1
2 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
3 *
4 * Last changed in libpng 1.6.18 [July 23, 2015]
5 * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 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
png_set_bgr(png_structrp png_ptr)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
png_set_swap(png_structrp png_ptr)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
png_set_packing(png_structrp png_ptr)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
png_set_packswap(png_structrp png_ptr)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
png_set_shift(png_structrp png_ptr,png_const_color_8p true_bits)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
png_set_interlace_handling(png_structrp png_ptr)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
png_set_filler(png_structrp png_ptr,png_uint_32 filler,int filler_loc)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 low bit depth gray output");
176 return;
177 }
178
179 default:
180 png_app_error(png_ptr,
181 "png_set_filler: inappropriate color type");
182 return;
183 }
184 # else
185 png_app_error(png_ptr, "png_set_filler not supported on write");
186 return;
187 # endif
188 }
189
190 /* Here on success - libpng supports the operation, set the transformation
191 * and the flag to say where the filler channel is.
192 */
193 png_ptr->transformations |= PNG_FILLER;
194
195 if (filler_loc == PNG_FILLER_AFTER)
196 png_ptr->flags |= PNG_FLAG_FILLER_AFTER;
197
198 else
199 png_ptr->flags &= ~PNG_FLAG_FILLER_AFTER;
200 }
201
202 /* Added to libpng-1.2.7 */
203 void PNGAPI
png_set_add_alpha(png_structrp png_ptr,png_uint_32 filler,int filler_loc)204 png_set_add_alpha(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
205 {
206 png_debug(1, "in png_set_add_alpha");
207
208 if (png_ptr == NULL)
209 return;
210
211 png_set_filler(png_ptr, filler, filler_loc);
212 /* The above may fail to do anything. */
213 if ((png_ptr->transformations & PNG_FILLER) != 0)
214 png_ptr->transformations |= PNG_ADD_ALPHA;
215 }
216
217 #endif
218
219 #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
220 defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
221 void PNGAPI
png_set_swap_alpha(png_structrp png_ptr)222 png_set_swap_alpha(png_structrp png_ptr)
223 {
224 png_debug(1, "in png_set_swap_alpha");
225
226 if (png_ptr == NULL)
227 return;
228
229 png_ptr->transformations |= PNG_SWAP_ALPHA;
230 }
231 #endif
232
233 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
234 defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
235 void PNGAPI
png_set_invert_alpha(png_structrp png_ptr)236 png_set_invert_alpha(png_structrp png_ptr)
237 {
238 png_debug(1, "in png_set_invert_alpha");
239
240 if (png_ptr == NULL)
241 return;
242
243 png_ptr->transformations |= PNG_INVERT_ALPHA;
244 }
245 #endif
246
247 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
248 void PNGAPI
png_set_invert_mono(png_structrp png_ptr)249 png_set_invert_mono(png_structrp png_ptr)
250 {
251 png_debug(1, "in png_set_invert_mono");
252
253 if (png_ptr == NULL)
254 return;
255
256 png_ptr->transformations |= PNG_INVERT_MONO;
257 }
258
259 /* Invert monochrome grayscale data */
260 void /* PRIVATE */
png_do_invert(png_row_infop row_info,png_bytep row)261 png_do_invert(png_row_infop row_info, png_bytep row)
262 {
263 png_debug(1, "in png_do_invert");
264
265 /* This test removed from libpng version 1.0.13 and 1.2.0:
266 * if (row_info->bit_depth == 1 &&
267 */
268 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
269 {
270 png_bytep rp = row;
271 png_size_t i;
272 png_size_t istop = row_info->rowbytes;
273
274 for (i = 0; i < istop; i++)
275 {
276 *rp = (png_byte)(~(*rp));
277 rp++;
278 }
279 }
280
281 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
282 row_info->bit_depth == 8)
283 {
284 png_bytep rp = row;
285 png_size_t i;
286 png_size_t istop = row_info->rowbytes;
287
288 for (i = 0; i < istop; i += 2)
289 {
290 *rp = (png_byte)(~(*rp));
291 rp += 2;
292 }
293 }
294
295 #ifdef PNG_16BIT_SUPPORTED
296 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
297 row_info->bit_depth == 16)
298 {
299 png_bytep rp = row;
300 png_size_t i;
301 png_size_t istop = row_info->rowbytes;
302
303 for (i = 0; i < istop; i += 4)
304 {
305 *rp = (png_byte)(~(*rp));
306 *(rp + 1) = (png_byte)(~(*(rp + 1)));
307 rp += 4;
308 }
309 }
310 #endif
311 }
312 #endif
313
314 #ifdef PNG_16BIT_SUPPORTED
315 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
316 /* Swaps byte order on 16-bit depth images */
317 void /* PRIVATE */
png_do_swap(png_row_infop row_info,png_bytep row)318 png_do_swap(png_row_infop row_info, png_bytep row)
319 {
320 png_debug(1, "in png_do_swap");
321
322 if (row_info->bit_depth == 16)
323 {
324 png_bytep rp = row;
325 png_uint_32 i;
326 png_uint_32 istop= row_info->width * row_info->channels;
327
328 for (i = 0; i < istop; i++, rp += 2)
329 {
330 #ifdef PNG_BUILTIN_BSWAP16_SUPPORTED
331 /* Feature added to libpng-1.6.11 for testing purposes, not
332 * enabled by default.
333 */
334 *(png_uint_16*)rp = __builtin_bswap16(*(png_uint_16*)rp);
335 #else
336 png_byte t = *rp;
337 *rp = *(rp + 1);
338 *(rp + 1) = t;
339 #endif
340 }
341 }
342 }
343 #endif
344 #endif
345
346 #if defined(PNG_READ_PACKSWAP_SUPPORTED)||defined(PNG_WRITE_PACKSWAP_SUPPORTED)
347 static PNG_CONST png_byte onebppswaptable[256] = {
348 0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0,
349 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0,
350 0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8,
351 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8,
352 0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4,
353 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4,
354 0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC,
355 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC,
356 0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2,
357 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2,
358 0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA,
359 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
360 0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6,
361 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6,
362 0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE,
363 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE,
364 0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1,
365 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
366 0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9,
367 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9,
368 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5,
369 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5,
370 0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED,
371 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
372 0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3,
373 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3,
374 0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB,
375 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB,
376 0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7,
377 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7,
378 0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF,
379 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
380 };
381
382 static PNG_CONST png_byte twobppswaptable[256] = {
383 0x00, 0x40, 0x80, 0xC0, 0x10, 0x50, 0x90, 0xD0,
384 0x20, 0x60, 0xA0, 0xE0, 0x30, 0x70, 0xB0, 0xF0,
385 0x04, 0x44, 0x84, 0xC4, 0x14, 0x54, 0x94, 0xD4,
386 0x24, 0x64, 0xA4, 0xE4, 0x34, 0x74, 0xB4, 0xF4,
387 0x08, 0x48, 0x88, 0xC8, 0x18, 0x58, 0x98, 0xD8,
388 0x28, 0x68, 0xA8, 0xE8, 0x38, 0x78, 0xB8, 0xF8,
389 0x0C, 0x4C, 0x8C, 0xCC, 0x1C, 0x5C, 0x9C, 0xDC,
390 0x2C, 0x6C, 0xAC, 0xEC, 0x3C, 0x7C, 0xBC, 0xFC,
391 0x01, 0x41, 0x81, 0xC1, 0x11, 0x51, 0x91, 0xD1,
392 0x21, 0x61, 0xA1, 0xE1, 0x31, 0x71, 0xB1, 0xF1,
393 0x05, 0x45, 0x85, 0xC5, 0x15, 0x55, 0x95, 0xD5,
394 0x25, 0x65, 0xA5, 0xE5, 0x35, 0x75, 0xB5, 0xF5,
395 0x09, 0x49, 0x89, 0xC9, 0x19, 0x59, 0x99, 0xD9,
396 0x29, 0x69, 0xA9, 0xE9, 0x39, 0x79, 0xB9, 0xF9,
397 0x0D, 0x4D, 0x8D, 0xCD, 0x1D, 0x5D, 0x9D, 0xDD,
398 0x2D, 0x6D, 0xAD, 0xED, 0x3D, 0x7D, 0xBD, 0xFD,
399 0x02, 0x42, 0x82, 0xC2, 0x12, 0x52, 0x92, 0xD2,
400 0x22, 0x62, 0xA2, 0xE2, 0x32, 0x72, 0xB2, 0xF2,
401 0x06, 0x46, 0x86, 0xC6, 0x16, 0x56, 0x96, 0xD6,
402 0x26, 0x66, 0xA6, 0xE6, 0x36, 0x76, 0xB6, 0xF6,
403 0x0A, 0x4A, 0x8A, 0xCA, 0x1A, 0x5A, 0x9A, 0xDA,
404 0x2A, 0x6A, 0xAA, 0xEA, 0x3A, 0x7A, 0xBA, 0xFA,
405 0x0E, 0x4E, 0x8E, 0xCE, 0x1E, 0x5E, 0x9E, 0xDE,
406 0x2E, 0x6E, 0xAE, 0xEE, 0x3E, 0x7E, 0xBE, 0xFE,
407 0x03, 0x43, 0x83, 0xC3, 0x13, 0x53, 0x93, 0xD3,
408 0x23, 0x63, 0xA3, 0xE3, 0x33, 0x73, 0xB3, 0xF3,
409 0x07, 0x47, 0x87, 0xC7, 0x17, 0x57, 0x97, 0xD7,
410 0x27, 0x67, 0xA7, 0xE7, 0x37, 0x77, 0xB7, 0xF7,
411 0x0B, 0x4B, 0x8B, 0xCB, 0x1B, 0x5B, 0x9B, 0xDB,
412 0x2B, 0x6B, 0xAB, 0xEB, 0x3B, 0x7B, 0xBB, 0xFB,
413 0x0F, 0x4F, 0x8F, 0xCF, 0x1F, 0x5F, 0x9F, 0xDF,
414 0x2F, 0x6F, 0xAF, 0xEF, 0x3F, 0x7F, 0xBF, 0xFF
415 };
416
417 static PNG_CONST png_byte fourbppswaptable[256] = {
418 0x00, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70,
419 0x80, 0x90, 0xA0, 0xB0, 0xC0, 0xD0, 0xE0, 0xF0,
420 0x01, 0x11, 0x21, 0x31, 0x41, 0x51, 0x61, 0x71,
421 0x81, 0x91, 0xA1, 0xB1, 0xC1, 0xD1, 0xE1, 0xF1,
422 0x02, 0x12, 0x22, 0x32, 0x42, 0x52, 0x62, 0x72,
423 0x82, 0x92, 0xA2, 0xB2, 0xC2, 0xD2, 0xE2, 0xF2,
424 0x03, 0x13, 0x23, 0x33, 0x43, 0x53, 0x63, 0x73,
425 0x83, 0x93, 0xA3, 0xB3, 0xC3, 0xD3, 0xE3, 0xF3,
426 0x04, 0x14, 0x24, 0x34, 0x44, 0x54, 0x64, 0x74,
427 0x84, 0x94, 0xA4, 0xB4, 0xC4, 0xD4, 0xE4, 0xF4,
428 0x05, 0x15, 0x25, 0x35, 0x45, 0x55, 0x65, 0x75,
429 0x85, 0x95, 0xA5, 0xB5, 0xC5, 0xD5, 0xE5, 0xF5,
430 0x06, 0x16, 0x26, 0x36, 0x46, 0x56, 0x66, 0x76,
431 0x86, 0x96, 0xA6, 0xB6, 0xC6, 0xD6, 0xE6, 0xF6,
432 0x07, 0x17, 0x27, 0x37, 0x47, 0x57, 0x67, 0x77,
433 0x87, 0x97, 0xA7, 0xB7, 0xC7, 0xD7, 0xE7, 0xF7,
434 0x08, 0x18, 0x28, 0x38, 0x48, 0x58, 0x68, 0x78,
435 0x88, 0x98, 0xA8, 0xB8, 0xC8, 0xD8, 0xE8, 0xF8,
436 0x09, 0x19, 0x29, 0x39, 0x49, 0x59, 0x69, 0x79,
437 0x89, 0x99, 0xA9, 0xB9, 0xC9, 0xD9, 0xE9, 0xF9,
438 0x0A, 0x1A, 0x2A, 0x3A, 0x4A, 0x5A, 0x6A, 0x7A,
439 0x8A, 0x9A, 0xAA, 0xBA, 0xCA, 0xDA, 0xEA, 0xFA,
440 0x0B, 0x1B, 0x2B, 0x3B, 0x4B, 0x5B, 0x6B, 0x7B,
441 0x8B, 0x9B, 0xAB, 0xBB, 0xCB, 0xDB, 0xEB, 0xFB,
442 0x0C, 0x1C, 0x2C, 0x3C, 0x4C, 0x5C, 0x6C, 0x7C,
443 0x8C, 0x9C, 0xAC, 0xBC, 0xCC, 0xDC, 0xEC, 0xFC,
444 0x0D, 0x1D, 0x2D, 0x3D, 0x4D, 0x5D, 0x6D, 0x7D,
445 0x8D, 0x9D, 0xAD, 0xBD, 0xCD, 0xDD, 0xED, 0xFD,
446 0x0E, 0x1E, 0x2E, 0x3E, 0x4E, 0x5E, 0x6E, 0x7E,
447 0x8E, 0x9E, 0xAE, 0xBE, 0xCE, 0xDE, 0xEE, 0xFE,
448 0x0F, 0x1F, 0x2F, 0x3F, 0x4F, 0x5F, 0x6F, 0x7F,
449 0x8F, 0x9F, 0xAF, 0xBF, 0xCF, 0xDF, 0xEF, 0xFF
450 };
451
452 /* Swaps pixel packing order within bytes */
453 void /* PRIVATE */
png_do_packswap(png_row_infop row_info,png_bytep row)454 png_do_packswap(png_row_infop row_info, png_bytep row)
455 {
456 png_debug(1, "in png_do_packswap");
457
458 if (row_info->bit_depth < 8)
459 {
460 png_bytep rp;
461 png_const_bytep end, table;
462
463 end = row + row_info->rowbytes;
464
465 if (row_info->bit_depth == 1)
466 table = onebppswaptable;
467
468 else if (row_info->bit_depth == 2)
469 table = twobppswaptable;
470
471 else if (row_info->bit_depth == 4)
472 table = fourbppswaptable;
473
474 else
475 return;
476
477 for (rp = row; rp < end; rp++)
478 *rp = table[*rp];
479 }
480 }
481 #endif /* PACKSWAP || WRITE_PACKSWAP */
482
483 #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
484 defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
485 /* Remove a channel - this used to be 'png_do_strip_filler' but it used a
486 * somewhat weird combination of flags to determine what to do. All the calls
487 * to png_do_strip_filler are changed in 1.5.2 to call this instead with the
488 * correct arguments.
489 *
490 * The routine isn't general - the channel must be the channel at the start or
491 * end (not in the middle) of each pixel.
492 */
493 void /* PRIVATE */
png_do_strip_channel(png_row_infop row_info,png_bytep row,int at_start)494 png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
495 {
496 png_bytep sp = row; /* source pointer */
497 png_bytep dp = row; /* destination pointer */
498 png_bytep ep = row + row_info->rowbytes; /* One beyond end of row */
499
500 /* At the start sp will point to the first byte to copy and dp to where
501 * it is copied to. ep always points just beyond the end of the row, so
502 * the loop simply copies (channels-1) channels until sp reaches ep.
503 *
504 * at_start: 0 -- convert AG, XG, ARGB, XRGB, AAGG, XXGG, etc.
505 * nonzero -- convert GA, GX, RGBA, RGBX, GGAA, RRGGBBXX, etc.
506 */
507
508 /* GA, GX, XG cases */
509 if (row_info->channels == 2)
510 {
511 if (row_info->bit_depth == 8)
512 {
513 if (at_start != 0) /* Skip initial filler */
514 ++sp;
515 else /* Skip initial channel and, for sp, the filler */
516 sp += 2, ++dp;
517
518 /* For a 1 pixel wide image there is nothing to do */
519 while (sp < ep)
520 *dp++ = *sp, sp += 2;
521
522 row_info->pixel_depth = 8;
523 }
524
525 else if (row_info->bit_depth == 16)
526 {
527 if (at_start != 0) /* Skip initial filler */
528 sp += 2;
529 else /* Skip initial channel and, for sp, the filler */
530 sp += 4, dp += 2;
531
532 while (sp < ep)
533 *dp++ = *sp++, *dp++ = *sp, sp += 3;
534
535 row_info->pixel_depth = 16;
536 }
537
538 else
539 return; /* bad bit depth */
540
541 row_info->channels = 1;
542
543 /* Finally fix the color type if it records an alpha channel */
544 if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
545 row_info->color_type = PNG_COLOR_TYPE_GRAY;
546 }
547
548 /* RGBA, RGBX, XRGB cases */
549 else if (row_info->channels == 4)
550 {
551 if (row_info->bit_depth == 8)
552 {
553 if (at_start != 0) /* Skip initial filler */
554 ++sp;
555 else /* Skip initial channels and, for sp, the filler */
556 sp += 4, dp += 3;
557
558 /* Note that the loop adds 3 to dp and 4 to sp each time. */
559 while (sp < ep)
560 *dp++ = *sp++, *dp++ = *sp++, *dp++ = *sp, sp += 2;
561
562 row_info->pixel_depth = 24;
563 }
564
565 else if (row_info->bit_depth == 16)
566 {
567 if (at_start != 0) /* Skip initial filler */
568 sp += 2;
569 else /* Skip initial channels and, for sp, the filler */
570 sp += 8, dp += 6;
571
572 while (sp < ep)
573 {
574 /* Copy 6 bytes, skip 2 */
575 *dp++ = *sp++, *dp++ = *sp++;
576 *dp++ = *sp++, *dp++ = *sp++;
577 *dp++ = *sp++, *dp++ = *sp, sp += 3;
578 }
579
580 row_info->pixel_depth = 48;
581 }
582
583 else
584 return; /* bad bit depth */
585
586 row_info->channels = 3;
587
588 /* Finally fix the color type if it records an alpha channel */
589 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
590 row_info->color_type = PNG_COLOR_TYPE_RGB;
591 }
592
593 else
594 return; /* The filler channel has gone already */
595
596 /* Fix the rowbytes value. */
597 row_info->rowbytes = dp-row;
598 }
599 #endif
600
601 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
602 /* Swaps red and blue bytes within a pixel */
603 void /* PRIVATE */
png_do_bgr(png_row_infop row_info,png_bytep row)604 png_do_bgr(png_row_infop row_info, png_bytep row)
605 {
606 png_debug(1, "in png_do_bgr");
607
608 if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
609 {
610 png_uint_32 row_width = row_info->width;
611 if (row_info->bit_depth == 8)
612 {
613 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
614 {
615 png_bytep rp;
616 png_uint_32 i;
617
618 for (i = 0, rp = row; i < row_width; i++, rp += 3)
619 {
620 png_byte save = *rp;
621 *rp = *(rp + 2);
622 *(rp + 2) = save;
623 }
624 }
625
626 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
627 {
628 png_bytep rp;
629 png_uint_32 i;
630
631 for (i = 0, rp = row; i < row_width; i++, rp += 4)
632 {
633 png_byte save = *rp;
634 *rp = *(rp + 2);
635 *(rp + 2) = save;
636 }
637 }
638 }
639
640 #ifdef PNG_16BIT_SUPPORTED
641 else if (row_info->bit_depth == 16)
642 {
643 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
644 {
645 png_bytep rp;
646 png_uint_32 i;
647
648 for (i = 0, rp = row; i < row_width; i++, rp += 6)
649 {
650 png_byte save = *rp;
651 *rp = *(rp + 4);
652 *(rp + 4) = save;
653 save = *(rp + 1);
654 *(rp + 1) = *(rp + 5);
655 *(rp + 5) = save;
656 }
657 }
658
659 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
660 {
661 png_bytep rp;
662 png_uint_32 i;
663
664 for (i = 0, rp = row; i < row_width; i++, rp += 8)
665 {
666 png_byte save = *rp;
667 *rp = *(rp + 4);
668 *(rp + 4) = save;
669 save = *(rp + 1);
670 *(rp + 1) = *(rp + 5);
671 *(rp + 5) = save;
672 }
673 }
674 }
675 #endif
676 }
677 }
678 #endif /* READ_BGR || WRITE_BGR */
679
680 #if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \
681 defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED)
682 /* Added at libpng-1.5.10 */
683 void /* PRIVATE */
png_do_check_palette_indexes(png_structrp png_ptr,png_row_infop row_info)684 png_do_check_palette_indexes(png_structrp png_ptr, png_row_infop row_info)
685 {
686 if (png_ptr->num_palette < (1 << row_info->bit_depth) &&
687 png_ptr->num_palette > 0) /* num_palette can be 0 in MNG files */
688 {
689 /* Calculations moved outside switch in an attempt to stop different
690 * compiler warnings. 'padding' is in *bits* within the last byte, it is
691 * an 'int' because pixel_depth becomes an 'int' in the expression below,
692 * and this calculation is used because it avoids warnings that other
693 * forms produced on either GCC or MSVC.
694 */
695 int padding = (-row_info->pixel_depth * row_info->width) & 7;
696 png_bytep rp = png_ptr->row_buf + row_info->rowbytes;
697
698 switch (row_info->bit_depth)
699 {
700 case 1:
701 {
702 /* in this case, all bytes must be 0 so we don't need
703 * to unpack the pixels except for the rightmost one.
704 */
705 for (; rp > png_ptr->row_buf; rp--)
706 {
707 if ((*rp >> padding) != 0)
708 png_ptr->num_palette_max = 1;
709 padding = 0;
710 }
711
712 break;
713 }
714
715 case 2:
716 {
717 for (; rp > png_ptr->row_buf; rp--)
718 {
719 int i = ((*rp >> padding) & 0x03);
720
721 if (i > png_ptr->num_palette_max)
722 png_ptr->num_palette_max = i;
723
724 i = (((*rp >> padding) >> 2) & 0x03);
725
726 if (i > png_ptr->num_palette_max)
727 png_ptr->num_palette_max = i;
728
729 i = (((*rp >> padding) >> 4) & 0x03);
730
731 if (i > png_ptr->num_palette_max)
732 png_ptr->num_palette_max = i;
733
734 i = (((*rp >> padding) >> 6) & 0x03);
735
736 if (i > png_ptr->num_palette_max)
737 png_ptr->num_palette_max = i;
738
739 padding = 0;
740 }
741
742 break;
743 }
744
745 case 4:
746 {
747 for (; rp > png_ptr->row_buf; rp--)
748 {
749 int i = ((*rp >> padding) & 0x0f);
750
751 if (i > png_ptr->num_palette_max)
752 png_ptr->num_palette_max = i;
753
754 i = (((*rp >> padding) >> 4) & 0x0f);
755
756 if (i > png_ptr->num_palette_max)
757 png_ptr->num_palette_max = i;
758
759 padding = 0;
760 }
761
762 break;
763 }
764
765 case 8:
766 {
767 for (; rp > png_ptr->row_buf; rp--)
768 {
769 if (*rp > png_ptr->num_palette_max)
770 png_ptr->num_palette_max = (int) *rp;
771 }
772
773 break;
774 }
775
776 default:
777 break;
778 }
779 }
780 }
781 #endif /* CHECK_FOR_INVALID_INDEX */
782
783 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
784 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
785 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
786 void PNGAPI
png_set_user_transform_info(png_structrp png_ptr,png_voidp user_transform_ptr,int user_transform_depth,int user_transform_channels)787 png_set_user_transform_info(png_structrp png_ptr, png_voidp
788 user_transform_ptr, int user_transform_depth, int user_transform_channels)
789 {
790 png_debug(1, "in png_set_user_transform_info");
791
792 if (png_ptr == NULL)
793 return;
794
795 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
796 if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
797 (png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
798 {
799 png_app_error(png_ptr,
800 "info change after png_start_read_image or png_read_update_info");
801 return;
802 }
803 #endif
804
805 png_ptr->user_transform_ptr = user_transform_ptr;
806 png_ptr->user_transform_depth = (png_byte)user_transform_depth;
807 png_ptr->user_transform_channels = (png_byte)user_transform_channels;
808 }
809 #endif
810
811 /* This function returns a pointer to the user_transform_ptr associated with
812 * the user transform functions. The application should free any memory
813 * associated with this pointer before png_write_destroy and png_read_destroy
814 * are called.
815 */
816 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
817 png_voidp PNGAPI
png_get_user_transform_ptr(png_const_structrp png_ptr)818 png_get_user_transform_ptr(png_const_structrp png_ptr)
819 {
820 if (png_ptr == NULL)
821 return (NULL);
822
823 return png_ptr->user_transform_ptr;
824 }
825 #endif
826
827 #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
828 png_uint_32 PNGAPI
png_get_current_row_number(png_const_structrp png_ptr)829 png_get_current_row_number(png_const_structrp png_ptr)
830 {
831 /* See the comments in png.h - this is the sub-image row when reading an
832 * interlaced image.
833 */
834 if (png_ptr != NULL)
835 return png_ptr->row_number;
836
837 return PNG_UINT_32_MAX; /* help the app not to fail silently */
838 }
839
840 png_byte PNGAPI
png_get_current_pass_number(png_const_structrp png_ptr)841 png_get_current_pass_number(png_const_structrp png_ptr)
842 {
843 if (png_ptr != NULL)
844 return png_ptr->pass;
845 return 8; /* invalid */
846 }
847 #endif /* USER_TRANSFORM_INFO */
848 #endif /* READ_USER_TRANSFORM || WRITE_USER_TRANSFORM */
849 #endif /* READ || WRITE */
850