pngtrans.c@ 104729

Last change on this file since 104729 was 96425, checked in by vboxsync, 2 years ago
src/libs: Switch to libpng-1.6.37, bugref:8515 [re-export]
Property svn:eol-style set to `native`
File size: 24.6 KB

Line
1
2	/* pngtrans.c - transforms the data in a row (used by both readers and writers)
3	*
4	* Copyright (c) 2018 Cosmin Truta
5	* Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
6	* Copyright (c) 1996-1997 Andreas Dilger
7	* Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
8	*
9	* This code is released under the libpng license.
10	* For conditions of distribution and use, see the disclaimer
11	* and license in png.h
12	*/
13
14	#include "pngpriv.h"
15
16	#if defined(PNG_READ_SUPPORTED) \|\| defined(PNG_WRITE_SUPPORTED)
17
18	#if defined(PNG_READ_BGR_SUPPORTED) \|\| defined(PNG_WRITE_BGR_SUPPORTED)
19	/* Turn on BGR-to-RGB mapping */
20	void PNGAPI
21	png_set_bgr(png_structrp png_ptr)
22	{
23	png_debug(1, "in png_set_bgr");
24
25	if (png_ptr == NULL)
26	return;
27
28	png_ptr->transformations \|= PNG_BGR;
29	}
30	#endif
31
32	#if defined(PNG_READ_SWAP_SUPPORTED) \|\| defined(PNG_WRITE_SWAP_SUPPORTED)
33	/* Turn on 16-bit byte swapping */
34	void PNGAPI
35	png_set_swap(png_structrp png_ptr)
36	{
37	png_debug(1, "in png_set_swap");
38
39	if (png_ptr == NULL)
40	return;
41
42	if (png_ptr->bit_depth == 16)
43	png_ptr->transformations \|= PNG_SWAP_BYTES;
44	}
45	#endif
46
47	#if defined(PNG_READ_PACK_SUPPORTED) \|\| defined(PNG_WRITE_PACK_SUPPORTED)
48	/* Turn on pixel packing */
49	void PNGAPI
50	png_set_packing(png_structrp png_ptr)
51	{
52	png_debug(1, "in png_set_packing");
53
54	if (png_ptr == NULL)
55	return;
56
57	if (png_ptr->bit_depth < 8)
58	{
59	png_ptr->transformations \|= PNG_PACK;
60	# ifdef PNG_WRITE_SUPPORTED
61	png_ptr->usr_bit_depth = 8;
62	# endif
63	}
64	}
65	#endif
66
67	#if defined(PNG_READ_PACKSWAP_SUPPORTED)\|\|defined(PNG_WRITE_PACKSWAP_SUPPORTED)
68	/* Turn on packed pixel swapping */
69	void PNGAPI
70	png_set_packswap(png_structrp png_ptr)
71	{
72	png_debug(1, "in png_set_packswap");
73
74	if (png_ptr == NULL)
75	return;
76
77	if (png_ptr->bit_depth < 8)
78	png_ptr->transformations \|= PNG_PACKSWAP;
79	}
80	#endif
81
82	#if defined(PNG_READ_SHIFT_SUPPORTED) \|\| defined(PNG_WRITE_SHIFT_SUPPORTED)
83	void PNGAPI
84	png_set_shift(png_structrp png_ptr, png_const_color_8p true_bits)
85	{
86	png_debug(1, "in png_set_shift");
87
88	if (png_ptr == NULL)
89	return;
90
91	png_ptr->transformations \|= PNG_SHIFT;
92	png_ptr->shift = *true_bits;
93	}
94	#endif
95
96	#if defined(PNG_READ_INTERLACING_SUPPORTED) \|\| \
97	defined(PNG_WRITE_INTERLACING_SUPPORTED)
98	int PNGAPI
99	png_set_interlace_handling(png_structrp png_ptr)
100	{
101	png_debug(1, "in png_set_interlace handling");
102
103	if (png_ptr != 0 && png_ptr->interlaced != 0)
104	{
105	png_ptr->transformations \|= PNG_INTERLACE;
106	return (7);
107	}
108
109	return (1);
110	}
111	#endif
112
113	#if defined(PNG_READ_FILLER_SUPPORTED) \|\| defined(PNG_WRITE_FILLER_SUPPORTED)
114	/* Add a filler byte on read, or remove a filler or alpha byte on write.
115	* The filler type has changed in v0.95 to allow future 2-byte fillers
116	* for 48-bit input data, as well as to avoid problems with some compilers
117	* that don't like bytes as parameters.
118	*/
119	void PNGAPI
120	png_set_filler(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
121	{
122	png_debug(1, "in png_set_filler");
123
124	if (png_ptr == NULL)
125	return;
126
127	/* In libpng 1.6 it is possible to determine whether this is a read or write
128	* operation and therefore to do more checking here for a valid call.
129	*/
130	if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
131	{
132	# ifdef PNG_READ_FILLER_SUPPORTED
133	/* On read png_set_filler is always valid, regardless of the base PNG
134	* format, because other transformations can give a format where the
135	* filler code can execute (basically an 8 or 16-bit component RGB or G
136	* format.)
137	*
138	* NOTE: usr_channels is not used by the read code! (This has led to
139	* confusion in the past.) The filler is only used in the read code.
140	*/
141	png_ptr->filler = (png_uint_16)filler;
142	# else
143	png_app_error(png_ptr, "png_set_filler not supported on read");
144	PNG_UNUSED(filler) /* not used in the write case */
145	return;
146	# endif
147	}
148
149	else /* write */
150	{
151	# ifdef PNG_WRITE_FILLER_SUPPORTED
152	/* On write the usr_channels parameter must be set correctly at the
153	* start to record the number of channels in the app-supplied data.
154	*/
155	switch (png_ptr->color_type)
156	{
157	case PNG_COLOR_TYPE_RGB:
158	png_ptr->usr_channels = 4;
159	break;
160
161	case PNG_COLOR_TYPE_GRAY:
162	if (png_ptr->bit_depth >= 8)
163	{
164	png_ptr->usr_channels = 2;
165	break;
166	}
167
168	else
169	{
170	/* There simply isn't any code in libpng to strip out bits
171	* from bytes when the components are less than a byte in
172	* size!
173	*/
174	png_app_error(png_ptr,
175	"png_set_filler is invalid for"
176	" low bit depth gray output");
177	return;
178	}
179
180	default:
181	png_app_error(png_ptr,
182	"png_set_filler: inappropriate color type");
183	return;
184	}
185	# else
186	png_app_error(png_ptr, "png_set_filler not supported on write");
187	return;
188	# endif
189	}
190
191	/* Here on success - libpng supports the operation, set the transformation
192	* and the flag to say where the filler channel is.
193	*/
194	png_ptr->transformations \|= PNG_FILLER;
195
196	if (filler_loc == PNG_FILLER_AFTER)
197	png_ptr->flags \|= PNG_FLAG_FILLER_AFTER;
198
199	else
200	png_ptr->flags &= ~PNG_FLAG_FILLER_AFTER;
201	}
202
203	/* Added to libpng-1.2.7 */
204	void PNGAPI
205	png_set_add_alpha(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
206	{
207	png_debug(1, "in png_set_add_alpha");
208
209	if (png_ptr == NULL)
210	return;
211
212	png_set_filler(png_ptr, filler, filler_loc);
213	/* The above may fail to do anything. */
214	if ((png_ptr->transformations & PNG_FILLER) != 0)
215	png_ptr->transformations \|= PNG_ADD_ALPHA;
216	}
217
218	#endif
219
220	#if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) \|\| \
221	defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
222	void PNGAPI
223	png_set_swap_alpha(png_structrp png_ptr)
224	{
225	png_debug(1, "in png_set_swap_alpha");
226
227	if (png_ptr == NULL)
228	return;
229
230	png_ptr->transformations \|= PNG_SWAP_ALPHA;
231	}
232	#endif
233
234	#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) \|\| \
235	defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
236	void PNGAPI
237	png_set_invert_alpha(png_structrp png_ptr)
238	{
239	png_debug(1, "in png_set_invert_alpha");
240
241	if (png_ptr == NULL)
242	return;
243
244	png_ptr->transformations \|= PNG_INVERT_ALPHA;
245	}
246	#endif
247
248	#if defined(PNG_READ_INVERT_SUPPORTED) \|\| defined(PNG_WRITE_INVERT_SUPPORTED)
249	void PNGAPI
250	png_set_invert_mono(png_structrp png_ptr)
251	{
252	png_debug(1, "in png_set_invert_mono");
253
254	if (png_ptr == NULL)
255	return;
256
257	png_ptr->transformations \|= PNG_INVERT_MONO;
258	}
259
260	/* Invert monochrome grayscale data */
261	void /* PRIVATE */
262	png_do_invert(png_row_infop row_info, png_bytep row)
263	{
264	png_debug(1, "in png_do_invert");
265
266	/* This test removed from libpng version 1.0.13 and 1.2.0:
267	* if (row_info->bit_depth == 1 &&
268	*/
269	if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
270	{
271	png_bytep rp = row;
272	size_t i;
273	size_t istop = row_info->rowbytes;
274
275	for (i = 0; i < istop; i++)
276	{
277	rp = (png_byte)(~(rp));
278	rp++;
279	}
280	}
281
282	else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
283	row_info->bit_depth == 8)
284	{
285	png_bytep rp = row;
286	size_t i;
287	size_t istop = row_info->rowbytes;
288
289	for (i = 0; i < istop; i += 2)
290	{
291	rp = (png_byte)(~(rp));
292	rp += 2;
293	}
294	}
295
296	#ifdef PNG_16BIT_SUPPORTED
297	else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
298	row_info->bit_depth == 16)
299	{
300	png_bytep rp = row;
301	size_t i;
302	size_t istop = row_info->rowbytes;
303
304	for (i = 0; i < istop; i += 4)
305	{
306	rp = (png_byte)(~(rp));
307	(rp + 1) = (png_byte)(~((rp + 1)));
308	rp += 4;
309	}
310	}
311	#endif
312	}
313	#endif
314
315	#ifdef PNG_16BIT_SUPPORTED
316	#if defined(PNG_READ_SWAP_SUPPORTED) \|\| defined(PNG_WRITE_SWAP_SUPPORTED)
317	/* Swaps byte order on 16-bit depth images */
318	void /* PRIVATE */
319	png_do_swap(png_row_infop row_info, png_bytep row)
320	{
321	png_debug(1, "in png_do_swap");
322
323	if (row_info->bit_depth == 16)
324	{
325	png_bytep rp = row;
326	png_uint_32 i;
327	png_uint_32 istop= row_info->width * row_info->channels;
328
329	for (i = 0; i < istop; i++, rp += 2)
330	{
331	#ifdef PNG_BUILTIN_BSWAP16_SUPPORTED
332	/* Feature added to libpng-1.6.11 for testing purposes, not
333	* enabled by default.
334	*/
335	(png_uint_16)rp = __builtin_bswap16((png_uint_16)rp);
336	#else
337	png_byte t = *rp;
338	rp = (rp + 1);
339	*(rp + 1) = t;
340	#endif
341	}
342	}
343	}
344	#endif
345	#endif
346
347	#if defined(PNG_READ_PACKSWAP_SUPPORTED)\|\|defined(PNG_WRITE_PACKSWAP_SUPPORTED)
348	static const png_byte onebppswaptable[256] = {
349	0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0,
350	0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0,
351	0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8,
352	0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8,
353	0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4,
354	0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4,
355	0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC,
356	0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC,
357	0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2,
358	0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2,
359	0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA,
360	0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
361	0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6,
362	0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6,
363	0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE,
364	0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE,
365	0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1,
366	0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
367	0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9,
368	0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9,
369	0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5,
370	0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5,
371	0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED,
372	0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
373	0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3,
374	0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3,
375	0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB,
376	0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB,
377	0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7,
378	0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7,
379	0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF,
380	0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
381	};
382
383	static const png_byte twobppswaptable[256] = {
384	0x00, 0x40, 0x80, 0xC0, 0x10, 0x50, 0x90, 0xD0,
385	0x20, 0x60, 0xA0, 0xE0, 0x30, 0x70, 0xB0, 0xF0,
386	0x04, 0x44, 0x84, 0xC4, 0x14, 0x54, 0x94, 0xD4,
387	0x24, 0x64, 0xA4, 0xE4, 0x34, 0x74, 0xB4, 0xF4,
388	0x08, 0x48, 0x88, 0xC8, 0x18, 0x58, 0x98, 0xD8,
389	0x28, 0x68, 0xA8, 0xE8, 0x38, 0x78, 0xB8, 0xF8,
390	0x0C, 0x4C, 0x8C, 0xCC, 0x1C, 0x5C, 0x9C, 0xDC,
391	0x2C, 0x6C, 0xAC, 0xEC, 0x3C, 0x7C, 0xBC, 0xFC,
392	0x01, 0x41, 0x81, 0xC1, 0x11, 0x51, 0x91, 0xD1,
393	0x21, 0x61, 0xA1, 0xE1, 0x31, 0x71, 0xB1, 0xF1,
394	0x05, 0x45, 0x85, 0xC5, 0x15, 0x55, 0x95, 0xD5,
395	0x25, 0x65, 0xA5, 0xE5, 0x35, 0x75, 0xB5, 0xF5,
396	0x09, 0x49, 0x89, 0xC9, 0x19, 0x59, 0x99, 0xD9,
397	0x29, 0x69, 0xA9, 0xE9, 0x39, 0x79, 0xB9, 0xF9,
398	0x0D, 0x4D, 0x8D, 0xCD, 0x1D, 0x5D, 0x9D, 0xDD,
399	0x2D, 0x6D, 0xAD, 0xED, 0x3D, 0x7D, 0xBD, 0xFD,
400	0x02, 0x42, 0x82, 0xC2, 0x12, 0x52, 0x92, 0xD2,
401	0x22, 0x62, 0xA2, 0xE2, 0x32, 0x72, 0xB2, 0xF2,
402	0x06, 0x46, 0x86, 0xC6, 0x16, 0x56, 0x96, 0xD6,
403	0x26, 0x66, 0xA6, 0xE6, 0x36, 0x76, 0xB6, 0xF6,
404	0x0A, 0x4A, 0x8A, 0xCA, 0x1A, 0x5A, 0x9A, 0xDA,
405	0x2A, 0x6A, 0xAA, 0xEA, 0x3A, 0x7A, 0xBA, 0xFA,
406	0x0E, 0x4E, 0x8E, 0xCE, 0x1E, 0x5E, 0x9E, 0xDE,
407	0x2E, 0x6E, 0xAE, 0xEE, 0x3E, 0x7E, 0xBE, 0xFE,
408	0x03, 0x43, 0x83, 0xC3, 0x13, 0x53, 0x93, 0xD3,
409	0x23, 0x63, 0xA3, 0xE3, 0x33, 0x73, 0xB3, 0xF3,
410	0x07, 0x47, 0x87, 0xC7, 0x17, 0x57, 0x97, 0xD7,
411	0x27, 0x67, 0xA7, 0xE7, 0x37, 0x77, 0xB7, 0xF7,
412	0x0B, 0x4B, 0x8B, 0xCB, 0x1B, 0x5B, 0x9B, 0xDB,
413	0x2B, 0x6B, 0xAB, 0xEB, 0x3B, 0x7B, 0xBB, 0xFB,
414	0x0F, 0x4F, 0x8F, 0xCF, 0x1F, 0x5F, 0x9F, 0xDF,
415	0x2F, 0x6F, 0xAF, 0xEF, 0x3F, 0x7F, 0xBF, 0xFF
416	};
417
418	static const png_byte fourbppswaptable[256] = {
419	0x00, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70,
420	0x80, 0x90, 0xA0, 0xB0, 0xC0, 0xD0, 0xE0, 0xF0,
421	0x01, 0x11, 0x21, 0x31, 0x41, 0x51, 0x61, 0x71,
422	0x81, 0x91, 0xA1, 0xB1, 0xC1, 0xD1, 0xE1, 0xF1,
423	0x02, 0x12, 0x22, 0x32, 0x42, 0x52, 0x62, 0x72,
424	0x82, 0x92, 0xA2, 0xB2, 0xC2, 0xD2, 0xE2, 0xF2,
425	0x03, 0x13, 0x23, 0x33, 0x43, 0x53, 0x63, 0x73,
426	0x83, 0x93, 0xA3, 0xB3, 0xC3, 0xD3, 0xE3, 0xF3,
427	0x04, 0x14, 0x24, 0x34, 0x44, 0x54, 0x64, 0x74,
428	0x84, 0x94, 0xA4, 0xB4, 0xC4, 0xD4, 0xE4, 0xF4,
429	0x05, 0x15, 0x25, 0x35, 0x45, 0x55, 0x65, 0x75,
430	0x85, 0x95, 0xA5, 0xB5, 0xC5, 0xD5, 0xE5, 0xF5,
431	0x06, 0x16, 0x26, 0x36, 0x46, 0x56, 0x66, 0x76,
432	0x86, 0x96, 0xA6, 0xB6, 0xC6, 0xD6, 0xE6, 0xF6,
433	0x07, 0x17, 0x27, 0x37, 0x47, 0x57, 0x67, 0x77,
434	0x87, 0x97, 0xA7, 0xB7, 0xC7, 0xD7, 0xE7, 0xF7,
435	0x08, 0x18, 0x28, 0x38, 0x48, 0x58, 0x68, 0x78,
436	0x88, 0x98, 0xA8, 0xB8, 0xC8, 0xD8, 0xE8, 0xF8,
437	0x09, 0x19, 0x29, 0x39, 0x49, 0x59, 0x69, 0x79,
438	0x89, 0x99, 0xA9, 0xB9, 0xC9, 0xD9, 0xE9, 0xF9,
439	0x0A, 0x1A, 0x2A, 0x3A, 0x4A, 0x5A, 0x6A, 0x7A,
440	0x8A, 0x9A, 0xAA, 0xBA, 0xCA, 0xDA, 0xEA, 0xFA,
441	0x0B, 0x1B, 0x2B, 0x3B, 0x4B, 0x5B, 0x6B, 0x7B,
442	0x8B, 0x9B, 0xAB, 0xBB, 0xCB, 0xDB, 0xEB, 0xFB,
443	0x0C, 0x1C, 0x2C, 0x3C, 0x4C, 0x5C, 0x6C, 0x7C,
444	0x8C, 0x9C, 0xAC, 0xBC, 0xCC, 0xDC, 0xEC, 0xFC,
445	0x0D, 0x1D, 0x2D, 0x3D, 0x4D, 0x5D, 0x6D, 0x7D,
446	0x8D, 0x9D, 0xAD, 0xBD, 0xCD, 0xDD, 0xED, 0xFD,
447	0x0E, 0x1E, 0x2E, 0x3E, 0x4E, 0x5E, 0x6E, 0x7E,
448	0x8E, 0x9E, 0xAE, 0xBE, 0xCE, 0xDE, 0xEE, 0xFE,
449	0x0F, 0x1F, 0x2F, 0x3F, 0x4F, 0x5F, 0x6F, 0x7F,
450	0x8F, 0x9F, 0xAF, 0xBF, 0xCF, 0xDF, 0xEF, 0xFF
451	};
452
453	/* Swaps pixel packing order within bytes */
454	void /* PRIVATE */
455	png_do_packswap(png_row_infop row_info, png_bytep row)
456	{
457	png_debug(1, "in png_do_packswap");
458
459	if (row_info->bit_depth < 8)
460	{
461	png_bytep rp;
462	png_const_bytep end, table;
463
464	end = row + row_info->rowbytes;
465
466	if (row_info->bit_depth == 1)
467	table = onebppswaptable;
468
469	else if (row_info->bit_depth == 2)
470	table = twobppswaptable;
471
472	else if (row_info->bit_depth == 4)
473	table = fourbppswaptable;
474
475	else
476	return;
477
478	for (rp = row; rp < end; rp++)
479	rp = table[rp];
480	}
481	}
482	#endif /* PACKSWAP \|\| WRITE_PACKSWAP */
483
484	#if defined(PNG_WRITE_FILLER_SUPPORTED) \|\| \
485	defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
486	/* Remove a channel - this used to be 'png_do_strip_filler' but it used a
487	* somewhat weird combination of flags to determine what to do. All the calls
488	* to png_do_strip_filler are changed in 1.5.2 to call this instead with the
489	* correct arguments.
490	*
491	* The routine isn't general - the channel must be the channel at the start or
492	* end (not in the middle) of each pixel.
493	*/
494	void /* PRIVATE */
495	png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
496	{
497	png_bytep sp = row; /* source pointer */
498	png_bytep dp = row; /* destination pointer */
499	png_bytep ep = row + row_info->rowbytes; /* One beyond end of row */
500
501	/* At the start sp will point to the first byte to copy and dp to where
502	* it is copied to. ep always points just beyond the end of the row, so
503	* the loop simply copies (channels-1) channels until sp reaches ep.
504	*
505	* at_start: 0 -- convert AG, XG, ARGB, XRGB, AAGG, XXGG, etc.
506	* nonzero -- convert GA, GX, RGBA, RGBX, GGAA, RRGGBBXX, etc.
507	*/
508
509	/* GA, GX, XG cases */
510	if (row_info->channels == 2)
511	{
512	if (row_info->bit_depth == 8)
513	{
514	if (at_start != 0) /* Skip initial filler */
515	++sp;
516	else /* Skip initial channel and, for sp, the filler */
517	{
518	sp += 2; ++dp;
519	}
520
521	/* For a 1 pixel wide image there is nothing to do */
522	while (sp < ep)
523	{
524	dp++ = sp; sp += 2;
525	}
526
527	row_info->pixel_depth = 8;
528	}
529
530	else if (row_info->bit_depth == 16)
531	{
532	if (at_start != 0) /* Skip initial filler */
533	sp += 2;
534	else /* Skip initial channel and, for sp, the filler */
535	{
536	sp += 4; dp += 2;
537	}
538
539	while (sp < ep)
540	{
541	dp++ = sp++; dp++ = sp; sp += 3;
542	}
543
544	row_info->pixel_depth = 16;
545	}
546
547	else
548	return; /* bad bit depth */
549
550	row_info->channels = 1;
551
552	/* Finally fix the color type if it records an alpha channel */
553	if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
554	row_info->color_type = PNG_COLOR_TYPE_GRAY;
555	}
556
557	/* RGBA, RGBX, XRGB cases */
558	else if (row_info->channels == 4)
559	{
560	if (row_info->bit_depth == 8)
561	{
562	if (at_start != 0) /* Skip initial filler */
563	++sp;
564	else /* Skip initial channels and, for sp, the filler */
565	{
566	sp += 4; dp += 3;
567	}
568
569	/* Note that the loop adds 3 to dp and 4 to sp each time. */
570	while (sp < ep)
571	{
572	dp++ = sp++; dp++ = sp++; dp++ = sp; sp += 2;
573	}
574
575	row_info->pixel_depth = 24;
576	}
577
578	else if (row_info->bit_depth == 16)
579	{
580	if (at_start != 0) /* Skip initial filler */
581	sp += 2;
582	else /* Skip initial channels and, for sp, the filler */
583	{
584	sp += 8; dp += 6;
585	}
586
587	while (sp < ep)
588	{
589	/* Copy 6 bytes, skip 2 */
590	dp++ = sp++; dp++ = sp++;
591	dp++ = sp++; dp++ = sp++;
592	dp++ = sp++; dp++ = sp; sp += 3;
593	}
594
595	row_info->pixel_depth = 48;
596	}
597
598	else
599	return; /* bad bit depth */
600
601	row_info->channels = 3;
602
603	/* Finally fix the color type if it records an alpha channel */
604	if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
605	row_info->color_type = PNG_COLOR_TYPE_RGB;
606	}
607
608	else
609	return; /* The filler channel has gone already */
610
611	/* Fix the rowbytes value. */
612	row_info->rowbytes = (size_t)(dp-row);
613	}
614	#endif
615
616	#if defined(PNG_READ_BGR_SUPPORTED) \|\| defined(PNG_WRITE_BGR_SUPPORTED)
617	/* Swaps red and blue bytes within a pixel */
618	void /* PRIVATE */
619	png_do_bgr(png_row_infop row_info, png_bytep row)
620	{
621	png_debug(1, "in png_do_bgr");
622
623	if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
624	{
625	png_uint_32 row_width = row_info->width;
626	if (row_info->bit_depth == 8)
627	{
628	if (row_info->color_type == PNG_COLOR_TYPE_RGB)
629	{
630	png_bytep rp;
631	png_uint_32 i;
632
633	for (i = 0, rp = row; i < row_width; i++, rp += 3)
634	{
635	png_byte save = *rp;
636	rp = (rp + 2);
637	*(rp + 2) = save;
638	}
639	}
640
641	else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
642	{
643	png_bytep rp;
644	png_uint_32 i;
645
646	for (i = 0, rp = row; i < row_width; i++, rp += 4)
647	{
648	png_byte save = *rp;
649	rp = (rp + 2);
650	*(rp + 2) = save;
651	}
652	}
653	}
654
655	#ifdef PNG_16BIT_SUPPORTED
656	else if (row_info->bit_depth == 16)
657	{
658	if (row_info->color_type == PNG_COLOR_TYPE_RGB)
659	{
660	png_bytep rp;
661	png_uint_32 i;
662
663	for (i = 0, rp = row; i < row_width; i++, rp += 6)
664	{
665	png_byte save = *rp;
666	rp = (rp + 4);
667	*(rp + 4) = save;
668	save = *(rp + 1);
669	(rp + 1) = (rp + 5);
670	*(rp + 5) = save;
671	}
672	}
673
674	else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
675	{
676	png_bytep rp;
677	png_uint_32 i;
678
679	for (i = 0, rp = row; i < row_width; i++, rp += 8)
680	{
681	png_byte save = *rp;
682	rp = (rp + 4);
683	*(rp + 4) = save;
684	save = *(rp + 1);
685	(rp + 1) = (rp + 5);
686	*(rp + 5) = save;
687	}
688	}
689	}
690	#endif
691	}
692	}
693	#endif /* READ_BGR \|\| WRITE_BGR */
694
695	#if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) \|\| \
696	defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED)
697	/* Added at libpng-1.5.10 */
698	void /* PRIVATE */
699	png_do_check_palette_indexes(png_structrp png_ptr, png_row_infop row_info)
700	{
701	if (png_ptr->num_palette < (1 << row_info->bit_depth) &&
702	png_ptr->num_palette > 0) /* num_palette can be 0 in MNG files */
703	{
704	/* Calculations moved outside switch in an attempt to stop different
705	* compiler warnings. 'padding' is in bits within the last byte, it is
706	* an 'int' because pixel_depth becomes an 'int' in the expression below,
707	* and this calculation is used because it avoids warnings that other
708	* forms produced on either GCC or MSVC.
709	*/
710	int padding = PNG_PADBITS(row_info->pixel_depth, row_info->width);
711	png_bytep rp = png_ptr->row_buf + row_info->rowbytes - 1;
712
713	switch (row_info->bit_depth)
714	{
715	case 1:
716	{
717	/* in this case, all bytes must be 0 so we don't need
718	* to unpack the pixels except for the rightmost one.
719	*/
720	for (; rp > png_ptr->row_buf; rp--)
721	{
722	if ((*rp >> padding) != 0)
723	png_ptr->num_palette_max = 1;
724	padding = 0;
725	}
726
727	break;
728	}
729
730	case 2:
731	{
732	for (; rp > png_ptr->row_buf; rp--)
733	{
734	int i = ((*rp >> padding) & 0x03);
735
736	if (i > png_ptr->num_palette_max)
737	png_ptr->num_palette_max = i;
738
739	i = (((*rp >> padding) >> 2) & 0x03);
740
741	if (i > png_ptr->num_palette_max)
742	png_ptr->num_palette_max = i;
743
744	i = (((*rp >> padding) >> 4) & 0x03);
745
746	if (i > png_ptr->num_palette_max)
747	png_ptr->num_palette_max = i;
748
749	i = (((*rp >> padding) >> 6) & 0x03);
750
751	if (i > png_ptr->num_palette_max)
752	png_ptr->num_palette_max = i;
753
754	padding = 0;
755	}
756
757	break;
758	}
759
760	case 4:
761	{
762	for (; rp > png_ptr->row_buf; rp--)
763	{
764	int i = ((*rp >> padding) & 0x0f);
765
766	if (i > png_ptr->num_palette_max)
767	png_ptr->num_palette_max = i;
768
769	i = (((*rp >> padding) >> 4) & 0x0f);
770
771	if (i > png_ptr->num_palette_max)
772	png_ptr->num_palette_max = i;
773
774	padding = 0;
775	}
776
777	break;
778	}
779
780	case 8:
781	{
782	for (; rp > png_ptr->row_buf; rp--)
783	{
784	if (*rp > png_ptr->num_palette_max)
785	png_ptr->num_palette_max = (int) *rp;
786	}
787
788	break;
789	}
790
791	default:
792	break;
793	}
794	}
795	}
796	#endif /* CHECK_FOR_INVALID_INDEX */
797
798	#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) \|\| \
799	defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
800	#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
801	void PNGAPI
802	png_set_user_transform_info(png_structrp png_ptr, png_voidp
803	user_transform_ptr, int user_transform_depth, int user_transform_channels)
804	{
805	png_debug(1, "in png_set_user_transform_info");
806
807	if (png_ptr == NULL)
808	return;
809
810	#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
811	if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
812	(png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
813	{
814	png_app_error(png_ptr,
815	"info change after png_start_read_image or png_read_update_info");
816	return;
817	}
818	#endif
819
820	png_ptr->user_transform_ptr = user_transform_ptr;
821	png_ptr->user_transform_depth = (png_byte)user_transform_depth;
822	png_ptr->user_transform_channels = (png_byte)user_transform_channels;
823	}
824	#endif
825
826	/* This function returns a pointer to the user_transform_ptr associated with
827	* the user transform functions. The application should free any memory
828	* associated with this pointer before png_write_destroy and png_read_destroy
829	* are called.
830	*/
831	#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
832	png_voidp PNGAPI
833	png_get_user_transform_ptr(png_const_structrp png_ptr)
834	{
835	if (png_ptr == NULL)
836	return (NULL);
837
838	return png_ptr->user_transform_ptr;
839	}
840	#endif
841
842	#ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
843	png_uint_32 PNGAPI
844	png_get_current_row_number(png_const_structrp png_ptr)
845	{
846	/* See the comments in png.h - this is the sub-image row when reading an
847	* interlaced image.
848	*/
849	if (png_ptr != NULL)
850	return png_ptr->row_number;
851
852	return PNG_UINT_32_MAX; /* help the app not to fail silently */
853	}
854
855	png_byte PNGAPI
856	png_get_current_pass_number(png_const_structrp png_ptr)
857	{
858	if (png_ptr != NULL)
859	return png_ptr->pass;
860	return 8; /* invalid */
861	}
862	#endif /* USER_TRANSFORM_INFO */
863	#endif /* READ_USER_TRANSFORM \|\| WRITE_USER_TRANSFORM */
864	#endif /* READ \|\| WRITE */

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source: vbox/trunk/src/libs/libpng-1.6.37/pngtrans.c@ 104729

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