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
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"
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
png_set_add_alpha(png_structrp png_ptr,png_uint_32 filler,int filler_loc)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
png_set_swap_alpha(png_structrp png_ptr)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
png_set_invert_alpha(png_structrp png_ptr)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
png_set_invert_mono(png_structrp png_ptr)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 */
png_do_invert(png_row_infop row_info,png_bytep row)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 */
png_do_swap(png_row_infop row_info,png_bytep row)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 */
png_do_packswap(png_row_infop row_info,png_bytep row)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 */
png_do_strip_channel(png_row_infop row_info,png_bytep row,int at_start)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 */
png_do_bgr(png_row_infop row_info,png_bytep row)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 */
png_do_check_palette_indexes(png_structrp png_ptr,png_row_infop row_info)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
png_set_user_transform_info(png_structrp png_ptr,png_voidp user_transform_ptr,int user_transform_depth,int user_transform_channels)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
png_get_user_transform_ptr(png_const_structrp png_ptr)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
png_get_current_row_number(png_const_structrp png_ptr)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
png_get_current_pass_number(png_const_structrp png_ptr)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 */
865