|  | 
 | /* pngread.c - read a PNG file | 
 |  * | 
 |  * libpng 1.0.2b - January 6, 1999 | 
 |  * For conditions of distribution and use, see copyright notice in png.h | 
 |  * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc. | 
 |  * Copyright (c) 1996, 1997 Andreas Dilger | 
 |  * Copyright (c) 1998, 1999 Glenn Randers-Pehrson | 
 |  * | 
 |  * This file contains routines that an application calls directly to | 
 |  * read a PNG file or stream. | 
 |  */ | 
 |  | 
 | #define PNG_INTERNAL | 
 | #include "png.h" | 
 |  | 
 | /* Create a PNG structure for reading, and allocate any memory needed. */ | 
 | png_structp | 
 | png_create_read_struct(png_const_charp user_png_ver, png_voidp error_ptr, | 
 |    png_error_ptr error_fn, png_error_ptr warn_fn) | 
 | { | 
 |  | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |    return (png_create_read_struct_2(user_png_ver, error_ptr, error_fn, | 
 |       warn_fn, NULL, NULL, NULL)); | 
 | } | 
 |  | 
 | /* Alternate create PNG structure for reading, and allocate any memory needed. */ | 
 | png_structp | 
 | png_create_read_struct_2(png_const_charp user_png_ver, png_voidp error_ptr, | 
 |    png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, | 
 |    png_malloc_ptr malloc_fn, png_free_ptr free_fn) | 
 | { | 
 | #endif /* PNG_USER_MEM_SUPPORTED */ | 
 |  | 
 |    png_structp png_ptr; | 
 | #ifdef USE_FAR_KEYWORD | 
 |    jmp_buf jmpbuf; | 
 | #endif | 
 |    png_debug(1, "in png_create_read_struct\n"); | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |    if ((png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG, | 
 |       (png_malloc_ptr)malloc_fn)) == NULL) | 
 | #else | 
 |    if ((png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG)) == NULL) | 
 | #endif | 
 |    { | 
 |       return (png_structp)NULL; | 
 |    } | 
 | #ifdef USE_FAR_KEYWORD | 
 |    if (setjmp(jmpbuf)) | 
 | #else | 
 |    if (setjmp(png_ptr->jmpbuf)) | 
 | #endif | 
 |    { | 
 |       png_free(png_ptr, png_ptr->zbuf); | 
 |       png_destroy_struct(png_ptr); | 
 |       return (png_structp)NULL; | 
 |    } | 
 | #ifdef USE_FAR_KEYWORD | 
 |    png_memcpy(png_ptr->jmpbuf,jmpbuf,sizeof(jmp_buf)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |    png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn); | 
 | #endif /* PNG_USER_MEM_SUPPORTED */ | 
 |  | 
 |    png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn); | 
 |  | 
 |    /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so | 
 |     * we must recompile any applications that use any older library version. | 
 |     * For versions after libpng 1.0, we will be compatible, so we need | 
 |     * only check the first digit. | 
 |     */ | 
 |    if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] || | 
 |        (user_png_ver[0] == '0' && user_png_ver[2] < '9')) | 
 |    { | 
 |       png_error(png_ptr, | 
 |          "Incompatible libpng version in application and library"); | 
 |    } | 
 |  | 
 |    /* initialize zbuf - compression buffer */ | 
 |    png_ptr->zbuf_size = PNG_ZBUF_SIZE; | 
 |    png_ptr->zbuf = (png_bytep)png_malloc(png_ptr, | 
 |      (png_uint_32)png_ptr->zbuf_size); | 
 |    png_ptr->zstream.zalloc = png_zalloc; | 
 |    png_ptr->zstream.zfree = png_zfree; | 
 |    png_ptr->zstream.opaque = (voidpf)png_ptr; | 
 |  | 
 |    switch (inflateInit(&png_ptr->zstream)) | 
 |    { | 
 |      case Z_OK: /* Do nothing */ break; | 
 |      case Z_MEM_ERROR: | 
 |      case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory error"); break; | 
 |      case Z_VERSION_ERROR: png_error(png_ptr, "zlib version error"); break; | 
 |      default: png_error(png_ptr, "Unknown zlib error"); | 
 |    } | 
 |  | 
 |    png_ptr->zstream.next_out = png_ptr->zbuf; | 
 |    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; | 
 |  | 
 |    png_set_read_fn(png_ptr, NULL, NULL); | 
 |  | 
 |    return (png_ptr); | 
 | } | 
 |  | 
 | /* Initialize PNG structure for reading, and allocate any memory needed. | 
 |    This interface is deprecated in favour of the png_create_read_struct(), | 
 |    and it will eventually disappear. */ | 
 | void | 
 | png_read_init(png_structp png_ptr) | 
 | { | 
 |    jmp_buf tmp_jmp;  /* to save current jump buffer */ | 
 |  | 
 |    png_debug(1, "in png_read_init\n"); | 
 |    /* save jump buffer and error functions */ | 
 |    png_memcpy(tmp_jmp, png_ptr->jmpbuf, sizeof (jmp_buf)); | 
 |  | 
 |    /* reset all variables to 0 */ | 
 |    png_memset(png_ptr, 0, sizeof (png_struct)); | 
 |  | 
 |    /* restore jump buffer */ | 
 |    png_memcpy(png_ptr->jmpbuf, tmp_jmp, sizeof (jmp_buf)); | 
 |  | 
 |    /* initialize zbuf - compression buffer */ | 
 |    png_ptr->zbuf_size = PNG_ZBUF_SIZE; | 
 |    png_ptr->zbuf = (png_bytep)png_malloc(png_ptr, | 
 |      (png_uint_32)png_ptr->zbuf_size); | 
 |    png_ptr->zstream.zalloc = png_zalloc; | 
 |    png_ptr->zstream.zfree = png_zfree; | 
 |    png_ptr->zstream.opaque = (voidpf)png_ptr; | 
 |  | 
 |    switch (inflateInit(&png_ptr->zstream)) | 
 |    { | 
 |      case Z_OK: /* Do nothing */ break; | 
 |      case Z_MEM_ERROR: | 
 |      case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory"); break; | 
 |      case Z_VERSION_ERROR: png_error(png_ptr, "zlib version"); break; | 
 |      default: png_error(png_ptr, "Unknown zlib error"); | 
 |    } | 
 |  | 
 |    png_ptr->zstream.next_out = png_ptr->zbuf; | 
 |    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; | 
 |  | 
 |    png_set_read_fn(png_ptr, NULL, NULL); | 
 | } | 
 |  | 
 | /* Read the information before the actual image data.  This has been | 
 |  * changed in v0.90 to allow reading a file that already has the magic | 
 |  * bytes read from the stream.  You can tell libpng how many bytes have | 
 |  * been read from the beginning of the stream (up to the maximum of 8) | 
 |  * via png_set_sig_bytes(), and we will only check the remaining bytes | 
 |  * here.  The application can then have access to the signature bytes we | 
 |  * read if it is determined that this isn't a valid PNG file. | 
 |  */ | 
 | void | 
 | png_read_info(png_structp png_ptr, png_infop info_ptr) | 
 | { | 
 |    png_debug(1, "in png_read_info\n"); | 
 |    /* save jump buffer and error functions */ | 
 |    /* If we haven't checked all of the PNG signature bytes, do so now. */ | 
 |    if (png_ptr->sig_bytes < 8) | 
 |    { | 
 |       png_size_t num_checked = png_ptr->sig_bytes, | 
 |                  num_to_check = 8 - num_checked; | 
 |  | 
 |       png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check); | 
 |       png_ptr->sig_bytes = 8; | 
 |  | 
 |       if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check)) | 
 |       { | 
 |          if (num_checked < 4 && | 
 |              png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4)) | 
 |             png_error(png_ptr, "Not a PNG file"); | 
 |          else | 
 |             png_error(png_ptr, "PNG file corrupted by ASCII conversion"); | 
 |       } | 
 |    } | 
 |  | 
 |    for(;;) | 
 |    { | 
 |       png_byte chunk_length[4]; | 
 |       png_uint_32 length; | 
 |  | 
 |       png_read_data(png_ptr, chunk_length, 4); | 
 |       length = png_get_uint_32(chunk_length); | 
 |  | 
 |       png_reset_crc(png_ptr); | 
 |       png_crc_read(png_ptr, png_ptr->chunk_name, 4); | 
 |  | 
 |       png_debug1(0, "Reading %s chunk.\n", png_ptr->chunk_name); | 
 |  | 
 |       /* This should be a binary subdivision search or a hash for | 
 |        * matching the chunk name rather than a linear search. | 
 |        */ | 
 |       if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4)) | 
 |          png_handle_IHDR(png_ptr, info_ptr, length); | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4)) | 
 |          png_handle_PLTE(png_ptr, info_ptr, length); | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4)) | 
 |          png_handle_IEND(png_ptr, info_ptr, length); | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4)) | 
 |       { | 
 |          if (!(png_ptr->mode & PNG_HAVE_IHDR)) | 
 |             png_error(png_ptr, "Missing IHDR before IDAT"); | 
 |          else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && | 
 |                   !(png_ptr->mode & PNG_HAVE_PLTE)) | 
 |             png_error(png_ptr, "Missing PLTE before IDAT"); | 
 |  | 
 |          png_ptr->idat_size = length; | 
 |          png_ptr->mode |= PNG_HAVE_IDAT; | 
 |          break; | 
 |       } | 
 | #if defined(PNG_READ_bKGD_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4)) | 
 |          png_handle_bKGD(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_cHRM_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4)) | 
 |          png_handle_cHRM(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_gAMA_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4)) | 
 |          png_handle_gAMA(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_hIST_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4)) | 
 |          png_handle_hIST(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_oFFs_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4)) | 
 |          png_handle_oFFs(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_pCAL_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4)) | 
 |          png_handle_pCAL(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_pHYs_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4)) | 
 |          png_handle_pHYs(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_sBIT_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4)) | 
 |          png_handle_sBIT(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_sRGB_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4)) | 
 |          png_handle_sRGB(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_tEXt_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4)) | 
 |          png_handle_tEXt(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_tIME_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4)) | 
 |          png_handle_tIME(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_tRNS_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4)) | 
 |          png_handle_tRNS(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_zTXt_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4)) | 
 |          png_handle_zTXt(png_ptr, info_ptr, length); | 
 | #endif | 
 |       else | 
 |          png_handle_unknown(png_ptr, info_ptr, length); | 
 |    } | 
 | } | 
 |  | 
 | /* optional call to update the users info_ptr structure */ | 
 | void | 
 | png_read_update_info(png_structp png_ptr, png_infop info_ptr) | 
 | { | 
 |    png_debug(1, "in png_read_update_info\n"); | 
 |    /* save jump buffer and error functions */ | 
 |    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT)) | 
 |       png_read_start_row(png_ptr); | 
 |    png_read_transform_info(png_ptr, info_ptr); | 
 | } | 
 |  | 
 | /* Initialize palette, background, etc, after transformations | 
 |  * are set, but before any reading takes place.  This allows | 
 |  * the user to obtain a gamma-corrected palette, for example. | 
 |  * If the user doesn't call this, we will do it ourselves. | 
 |  */ | 
 | void | 
 | png_start_read_image(png_structp png_ptr) | 
 | { | 
 |    png_debug(1, "in png_start_read_image\n"); | 
 |    /* save jump buffer and error functions */ | 
 |    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT)) | 
 |       png_read_start_row(png_ptr); | 
 | } | 
 |  | 
 | void | 
 | png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) | 
 | { | 
 |    int ret; | 
 |    png_debug2(1, "in png_read_row (row %d, pass %d)\n", | 
 |       png_ptr->row_number, png_ptr->pass); | 
 |    /* save jump buffer and error functions */ | 
 |    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT)) | 
 |       png_read_start_row(png_ptr); | 
 |    if (png_ptr->row_number == 0 && png_ptr->pass == 0) | 
 |    { | 
 |    /* check for transforms that have been set but were defined out */ | 
 | #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED) | 
 |    if (png_ptr->transformations & PNG_INVERT_MONO) | 
 |       png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined."); | 
 | #endif | 
 | #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED) | 
 |    if (png_ptr->transformations & PNG_FILLER) | 
 |       png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined."); | 
 | #endif | 
 | #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && !defined(PNG_READ_PACKSWAP_SUPPORTED) | 
 |    if (png_ptr->transformations & PNG_PACKSWAP) | 
 |       png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined."); | 
 | #endif | 
 | #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED) | 
 |    if (png_ptr->transformations & PNG_PACK) | 
 |       png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined."); | 
 | #endif | 
 | #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED) | 
 |    if (png_ptr->transformations & PNG_SHIFT) | 
 |       png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined."); | 
 | #endif | 
 | #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED) | 
 |    if (png_ptr->transformations & PNG_BGR) | 
 |       png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined."); | 
 | #endif | 
 | #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED) | 
 |    if (png_ptr->transformations & PNG_SWAP_BYTES) | 
 |       png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined."); | 
 | #endif | 
 |    } | 
 |  | 
 | #if defined(PNG_READ_INTERLACING_SUPPORTED) | 
 |    /* if interlaced and we do not need a new row, combine row and return */ | 
 |    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE)) | 
 |    { | 
 |       switch (png_ptr->pass) | 
 |       { | 
 |          case 0: | 
 |             if (png_ptr->row_number & 7) | 
 |             { | 
 |                if (dsp_row != NULL) | 
 |                   png_combine_row(png_ptr, dsp_row, | 
 |                      png_pass_dsp_mask[png_ptr->pass]); | 
 |                png_read_finish_row(png_ptr); | 
 |                return; | 
 |             } | 
 |             break; | 
 |          case 1: | 
 |             if ((png_ptr->row_number & 7) || png_ptr->width < 5) | 
 |             { | 
 |                if (dsp_row != NULL) | 
 |                   png_combine_row(png_ptr, dsp_row, | 
 |                      png_pass_dsp_mask[png_ptr->pass]); | 
 |                png_read_finish_row(png_ptr); | 
 |                return; | 
 |             } | 
 |             break; | 
 |          case 2: | 
 |             if ((png_ptr->row_number & 7) != 4) | 
 |             { | 
 |                if (dsp_row != NULL && (png_ptr->row_number & 4)) | 
 |                   png_combine_row(png_ptr, dsp_row, | 
 |                      png_pass_dsp_mask[png_ptr->pass]); | 
 |                png_read_finish_row(png_ptr); | 
 |                return; | 
 |             } | 
 |             break; | 
 |          case 3: | 
 |             if ((png_ptr->row_number & 3) || png_ptr->width < 3) | 
 |             { | 
 |                if (dsp_row != NULL) | 
 |                   png_combine_row(png_ptr, dsp_row, | 
 |                      png_pass_dsp_mask[png_ptr->pass]); | 
 |                png_read_finish_row(png_ptr); | 
 |                return; | 
 |             } | 
 |             break; | 
 |          case 4: | 
 |             if ((png_ptr->row_number & 3) != 2) | 
 |             { | 
 |                if (dsp_row != NULL && (png_ptr->row_number & 2)) | 
 |                   png_combine_row(png_ptr, dsp_row, | 
 |                      png_pass_dsp_mask[png_ptr->pass]); | 
 |                png_read_finish_row(png_ptr); | 
 |                return; | 
 |             } | 
 |             break; | 
 |          case 5: | 
 |             if ((png_ptr->row_number & 1) || png_ptr->width < 2) | 
 |             { | 
 |                if (dsp_row != NULL) | 
 |                   png_combine_row(png_ptr, dsp_row, | 
 |                      png_pass_dsp_mask[png_ptr->pass]); | 
 |                png_read_finish_row(png_ptr); | 
 |                return; | 
 |             } | 
 |             break; | 
 |          case 6: | 
 |             if (!(png_ptr->row_number & 1)) | 
 |             { | 
 |                png_read_finish_row(png_ptr); | 
 |                return; | 
 |             } | 
 |             break; | 
 |       } | 
 |    } | 
 | #endif | 
 |  | 
 |    if (!(png_ptr->mode & PNG_HAVE_IDAT)) | 
 |       png_error(png_ptr, "Invalid attempt to read row data"); | 
 |  | 
 |    png_ptr->zstream.next_out = png_ptr->row_buf; | 
 |    png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes; | 
 |    do | 
 |    { | 
 |       if (!(png_ptr->zstream.avail_in)) | 
 |       { | 
 |          while (!png_ptr->idat_size) | 
 |          { | 
 |             png_byte chunk_length[4]; | 
 |  | 
 |             png_crc_finish(png_ptr, 0); | 
 |  | 
 |             png_read_data(png_ptr, chunk_length, 4); | 
 |             png_ptr->idat_size = png_get_uint_32(chunk_length); | 
 |  | 
 |             png_reset_crc(png_ptr); | 
 |             png_crc_read(png_ptr, png_ptr->chunk_name, 4); | 
 |             if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4)) | 
 |                png_error(png_ptr, "Not enough image data"); | 
 |          } | 
 |          png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size; | 
 |          png_ptr->zstream.next_in = png_ptr->zbuf; | 
 |          if (png_ptr->zbuf_size > png_ptr->idat_size) | 
 |             png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size; | 
 |          png_crc_read(png_ptr, png_ptr->zbuf, | 
 |             (png_size_t)png_ptr->zstream.avail_in); | 
 |          png_ptr->idat_size -= png_ptr->zstream.avail_in; | 
 |       } | 
 |       ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH); | 
 |       if (ret == Z_STREAM_END) | 
 |       { | 
 |          if (png_ptr->zstream.avail_out || png_ptr->zstream.avail_in || | 
 |             png_ptr->idat_size) | 
 |             png_error(png_ptr, "Extra compressed data"); | 
 |          png_ptr->mode |= PNG_AFTER_IDAT; | 
 |          png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED; | 
 |          break; | 
 |       } | 
 |       if (ret != Z_OK) | 
 |          png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg : | 
 |                    "Decompression error"); | 
 |  | 
 |    } while (png_ptr->zstream.avail_out); | 
 |  | 
 |    png_ptr->row_info.color_type = png_ptr->color_type; | 
 |    png_ptr->row_info.width = png_ptr->iwidth; | 
 |    png_ptr->row_info.channels = png_ptr->channels; | 
 |    png_ptr->row_info.bit_depth = png_ptr->bit_depth; | 
 |    png_ptr->row_info.pixel_depth = png_ptr->pixel_depth; | 
 |    { | 
 |       png_ptr->row_info.rowbytes = ((png_ptr->row_info.width * | 
 |          (png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3); | 
 |    } | 
 |  | 
 |    png_read_filter_row(png_ptr, &(png_ptr->row_info), | 
 |       png_ptr->row_buf + 1, png_ptr->prev_row + 1, | 
 |       (int)(png_ptr->row_buf[0])); | 
 |  | 
 |    png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf, | 
 |       png_ptr->rowbytes + 1); | 
 |  | 
 |    if (png_ptr->transformations) | 
 |       png_do_read_transformations(png_ptr); | 
 |  | 
 | #if defined(PNG_READ_INTERLACING_SUPPORTED) | 
 |    /* blow up interlaced rows to full size */ | 
 |    if (png_ptr->interlaced && | 
 |       (png_ptr->transformations & PNG_INTERLACE)) | 
 |    { | 
 |       if (png_ptr->pass < 6) | 
 |          png_do_read_interlace(&(png_ptr->row_info), | 
 |             png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations); | 
 |  | 
 |       if (dsp_row != NULL) | 
 |          png_combine_row(png_ptr, dsp_row, | 
 |             png_pass_dsp_mask[png_ptr->pass]); | 
 |       if (row != NULL) | 
 |          png_combine_row(png_ptr, row, | 
 |             png_pass_mask[png_ptr->pass]); | 
 |    } | 
 |    else | 
 | #endif | 
 |    { | 
 |       if (row != NULL) | 
 |          png_combine_row(png_ptr, row, 0xff); | 
 |       if (dsp_row != NULL) | 
 |          png_combine_row(png_ptr, dsp_row, 0xff); | 
 |    } | 
 |    png_read_finish_row(png_ptr); | 
 |  | 
 |    if (png_ptr->read_row_fn != NULL) | 
 |       (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass); | 
 | } | 
 |  | 
 | /* Read one or more rows of image data.  If the image is interlaced, | 
 |  * and png_set_interlace_handling() has been called, the rows need to | 
 |  * contain the contents of the rows from the previous pass.  If the | 
 |  * image has alpha or transparency, and png_handle_alpha()[*] has been | 
 |  * called, the rows contents must be initialized to the contents of the | 
 |  * screen. | 
 |  * | 
 |  * "row" holds the actual image, and pixels are placed in it | 
 |  * as they arrive.  If the image is displayed after each pass, it will | 
 |  * appear to "sparkle" in.  "display_row" can be used to display a | 
 |  * "chunky" progressive image, with finer detail added as it becomes | 
 |  * available.  If you do not want this "chunky" display, you may pass | 
 |  * NULL for display_row.  If you do not want the sparkle display, and | 
 |  * you have not called png_handle_alpha(), you may pass NULL for rows. | 
 |  * If you have called png_handle_alpha(), and the image has either an | 
 |  * alpha channel or a transparency chunk, you must provide a buffer for | 
 |  * rows.  In this case, you do not have to provide a display_row buffer | 
 |  * also, but you may.  If the image is not interlaced, or if you have | 
 |  * not called png_set_interlace_handling(), the display_row buffer will | 
 |  * be ignored, so pass NULL to it. | 
 |  * | 
 |  * [*] png_handle_alpha() does not exist yet, as of libpng version 1.0.2b. | 
 |  */ | 
 |  | 
 | void | 
 | png_read_rows(png_structp png_ptr, png_bytepp row, | 
 |    png_bytepp display_row, png_uint_32 num_rows) | 
 | { | 
 |    png_uint_32 i; | 
 |    png_bytepp rp; | 
 |    png_bytepp dp; | 
 |  | 
 |    png_debug(1, "in png_read_rows\n"); | 
 |    /* save jump buffer and error functions */ | 
 |    rp = row; | 
 |    dp = display_row; | 
 |    if (rp != NULL && dp != NULL) | 
 |       for (i = 0; i < num_rows; i++) | 
 |       { | 
 |          png_bytep rptr = *rp++; | 
 |          png_bytep dptr = *dp++; | 
 |  | 
 |          png_read_row(png_ptr, rptr, dptr); | 
 |       } | 
 |    else if(rp != NULL) | 
 |       for (i = 0; i < num_rows; i++) | 
 |       { | 
 |          png_bytep rptr = *rp; | 
 |          png_read_row(png_ptr, rptr, NULL); | 
 |          rp++; | 
 |       } | 
 |    else if(dp != NULL) | 
 |       for (i = 0; i < num_rows; i++) | 
 |       { | 
 |          png_bytep dptr = *dp; | 
 |          png_read_row(png_ptr, NULL, dptr); | 
 |          dp++; | 
 |       } | 
 | } | 
 |  | 
 | /* Read the entire image.  If the image has an alpha channel or a tRNS | 
 |  * chunk, and you have called png_handle_alpha()[*], you will need to | 
 |  * initialize the image to the current image that PNG will be overlaying. | 
 |  * We set the num_rows again here, in case it was incorrectly set in | 
 |  * png_read_start_row() by a call to png_read_update_info() or | 
 |  * png_start_read_image() if png_set_interlace_handling() wasn't called | 
 |  * prior to either of these functions like it should have been.  You can | 
 |  * only call this function once.  If you desire to have an image for | 
 |  * each pass of a interlaced image, use png_read_rows() instead. | 
 |  * | 
 |  * [*] png_handle_alpha() does not exist yet, as of libpng version 1.0.2b. | 
 |  */ | 
 | void | 
 | png_read_image(png_structp png_ptr, png_bytepp image) | 
 | { | 
 |    png_uint_32 i,image_height; | 
 |    int pass, j; | 
 |    png_bytepp rp; | 
 |  | 
 |    png_debug(1, "in png_read_image\n"); | 
 |    /* save jump buffer and error functions */ | 
 |    pass = png_set_interlace_handling(png_ptr); | 
 |  | 
 |    image_height=png_ptr->height; | 
 |    png_ptr->num_rows = image_height; /* Make sure this is set correctly */ | 
 |  | 
 |    for (j = 0; j < pass; j++) | 
 |    { | 
 |       rp = image; | 
 |       for (i = 0; i < image_height; i++) | 
 |       { | 
 |          png_read_row(png_ptr, *rp, NULL); | 
 |          rp++; | 
 |       } | 
 |    } | 
 | } | 
 |  | 
 | /* Read the end of the PNG file.  Will not read past the end of the | 
 |  * file, will verify the end is accurate, and will read any comments | 
 |  * or time information at the end of the file, if info is not NULL. | 
 |  */ | 
 | void | 
 | png_read_end(png_structp png_ptr, png_infop info_ptr) | 
 | { | 
 |    png_byte chunk_length[4]; | 
 |    png_uint_32 length; | 
 |  | 
 |    png_debug(1, "in png_read_end\n"); | 
 |    /* save jump buffer and error functions */ | 
 |    png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */ | 
 |  | 
 |    do | 
 |    { | 
 |       png_read_data(png_ptr, chunk_length, 4); | 
 |       length = png_get_uint_32(chunk_length); | 
 |  | 
 |       png_reset_crc(png_ptr); | 
 |       png_crc_read(png_ptr, png_ptr->chunk_name, 4); | 
 |  | 
 |       png_debug1(0, "Reading %s chunk.\n", png_ptr->chunk_name); | 
 |  | 
 |       if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4)) | 
 |          png_handle_IHDR(png_ptr, info_ptr, length); | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4)) | 
 |       { | 
 |          /* Zero length IDATs are legal after the last IDAT has been | 
 |           * read, but not after other chunks have been read. | 
 |           */ | 
 |          if (length > 0 || png_ptr->mode & PNG_AFTER_IDAT) | 
 |             png_error(png_ptr, "Too many IDAT's found"); | 
 |          else | 
 |             png_crc_finish(png_ptr, 0); | 
 |       } | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4)) | 
 |          png_handle_PLTE(png_ptr, info_ptr, length); | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4)) | 
 |          png_handle_IEND(png_ptr, info_ptr, length); | 
 | #if defined(PNG_READ_bKGD_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4)) | 
 |          png_handle_bKGD(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_cHRM_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4)) | 
 |          png_handle_cHRM(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_gAMA_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4)) | 
 |          png_handle_gAMA(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_hIST_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4)) | 
 |          png_handle_hIST(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_oFFs_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4)) | 
 |          png_handle_oFFs(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_pCAL_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4)) | 
 |          png_handle_pCAL(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_pHYs_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4)) | 
 |          png_handle_pHYs(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_sBIT_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4)) | 
 |          png_handle_sBIT(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_sRGB_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4)) | 
 |          png_handle_sRGB(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_tEXt_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4)) | 
 |          png_handle_tEXt(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_tIME_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4)) | 
 |          png_handle_tIME(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_tRNS_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4)) | 
 |          png_handle_tRNS(png_ptr, info_ptr, length); | 
 | #endif | 
 | #if defined(PNG_READ_zTXt_SUPPORTED) | 
 |       else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4)) | 
 |          png_handle_zTXt(png_ptr, info_ptr, length); | 
 | #endif | 
 |       else | 
 |          png_handle_unknown(png_ptr, info_ptr, length); | 
 |    } while (!(png_ptr->mode & PNG_HAVE_IEND)); | 
 | } | 
 |  | 
 | /* free all memory used by the read */ | 
 | void | 
 | png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, | 
 |    png_infopp end_info_ptr_ptr) | 
 | { | 
 |    png_structp png_ptr = NULL; | 
 |    png_infop info_ptr = NULL, end_info_ptr = NULL; | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |    png_free_ptr free_fn = NULL; | 
 | #endif /* PNG_USER_MEM_SUPPORTED */ | 
 |  | 
 |    png_debug(1, "in png_destroy_read_struct\n"); | 
 |    /* save jump buffer and error functions */ | 
 |    if (png_ptr_ptr != NULL) | 
 |       png_ptr = *png_ptr_ptr; | 
 |  | 
 |    if (info_ptr_ptr != NULL) | 
 |       info_ptr = *info_ptr_ptr; | 
 |  | 
 |    if (end_info_ptr_ptr != NULL) | 
 |       end_info_ptr = *end_info_ptr_ptr; | 
 |  | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |    free_fn = png_ptr->free_fn; | 
 | #endif | 
 |  | 
 |    png_read_destroy(png_ptr, info_ptr, end_info_ptr); | 
 |  | 
 |    if (info_ptr != NULL) | 
 |    { | 
 | #if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED) | 
 |       png_free(png_ptr, info_ptr->text); | 
 | #endif | 
 |  | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |       png_destroy_struct_2((png_voidp)info_ptr, free_fn); | 
 | #else | 
 |       png_destroy_struct((png_voidp)info_ptr); | 
 | #endif | 
 |       *info_ptr_ptr = (png_infop)NULL; | 
 |    } | 
 |  | 
 |    if (end_info_ptr != NULL) | 
 |    { | 
 | #if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED) | 
 |       png_free(png_ptr, end_info_ptr->text); | 
 | #endif | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |       png_destroy_struct_2((png_voidp)end_info_ptr, free_fn); | 
 | #else | 
 |       png_destroy_struct((png_voidp)end_info_ptr); | 
 | #endif | 
 |       *end_info_ptr_ptr = (png_infop)NULL; | 
 |    } | 
 |  | 
 |    if (png_ptr != NULL) | 
 |    { | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |       png_destroy_struct_2((png_voidp)png_ptr, free_fn); | 
 | #else | 
 |       png_destroy_struct((png_voidp)png_ptr); | 
 | #endif | 
 |       *png_ptr_ptr = (png_structp)NULL; | 
 |    } | 
 | } | 
 |  | 
 | /* free all memory used by the read (old method) */ | 
 | void | 
 | png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr) | 
 | { | 
 |    jmp_buf tmp_jmp; | 
 |    png_error_ptr error_fn; | 
 |    png_error_ptr warning_fn; | 
 |    png_voidp error_ptr; | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |    png_free_ptr free_fn; | 
 | #endif | 
 |  | 
 |    png_debug(1, "in png_read_destroy\n"); | 
 |    /* save jump buffer and error functions */ | 
 |    if (info_ptr != NULL) | 
 |       png_info_destroy(png_ptr, info_ptr); | 
 |  | 
 |    if (end_info_ptr != NULL) | 
 |       png_info_destroy(png_ptr, end_info_ptr); | 
 |  | 
 |    png_free(png_ptr, png_ptr->zbuf); | 
 |    png_free(png_ptr, png_ptr->row_buf); | 
 |    png_free(png_ptr, png_ptr->prev_row); | 
 | #if defined(PNG_READ_DITHER_SUPPORTED) | 
 |    png_free(png_ptr, png_ptr->palette_lookup); | 
 |    png_free(png_ptr, png_ptr->dither_index); | 
 | #endif | 
 | #if defined(PNG_READ_GAMMA_SUPPORTED) | 
 |    png_free(png_ptr, png_ptr->gamma_table); | 
 | #endif | 
 | #if defined(PNG_READ_BACKGROUND_SUPPORTED) | 
 |    png_free(png_ptr, png_ptr->gamma_from_1); | 
 |    png_free(png_ptr, png_ptr->gamma_to_1); | 
 | #endif | 
 |    if (png_ptr->flags & PNG_FLAG_FREE_PALETTE) | 
 |       png_zfree(png_ptr, png_ptr->palette); | 
 |    if (png_ptr->flags & PNG_FLAG_FREE_TRANS) | 
 |       png_free(png_ptr, png_ptr->trans); | 
 | #if defined(PNG_READ_hIST_SUPPORTED) | 
 |    if (png_ptr->flags & PNG_FLAG_FREE_HIST) | 
 |       png_free(png_ptr, png_ptr->hist); | 
 | #endif | 
 | #if defined(PNG_READ_GAMMA_SUPPORTED) | 
 |    if (png_ptr->gamma_16_table != NULL) | 
 |    { | 
 |       int i; | 
 |       int istop = (1 << (8 - png_ptr->gamma_shift)); | 
 |       for (i = 0; i < istop; i++) | 
 |       { | 
 |          png_free(png_ptr, png_ptr->gamma_16_table[i]); | 
 |       } | 
 |    png_free(png_ptr, png_ptr->gamma_16_table); | 
 |    } | 
 | #if defined(PNG_READ_BACKGROUND_SUPPORTED) | 
 |    if (png_ptr->gamma_16_from_1 != NULL) | 
 |    { | 
 |       int i; | 
 |       int istop = (1 << (8 - png_ptr->gamma_shift)); | 
 |       for (i = 0; i < istop; i++) | 
 |       { | 
 |          png_free(png_ptr, png_ptr->gamma_16_from_1[i]); | 
 |       } | 
 |    png_free(png_ptr, png_ptr->gamma_16_from_1); | 
 |    } | 
 |    if (png_ptr->gamma_16_to_1 != NULL) | 
 |    { | 
 |       int i; | 
 |       int istop = (1 << (8 - png_ptr->gamma_shift)); | 
 |       for (i = 0; i < istop; i++) | 
 |       { | 
 |          png_free(png_ptr, png_ptr->gamma_16_to_1[i]); | 
 |       } | 
 |    png_free(png_ptr, png_ptr->gamma_16_to_1); | 
 |    } | 
 | #endif | 
 | #endif | 
 | #if defined(PNG_TIME_RFC1123_SUPPORTED) | 
 |    png_free(png_ptr, png_ptr->time_buffer); | 
 | #endif /* PNG_TIME_RFC1123_SUPPORTED */ | 
 |  | 
 |    inflateEnd(&png_ptr->zstream); | 
 | #ifdef PNG_PROGRESSIVE_READ_SUPPORTED | 
 |    png_free(png_ptr, png_ptr->save_buffer); | 
 | #endif | 
 |  | 
 |    /* Save the important info out of the png_struct, in case it is | 
 |     * being used again. | 
 |     */ | 
 |    png_memcpy(tmp_jmp, png_ptr->jmpbuf, sizeof (jmp_buf)); | 
 |  | 
 |    error_fn = png_ptr->error_fn; | 
 |    warning_fn = png_ptr->warning_fn; | 
 |    error_ptr = png_ptr->error_ptr; | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |    free_fn = png_ptr->free_fn; | 
 | #endif | 
 |  | 
 |    png_memset(png_ptr, 0, sizeof (png_struct)); | 
 |  | 
 |    png_ptr->error_fn = error_fn; | 
 |    png_ptr->warning_fn = warning_fn; | 
 |    png_ptr->error_ptr = error_ptr; | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 |    png_ptr->free_fn = free_fn; | 
 | #endif | 
 |  | 
 |    png_memcpy(png_ptr->jmpbuf, tmp_jmp, sizeof (jmp_buf)); | 
 | } | 
 |  | 
 | void | 
 | png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn) | 
 | { | 
 |    png_ptr->read_row_fn = read_row_fn; | 
 | } |