFF + VP8(L) | |
48 // RIFF + VP8X + (optional chunks) + VP8(L) | |
49 // ALPH + VP8 <-- Not a valid WebP format: only allowed for internal purpose. | |
50 // VP8(L) <-- Not a valid WebP format: only allowed for internal purpose. | |
51 WEBP_NODISCARD WEBP_EXTERN int WebPGetInfo( | |
52 const uint8_t* data, size_t data_size, int* width, int* height); | |
53 | |
54 // Decodes WebP images pointed to by 'data' and returns RGBA samples, along | |
55 // with the dimensions in *width and *height. The ordering of samples in | |
56 // memory is R, G, B, A, R, G, B, A... in scan order (endian-independent). | |
57 // The returned pointer should be deleted calling WebPFree(). | |
58 // Returns NULL in case of error. | |
59 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeRGBA( | |
60 const uint8_t* data, size_t data_size, int* width, int* height); | |
61 | |
62 // Same as WebPDecodeRGBA, but returning A, R, G, B, A, R, G, B... ordered data. | |
63 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeARGB( | |
64 const uint8_t* data, size_t data_size, int* width, int* height); | |
65 | |
66 // Same as WebPDecodeRGBA, but returning B, G, R, A, B, G, R, A... ordered data. | |
67 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeBGRA( | |
68 const uint8_t* data, size_t data_size, int* width, int* height); | |
69 | |
70 // Same as WebPDecodeRGBA, but returning R, G, B, R, G, B... ordered data. | |
71 // If the bitstream contains transparency, it is ignored. | |
72 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeRGB( | |
73 const uint8_t* data, size_t data_size, int* width, int* height); | |
74 | |
75 // Same as WebPDecodeRGB, but returning B, G, R, B, G, R... ordered data. | |
76 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeBGR( | |
77 const uint8_t* data, size_t data_size, int* width, int* height); | |
78 | |
79 // Decode WebP images pointed to by 'data' to Y'UV format(*). The pointer | |
80 // returned is the Y samples buffer. Upon return, *u and *v will point to | |
81 // the U and V chroma data. These U and V buffers need NOT be passed to | |
82 // WebPFree(), unlike the returned Y luma one. The dimension of the U and V | |
83 // planes are both (*width + 1) / 2 and (*height + 1) / 2. | |
84 // Upon return, the Y buffer has a stride returned as '*stride', while U and V | |
85 // have a common stride returned as '*uv_stride'. | |
86 // 'width' and 'height' may be NULL, the other pointers must not be. | |
87 // Returns NULL in case of error. | |
88 // (*) Also named Y'CbCr. See: https://en.wikipedia.org/wiki/YCbCr | |
89 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeYUV( | |
90 const uint8_t* data, size_t data_size, int* width, int* height, | |
91 uint8_t** u, uint8_t** v, int* stride, int* uv_stride); | |
92 | |
93 // These five functions are variants of the above ones, that decode the image | |
94 // directly into a pre-allocated buffer 'output_buffer'. The maximum storage | |
95 // available in this buffer is indicated by 'output_buffer_size'. If this | |
96 // storage is not sufficient (or an error occurred), NULL is returned. | |
97 // Otherwise, output_buffer is returned, for convenience. | |
98 // The parameter 'output_stride' specifies the distance (in bytes) | |
99 // between scanlines. Hence, output_buffer_size is expected to be at least | |
100 // output_stride x picture-height. | |
101 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeRGBAInto( | |
102 const uint8_t* data, size_t data_size, | |
103 uint8_t* output_buffer, size_t output_buffer_size, int output_stride); | |
104 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeARGBInto( | |
105 const uint8_t* data, size_t data_size, | |
106 uint8_t* output_buffer, size_t output_buffer_size, int output_stride); | |
107 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeBGRAInto( | |
108 const uint8_t* data, size_t data_size, | |
109 uint8_t* output_buffer, size_t output_buffer_size, int output_stride); | |
110 | |
111 // RGB and BGR variants. Here too the transparency information, if present, | |
112 // will be dropped and ignored. | |
113 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeRGBInto( | |
114 const uint8_t* data, size_t data_size, | |
115 uint8_t* output_buffer, size_t output_buffer_size, int output_stride); | |
116 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeBGRInto( | |
117 const uint8_t* data, size_t data_size, | |
118 uint8_t* output_buffer, size_t output_buffer_size, int output_stride); | |
119 | |
120 // WebPDecodeYUVInto() is a variant of WebPDecodeYUV() that operates directly | |
121 // into pre-allocated luma/chroma plane buffers. This function requires the | |
122 // strides to be passed: one for the luma plane and one for each of the | |
123 // chroma ones. The size of each plane buffer is passed as 'luma_size', | |
124 // 'u_size' and 'v_size' respectively. | |
125 // Pointer to the luma plane ('*luma') is returned or NULL if an error occurred | |
126 // during decoding (or because some buffers were found to be too small). | |
127 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPDecodeYUVInto( | |
128 const uint8_t* data, size_t data_size, | |
129 uint8_t* luma, size_t luma_size, int luma_stride, | |
130 uint8_t* u, size_t u_size, int u_stride, | |
131 uint8_t* v, size_t v_size, int v_stride); | |
132 | |
133 //------------------------------------------------------------------------------ | |
134 // Output colorspaces and buffer | |
135 | |
136 // Colorspaces | |
137 // Note: the naming describes the byte-ordering of packed samples in memory. | |
138 // For instance, MODE_BGRA relates to samples ordered as B,G,R,A,B,G,R,A,... | |
139 // Non-capital names (e.g.:MODE_Argb) relates to pre-multiplied RGB channels. | |
140 // RGBA-4444 and RGB-565 colorspaces are represented by following byte-order: | |
141 // RGBA-4444: [r3 r2 r1 r0 g3 g2 g1 g0], [b3 b2 b1 b0 a3 a2 a1 a0], ... | |
142 // RGB-565: [r4 r3 r2 r1 r0 g5 g4 g3], [g2 g1 g0 b4 b3 b2 b1 b0], ... | |
143 // In the case WEBP_SWAP_16BITS_CSP is defined, the bytes are swapped for | |
144 // these two modes: | |
145 // RGBA-4444: [b3 b2 b1 b0 a3 a2 a1 a0], [r3 r2 r1 r0 g3 g2 g1 g0], ... | |
146 // RGB-565: [g2 g1 g0 b4 b3 b2 b1 b0], [r4 r3 r2 r1 r0 g5 g4 g3], ... | |
147 | |
148 typedef enum WEBP_CSP_MODE { | |
149 MODE_RGB = 0, MODE_RGBA = 1, | |
150 MODE_BGR = 2, MODE_BGRA = 3, | |
151 MODE_ARGB = 4, MODE_RGBA_4444 = 5, | |
152 MODE_RGB_565 = 6, | |
153 // RGB-premultiplied transparent modes (alpha value is preserved) | |
154 MODE_rgbA = 7, | |
155 MODE_bgrA = 8, | |
156 MODE_Argb = 9, | |
157 MODE_rgbA_4444 = 10, | |
158 // YUV modes must come after RGB ones. | |
159 MODE_YUV = 11, MODE_YUVA = 12, // yuv 4:2:0 | |
160 MODE_LAST = 13 | |
161 } WEBP_CSP_MODE; | |
162 | |
163 // Some useful macros: | |
164 static WEBP_INLINE int WebPIsPremultipliedMode(WEBP_CSP_MODE mode) { | |
165 return (mode == MODE_rgbA || mode == MODE_bgrA || mode == MODE_Argb || | |
166 mode == MODE_rgbA_4444); | |
167 } | |
168 | |
169 static WEBP_INLINE int WebPIsAlphaMode(WEBP_CSP_MODE mode) { | |
170 return (mode == MODE_RGBA || mode == MODE_BGRA || mode == MODE_ARGB || | |
171 mode == MODE_RGBA_4444 || mode == MODE_YUVA || | |
172 WebPIsPremultipliedMode(mode)); | |
173 } | |
174 | |
175 static WEBP_INLINE int WebPIsRGBMode(WEBP_CSP_MODE mode) { | |
176 return (mode < MODE_YUV); | |
177 } | |
178 | |
179 //------------------------------------------------------------------------------ | |
180 // WebPDecBuffer: Generic structure for describing the output sample buffer. | |
181 | |
182 struct WebPRGBABuffer { // view as RGBA | |
183 uint8_t* rgba; // pointer to RGBA samples | |
184 int stride; // stride in bytes from one scanline to the next. | |
185 size_t size; // total size of the *rgba buffer. | |
186 }; | |
187 | |
188 struct WebPYUVABuffer { // view as YUVA | |
189 uint8_t* y, *u, *v, *a; // pointer to luma, chroma U/V, alpha samples | |
190 int y_stride; // luma stride | |
191 int u_stride, v_stride; // chroma strides | |
192 int a_stride; // alpha stride | |
193 size_t y_size; // luma plane size | |
194 size_t u_size, v_size; // chroma planes size | |
195 size_t a_size; // alpha-plane size | |
196 }; | |
197 | |
198 // Output buffer | |
199 struct WebPDecBuffer { | |
200 WEBP_CSP_MODE colorspace; // Colorspace. | |
201 int width, height; // Dimensions. | |
202 int is_external_memory; // If non-zero, 'internal_memory' pointer is not | |
203 // used. If value is '2' or more, the external | |
204 // memory is considered 'slow' and multiple | |
205 // read/write will be avoided. | |
206 union { | |
207 WebPRGBABuffer RGBA; | |
208 WebPYUVABuffer YUVA; | |
209 } u; // Nameless union of buffer parameters. | |
210 uint32_t pad[4]; // padding for later use | |
211 | |
212 uint8_t* private_memory; // Internally allocated memory (only when | |
213 // is_external_memory is 0). Should not be used | |
214 // externally, but accessed via the buffer union. | |
215 }; | |
216 | |
217 // Internal, version-checked, entry point | |
218 WEBP_NODISCARD WEBP_EXTERN int WebPInitDecBufferInternal(WebPDecBuffer*, int); | |
219 | |
220 // Initialize the structure as empty. Must be called before any other use. | |
221 // Returns false in case of version mismatch | |
222 WEBP_NODISCARD static WEBP_INLINE int WebPInitDecBuffer(WebPDecBuffer* buffer) { | |
223 return WebPInitDecBufferInternal(buffer, WEBP_DECODER_ABI_VERSION); | |
224 } | |
225 | |
226 // Free any memory associated with the buffer. Must always be called last. | |
227 // Note: doesn't free the 'buffer' structure itself. | |
228 WEBP_EXTERN void WebPFreeDecBuffer(WebPDecBuffer* buffer); | |
229 | |
230 //------------------------------------------------------------------------------ | |
231 // Enumeration of the status codes | |
232 | |
233 typedef enum WEBP_NODISCARD VP8StatusCode { | |
234 VP8_STATUS_OK = 0, | |
235 VP8_STATUS_OUT_OF_MEMORY, | |
236 VP8_STATUS_INVALID_PARAM, | |
237 VP8_STATUS_BITSTREAM_ERROR, | |
238 VP8_STATUS_UNSUPPORTED_FEATURE, | |
239 VP8_STATUS_SUSPENDED, | |
240 VP8_STATUS_USER_ABORT, | |
241 VP8_STATUS_NOT_ENOUGH_DATA | |
242 } VP8StatusCode; | |
243 | |
244 //------------------------------------------------------------------------------ | |
245 // Incremental decoding | |
246 // | |
247 // This API allows streamlined decoding of partial data. | |
248 // Picture can be incrementally decoded as data become available thanks to the | |
249 // WebPIDecoder object. This object can be left in a SUSPENDED state if the | |
250 // picture is only partially decoded, pending additional input. | |
251 // Code example: | |
252 /* | |
253 WebPInitDecBuffer(&output_buffer); | |
254 output_buffer.colorspace = mode; | |
255 ... | |
256 WebPIDecoder* idec = WebPINewDecoder(&output_buffer); | |
257 while (additional_data_is_available) { | |
258 // ... (get additional data in some new_data[] buffer) | |
259 status = WebPIAppend(idec, new_data, new_data_size); | |
260 if (status != VP8_STATUS_OK && status != VP8_STATUS_SUSPENDED) { | |
261 break; // an error occurred. | |
262 } | |
263 | |
264 // The above call decodes the current available buffer. | |
265 // Part of the image can now be refreshed by calling | |
266 // WebPIDecGetRGB()/WebPIDecGetYUVA() etc. | |
267 } | |
268 WebPIDelete(idec); | |
269 */ | |
270 | |
271 // Creates a new incremental decoder with the supplied buffer parameter. | |
272 // This output_buffer can be passed NULL, in which case a default output buffer | |
273 // is used (with MODE_RGB). Otherwise, an internal reference to 'output_buffer' | |
274 // is kept, which means that the lifespan of 'output_buffer' must be larger than | |
275 // that of the returned WebPIDecoder object. | |
276 // The supplied 'output_buffer' content MUST NOT be changed between calls to | |
277 // WebPIAppend() or WebPIUpdate() unless 'output_buffer.is_external_memory' is | |
278 // not set to 0. In such a case, it is allowed to modify the pointers, size and | |
279 // stride of output_buffer.u.RGBA or output_buffer.u.YUVA, provided they remain | |
280 // within valid bounds. | |
281 // All other fields of WebPDecBuffer MUST remain constant between calls. | |
282 // Returns NULL if the allocation failed. | |
283 WEBP_NODISCARD WEBP_EXTERN WebPIDecoder* WebPINewDecoder( | |
284 WebPDecBuffer* output_buffer); | |
285 | |
286 // This function allocates and initializes an incremental-decoder object, which | |
287 // will output the RGB/A samples specified by 'csp' into a preallocated | |
288 // buffer 'output_buffer'. The size of this buffer is at least | |
289 // 'output_buffer_size' and the stride (distance in bytes between two scanlines) | |
290 // is specified by 'output_stride'. | |
291 // Additionally, output_buffer can be passed NULL in which case the output | |
292 // buffer will be allocated automatically when the decoding starts. The | |
293 // colorspace 'csp' is taken into account for allocating this buffer. All other | |
294 // parameters are ignored. | |
295 // Returns NULL if the allocation failed, or if some parameters are invalid. | |
296 WEBP_NODISCARD WEBP_EXTERN WebPIDecoder* WebPINewRGB( | |
297 WEBP_CSP_MODE csp, | |
298 uint8_t* output_buffer, size_t output_buffer_size, int output_stride); | |
299 | |
300 // This function allocates and initializes an incremental-decoder object, which | |
301 // will output the raw luma/chroma samples into a preallocated planes if | |
302 // supplied. The luma plane is specified by its pointer 'luma', its size | |
303 // 'luma_size' and its stride 'luma_stride'. Similarly, the chroma-u plane | |
304 // is specified by the 'u', 'u_size' and 'u_stride' parameters, and the chroma-v | |
305 // plane by 'v' and 'v_size'. And same for the alpha-plane. The 'a' pointer | |
306 // can be pass NULL in case one is not interested in the transparency plane. | |
307 // Conversely, 'luma' can be passed NULL if no preallocated planes are supplied. | |
308 // In this case, the output buffer will be automatically allocated (using | |
309 // MODE_YUVA) when decoding starts. All parameters are then ignored. | |
310 // Returns NULL if the allocation failed or if a parameter is invalid. | |
311 WEBP_NODISCARD WEBP_EXTERN WebPIDecoder* WebPINewYUVA( | |
312 uint8_t* luma, size_t luma_size, int luma_stride, | |
313 uint8_t* u, size_t u_size, int u_stride, | |
314 uint8_t* v, size_t v_size, int v_stride, | |
315 uint8_t* a, size_t a_size, int a_stride); | |
316 | |
317 // Deprecated version of the above, without the alpha plane. | |
318 // Kept for backward compatibility. | |
319 WEBP_NODISCARD WEBP_EXTERN WebPIDecoder* WebPINewYUV( | |
320 uint8_t* luma, size_t luma_size, int luma_stride, | |
321 uint8_t* u, size_t u_size, int u_stride, | |
322 uint8_t* v, size_t v_size, int v_stride); | |
323 | |
324 // Deletes the WebPIDecoder object and associated memory. Must always be called | |
325 // if WebPINewDecoder, WebPINewRGB or WebPINewYUV succeeded. | |
326 WEBP_EXTERN void WebPIDelete(WebPIDecoder* idec); | |
327 | |
328 // Copies and decodes the next available data. Returns VP8_STATUS_OK when | |
329 // the image is successfully decoded. Returns VP8_STATUS_SUSPENDED when more | |
330 // data is expected. Returns error in other cases. | |
331 WEBP_EXTERN VP8StatusCode WebPIAppend( | |
332 WebPIDecoder* idec, const uint8_t* data, size_t data_size); | |
333 | |
334 // A variant of the above function to be used when data buffer contains | |
335 // partial data from the beginning. In this case data buffer is not copied | |
336 // to the internal memory. | |
337 // Note that the value of the 'data' pointer can change between calls to | |
338 // WebPIUpdate, for instance when the data buffer is resized to fit larger data. | |
339 WEBP_EXTERN VP8StatusCode WebPIUpdate( | |
340 WebPIDecoder* idec, const uint8_t* data, size_t data_size); | |
341 | |
342 // Returns the RGB/A image decoded so far. Returns NULL if output params | |
343 // are not initialized yet. The RGB/A output type corresponds to the colorspace | |
344 // specified during call to WebPINewDecoder() or WebPINewRGB(). | |
345 // *last_y is the index of last decoded row in raster scan order. Some pointers | |
346 // (*last_y, *width etc.) can be NULL if corresponding information is not | |
347 // needed. The values in these pointers are only valid on successful (non-NULL) | |
348 // return. | |
349 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPIDecGetRGB( | |
350 const WebPIDecoder* idec, int* last_y, | |
351 int* width, int* height, int* stride); | |
352 | |
353 // Same as above function to get a YUVA image. Returns pointer to the luma | |
354 // plane or NULL in case of error. If there is no alpha information | |
355 // the alpha pointer '*a' will be returned NULL. | |
356 WEBP_NODISCARD WEBP_EXTERN uint8_t* WebPIDecGetYUVA( | |
357 const WebPIDecoder* idec, int* last_y, | |
358 uint8_t** u, uint8_t** v, uint8_t** a, | |
359 int* width, int* height, int* stride, int* uv_stride, int* a_stride); | |
360 | |
361 // Deprecated alpha-less version of WebPIDecGetYUVA(): it will ignore the | |
362 // alpha information (if present). Kept for backward compatibility. | |
363 WEBP_NODISCARD static WEBP_INLINE uint8_t* WebPIDecGetYUV( | |
364 const WebPIDecoder* idec, int* last_y, uint8_t** u, uint8_t** v, | |
365 int* width, int* height, int* stride, int* uv_stride) { | |
366 return WebPIDecGetYUVA(idec, last_y, u, v, NULL, width, height, | |
367 stride, uv_stride, NULL); | |
368 } | |
369 | |
370 // Generic call to retrieve information about the displayable area. | |
371 // If non NULL, the left/right/width/height pointers are filled with the visible | |
372 // rectangular area so far. | |
373 // Returns NULL in case the incremental decoder object is in an invalid state. | |
374 // Otherwise returns the pointer to the internal representation. This structure | |
375 // is read-only, tied to WebPIDecoder's lifespan and should not be modified. | |
376 WEBP_NODISCARD WEBP_EXTERN const WebPDecBuffer* WebPIDecodedArea( | |
377 const WebPIDecoder* idec, int* left, int* top, int* width, int* height); | |
378 | |
379 //------------------------------------------------------------------------------ | |
380 // Advanced decoding parametrization | |
381 // | |
382 // Code sample for using the advanced decoding API | |
383 /* | |
384 // A) Init a configuration object | |
385 WebPDecoderConfig config; | |
386 CHECK(WebPInitDecoderConfig(&config)); | |
387 | |
388 // B) optional: retrieve the bitstream's features. | |
389 CHECK(WebPGetFeatures(data, data_size, &config.input) == VP8_STATUS_OK); | |
390 | |
391 // C) Adjust 'config', if needed | |
392 config.options.no_fancy_upsampling = 1; | |
393 config.output.colorspace = MODE_BGRA; | |
394 // etc. | |
395 | |
396 // Note that you can also make config.output point to an externally | |
397 // supplied memory buffer, provided it's big enough to store the decoded | |
398 // picture. Otherwise, config.output will just be used to allocate memory | |
399 // and store the decoded picture. | |
400 | |
401 // D) Decode! | |
402 CHECK(WebPDecode(data, data_size, &config) == VP8_STATUS_OK); | |
403 | |
404 // E) Decoded image is now in config.output (and config.output.u.RGBA) | |
405 | |
406 // F) Reclaim memory allocated in config's object. It's safe to call | |
407 // this function even if the memory is external and wasn't allocated | |
408 // by WebPDecode(). | |
409 WebPFreeDecBuffer(&config.output); | |
410 */ | |
411 | |
412 // Features gathered from the bitstream | |
413 struct WebPBitstreamFeatures { | |
414 int width; // Width in pixels, as read from the bitstream. | |
415 int height; // Height in pixels, as read from the bitstream. | |
416 int has_alpha; // True if the bitstream contains an alpha channel. | |
417 int has_animation; // True if the bitstream is an animation. | |
418 int format; // 0 = undefined (/mixed), 1 = lossy, 2 = lossless | |
419 | |
420 uint32_t pad[5]; // padding for later use | |
421 }; | |
422 | |
423 // Internal, version-checked, entry point | |
424 WEBP_EXTERN VP8StatusCode WebPGetFeaturesInternal( | |
425 const uint8_t*, size_t, WebPBitstreamFeatures*, int); | |
426 | |
427 // Retrieve features from the bitstream. The *features structure is filled | |
428 // with information gathered from the bitstream. | |
429 // Returns VP8_STATUS_OK when the features are successfully retrieved. Returns | |
430 // VP8_STATUS_NOT_ENOUGH_DATA when more data is needed to retrieve the | |
431 // features from headers. Returns error in other cases. | |
432 // Note: The following chunk sequences (before the raw VP8/VP8L data) are | |
433 // considered valid by this function: | |
434 // RIFF + VP8(L) | |
435 // RIFF + VP8X + (optional chunks) + VP8(L) | |
436 // ALPH + VP8 <-- Not a valid WebP format: only allowed for internal purpose. | |
437 // VP8(L) <-- Not a valid WebP format: only allowed for internal purpose. | |
438 static WEBP_INLINE VP8StatusCode WebPGetFeatures( | |
439 const uint8_t* data, size_t data_size, | |
440 WebPBitstreamFeatures* features) { | |
441 return WebPGetFeaturesInternal(data, data_size, features, | |
442 WEBP_DECODER_ABI_VERSION); | |
443 } | |
444 | |
445 // Decoding options | |
446 struct WebPDecoderOptions { | |
447 int bypass_filtering; // if true, skip the in-loop filtering | |
448 int no_fancy_upsampling; // if true, use faster pointwise upsampler | |
449 int use_cropping; // if true, cropping is applied _first_ | |
450 int crop_left, crop_top; // top-left position for cropping. | |
451 // Will be snapped to even values. | |
452 int crop_width, crop_height; // dimension of the cropping area | |
453 int use_scaling; // if true, scaling is applied _afterward_ | |
454 int scaled_width, scaled_height; // final resolution | |
455 int use_threads; // if true, use multi-threaded decoding | |
456 int dithering_strength; // dithering strength (0=Off, 100=full) | |
457 int flip; // if true, flip output vertically | |
458 int alpha_dithering_strength; // alpha dithering strength in [0..100] | |
459 | |
460 uint32_t pad[5]; // padding for later use | |
461 }; | |
462 | |
463 // Main object storing the configuration for advanced decoding. | |
464 struct WebPDecoderConfig { | |
465 WebPBitstreamFeatures input; // Immutable bitstream features (optional) | |
466 WebPDecBuffer output; // Output buffer (can point to external mem) | |
467 WebPDecoderOptions options; // Decoding options | |
468 }; | |
469 | |
470 // Internal, version-checked, entry point | |
471 WEBP_NODISCARD WEBP_EXTERN int WebPInitDecoderConfigInternal(WebPDecoderConfig*, | |
472 int); | |
473 | |
474 // Initialize the configuration as empty. This function must always be | |
475 // called first, unless WebPGetFeatures() is to be called. | |
476 // Returns false in case of mismatched version. | |
477 WEBP_NODISCARD static WEBP_INLINE int WebPInitDecoderConfig( | |
478 WebPDecoderConfig* config) { | |
479 return WebPInitDecoderConfigInternal(config, WEBP_DECODER_ABI_VERSION); | |
480 } | |
481 | |
482 // Instantiate a new incremental decoder object with the requested | |
483 // configuration. The bitstream can be passed using 'data' and 'data_size' | |
484 // parameter, in which case the features will be parsed and stored into | |
485 // config->input. Otherwise, 'data' can be NULL and no parsing will occur. | |
486 // Note that 'config' can be NULL too, in which case a default configuration | |
487 // is used. If 'config' is not NULL, it must outlive the WebPIDecoder object | |
488 // as some references to its fields will be used. No internal copy of 'config' | |
489 // is made. | |
490 // The return WebPIDecoder object must always be deleted calling WebPIDelete(). | |
491 // Returns NULL in case of error (and config->status will then reflect | |
492 // the error condition, if available). | |
493 WEBP_NODISCARD WEBP_EXTERN WebPIDecoder* WebPIDecode( | |
494 const uint8_t* data, size_t data_size, WebPDecoderConfig* config); | |
495 | |
496 // Non-incremental version. This version decodes the full data at once, taking | |
497 // 'config' into account. Returns decoding status (which should be VP8_STATUS_OK | |
498 // if the decoding was successful). Note that 'config' cannot be NULL. | |
499 WEBP_EXTERN VP8StatusCode WebPDecode(const uint8_t* data, size_t data_size, | |
500 WebPDecoderConfig* config); | |
501 | |
502 #ifdef __cplusplus | |
503 } // extern "C" | |
504 #endif | |
505 | |
506 #endif // WEBP_WEBP_DECODE_H_ |