libavformat/png.c

   1 /*
   2  * PNG image format
   3  * Copyright (c) 2003 Fabrice Bellard.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19 #include "avformat.h"
  20
  21 /* TODO:
  22  * - add 2, 4 and 16 bit depth support
  23  * - use filters when generating a png (better compression)
  24  */
  25
  26 #ifdef CONFIG_ZLIB
  27 #include <zlib.h>
  28
  29 //#define DEBUG
  30
  31 #define PNG_COLOR_MASK_PALETTE    1
  32 #define PNG_COLOR_MASK_COLOR      2
  33 #define PNG_COLOR_MASK_ALPHA      4
  34
  35 #define PNG_COLOR_TYPE_GRAY 0
  36 #define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
  37 #define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)
  38 #define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
  39 #define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
  40
  41 #define PNG_FILTER_VALUE_NONE  0
  42 #define PNG_FILTER_VALUE_SUB   1
  43 #define PNG_FILTER_VALUE_UP    2
  44 #define PNG_FILTER_VALUE_AVG   3
  45 #define PNG_FILTER_VALUE_PAETH 4
  46
  47 #define PNG_IHDR      0x0001
  48 #define PNG_IDAT      0x0002
  49 #define PNG_ALLIMAGE  0x0004
  50 #define PNG_PLTE      0x0008
  51
  52 #define NB_PASSES 7
  53
  54 #define IOBUF_SIZE 4096
  55
  56 typedef struct PNGDecodeState {
  57     int state;
  58     int width, height;
  59     int bit_depth;
  60     int color_type;
  61     int compression_type;
  62     int interlace_type;
  63     int filter_type;
  64     int channels;
  65     int bits_per_pixel;
  66     int bpp;
  67
  68     uint8_t *image_buf;
  69     int image_linesize;
  70     uint32_t palette[256];
  71     uint8_t *crow_buf;
  72     uint8_t *last_row;
  73     uint8_t *tmp_row;
  74     int pass;
  75     int crow_size; /* compressed row size (include filter type) */
  76     int row_size; /* decompressed row size */
  77     int pass_row_size; /* decompress row size of the current pass */
  78     int y;
  79     z_stream zstream;
  80 } PNGDecodeState;
  81
  82 static const uint8_t pngsig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
  83
  84 /* Mask to determine which y pixels are valid in a pass */
  85 static const uint8_t png_pass_ymask[NB_PASSES] = {
  86     0x80, 0x80, 0x08, 0x88, 0x22, 0xaa, 0x55,
  87 };
  88
  89 /* Mask to determine which y pixels can be written in a pass */
  90 static const uint8_t png_pass_dsp_ymask[NB_PASSES] = {
  91     0xff, 0xff, 0x0f, 0xcc, 0x33, 0xff, 0x55,
  92 };
  93
  94 /* minimum x value */
  95 static const uint8_t png_pass_xmin[NB_PASSES] = {
  96     0, 4, 0, 2, 0, 1, 0
  97 };
  98
  99 /* x shift to get row width */
 100 static const uint8_t png_pass_xshift[NB_PASSES] = {
 101     3, 3, 2, 2, 1, 1, 0
 102 };
 103
 104 /* Mask to determine which pixels are valid in a pass */
 105 static const uint8_t png_pass_mask[NB_PASSES] = {
 106     0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff
 107 };
 108
 109 /* Mask to determine which pixels to overwrite while displaying */
 110 static const uint8_t png_pass_dsp_mask[NB_PASSES] = {
 111     0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff
 112 };
 113
 114 static int png_probe(AVProbeData *pd)
 115 {
 116     if (pd->buf_size >= 8 &&
 117         memcmp(pd->buf, pngsig, 8) == 0)
 118         return AVPROBE_SCORE_MAX;
 119     else
 120         return 0;
 121 }
 122
 123 static void *png_zalloc(void *opaque, unsigned int items, unsigned int size)
 124 {
 125     return av_malloc(items * size);
 126 }
 127
 128 static void png_zfree(void *opaque, void *ptr)
 129 {
 130     av_free(ptr);
 131 }
 132
 133 static int png_get_nb_channels(int color_type)
 134 {
 135     int channels;
 136     channels = 1;
 137     if ((color_type & (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)) ==
 138         PNG_COLOR_MASK_COLOR)
 139         channels = 3;
 140     if (color_type & PNG_COLOR_MASK_ALPHA)
 141         channels++;
 142     return channels;
 143 }
 144
 145 /* compute the row size of an interleaved pass */
 146 static int png_pass_row_size(int pass, int bits_per_pixel, int width)
 147 {
 148     int shift, xmin, pass_width;
 149
 150     xmin = png_pass_xmin[pass];
 151     if (width <= xmin)
 152         return 0;
 153     shift = png_pass_xshift[pass];
 154     pass_width = (width - xmin + (1 << shift) - 1) >> shift;
 155     return (pass_width * bits_per_pixel + 7) >> 3;
 156 }
 157
 158 /* NOTE: we try to construct a good looking image at each pass. width
 159    is the original image width. We also do pixel format convertion at
 160    this stage */
 161 static void png_put_interlaced_row(uint8_t *dst, int width,
 162                                    int bits_per_pixel, int pass,
 163                                    int color_type, const uint8_t *src)
 164 {
 165     int x, mask, dsp_mask, j, src_x, b, bpp;
 166     uint8_t *d;
 167     const uint8_t *s;
 168
 169     mask = png_pass_mask[pass];
 170     dsp_mask = png_pass_dsp_mask[pass];
 171     switch(bits_per_pixel) {
 172     case 1:
 173         /* we must intialize the line to zero before writing to it */
 174         if (pass == 0)
 175             memset(dst, 0, (width + 7) >> 3);
 176         src_x = 0;
 177         for(x = 0; x < width; x++) {
 178             j = (x & 7);
 179             if ((dsp_mask << j) & 0x80) {
 180                 b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;
 181                 dst[x >> 3] |= b << (7 - j);
 182             }
 183             if ((mask << j) & 0x80)
 184                 src_x++;
 185         }
 186         break;
 187     default:
 188         bpp = bits_per_pixel >> 3;
 189         d = dst;
 190         s = src;
 191         if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 192             for(x = 0; x < width; x++) {
 193                 j = x & 7;
 194                 if ((dsp_mask << j) & 0x80) {
 195                     *(uint32_t *)d = (s[3] << 24) | (s[0] << 16) | (s[1] << 8) | s[2];
 196                 }
 197                 d += bpp;
 198                 if ((mask << j) & 0x80)
 199                     s += bpp;
 200             }
 201         } else {
 202             for(x = 0; x < width; x++) {
 203                 j = x & 7;
 204                 if ((dsp_mask << j) & 0x80) {
 205                     memcpy(d, s, bpp);
 206                 }
 207                 d += bpp;
 208                 if ((mask << j) & 0x80)
 209                     s += bpp;
 210             }
 211         }
 212         break;
 213     }
 214 }
 215
 216 static void png_get_interlaced_row(uint8_t *dst, int row_size,
 217                                    int bits_per_pixel, int pass,
 218                                    const uint8_t *src, int width)
 219 {
 220     int x, mask, dst_x, j, b, bpp;
 221     uint8_t *d;
 222     const uint8_t *s;
 223
 224     mask = png_pass_mask[pass];
 225     switch(bits_per_pixel) {
 226     case 1:
 227         memset(dst, 0, row_size);
 228         dst_x = 0;
 229         for(x = 0; x < width; x++) {
 230             j = (x & 7);
 231             if ((mask << j) & 0x80) {
 232                 b = (src[x >> 3] >> (7 - j)) & 1;
 233                 dst[dst_x >> 3] |= b << (7 - (dst_x & 7));
 234                 dst_x++;
 235             }
 236         }
 237         break;
 238     default:
 239         bpp = bits_per_pixel >> 3;
 240         d = dst;
 241         s = src;
 242         for(x = 0; x < width; x++) {
 243             j = x & 7;
 244             if ((mask << j) & 0x80) {
 245                 memcpy(d, s, bpp);
 246                 d += bpp;
 247             }
 248             s += bpp;
 249         }
 250         break;
 251     }
 252 }
 253
 254 /* XXX: optimize */
 255 /* NOTE: 'dst' can be equal to 'last' */
 256 static void png_filter_row(uint8_t *dst, int filter_type,
 257                            uint8_t *src, uint8_t *last, int size, int bpp)
 258 {
 259     int i, p;
 260
 261     switch(filter_type) {
 262     case PNG_FILTER_VALUE_NONE:
 263         memcpy(dst, src, size);
 264         break;
 265     case PNG_FILTER_VALUE_SUB:
 266         for(i = 0; i < bpp; i++) {
 267             dst[i] = src[i];
 268         }
 269         for(i = bpp; i < size; i++) {
 270             p = dst[i - bpp];
 271             dst[i] = p + src[i];
 272         }
 273         break;
 274     case PNG_FILTER_VALUE_UP:
 275         for(i = 0; i < size; i++) {
 276             p = last[i];
 277             dst[i] = p + src[i];
 278         }
 279         break;
 280     case PNG_FILTER_VALUE_AVG:
 281         for(i = 0; i < bpp; i++) {
 282             p = (last[i] >> 1);
 283             dst[i] = p + src[i];
 284         }
 285         for(i = bpp; i < size; i++) {
 286             p = ((dst[i - bpp] + last[i]) >> 1);
 287             dst[i] = p + src[i];
 288         }
 289         break;
 290     case PNG_FILTER_VALUE_PAETH:
 291         for(i = 0; i < bpp; i++) {
 292             p = last[i];
 293             dst[i] = p + src[i];
 294         }
 295         for(i = bpp; i < size; i++) {
 296             int a, b, c, pa, pb, pc;
 297
 298             a = dst[i - bpp];
 299             b = last[i];
 300             c = last[i - bpp];
 301
 302             p = b - c;
 303             pc = a - c;
 304
 305             pa = abs(p);
 306             pb = abs(pc);
 307             pc = abs(p + pc);
 308
 309             if (pa <= pb && pa <= pc)
 310                 p = a;
 311             else if (pb <= pc)
 312                 p = b;
 313             else
 314                 p = c;
 315             dst[i] = p + src[i];
 316         }
 317         break;
 318     }
 319 }
 320
 321 static void convert_from_rgba32(uint8_t *dst, const uint8_t *src, int width)
 322 {
 323     uint8_t *d;
 324     int j;
 325     unsigned int v;
 326
 327     d = dst;
 328     for(j = 0; j < width; j++) {
 329         v = ((const uint32_t *)src)[j];
 330         d[0] = v >> 16;
 331         d[1] = v >> 8;
 332         d[2] = v;
 333         d[3] = v >> 24;
 334         d += 4;
 335     }
 336 }
 337
 338 static void convert_to_rgba32(uint8_t *dst, const uint8_t *src, int width)
 339 {
 340     int j;
 341     unsigned int r, g, b, a;
 342
 343     for(j = 0;j < width; j++) {
 344         r = src[0];
 345         g = src[1];
 346         b = src[2];
 347         a = src[3];
 348         *(uint32_t *)dst = (a << 24) | (r << 16) | (g << 8) | b;
 349         dst += 4;
 350         src += 4;
 351     }
 352 }
 353
 354 /* process exactly one decompressed row */
 355 static void png_handle_row(PNGDecodeState *s)
 356 {
 357     uint8_t *ptr, *last_row;
 358     int got_line;
 359
 360     if (!s->interlace_type) {
 361         ptr = s->image_buf + s->image_linesize * s->y;
 362         /* need to swap bytes correctly for RGB_ALPHA */
 363         if (s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 364             png_filter_row(s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
 365                            s->last_row, s->row_size, s->bpp);
 366             memcpy(s->last_row, s->tmp_row, s->row_size);
 367             convert_to_rgba32(ptr, s->tmp_row, s->width);
 368         } else {
 369             /* in normal case, we avoid one copy */
 370             if (s->y == 0)
 371                 last_row = s->last_row;
 372             else
 373                 last_row = ptr - s->image_linesize;
 374
 375             png_filter_row(ptr, s->crow_buf[0], s->crow_buf + 1,
 376                            last_row, s->row_size, s->bpp);
 377         }
 378         s->y++;
 379         if (s->y == s->height) {
 380             s->state |= PNG_ALLIMAGE;
 381         }
 382     } else {
 383         got_line = 0;
 384         for(;;) {
 385             ptr = s->image_buf + s->image_linesize * s->y;
 386             if ((png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
 387                 /* if we already read one row, it is time to stop to
 388                    wait for the next one */
 389                 if (got_line)
 390                     break;
 391                 png_filter_row(s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
 392                                s->last_row, s->pass_row_size, s->bpp);
 393                 memcpy(s->last_row, s->tmp_row, s->pass_row_size);
 394                 got_line = 1;
 395             }
 396             if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
 397                 /* NOTE: rgba32 is handled directly in png_put_interlaced_row */
 398                 png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
 399                                        s->color_type, s->last_row);
 400             }
 401             s->y++;
 402             if (s->y == s->height) {
 403                 for(;;) {
 404                     if (s->pass == NB_PASSES - 1) {
 405                         s->state |= PNG_ALLIMAGE;
 406                         goto the_end;
 407                     } else {
 408                         s->pass++;
 409                         s->y = 0;
 410                         s->pass_row_size = png_pass_row_size(s->pass,
 411                                                              s->bits_per_pixel,
 412                                                              s->width);
 413                         s->crow_size = s->pass_row_size + 1;
 414                         if (s->pass_row_size != 0)
 415                             break;
 416                         /* skip pass if empty row */
 417                     }
 418                 }
 419             }
 420         }
 421     the_end: ;
 422     }
 423 }
 424
 425 static int png_decode_idat(PNGDecodeState *s, ByteIOContext *f, int length)
 426 {
 427     uint8_t buf[IOBUF_SIZE];
 428     int buf_size;
 429     int ret;
 430     while (length > 0) {
 431         /* read the buffer */
 432         buf_size = IOBUF_SIZE;
 433         if (buf_size > length)
 434             buf_size = length;
 435         ret = get_buffer(f, buf, buf_size);
 436         if (ret != buf_size)
 437             return -1;
 438         s->zstream.avail_in = buf_size;
 439         s->zstream.next_in = buf;
 440         /* decode one line if possible */
 441         while (s->zstream.avail_in > 0) {
 442             ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
 443             if (ret != Z_OK && ret != Z_STREAM_END) {
 444                 return -1;
 445             }
 446             if (s->zstream.avail_out == 0) {
 447                 if (!(s->state & PNG_ALLIMAGE)) {
 448                     png_handle_row(s);
 449                 }
 450                 s->zstream.avail_out = s->crow_size;
 451                 s->zstream.next_out = s->crow_buf;
 452             }
 453         }
 454         length -= buf_size;
 455     }
 456     return 0;
 457 }
 458
 459 static int png_read(ByteIOContext *f,
 460                     int (*alloc_cb)(void *opaque, AVImageInfo *info), void *opaque)
 461 {
 462     AVImageInfo info1, *info = &info1;
 463     PNGDecodeState s1, *s = &s1;
 464     uint32_t tag, length;
 465     int ret, crc;
 466     uint8_t buf[8];
 467
 468     /* check signature */
 469     ret = get_buffer(f, buf, 8);
 470     if (ret != 8)
 471         return -1;
 472     if (memcmp(buf, pngsig, 8) != 0)
 473         return -1;
 474     memset(s, 0, sizeof(PNGDecodeState));
 475     /* init the zlib */
 476     s->zstream.zalloc = png_zalloc;
 477     s->zstream.zfree = png_zfree;
 478     s->zstream.opaque = NULL;
 479     ret = inflateInit(&s->zstream);
 480     if (ret != Z_OK)
 481         return -1;
 482     for(;;) {
 483         if (url_feof(f))
 484             goto fail;
 485         length = get_be32(f);
 486         if (length > 0x7fffffff)
 487             goto fail;
 488         tag = get_le32(f);
 489 #ifdef DEBUG
 490         printf("png: tag=%c%c%c%c length=%u\n",
 491                (tag & 0xff),
 492                ((tag >> 8) & 0xff),
 493                ((tag >> 16) & 0xff),
 494                ((tag >> 24) & 0xff), length);
 495 #endif
 496         switch(tag) {
 497         case MKTAG('I', 'H', 'D', 'R'):
 498             if (length != 13)
 499                 goto fail;
 500             s->width = get_be32(f);
 501             s->height = get_be32(f);
 502             s->bit_depth = get_byte(f);
 503             s->color_type = get_byte(f);
 504             s->compression_type = get_byte(f);
 505             s->filter_type = get_byte(f);
 506             s->interlace_type = get_byte(f);
 507             crc = get_be32(f);
 508             s->state |= PNG_IHDR;
 509 #ifdef DEBUG
 510             printf("width=%d height=%d depth=%d color_type=%d compression_type=%d filter_type=%d interlace_type=%d\n",
 511                    s->width, s->height, s->bit_depth, s->color_type,
 512                    s->compression_type, s->filter_type, s->interlace_type);
 513 #endif
 514             break;
 515         case MKTAG('I', 'D', 'A', 'T'):
 516             if (!(s->state & PNG_IHDR))
 517                 goto fail;
 518             if (!(s->state & PNG_IDAT)) {
 519                 /* init image info */
 520                 info->width = s->width;
 521                 info->height = s->height;
 522                 info->interleaved = (s->interlace_type != 0);
 523
 524                 s->channels = png_get_nb_channels(s->color_type);
 525                 s->bits_per_pixel = s->bit_depth * s->channels;
 526                 s->bpp = (s->bits_per_pixel + 7) >> 3;
 527                 s->row_size = (info->width * s->bits_per_pixel + 7) >> 3;
 528
 529                 if (s->bit_depth == 8 &&
 530                     s->color_type == PNG_COLOR_TYPE_RGB) {
 531                     info->pix_fmt = PIX_FMT_RGB24;
 532                 } else if (s->bit_depth == 8 &&
 533                            s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 534                     info->pix_fmt = PIX_FMT_RGBA32;
 535                 } else if (s->bit_depth == 8 &&
 536                            s->color_type == PNG_COLOR_TYPE_GRAY) {
 537                     info->pix_fmt = PIX_FMT_GRAY8;
 538                 } else if (s->bit_depth == 1 &&
 539                            s->color_type == PNG_COLOR_TYPE_GRAY) {
 540                     info->pix_fmt = PIX_FMT_MONOBLACK;
 541                 } else if (s->color_type == PNG_COLOR_TYPE_PALETTE) {
 542                     info->pix_fmt = PIX_FMT_PAL8;
 543                 } else {
 544                     goto fail;
 545                 }
 546                 ret = alloc_cb(opaque, info);
 547                 if (ret)
 548                     goto the_end;
 549
 550                 /* compute the compressed row size */
 551                 if (!s->interlace_type) {
 552                     s->crow_size = s->row_size + 1;
 553                 } else {
 554                     s->pass = 0;
 555                     s->pass_row_size = png_pass_row_size(s->pass,
 556                                                          s->bits_per_pixel,
 557                                                          s->width);
 558                     s->crow_size = s->pass_row_size + 1;
 559                 }
 560 #ifdef DEBUG
 561                 printf("row_size=%d crow_size =%d\n",
 562                        s->row_size, s->crow_size);
 563 #endif
 564                 s->image_buf = info->pict.data[0];
 565                 s->image_linesize = info->pict.linesize[0];
 566                 /* copy the palette if needed */
 567                 if (s->color_type == PNG_COLOR_TYPE_PALETTE)
 568                     memcpy(info->pict.data[1], s->palette, 256 * sizeof(uint32_t));
 569                 /* empty row is used if differencing to the first row */
 570                 s->last_row = av_mallocz(s->row_size);
 571                 if (!s->last_row)
 572                     goto fail;
 573                 if (s->interlace_type ||
 574                     s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 575                     s->tmp_row = av_malloc(s->row_size);
 576                     if (!s->tmp_row)
 577                         goto fail;
 578                 }
 579                 /* compressed row */
 580                 s->crow_buf = av_malloc(s->row_size + 1);
 581                 if (!s->crow_buf)
 582                     goto fail;
 583                 s->zstream.avail_out = s->crow_size;
 584                 s->zstream.next_out = s->crow_buf;
 585             }
 586             s->state |= PNG_IDAT;
 587             if (png_decode_idat(s, f, length) < 0)
 588                 goto fail;
 589             /* skip crc */
 590             crc = get_be32(f);
 591             break;
 592         case MKTAG('P', 'L', 'T', 'E'):
 593             {
 594                 int n, i, r, g, b;
 595
 596                 if ((length % 3) != 0 || length > 256 * 3)
 597                     goto skip_tag;
 598                 /* read the palette */
 599                 n = length / 3;
 600                 for(i=0;i<n;i++) {
 601                     r = get_byte(f);
 602                     g = get_byte(f);
 603                     b = get_byte(f);
 604                     s->palette[i] = (0xff << 24) | (r << 16) | (g << 8) | b;
 605                 }
 606                 for(;i<256;i++) {
 607                     s->palette[i] = (0xff << 24);
 608                 }
 609                 s->state |= PNG_PLTE;
 610                 crc = get_be32(f);
 611             }
 612             break;
 613         case MKTAG('t', 'R', 'N', 'S'):
 614             {
 615                 int v, i;
 616
 617                 /* read the transparency. XXX: Only palette mode supported */
 618                 if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
 619                     length > 256 ||
 620                     !(s->state & PNG_PLTE))
 621                     goto skip_tag;
 622                 for(i=0;i<length;i++) {
 623                     v = get_byte(f);
 624                     s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
 625                 }
 626                 crc = get_be32(f);
 627             }
 628             break;
 629         case MKTAG('I', 'E', 'N', 'D'):
 630             if (!(s->state & PNG_ALLIMAGE))
 631                 goto fail;
 632             crc = get_be32(f);
 633             goto exit_loop;
 634         default:
 635             /* skip tag */
 636         skip_tag:
 637             url_fskip(f, length + 4);
 638             break;
 639         }
 640     }
 641  exit_loop:
 642     ret = 0;
 643  the_end:
 644     inflateEnd(&s->zstream);
 645     av_free(s->crow_buf);
 646     av_free(s->last_row);
 647     av_free(s->tmp_row);
 648     return ret;
 649  fail:
 650     ret = -1;
 651     goto the_end;
 652 }
 653
 654 static void png_write_chunk(ByteIOContext *f, uint32_t tag,
 655                             const uint8_t *buf, int length)
 656 {
 657     uint32_t crc;
 658     uint8_t tagbuf[4];
 659
 660     put_be32(f, length);
 661     crc = crc32(0, Z_NULL, 0);
 662     tagbuf[0] = tag;
 663     tagbuf[1] = tag >> 8;
 664     tagbuf[2] = tag >> 16;
 665     tagbuf[3] = tag >> 24;
 666     crc = crc32(crc, tagbuf, 4);
 667     put_le32(f, tag);
 668     if (length > 0) {
 669         crc = crc32(crc, buf, length);
 670         put_buffer(f, buf, length);
 671     }
 672     put_be32(f, crc);
 673 }
 674
 675 /* XXX: use avcodec generic function ? */
 676 static void to_be32(uint8_t *p, uint32_t v)
 677 {
 678     p[0] = v >> 24;
 679     p[1] = v >> 16;
 680     p[2] = v >> 8;
 681     p[3] = v;
 682 }
 683
 684 typedef struct PNGEncodeState {
 685     ByteIOContext *f;
 686     z_stream zstream;
 687     uint8_t buf[IOBUF_SIZE];
 688 } PNGEncodeState;
 689
 690
 691 /* XXX: do filtering */
 692 static int png_write_row(PNGEncodeState *s, const uint8_t *data, int size)
 693 {
 694     int ret;
 695
 696     s->zstream.avail_in = size;
 697     s->zstream.next_in = (uint8_t *)data;
 698     while (s->zstream.avail_in > 0) {
 699         ret = deflate(&s->zstream, Z_NO_FLUSH);
 700         if (ret != Z_OK)
 701             return -1;
 702         if (s->zstream.avail_out == 0) {
 703             png_write_chunk(s->f, MKTAG('I', 'D', 'A', 'T'), s->buf, IOBUF_SIZE);
 704             s->zstream.avail_out = IOBUF_SIZE;
 705             s->zstream.next_out = s->buf;
 706         }
 707     }
 708     return 0;
 709 }
 710
 711 static int png_write(ByteIOContext *f, AVImageInfo *info)
 712 {
 713     PNGEncodeState s1, *s = &s1;
 714     int bit_depth, color_type, y, len, row_size, ret, is_progressive;
 715     int bits_per_pixel, pass_row_size;
 716     uint8_t *ptr;
 717     uint8_t *crow_buf = NULL;
 718     uint8_t *tmp_buf = NULL;
 719
 720     s->f = f;
 721     is_progressive = info->interleaved;
 722     switch(info->pix_fmt) {
 723     case PIX_FMT_RGBA32:
 724         bit_depth = 8;
 725         color_type = PNG_COLOR_TYPE_RGB_ALPHA;
 726         break;
 727     case PIX_FMT_RGB24:
 728         bit_depth = 8;
 729         color_type = PNG_COLOR_TYPE_RGB;
 730         break;
 731     case PIX_FMT_GRAY8:
 732         bit_depth = 8;
 733         color_type = PNG_COLOR_TYPE_GRAY;
 734         break;
 735     case PIX_FMT_MONOBLACK:
 736         bit_depth = 1;
 737         color_type = PNG_COLOR_TYPE_GRAY;
 738         break;
 739     case PIX_FMT_PAL8:
 740         bit_depth = 8;
 741         color_type = PNG_COLOR_TYPE_PALETTE;
 742         break;
 743     default:
 744         return -1;
 745     }
 746     bits_per_pixel = png_get_nb_channels(color_type) * bit_depth;
 747     row_size = (info->width * bits_per_pixel + 7) >> 3;
 748
 749     s->zstream.zalloc = png_zalloc;
 750     s->zstream.zfree = png_zfree;
 751     s->zstream.opaque = NULL;
 752     ret = deflateInit2(&s->zstream, Z_DEFAULT_COMPRESSION,
 753                        Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
 754     if (ret != Z_OK)
 755         return -1;
 756     crow_buf = av_malloc(row_size + 1);
 757     if (!crow_buf)
 758         goto fail;
 759     if (is_progressive) {
 760         tmp_buf = av_malloc(row_size + 1);
 761         if (!tmp_buf)
 762             goto fail;
 763     }
 764
 765     /* write png header */
 766     put_buffer(f, pngsig, 8);
 767
 768     to_be32(s->buf, info->width);
 769     to_be32(s->buf + 4, info->height);
 770     s->buf[8] = bit_depth;
 771     s->buf[9] = color_type;
 772     s->buf[10] = 0; /* compression type */
 773     s->buf[11] = 0; /* filter type */
 774     s->buf[12] = is_progressive; /* interlace type */
 775
 776     png_write_chunk(f, MKTAG('I', 'H', 'D', 'R'), s->buf, 13);
 777
 778     /* put the palette if needed */
 779     if (color_type == PNG_COLOR_TYPE_PALETTE) {
 780         int has_alpha, alpha, i;
 781         unsigned int v;
 782         uint32_t *palette;
 783         uint8_t *alpha_ptr;
 784
 785         palette = (uint32_t *)info->pict.data[1];
 786         ptr = s->buf;
 787         alpha_ptr = s->buf + 256 * 3;
 788         has_alpha = 0;
 789         for(i = 0; i < 256; i++) {
 790             v = palette[i];
 791             alpha = v >> 24;
 792             if (alpha != 0xff)
 793                 has_alpha = 1;
 794             *alpha_ptr++ = alpha;
 795             ptr[0] = v >> 16;
 796             ptr[1] = v >> 8;
 797             ptr[2] = v;
 798             ptr += 3;
 799         }
 800         png_write_chunk(f, MKTAG('P', 'L', 'T', 'E'), s->buf, 256 * 3);
 801         if (has_alpha) {
 802             png_write_chunk(f, MKTAG('t', 'R', 'N', 'S'), s->buf + 256 * 3, 256);
 803         }
 804     }
 805
 806     /* now put each row */
 807     s->zstream.avail_out = IOBUF_SIZE;
 808     s->zstream.next_out = s->buf;
 809     if (is_progressive) {
 810         uint8_t *ptr1;
 811         int pass;
 812
 813         for(pass = 0; pass < NB_PASSES; pass++) {
 814             /* NOTE: a pass is completely omited if no pixels would be
 815                output */
 816             pass_row_size = png_pass_row_size(pass, bits_per_pixel, info->width);
 817             if (pass_row_size > 0) {
 818                 for(y = 0; y < info->height; y++) {
 819                     if ((png_pass_ymask[pass] << (y & 7)) & 0x80) {
 820                         ptr = info->pict.data[0] + y * info->pict.linesize[0];
 821                         if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 822                             convert_from_rgba32(tmp_buf, ptr, info->width);
 823                             ptr1 = tmp_buf;
 824                         } else {
 825                             ptr1 = ptr;
 826                         }
 827                         png_get_interlaced_row(crow_buf + 1, pass_row_size,
 828                                                bits_per_pixel, pass,
 829                                                ptr1, info->width);
 830                         crow_buf[0] = PNG_FILTER_VALUE_NONE;
 831                         png_write_row(s, crow_buf, pass_row_size + 1);
 832                     }
 833                 }
 834             }
 835         }
 836     } else {
 837         for(y = 0; y < info->height; y++) {
 838             ptr = info->pict.data[0] + y * info->pict.linesize[0];
 839             if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
 840                 convert_from_rgba32(crow_buf + 1, ptr, info->width);
 841             else
 842                 memcpy(crow_buf + 1, ptr, row_size);
 843             crow_buf[0] = PNG_FILTER_VALUE_NONE;
 844             png_write_row(s, crow_buf, row_size + 1);
 845         }
 846     }
 847     /* compress last bytes */
 848     for(;;) {
 849         ret = deflate(&s->zstream, Z_FINISH);
 850         if (ret == Z_OK || ret == Z_STREAM_END) {
 851             len = IOBUF_SIZE - s->zstream.avail_out;
 852             if (len > 0) {
 853                 png_write_chunk(f, MKTAG('I', 'D', 'A', 'T'), s->buf, len);
 854             }
 855             s->zstream.avail_out = IOBUF_SIZE;
 856             s->zstream.next_out = s->buf;
 857             if (ret == Z_STREAM_END)
 858                 break;
 859         } else {
 860             goto fail;
 861         }
 862     }
 863     png_write_chunk(f, MKTAG('I', 'E', 'N', 'D'), NULL, 0);
 864
 865     put_flush_packet(f);
 866     ret = 0;
 867  the_end:
 868     av_free(crow_buf);
 869     av_free(tmp_buf);
 870     deflateEnd(&s->zstream);
 871     return ret;
 872  fail:
 873     ret = -1;
 874     goto the_end;
 875 }
 876
 877 AVImageFormat png_image_format = {
 878     "png",
 879     "png",
 880     png_probe,
 881     png_read,
 882     (1 << PIX_FMT_RGBA32) | (1 << PIX_FMT_RGB24) | (1 << PIX_FMT_GRAY8) |
 883     (1 << PIX_FMT_MONOBLACK) | (1 << PIX_FMT_PAL8),
 884     png_write,
 885     AVIMAGE_INTERLEAVED,
 886 };
 887 #endif