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