2 /* pngwtran.c - transforms the data in a row for PNG writers
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4 * Last changed in libpng 1.2.9 April 14, 2006
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5 * For conditions of distribution and use, see copyright notice in png.h
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6 * Copyright (c) 1998-2006 Glenn Randers-Pehrson
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7 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
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8 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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11 #define PNG_INTERNAL
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13 #ifdef PNG_WRITE_SUPPORTED
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15 /* Transform the data according to the user's wishes. The order of
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16 * transformations is significant.
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19 png_do_write_transformations(png_structp png_ptr)
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21 png_debug(1, "in png_do_write_transformations\n");
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23 if (png_ptr == NULL)
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26 #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
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27 if (png_ptr->transformations & PNG_USER_TRANSFORM)
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28 if (png_ptr->write_user_transform_fn != NULL)
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29 (*(png_ptr->write_user_transform_fn)) /* user write transform function */
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30 (png_ptr, /* png_ptr */
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31 &(png_ptr->row_info), /* row_info: */
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32 /* png_uint_32 width; width of row */
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33 /* png_uint_32 rowbytes; number of bytes in row */
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34 /* png_byte color_type; color type of pixels */
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35 /* png_byte bit_depth; bit depth of samples */
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36 /* png_byte channels; number of channels (1-4) */
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37 /* png_byte pixel_depth; bits per pixel (depth*channels) */
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38 png_ptr->row_buf + 1); /* start of pixel data for row */
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40 #if defined(PNG_WRITE_FILLER_SUPPORTED)
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41 if (png_ptr->transformations & PNG_FILLER)
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42 png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
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45 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED)
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46 if (png_ptr->transformations & PNG_PACKSWAP)
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47 png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
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49 #if defined(PNG_WRITE_PACK_SUPPORTED)
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50 if (png_ptr->transformations & PNG_PACK)
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51 png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
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52 (png_uint_32)png_ptr->bit_depth);
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54 #if defined(PNG_WRITE_SWAP_SUPPORTED)
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55 if (png_ptr->transformations & PNG_SWAP_BYTES)
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56 png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
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58 #if defined(PNG_WRITE_SHIFT_SUPPORTED)
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59 if (png_ptr->transformations & PNG_SHIFT)
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60 png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
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63 #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
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64 if (png_ptr->transformations & PNG_SWAP_ALPHA)
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65 png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
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67 #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
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68 if (png_ptr->transformations & PNG_INVERT_ALPHA)
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69 png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
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71 #if defined(PNG_WRITE_BGR_SUPPORTED)
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72 if (png_ptr->transformations & PNG_BGR)
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73 png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
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75 #if defined(PNG_WRITE_INVERT_SUPPORTED)
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76 if (png_ptr->transformations & PNG_INVERT_MONO)
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77 png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
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81 #if defined(PNG_WRITE_PACK_SUPPORTED)
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82 /* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
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83 * row_info bit depth should be 8 (one pixel per byte). The channels
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84 * should be 1 (this only happens on grayscale and paletted images).
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87 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
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89 png_debug(1, "in png_do_pack\n");
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90 if (row_info->bit_depth == 8 &&
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91 #if defined(PNG_USELESS_TESTS_SUPPORTED)
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92 row != NULL && row_info != NULL &&
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94 row_info->channels == 1)
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96 switch ((int)bit_depth)
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103 png_uint_32 row_width = row_info->width;
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110 for (i = 0; i < row_width; i++)
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134 png_uint_32 row_width = row_info->width;
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140 for (i = 0; i < row_width; i++)
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144 value = (png_byte)(*sp & 0x03);
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145 v |= (value << shift);
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166 png_uint_32 row_width = row_info->width;
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172 for (i = 0; i < row_width; i++)
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176 value = (png_byte)(*sp & 0x0f);
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177 v |= (value << shift);
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196 row_info->bit_depth = (png_byte)bit_depth;
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197 row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
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198 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
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204 #if defined(PNG_WRITE_SHIFT_SUPPORTED)
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205 /* Shift pixel values to take advantage of whole range. Pass the
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206 * true number of bits in bit_depth. The row should be packed
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207 * according to row_info->bit_depth. Thus, if you had a row of
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208 * bit depth 4, but the pixels only had values from 0 to 7, you
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209 * would pass 3 as bit_depth, and this routine would translate the
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213 png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
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215 png_debug(1, "in png_do_shift\n");
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216 #if defined(PNG_USELESS_TESTS_SUPPORTED)
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217 if (row != NULL && row_info != NULL &&
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221 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
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223 int shift_start[4], shift_dec[4];
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226 if (row_info->color_type & PNG_COLOR_MASK_COLOR)
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228 shift_start[channels] = row_info->bit_depth - bit_depth->red;
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229 shift_dec[channels] = bit_depth->red;
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231 shift_start[channels] = row_info->bit_depth - bit_depth->green;
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232 shift_dec[channels] = bit_depth->green;
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234 shift_start[channels] = row_info->bit_depth - bit_depth->blue;
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235 shift_dec[channels] = bit_depth->blue;
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240 shift_start[channels] = row_info->bit_depth - bit_depth->gray;
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241 shift_dec[channels] = bit_depth->gray;
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244 if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
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246 shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
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247 shift_dec[channels] = bit_depth->alpha;
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251 /* with low row depths, could only be grayscale, so one channel */
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252 if (row_info->bit_depth < 8)
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254 png_bytep bp = row;
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257 png_uint_32 row_bytes = row_info->rowbytes;
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259 if (bit_depth->gray == 1 && row_info->bit_depth == 2)
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261 else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
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266 for (i = 0; i < row_bytes; i++, bp++)
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273 for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
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276 *bp |= (png_byte)((v << j) & 0xff);
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278 *bp |= (png_byte)((v >> (-j)) & mask);
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282 else if (row_info->bit_depth == 8)
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284 png_bytep bp = row;
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286 png_uint_32 istop = channels * row_info->width;
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288 for (i = 0; i < istop; i++, bp++)
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293 int c = (int)(i%channels);
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297 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
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300 *bp |= (png_byte)((v << j) & 0xff);
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302 *bp |= (png_byte)((v >> (-j)) & 0xff);
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310 png_uint_32 istop = channels * row_info->width;
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312 for (bp = row, i = 0; i < istop; i++)
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314 int c = (int)(i%channels);
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315 png_uint_16 value, v;
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318 v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));
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320 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
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323 value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
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325 value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
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327 *bp++ = (png_byte)(value >> 8);
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328 *bp++ = (png_byte)(value & 0xff);
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335 #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
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337 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
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339 png_debug(1, "in png_do_write_swap_alpha\n");
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340 #if defined(PNG_USELESS_TESTS_SUPPORTED)
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341 if (row != NULL && row_info != NULL)
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344 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
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346 /* This converts from ARGB to RGBA */
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347 if (row_info->bit_depth == 8)
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351 png_uint_32 row_width = row_info->width;
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352 for (i = 0, sp = dp = row; i < row_width; i++)
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354 png_byte save = *(sp++);
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361 /* This converts from AARRGGBB to RRGGBBAA */
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366 png_uint_32 row_width = row_info->width;
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368 for (i = 0, sp = dp = row; i < row_width; i++)
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384 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
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386 /* This converts from AG to GA */
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387 if (row_info->bit_depth == 8)
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391 png_uint_32 row_width = row_info->width;
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393 for (i = 0, sp = dp = row; i < row_width; i++)
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395 png_byte save = *(sp++);
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400 /* This converts from AAGG to GGAA */
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405 png_uint_32 row_width = row_info->width;
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407 for (i = 0, sp = dp = row; i < row_width; i++)
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423 #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
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425 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
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427 png_debug(1, "in png_do_write_invert_alpha\n");
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428 #if defined(PNG_USELESS_TESTS_SUPPORTED)
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429 if (row != NULL && row_info != NULL)
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432 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
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434 /* This inverts the alpha channel in RGBA */
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435 if (row_info->bit_depth == 8)
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439 png_uint_32 row_width = row_info->width;
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440 for (i = 0, sp = dp = row; i < row_width; i++)
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448 *(dp++) = (png_byte)(255 - *(sp++));
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451 /* This inverts the alpha channel in RRGGBBAA */
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456 png_uint_32 row_width = row_info->width;
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458 for (i = 0, sp = dp = row; i < row_width; i++)
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469 *(dp++) = (png_byte)(255 - *(sp++));
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470 *(dp++) = (png_byte)(255 - *(sp++));
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474 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
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476 /* This inverts the alpha channel in GA */
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477 if (row_info->bit_depth == 8)
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481 png_uint_32 row_width = row_info->width;
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483 for (i = 0, sp = dp = row; i < row_width; i++)
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486 *(dp++) = (png_byte)(255 - *(sp++));
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489 /* This inverts the alpha channel in GGAA */
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494 png_uint_32 row_width = row_info->width;
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496 for (i = 0, sp = dp = row; i < row_width; i++)
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503 *(dp++) = (png_byte)(255 - *(sp++));
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504 *(dp++) = (png_byte)(255 - *(sp++));
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512 #if defined(PNG_MNG_FEATURES_SUPPORTED)
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513 /* undoes intrapixel differencing */
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515 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
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517 png_debug(1, "in png_do_write_intrapixel\n");
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519 #if defined(PNG_USELESS_TESTS_SUPPORTED)
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520 row != NULL && row_info != NULL &&
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522 (row_info->color_type & PNG_COLOR_MASK_COLOR))
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524 int bytes_per_pixel;
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525 png_uint_32 row_width = row_info->width;
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526 if (row_info->bit_depth == 8)
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531 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
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532 bytes_per_pixel = 3;
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533 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
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534 bytes_per_pixel = 4;
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538 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
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540 *(rp) = (png_byte)((*rp - *(rp+1))&0xff);
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541 *(rp+2) = (png_byte)((*(rp+2) - *(rp+1))&0xff);
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544 else if (row_info->bit_depth == 16)
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549 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
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550 bytes_per_pixel = 6;
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551 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
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552 bytes_per_pixel = 8;
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556 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
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558 png_uint_32 s0 = (*(rp ) << 8) | *(rp+1);
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559 png_uint_32 s1 = (*(rp+2) << 8) | *(rp+3);
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560 png_uint_32 s2 = (*(rp+4) << 8) | *(rp+5);
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561 png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
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562 png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
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563 *(rp ) = (png_byte)((red >> 8) & 0xff);
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564 *(rp+1) = (png_byte)(red & 0xff);
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565 *(rp+4) = (png_byte)((blue >> 8) & 0xff);
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566 *(rp+5) = (png_byte)(blue & 0xff);
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571 #endif /* PNG_MNG_FEATURES_SUPPORTED */
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572 #endif /* PNG_WRITE_SUPPORTED */
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