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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "ui/gfx/codec/jpeg_codec.h" | |
6 | |
7 #include <setjmp.h> | |
8 | |
9 #include "base/logging.h" | |
10 #include "base/memory/scoped_ptr.h" | |
11 #include "third_party/skia/include/core/SkBitmap.h" | |
12 #include "third_party/skia/include/core/SkColorPriv.h" | |
13 | |
14 extern "C" { | |
15 #if defined(USE_SYSTEM_LIBJPEG) | |
16 #include <jpeglib.h> | |
17 #elif defined(USE_LIBJPEG_TURBO) | |
18 #include "third_party/libjpeg_turbo/jpeglib.h" | |
19 #else | |
20 #include "third_party/libjpeg/jpeglib.h" | |
21 #endif | |
22 } | |
23 | |
24 namespace gfx { | |
25 | |
26 // Encoder/decoder shared stuff ------------------------------------------------ | |
27 | |
28 namespace { | |
29 | |
30 // used to pass error info through the JPEG library | |
31 struct CoderErrorMgr { | |
32 jpeg_error_mgr pub; | |
33 jmp_buf setjmp_buffer; | |
34 }; | |
35 | |
36 void ErrorExit(jpeg_common_struct* cinfo) { | |
37 CoderErrorMgr *err = reinterpret_cast<CoderErrorMgr*>(cinfo->err); | |
38 | |
39 // Return control to the setjmp point. | |
40 longjmp(err->setjmp_buffer, false); | |
41 } | |
42 | |
43 } // namespace | |
44 | |
45 // This method helps identify at run time which library chromium is using. | |
46 JPEGCodec::LibraryVariant JPEGCodec::JpegLibraryVariant() { | |
47 #if defined(USE_SYSTEM_LIBJPEG) | |
48 return SYSTEM_LIBJPEG; | |
49 #elif defined(USE_LIBJPEG_TURBO) | |
50 return LIBJPEG_TURBO; | |
51 #else | |
52 return IJG_LIBJPEG; | |
53 #endif | |
54 } | |
55 | |
56 // Encoder --------------------------------------------------------------------- | |
57 // | |
58 // This code is based on nsJPEGEncoder from Mozilla. | |
59 // Copyright 2005 Google Inc. (Brett Wilson, contributor) | |
60 | |
61 namespace { | |
62 | |
63 // Initial size for the output buffer in the JpegEncoderState below. | |
64 static const int initial_output_buffer_size = 8192; | |
65 | |
66 struct JpegEncoderState { | |
67 explicit JpegEncoderState(std::vector<unsigned char>* o) | |
68 : out(o), | |
69 image_buffer_used(0) { | |
70 } | |
71 | |
72 // Output buffer, of which 'image_buffer_used' bytes are actually used (this | |
73 // will often be less than the actual size of the vector because we size it | |
74 // so that libjpeg can write directly into it. | |
75 std::vector<unsigned char>* out; | |
76 | |
77 // Number of bytes in the 'out' buffer that are actually used (see above). | |
78 size_t image_buffer_used; | |
79 }; | |
80 | |
81 // Initializes the JpegEncoderState for encoding, and tells libjpeg about where | |
82 // the output buffer is. | |
83 // | |
84 // From the JPEG library: | |
85 // "Initialize destination. This is called by jpeg_start_compress() before | |
86 // any data is actually written. It must initialize next_output_byte and | |
87 // free_in_buffer. free_in_buffer must be initialized to a positive value." | |
88 void InitDestination(jpeg_compress_struct* cinfo) { | |
89 JpegEncoderState* state = static_cast<JpegEncoderState*>(cinfo->client_data); | |
90 DCHECK(state->image_buffer_used == 0) << "initializing after use"; | |
91 | |
92 state->out->resize(initial_output_buffer_size); | |
93 state->image_buffer_used = 0; | |
94 | |
95 cinfo->dest->next_output_byte = &(*state->out)[0]; | |
96 cinfo->dest->free_in_buffer = initial_output_buffer_size; | |
97 } | |
98 | |
99 // Resize the buffer that we give to libjpeg and update our and its state. | |
100 // | |
101 // From the JPEG library: | |
102 // "Callback used by libjpeg whenever the buffer has filled (free_in_buffer | |
103 // reaches zero). In typical applications, it should write out the *entire* | |
104 // buffer (use the saved start address and buffer length; ignore the current | |
105 // state of next_output_byte and free_in_buffer). Then reset the pointer & | |
106 // count to the start of the buffer, and return TRUE indicating that the | |
107 // buffer has been dumped. free_in_buffer must be set to a positive value | |
108 // when TRUE is returned. A FALSE return should only be used when I/O | |
109 // suspension is desired (this operating mode is discussed in the next | |
110 // section)." | |
111 boolean EmptyOutputBuffer(jpeg_compress_struct* cinfo) { | |
112 JpegEncoderState* state = static_cast<JpegEncoderState*>(cinfo->client_data); | |
113 | |
114 // note the new size, the buffer is full | |
115 state->image_buffer_used = state->out->size(); | |
116 | |
117 // expand buffer, just double size each time | |
118 state->out->resize(state->out->size() * 2); | |
119 | |
120 // tell libjpeg where to write the next data | |
121 cinfo->dest->next_output_byte = &(*state->out)[state->image_buffer_used]; | |
122 cinfo->dest->free_in_buffer = state->out->size() - state->image_buffer_used; | |
123 return 1; | |
124 } | |
125 | |
126 // Cleans up the JpegEncoderState to prepare for returning in the final form. | |
127 // | |
128 // From the JPEG library: | |
129 // "Terminate destination --- called by jpeg_finish_compress() after all data | |
130 // has been written. In most applications, this must flush any data | |
131 // remaining in the buffer. Use either next_output_byte or free_in_buffer to | |
132 // determine how much data is in the buffer." | |
133 void TermDestination(jpeg_compress_struct* cinfo) { | |
134 JpegEncoderState* state = static_cast<JpegEncoderState*>(cinfo->client_data); | |
135 DCHECK(state->out->size() >= state->image_buffer_used); | |
136 | |
137 // update the used byte based on the next byte libjpeg would write to | |
138 state->image_buffer_used = cinfo->dest->next_output_byte - &(*state->out)[0]; | |
139 DCHECK(state->image_buffer_used < state->out->size()) << | |
140 "JPEG library busted, got a bad image buffer size"; | |
141 | |
142 // update our buffer so that it exactly encompases the desired data | |
143 state->out->resize(state->image_buffer_used); | |
144 } | |
145 | |
146 #if !defined(JCS_EXTENSIONS) | |
147 // Converts RGBA to RGB (removing the alpha values) to prepare to send data to | |
148 // libjpeg. This converts one row of data in rgba with the given width in | |
149 // pixels the the given rgb destination buffer (which should have enough space | |
150 // reserved for the final data). | |
151 void StripAlpha(const unsigned char* rgba, int pixel_width, unsigned char* rgb) | |
152 { | |
153 for (int x = 0; x < pixel_width; x++) | |
154 memcpy(&rgb[x * 3], &rgba[x * 4], 3); | |
155 } | |
156 | |
157 // Converts BGRA to RGB by reordering the color components and dropping the | |
158 // alpha. This converts one row of data in rgba with the given width in | |
159 // pixels the the given rgb destination buffer (which should have enough space | |
160 // reserved for the final data). | |
161 void BGRAtoRGB(const unsigned char* bgra, int pixel_width, unsigned char* rgb) | |
162 { | |
163 for (int x = 0; x < pixel_width; x++) { | |
164 const unsigned char* pixel_in = &bgra[x * 4]; | |
165 unsigned char* pixel_out = &rgb[x * 3]; | |
166 pixel_out[0] = pixel_in[2]; | |
167 pixel_out[1] = pixel_in[1]; | |
168 pixel_out[2] = pixel_in[0]; | |
169 } | |
170 } | |
171 #endif // !defined(JCS_EXTENSIONS) | |
172 | |
173 // This class destroys the given jpeg_compress object when it goes out of | |
174 // scope. It simplifies the error handling in Encode (and even applies to the | |
175 // success case). | |
176 class CompressDestroyer { | |
177 public: | |
178 CompressDestroyer() : cinfo_(NULL) { | |
179 } | |
180 ~CompressDestroyer() { | |
181 DestroyManagedObject(); | |
182 } | |
183 void SetManagedObject(jpeg_compress_struct* ci) { | |
184 DestroyManagedObject(); | |
185 cinfo_ = ci; | |
186 } | |
187 void DestroyManagedObject() { | |
188 if (cinfo_) { | |
189 jpeg_destroy_compress(cinfo_); | |
190 cinfo_ = NULL; | |
191 } | |
192 } | |
193 private: | |
194 jpeg_compress_struct* cinfo_; | |
195 }; | |
196 | |
197 } // namespace | |
198 | |
199 bool JPEGCodec::Encode(const unsigned char* input, ColorFormat format, | |
200 int w, int h, int row_byte_width, | |
201 int quality, std::vector<unsigned char>* output) { | |
202 jpeg_compress_struct cinfo; | |
203 CompressDestroyer destroyer; | |
204 destroyer.SetManagedObject(&cinfo); | |
205 output->clear(); | |
206 #if !defined(JCS_EXTENSIONS) | |
207 unsigned char* row_buffer = NULL; | |
208 #endif | |
209 | |
210 // We set up the normal JPEG error routines, then override error_exit. | |
211 // This must be done before the call to create_compress. | |
212 CoderErrorMgr errmgr; | |
213 cinfo.err = jpeg_std_error(&errmgr.pub); | |
214 errmgr.pub.error_exit = ErrorExit; | |
215 | |
216 // Establish the setjmp return context for ErrorExit to use. | |
217 if (setjmp(errmgr.setjmp_buffer)) { | |
218 // If we get here, the JPEG code has signaled an error. | |
219 // MSDN notes: "if you intend your code to be portable, do not rely on | |
220 // correct destruction of frame-based objects when executing a nonlocal | |
221 // goto using a call to longjmp." So we delete the CompressDestroyer's | |
222 // object manually instead. | |
223 destroyer.DestroyManagedObject(); | |
224 #if !defined(JCS_EXTENSIONS) | |
225 delete[] row_buffer; | |
226 #endif | |
227 return false; | |
228 } | |
229 | |
230 // The destroyer will destroy() cinfo on exit. | |
231 jpeg_create_compress(&cinfo); | |
232 | |
233 cinfo.image_width = w; | |
234 cinfo.image_height = h; | |
235 cinfo.input_components = 3; | |
236 #ifdef JCS_EXTENSIONS | |
237 // Choose an input colorspace and return if it is an unsupported one. Since | |
238 // libjpeg-turbo supports all input formats used by Chromium (i.e. RGB, RGBA, | |
239 // and BGRA), we just map the input parameters to a colorspace used by | |
240 // libjpeg-turbo. | |
241 if (format == FORMAT_RGB) { | |
242 cinfo.input_components = 3; | |
243 cinfo.in_color_space = JCS_RGB; | |
244 } else if (format == FORMAT_RGBA || | |
245 (format == FORMAT_SkBitmap && SK_R32_SHIFT == 0)) { | |
246 cinfo.input_components = 4; | |
247 cinfo.in_color_space = JCS_EXT_RGBX; | |
248 } else if (format == FORMAT_BGRA || | |
249 (format == FORMAT_SkBitmap && SK_B32_SHIFT == 0)) { | |
250 cinfo.input_components = 4; | |
251 cinfo.in_color_space = JCS_EXT_BGRX; | |
252 } else { | |
253 // We can exit this function without calling jpeg_destroy_compress() because | |
254 // CompressDestroyer automaticaly calls it. | |
255 NOTREACHED() << "Invalid pixel format"; | |
256 return false; | |
257 } | |
258 #else | |
259 cinfo.in_color_space = JCS_RGB; | |
260 #endif | |
261 cinfo.data_precision = 8; | |
262 | |
263 jpeg_set_defaults(&cinfo); | |
264 jpeg_set_quality(&cinfo, quality, 1); // quality here is 0-100 | |
265 | |
266 // set up the destination manager | |
267 jpeg_destination_mgr destmgr; | |
268 destmgr.init_destination = InitDestination; | |
269 destmgr.empty_output_buffer = EmptyOutputBuffer; | |
270 destmgr.term_destination = TermDestination; | |
271 cinfo.dest = &destmgr; | |
272 | |
273 JpegEncoderState state(output); | |
274 cinfo.client_data = &state; | |
275 | |
276 jpeg_start_compress(&cinfo, 1); | |
277 | |
278 // feed it the rows, doing necessary conversions for the color format | |
279 #ifdef JCS_EXTENSIONS | |
280 // This function already returns when the input format is not supported by | |
281 // libjpeg-turbo and needs conversion. Therefore, we just encode lines without | |
282 // conversions. | |
283 while (cinfo.next_scanline < cinfo.image_height) { | |
284 const unsigned char* row = &input[cinfo.next_scanline * row_byte_width]; | |
285 jpeg_write_scanlines(&cinfo, const_cast<unsigned char**>(&row), 1); | |
286 } | |
287 #else | |
288 if (format == FORMAT_RGB) { | |
289 // no conversion necessary | |
290 while (cinfo.next_scanline < cinfo.image_height) { | |
291 const unsigned char* row = &input[cinfo.next_scanline * row_byte_width]; | |
292 jpeg_write_scanlines(&cinfo, const_cast<unsigned char**>(&row), 1); | |
293 } | |
294 } else { | |
295 // get the correct format converter | |
296 void (*converter)(const unsigned char* in, int w, unsigned char* rgb); | |
297 if (format == FORMAT_RGBA || | |
298 (format == FORMAT_SkBitmap && SK_R32_SHIFT == 0)) { | |
299 converter = StripAlpha; | |
300 } else if (format == FORMAT_BGRA || | |
301 (format == FORMAT_SkBitmap && SK_B32_SHIFT == 0)) { | |
302 converter = BGRAtoRGB; | |
303 } else { | |
304 NOTREACHED() << "Invalid pixel format"; | |
305 return false; | |
306 } | |
307 | |
308 // output row after converting | |
309 row_buffer = new unsigned char[w * 3]; | |
310 | |
311 while (cinfo.next_scanline < cinfo.image_height) { | |
312 converter(&input[cinfo.next_scanline * row_byte_width], w, row_buffer); | |
313 jpeg_write_scanlines(&cinfo, &row_buffer, 1); | |
314 } | |
315 delete[] row_buffer; | |
316 } | |
317 #endif | |
318 | |
319 jpeg_finish_compress(&cinfo); | |
320 return true; | |
321 } | |
322 | |
323 // Decoder -------------------------------------------------------------------- | |
324 | |
325 namespace { | |
326 | |
327 struct JpegDecoderState { | |
328 JpegDecoderState(const unsigned char* in, size_t len) | |
329 : input_buffer(in), input_buffer_length(len) { | |
330 } | |
331 | |
332 const unsigned char* input_buffer; | |
333 size_t input_buffer_length; | |
334 }; | |
335 | |
336 // Callback to initialize the source. | |
337 // | |
338 // From the JPEG library: | |
339 // "Initialize source. This is called by jpeg_read_header() before any data is | |
340 // actually read. May leave bytes_in_buffer set to 0 (in which case a | |
341 // fill_input_buffer() call will occur immediately)." | |
342 void InitSource(j_decompress_ptr cinfo) { | |
343 JpegDecoderState* state = static_cast<JpegDecoderState*>(cinfo->client_data); | |
344 cinfo->src->next_input_byte = state->input_buffer; | |
345 cinfo->src->bytes_in_buffer = state->input_buffer_length; | |
346 } | |
347 | |
348 // Callback to fill the buffer. Since our buffer already contains all the data, | |
349 // we should never need to provide more data. If libjpeg thinks it needs more | |
350 // data, our input is probably corrupt. | |
351 // | |
352 // From the JPEG library: | |
353 // "This is called whenever bytes_in_buffer has reached zero and more data is | |
354 // wanted. In typical applications, it should read fresh data into the buffer | |
355 // (ignoring the current state of next_input_byte and bytes_in_buffer), reset | |
356 // the pointer & count to the start of the buffer, and return TRUE indicating | |
357 // that the buffer has been reloaded. It is not necessary to fill the buffer | |
358 // entirely, only to obtain at least one more byte. bytes_in_buffer MUST be | |
359 // set to a positive value if TRUE is returned. A FALSE return should only | |
360 // be used when I/O suspension is desired." | |
361 boolean FillInputBuffer(j_decompress_ptr cinfo) { | |
362 return false; | |
363 } | |
364 | |
365 // Skip data in the buffer. Since we have all the data at once, this operation | |
366 // is easy. It is not clear if this ever gets called because the JPEG library | |
367 // should be able to do the skip itself (it has all the data). | |
368 // | |
369 // From the JPEG library: | |
370 // "Skip num_bytes worth of data. The buffer pointer and count should be | |
371 // advanced over num_bytes input bytes, refilling the buffer as needed. This | |
372 // is used to skip over a potentially large amount of uninteresting data | |
373 // (such as an APPn marker). In some applications it may be possible to | |
374 // optimize away the reading of the skipped data, but it's not clear that | |
375 // being smart is worth much trouble; large skips are uncommon. | |
376 // bytes_in_buffer may be zero on return. A zero or negative skip count | |
377 // should be treated as a no-op." | |
378 void SkipInputData(j_decompress_ptr cinfo, long num_bytes) { | |
379 if (num_bytes > static_cast<long>(cinfo->src->bytes_in_buffer)) { | |
380 // Since all our data should be in the buffer, trying to skip beyond it | |
381 // means that there is some kind of error or corrupt input data. A 0 for | |
382 // bytes left means it will call FillInputBuffer which will then fail. | |
383 cinfo->src->next_input_byte += cinfo->src->bytes_in_buffer; | |
384 cinfo->src->bytes_in_buffer = 0; | |
385 } else if (num_bytes > 0) { | |
386 cinfo->src->bytes_in_buffer -= static_cast<size_t>(num_bytes); | |
387 cinfo->src->next_input_byte += num_bytes; | |
388 } | |
389 } | |
390 | |
391 // Our source doesn't need any cleanup, so this is a NOP. | |
392 // | |
393 // From the JPEG library: | |
394 // "Terminate source --- called by jpeg_finish_decompress() after all data has | |
395 // been read to clean up JPEG source manager. NOT called by jpeg_abort() or | |
396 // jpeg_destroy()." | |
397 void TermSource(j_decompress_ptr cinfo) { | |
398 } | |
399 | |
400 #if !defined(JCS_EXTENSIONS) | |
401 // Converts one row of rgb data to rgba data by adding a fully-opaque alpha | |
402 // value. | |
403 void AddAlpha(const unsigned char* rgb, int pixel_width, unsigned char* rgba) { | |
404 for (int x = 0; x < pixel_width; x++) { | |
405 memcpy(&rgba[x * 4], &rgb[x * 3], 3); | |
406 rgba[x * 4 + 3] = 0xff; | |
407 } | |
408 } | |
409 | |
410 // Converts one row of RGB data to BGRA by reordering the color components and | |
411 // adding alpha values of 0xff. | |
412 void RGBtoBGRA(const unsigned char* bgra, int pixel_width, unsigned char* rgb) | |
413 { | |
414 for (int x = 0; x < pixel_width; x++) { | |
415 const unsigned char* pixel_in = &bgra[x * 3]; | |
416 unsigned char* pixel_out = &rgb[x * 4]; | |
417 pixel_out[0] = pixel_in[2]; | |
418 pixel_out[1] = pixel_in[1]; | |
419 pixel_out[2] = pixel_in[0]; | |
420 pixel_out[3] = 0xff; | |
421 } | |
422 } | |
423 #endif // !defined(JCS_EXTENSIONS) | |
424 | |
425 // This class destroys the given jpeg_decompress object when it goes out of | |
426 // scope. It simplifies the error handling in Decode (and even applies to the | |
427 // success case). | |
428 class DecompressDestroyer { | |
429 public: | |
430 DecompressDestroyer() : cinfo_(NULL) { | |
431 } | |
432 ~DecompressDestroyer() { | |
433 DestroyManagedObject(); | |
434 } | |
435 void SetManagedObject(jpeg_decompress_struct* ci) { | |
436 DestroyManagedObject(); | |
437 cinfo_ = ci; | |
438 } | |
439 void DestroyManagedObject() { | |
440 if (cinfo_) { | |
441 jpeg_destroy_decompress(cinfo_); | |
442 cinfo_ = NULL; | |
443 } | |
444 } | |
445 private: | |
446 jpeg_decompress_struct* cinfo_; | |
447 }; | |
448 | |
449 } // namespace | |
450 | |
451 bool JPEGCodec::Decode(const unsigned char* input, size_t input_size, | |
452 ColorFormat format, std::vector<unsigned char>* output, | |
453 int* w, int* h) { | |
454 jpeg_decompress_struct cinfo; | |
455 DecompressDestroyer destroyer; | |
456 destroyer.SetManagedObject(&cinfo); | |
457 output->clear(); | |
458 | |
459 // We set up the normal JPEG error routines, then override error_exit. | |
460 // This must be done before the call to create_decompress. | |
461 CoderErrorMgr errmgr; | |
462 cinfo.err = jpeg_std_error(&errmgr.pub); | |
463 errmgr.pub.error_exit = ErrorExit; | |
464 // Establish the setjmp return context for ErrorExit to use. | |
465 if (setjmp(errmgr.setjmp_buffer)) { | |
466 // If we get here, the JPEG code has signaled an error. | |
467 // See note in JPEGCodec::Encode() for why we need to destroy the cinfo | |
468 // manually here. | |
469 destroyer.DestroyManagedObject(); | |
470 return false; | |
471 } | |
472 | |
473 // The destroyer will destroy() cinfo on exit. We don't want to set the | |
474 // destroyer's object until cinfo is initialized. | |
475 jpeg_create_decompress(&cinfo); | |
476 | |
477 // set up the source manager | |
478 jpeg_source_mgr srcmgr; | |
479 srcmgr.init_source = InitSource; | |
480 srcmgr.fill_input_buffer = FillInputBuffer; | |
481 srcmgr.skip_input_data = SkipInputData; | |
482 srcmgr.resync_to_restart = jpeg_resync_to_restart; // use default routine | |
483 srcmgr.term_source = TermSource; | |
484 cinfo.src = &srcmgr; | |
485 | |
486 JpegDecoderState state(input, input_size); | |
487 cinfo.client_data = &state; | |
488 | |
489 // fill the file metadata into our buffer | |
490 if (jpeg_read_header(&cinfo, true) != JPEG_HEADER_OK) | |
491 return false; | |
492 | |
493 // we want to always get RGB data out | |
494 switch (cinfo.jpeg_color_space) { | |
495 case JCS_GRAYSCALE: | |
496 case JCS_RGB: | |
497 case JCS_YCbCr: | |
498 #ifdef JCS_EXTENSIONS | |
499 // Choose an output colorspace and return if it is an unsupported one. | |
500 // Same as JPEGCodec::Encode(), libjpeg-turbo supports all input formats | |
501 // used by Chromium (i.e. RGB, RGBA, and BGRA) and we just map the input | |
502 // parameters to a colorspace. | |
503 if (format == FORMAT_RGB) { | |
504 cinfo.out_color_space = JCS_RGB; | |
505 cinfo.output_components = 3; | |
506 } else if (format == FORMAT_RGBA || | |
507 (format == FORMAT_SkBitmap && SK_R32_SHIFT == 0)) { | |
508 cinfo.out_color_space = JCS_EXT_RGBX; | |
509 cinfo.output_components = 4; | |
510 } else if (format == FORMAT_BGRA || | |
511 (format == FORMAT_SkBitmap && SK_B32_SHIFT == 0)) { | |
512 cinfo.out_color_space = JCS_EXT_BGRX; | |
513 cinfo.output_components = 4; | |
514 } else { | |
515 // We can exit this function without calling jpeg_destroy_decompress() | |
516 // because DecompressDestroyer automaticaly calls it. | |
517 NOTREACHED() << "Invalid pixel format"; | |
518 return false; | |
519 } | |
520 #else | |
521 cinfo.out_color_space = JCS_RGB; | |
522 #endif | |
523 break; | |
524 case JCS_CMYK: | |
525 case JCS_YCCK: | |
526 default: | |
527 // Mozilla errors out on these color spaces, so I presume that the jpeg | |
528 // library can't do automatic color space conversion for them. We don't | |
529 // care about these anyway. | |
530 return false; | |
531 } | |
532 #ifndef JCS_EXTENSIONS | |
533 cinfo.output_components = 3; | |
534 #endif | |
535 | |
536 jpeg_calc_output_dimensions(&cinfo); | |
537 *w = cinfo.output_width; | |
538 *h = cinfo.output_height; | |
539 | |
540 jpeg_start_decompress(&cinfo); | |
541 | |
542 // FIXME(brettw) we may want to allow the capability for callers to request | |
543 // how to align row lengths as we do for the compressor. | |
544 int row_read_stride = cinfo.output_width * cinfo.output_components; | |
545 | |
546 #ifdef JCS_EXTENSIONS | |
547 // Create memory for a decoded image and write decoded lines to the memory | |
548 // without conversions same as JPEGCodec::Encode(). | |
549 int row_write_stride = row_read_stride; | |
550 output->resize(row_write_stride * cinfo.output_height); | |
551 | |
552 for (int row = 0; row < static_cast<int>(cinfo.output_height); row++) { | |
553 unsigned char* rowptr = &(*output)[row * row_write_stride]; | |
554 if (!jpeg_read_scanlines(&cinfo, &rowptr, 1)) | |
555 return false; | |
556 } | |
557 #else | |
558 if (format == FORMAT_RGB) { | |
559 // easy case, row needs no conversion | |
560 int row_write_stride = row_read_stride; | |
561 output->resize(row_write_stride * cinfo.output_height); | |
562 | |
563 for (int row = 0; row < static_cast<int>(cinfo.output_height); row++) { | |
564 unsigned char* rowptr = &(*output)[row * row_write_stride]; | |
565 if (!jpeg_read_scanlines(&cinfo, &rowptr, 1)) | |
566 return false; | |
567 } | |
568 } else { | |
569 // Rows need conversion to output format: read into a temporary buffer and | |
570 // expand to the final one. Performance: we could avoid the extra | |
571 // allocation by doing the expansion in-place. | |
572 int row_write_stride; | |
573 void (*converter)(const unsigned char* rgb, int w, unsigned char* out); | |
574 if (format == FORMAT_RGBA || | |
575 (format == FORMAT_SkBitmap && SK_R32_SHIFT == 0)) { | |
576 row_write_stride = cinfo.output_width * 4; | |
577 converter = AddAlpha; | |
578 } else if (format == FORMAT_BGRA || | |
579 (format == FORMAT_SkBitmap && SK_B32_SHIFT == 0)) { | |
580 row_write_stride = cinfo.output_width * 4; | |
581 converter = RGBtoBGRA; | |
582 } else { | |
583 NOTREACHED() << "Invalid pixel format"; | |
584 jpeg_destroy_decompress(&cinfo); | |
585 return false; | |
586 } | |
587 | |
588 output->resize(row_write_stride * cinfo.output_height); | |
589 | |
590 scoped_ptr<unsigned char[]> row_data(new unsigned char[row_read_stride]); | |
591 unsigned char* rowptr = row_data.get(); | |
592 for (int row = 0; row < static_cast<int>(cinfo.output_height); row++) { | |
593 if (!jpeg_read_scanlines(&cinfo, &rowptr, 1)) | |
594 return false; | |
595 converter(rowptr, *w, &(*output)[row * row_write_stride]); | |
596 } | |
597 } | |
598 #endif | |
599 | |
600 jpeg_finish_decompress(&cinfo); | |
601 jpeg_destroy_decompress(&cinfo); | |
602 return true; | |
603 } | |
604 | |
605 // static | |
606 SkBitmap* JPEGCodec::Decode(const unsigned char* input, size_t input_size) { | |
607 int w, h; | |
608 std::vector<unsigned char> data_vector; | |
609 if (!Decode(input, input_size, FORMAT_SkBitmap, &data_vector, &w, &h)) | |
610 return NULL; | |
611 | |
612 // Skia only handles 32 bit images. | |
613 int data_length = w * h * 4; | |
614 | |
615 SkBitmap* bitmap = new SkBitmap(); | |
616 bitmap->allocN32Pixels(w, h); | |
617 memcpy(bitmap->getAddr32(0, 0), &data_vector[0], data_length); | |
618 | |
619 return bitmap; | |
620 } | |
621 | |
622 } // namespace gfx | |
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