/* pngread.c - read a PNG file * * Last changed in libpng 1.6.0 [(PENDING RELEASE)] * Copyright (c) 1998-2011 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer * and license in png.h * * This file contains routines that an application calls directly to * read a PNG file or stream. */ #include "pngpriv.h" #if defined PNG_SIMPLIFIED_READ_SUPPORTED && defined PNG_STDIO_SUPPORTED # include #endif #ifdef PNG_READ_SUPPORTED /* Create a PNG structure for reading, and allocate any memory needed. */ PNG_FUNCTION(png_structp,PNGAPI png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED) { #ifndef PNG_USER_MEM_SUPPORTED png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, error_fn, warn_fn, NULL, NULL, NULL); #else 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_FUNCTION(png_structp,PNGAPI 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),PNG_ALLOCATED) { png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, error_fn, warn_fn, mem_ptr, malloc_fn, free_fn); #endif /* PNG_USER_MEM_SUPPORTED */ if (png_ptr != NULL) { int ok = 0; /* TODO: why does this happen here on read, but in png_write_IHDR on * write? */ png_ptr->zstream.zalloc = png_zalloc; png_ptr->zstream.zfree = png_zfree; png_ptr->zstream.opaque = png_ptr; switch (inflateInit(&png_ptr->zstream)) { case Z_OK: ok = 1; break; case Z_MEM_ERROR: png_warning(png_ptr, "zlib memory error"); break; case Z_STREAM_ERROR: png_warning(png_ptr, "zlib stream error"); break; case Z_VERSION_ERROR: png_warning(png_ptr, "zlib version error"); break; default: png_warning(png_ptr, "Unknown zlib error"); break; } if (ok) { png_ptr->zstream.next_out = png_ptr->zbuf; png_ptr->zstream.avail_out = png_ptr->zbuf_size; /* TODO: delay this, it can be done in png_init_io (if the app doesn't * do it itself) avoiding setting the default function if it is not * required. */ png_set_read_fn(png_ptr, NULL, NULL); return png_ptr; } /* Else something went wrong in the zlib initialization above; it would * much simplify this code if the creation of the zlib stuff was to be * delayed until it is needed. */ png_destroy_read_struct(&png_ptr, NULL, NULL); } return NULL; } #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* 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 PNGAPI png_read_info(png_structp png_ptr, png_infop info_ptr) { png_debug(1, "in png_read_info"); if (png_ptr == NULL || info_ptr == NULL) return; /* Read and check the PNG file signature. */ png_read_sig(png_ptr, info_ptr); for (;;) { png_uint_32 length = png_read_chunk_header(png_ptr); png_uint_32 chunk_name = 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 (chunk_name == png_IDAT) if (png_ptr->mode & PNG_AFTER_IDAT) png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT; if (chunk_name == png_IHDR) png_handle_IHDR(png_ptr, info_ptr, length); else if (chunk_name == png_IEND) png_handle_IEND(png_ptr, info_ptr, length); #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED else if (png_chunk_unknown_handling(png_ptr, chunk_name) != PNG_HANDLE_CHUNK_AS_DEFAULT) { if (chunk_name == png_IDAT) png_ptr->mode |= PNG_HAVE_IDAT; png_handle_unknown(png_ptr, info_ptr, length); if (chunk_name == png_PLTE) png_ptr->mode |= PNG_HAVE_PLTE; else if (chunk_name == png_IDAT) { 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"); break; } } #endif else if (chunk_name == png_PLTE) png_handle_PLTE(png_ptr, info_ptr, length); else if (chunk_name == png_IDAT) { 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; } #ifdef PNG_READ_bKGD_SUPPORTED else if (chunk_name == png_bKGD) png_handle_bKGD(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_cHRM_SUPPORTED else if (chunk_name == png_cHRM) png_handle_cHRM(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_gAMA_SUPPORTED else if (chunk_name == png_gAMA) png_handle_gAMA(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_hIST_SUPPORTED else if (chunk_name == png_hIST) png_handle_hIST(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_oFFs_SUPPORTED else if (chunk_name == png_oFFs) png_handle_oFFs(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_pCAL_SUPPORTED else if (chunk_name == png_pCAL) png_handle_pCAL(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_sCAL_SUPPORTED else if (chunk_name == png_sCAL) png_handle_sCAL(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_pHYs_SUPPORTED else if (chunk_name == png_pHYs) png_handle_pHYs(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_sBIT_SUPPORTED else if (chunk_name == png_sBIT) png_handle_sBIT(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_sRGB_SUPPORTED else if (chunk_name == png_sRGB) png_handle_sRGB(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_iCCP_SUPPORTED else if (chunk_name == png_iCCP) png_handle_iCCP(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_sPLT_SUPPORTED else if (chunk_name == png_sPLT) png_handle_sPLT(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_tEXt_SUPPORTED else if (chunk_name == png_tEXt) png_handle_tEXt(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_tIME_SUPPORTED else if (chunk_name == png_tIME) png_handle_tIME(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_tRNS_SUPPORTED else if (chunk_name == png_tRNS) png_handle_tRNS(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_zTXt_SUPPORTED else if (chunk_name == png_zTXt) png_handle_zTXt(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_iTXt_SUPPORTED else if (chunk_name == png_iTXt) png_handle_iTXt(png_ptr, info_ptr, length); #endif else png_handle_unknown(png_ptr, info_ptr, length); } } #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ /* Optional call to update the users info_ptr structure */ void PNGAPI png_read_update_info(png_structp png_ptr, png_infop info_ptr) { png_debug(1, "in png_read_update_info"); if (png_ptr == NULL) return; png_read_start_row(png_ptr); #ifdef PNG_READ_TRANSFORMS_SUPPORTED png_read_transform_info(png_ptr, info_ptr); #else PNG_UNUSED(info_ptr) #endif } #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* 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 PNGAPI png_start_read_image(png_structp png_ptr) { png_debug(1, "in png_start_read_image"); if (png_ptr != NULL) png_read_start_row(png_ptr); } #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED void PNGAPI png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) { int ret; png_row_info row_info; if (png_ptr == NULL) return; png_debug2(1, "in png_read_row (row %lu, pass %d)", (unsigned long)png_ptr->row_number, png_ptr->pass); /* png_read_start_row sets the information (in particular iwidth) for this * interlace pass. */ if (!(png_ptr->flags & PNG_FLAG_ROW_INIT)) png_read_start_row(png_ptr); /* 1.5.6: row_info moved out of png_struct to a local here. */ row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */ row_info.color_type = png_ptr->color_type; row_info.bit_depth = png_ptr->bit_depth; row_info.channels = png_ptr->channels; row_info.pixel_depth = png_ptr->pixel_depth; row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width); 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 } #ifdef PNG_READ_INTERLACING_SUPPORTED /* If interlaced and we do not need a new row, combine row and return. * Notice that the pixels we have from previous rows have been transformed * already; we can only combine like with like (transformed or * untransformed) and, because of the libpng API for interlaced images, this * means we must transform before de-interlacing. */ if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE)) { switch (png_ptr->pass) { case 0: if (png_ptr->row_number & 0x07) { if (dsp_row != NULL) png_combine_row(png_ptr, dsp_row, 1/*display*/); png_read_finish_row(png_ptr); return; } break; case 1: if ((png_ptr->row_number & 0x07) || png_ptr->width < 5) { if (dsp_row != NULL) png_combine_row(png_ptr, dsp_row, 1/*display*/); png_read_finish_row(png_ptr); return; } break; case 2: if ((png_ptr->row_number & 0x07) != 4) { if (dsp_row != NULL && (png_ptr->row_number & 4)) png_combine_row(png_ptr, dsp_row, 1/*display*/); 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, 1/*display*/); 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, 1/*display*/); 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, 1/*display*/); png_read_finish_row(png_ptr); return; } break; default: 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_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1); do { if (!(png_ptr->zstream.avail_in)) { while (!png_ptr->idat_size) { png_crc_finish(png_ptr, 0); png_ptr->idat_size = png_read_chunk_header(png_ptr); if (png_ptr->chunk_name != png_IDAT) 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_benign_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); if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE) { if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST) png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1, png_ptr->prev_row + 1, png_ptr->row_buf[0]); else png_error(png_ptr, "bad adaptive filter value"); } /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before * 1.5.6, while the buffer really is this big in current versions of libpng * it may not be in the future, so this was changed just to copy the * interlaced count: */ png_memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1); #ifdef PNG_MNG_FEATURES_SUPPORTED if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) && (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING)) { /* Intrapixel differencing */ png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1); } #endif #ifdef PNG_READ_TRANSFORMS_SUPPORTED if (png_ptr->transformations) png_do_read_transformations(png_ptr, &row_info); #endif /* The transformed pixel depth should match the depth now in row_info. */ if (png_ptr->transformed_pixel_depth == 0) { png_ptr->transformed_pixel_depth = row_info.pixel_depth; if (row_info.pixel_depth > png_ptr->maximum_pixel_depth) png_error(png_ptr, "sequential row overflow"); } else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth) png_error(png_ptr, "internal sequential row size calculation error"); #ifdef 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(&row_info, png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations); if (dsp_row != NULL) png_combine_row(png_ptr, dsp_row, 1/*display*/); if (row != NULL) png_combine_row(png_ptr, row, 0/*row*/); } else #endif { if (row != NULL) png_combine_row(png_ptr, row, -1/*ignored*/); if (dsp_row != NULL) png_combine_row(png_ptr, dsp_row, -1/*ignored*/); } 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); } #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* 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 this version of libpng */ void PNGAPI 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"); if (png_ptr == NULL) return; 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++; } } #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* 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 this version of libpng */ void PNGAPI 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"); if (png_ptr == NULL) return; #ifdef PNG_READ_INTERLACING_SUPPORTED if (!(png_ptr->flags & PNG_FLAG_ROW_INIT)) { pass = png_set_interlace_handling(png_ptr); /* And make sure transforms are initialized. */ png_start_read_image(png_ptr); } else { if (png_ptr->interlaced && !(png_ptr->transformations & PNG_INTERLACE)) { /* Caller called png_start_read_image or png_read_update_info without * first turning on the PNG_INTERLACE transform. We can fix this here, * but the caller should do it! */ png_warning(png_ptr, "Interlace handling should be turned on when " "using png_read_image"); /* Make sure this is set correctly */ png_ptr->num_rows = png_ptr->height; } /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in * the above error case. */ pass = png_set_interlace_handling(png_ptr); } #else if (png_ptr->interlaced) png_error(png_ptr, "Cannot read interlaced image -- interlace handler disabled"); pass = 1; #endif image_height=png_ptr->height; for (j = 0; j < pass; j++) { rp = image; for (i = 0; i < image_height; i++) { png_read_row(png_ptr, *rp, NULL); rp++; } } } #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* 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 PNGAPI png_read_end(png_structp png_ptr, png_infop info_ptr) { png_debug(1, "in png_read_end"); if (png_ptr == NULL) return; png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */ do { png_uint_32 length = png_read_chunk_header(png_ptr); png_uint_32 chunk_name = png_ptr->chunk_name; if (chunk_name == png_IHDR) png_handle_IHDR(png_ptr, info_ptr, length); else if (chunk_name == png_IEND) png_handle_IEND(png_ptr, info_ptr, length); #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED else if (png_chunk_unknown_handling(png_ptr, chunk_name) != PNG_HANDLE_CHUNK_AS_DEFAULT) { if (chunk_name == png_IDAT) { if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT)) png_benign_error(png_ptr, "Too many IDATs found"); } png_handle_unknown(png_ptr, info_ptr, length); if (chunk_name == png_PLTE) png_ptr->mode |= PNG_HAVE_PLTE; } #endif else if (chunk_name == png_IDAT) { /* 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_HAVE_CHUNK_AFTER_IDAT)) png_benign_error(png_ptr, "Too many IDATs found"); png_crc_finish(png_ptr, length); } else if (chunk_name == png_PLTE) png_handle_PLTE(png_ptr, info_ptr, length); #ifdef PNG_READ_bKGD_SUPPORTED else if (chunk_name == png_bKGD) png_handle_bKGD(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_cHRM_SUPPORTED else if (chunk_name == png_cHRM) png_handle_cHRM(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_gAMA_SUPPORTED else if (chunk_name == png_gAMA) png_handle_gAMA(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_hIST_SUPPORTED else if (chunk_name == png_hIST) png_handle_hIST(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_oFFs_SUPPORTED else if (chunk_name == png_oFFs) png_handle_oFFs(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_pCAL_SUPPORTED else if (chunk_name == png_pCAL) png_handle_pCAL(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_sCAL_SUPPORTED else if (chunk_name == png_sCAL) png_handle_sCAL(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_pHYs_SUPPORTED else if (chunk_name == png_pHYs) png_handle_pHYs(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_sBIT_SUPPORTED else if (chunk_name == png_sBIT) png_handle_sBIT(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_sRGB_SUPPORTED else if (chunk_name == png_sRGB) png_handle_sRGB(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_iCCP_SUPPORTED else if (chunk_name == png_iCCP) png_handle_iCCP(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_sPLT_SUPPORTED else if (chunk_name == png_sPLT) png_handle_sPLT(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_tEXt_SUPPORTED else if (chunk_name == png_tEXt) png_handle_tEXt(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_tIME_SUPPORTED else if (chunk_name == png_tIME) png_handle_tIME(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_tRNS_SUPPORTED else if (chunk_name == png_tRNS) png_handle_tRNS(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_zTXt_SUPPORTED else if (chunk_name == png_zTXt) png_handle_zTXt(png_ptr, info_ptr, length); #endif #ifdef PNG_READ_iTXt_SUPPORTED else if (chunk_name == png_iTXt) png_handle_iTXt(png_ptr, info_ptr, length); #endif else png_handle_unknown(png_ptr, info_ptr, length); } while (!(png_ptr->mode & PNG_HAVE_IEND)); } #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ /* Free all memory used in the read struct */ static void png_read_destroy(png_structp png_ptr) { png_debug(1, "in png_read_destroy"); #ifdef PNG_READ_GAMMA_SUPPORTED png_destroy_gamma_table(png_ptr); #endif png_free(png_ptr, png_ptr->zbuf); png_free(png_ptr, png_ptr->big_row_buf); png_free(png_ptr, png_ptr->big_prev_row); png_free(png_ptr, png_ptr->chunkdata); #ifdef PNG_READ_QUANTIZE_SUPPORTED png_free(png_ptr, png_ptr->palette_lookup); png_free(png_ptr, png_ptr->quantize_index); #endif if (png_ptr->free_me & PNG_FREE_PLTE) png_zfree(png_ptr, png_ptr->palette); png_ptr->free_me &= ~PNG_FREE_PLTE; #if defined(PNG_tRNS_SUPPORTED) || \ defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) if (png_ptr->free_me & PNG_FREE_TRNS) png_free(png_ptr, png_ptr->trans_alpha); png_ptr->free_me &= ~PNG_FREE_TRNS; #endif #ifdef PNG_READ_hIST_SUPPORTED if (png_ptr->free_me & PNG_FREE_HIST) png_free(png_ptr, png_ptr->hist); png_ptr->free_me &= ~PNG_FREE_HIST; #endif inflateEnd(&png_ptr->zstream); #ifdef PNG_PROGRESSIVE_READ_SUPPORTED png_free(png_ptr, png_ptr->save_buffer); #endif #ifdef PNG_PROGRESSIVE_READ_SUPPORTED #ifdef PNG_TEXT_SUPPORTED png_free(png_ptr, png_ptr->current_text); #endif /* PNG_TEXT_SUPPORTED */ #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */ /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error * callbacks are still set at this point. They are required to complete the * destruction of the png_struct itself. */ } /* Free all memory used by the read */ void PNGAPI 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_debug(1, "in png_destroy_read_struct"); if (png_ptr_ptr != NULL) png_ptr = *png_ptr_ptr; if (png_ptr == NULL) return; /* libpng 1.6.0: use the API to destroy info structs to ensure consistent * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API. * The extra was, apparently, unnecessary yet this hides memory leak bugs. */ png_destroy_info_struct(png_ptr, end_info_ptr_ptr); png_destroy_info_struct(png_ptr, info_ptr_ptr); *png_ptr_ptr = NULL; png_read_destroy(png_ptr); png_destroy_png_struct(png_ptr); } void PNGAPI png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn) { if (png_ptr == NULL) return; png_ptr->read_row_fn = read_row_fn; } #ifdef PNG_SEQUENTIAL_READ_SUPPORTED #ifdef PNG_INFO_IMAGE_SUPPORTED void PNGAPI png_read_png(png_structp png_ptr, png_infop info_ptr, int transforms, voidp params) { int row; if (png_ptr == NULL || info_ptr == NULL) return; /* png_read_info() gives us all of the information from the * PNG file before the first IDAT (image data chunk). */ png_read_info(png_ptr, info_ptr); if (info_ptr->height > PNG_UINT_32_MAX/png_sizeof(png_bytep)) png_error(png_ptr, "Image is too high to process with png_read_png()"); /* -------------- image transformations start here ------------------- */ #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED /* Tell libpng to strip 16-bit/color files down to 8 bits per color. */ if (transforms & PNG_TRANSFORM_SCALE_16) { /* Added at libpng-1.5.4. "strip_16" produces the same result that it * did in earlier versions, while "scale_16" is now more accurate. */ png_set_scale_16(png_ptr); } #endif #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED /* If both SCALE and STRIP are required pngrtran will effectively cancel the * latter by doing SCALE first. This is ok and allows apps not to check for * which is supported to get the right answer. */ if (transforms & PNG_TRANSFORM_STRIP_16) png_set_strip_16(png_ptr); #endif #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED /* Strip alpha bytes from the input data without combining with * the background (not recommended). */ if (transforms & PNG_TRANSFORM_STRIP_ALPHA) png_set_strip_alpha(png_ptr); #endif #if defined(PNG_READ_PACK_SUPPORTED) && !defined(PNG_READ_EXPAND_SUPPORTED) /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single * byte into separate bytes (useful for paletted and grayscale images). */ if (transforms & PNG_TRANSFORM_PACKING) png_set_packing(png_ptr); #endif #ifdef PNG_READ_PACKSWAP_SUPPORTED /* Change the order of packed pixels to least significant bit first * (not useful if you are using png_set_packing). */ if (transforms & PNG_TRANSFORM_PACKSWAP) png_set_packswap(png_ptr); #endif #ifdef PNG_READ_EXPAND_SUPPORTED /* Expand paletted colors into true RGB triplets * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel * Expand paletted or RGB images with transparency to full alpha * channels so the data will be available as RGBA quartets. */ if (transforms & PNG_TRANSFORM_EXPAND) if ((png_ptr->bit_depth < 8) || (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) || (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))) png_set_expand(png_ptr); #endif /* We don't handle background color or gamma transformation or quantizing. */ #ifdef PNG_READ_INVERT_SUPPORTED /* Invert monochrome files to have 0 as white and 1 as black */ if (transforms & PNG_TRANSFORM_INVERT_MONO) png_set_invert_mono(png_ptr); #endif #ifdef PNG_READ_SHIFT_SUPPORTED /* If you want to shift the pixel values from the range [0,255] or * [0,65535] to the original [0,7] or [0,31], or whatever range the * colors were originally in: */ if ((transforms & PNG_TRANSFORM_SHIFT) && png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT)) { png_color_8p sig_bit; png_get_sBIT(png_ptr, info_ptr, &sig_bit); png_set_shift(png_ptr, sig_bit); } #endif #ifdef PNG_READ_BGR_SUPPORTED /* Flip the RGB pixels to BGR (or RGBA to BGRA) */ if (transforms & PNG_TRANSFORM_BGR) png_set_bgr(png_ptr); #endif #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */ if (transforms & PNG_TRANSFORM_SWAP_ALPHA) png_set_swap_alpha(png_ptr); #endif #ifdef PNG_READ_SWAP_SUPPORTED /* Swap bytes of 16-bit files to least significant byte first */ if (transforms & PNG_TRANSFORM_SWAP_ENDIAN) png_set_swap(png_ptr); #endif /* Added at libpng-1.2.41 */ #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED /* Invert the alpha channel from opacity to transparency */ if (transforms & PNG_TRANSFORM_INVERT_ALPHA) png_set_invert_alpha(png_ptr); #endif /* Added at libpng-1.2.41 */ #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED /* Expand grayscale image to RGB */ if (transforms & PNG_TRANSFORM_GRAY_TO_RGB) png_set_gray_to_rgb(png_ptr); #endif /* Added at libpng-1.5.4 */ #ifdef PNG_READ_EXPAND_16_SUPPORTED if (transforms & PNG_TRANSFORM_EXPAND_16) png_set_expand_16(png_ptr); #endif /* We don't handle adding filler bytes */ /* We use png_read_image and rely on that for interlace handling, but we also * call png_read_update_info therefore must turn on interlace handling now: */ (void)png_set_interlace_handling(png_ptr); /* Optional call to gamma correct and add the background to the palette * and update info structure. REQUIRED if you are expecting libpng to * update the palette for you (i.e., you selected such a transform above). */ png_read_update_info(png_ptr, info_ptr); /* -------------- image transformations end here ------------------- */ png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0); if (info_ptr->row_pointers == NULL) { png_uint_32 iptr; info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr, info_ptr->height * png_sizeof(png_bytep)); for (iptr=0; iptrheight; iptr++) info_ptr->row_pointers[iptr] = NULL; info_ptr->free_me |= PNG_FREE_ROWS; for (row = 0; row < (int)info_ptr->height; row++) info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); } png_read_image(png_ptr, info_ptr->row_pointers); info_ptr->valid |= PNG_INFO_IDAT; /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */ png_read_end(png_ptr, info_ptr); PNG_UNUSED(transforms) /* Quiet compiler warnings */ PNG_UNUSED(params) } #endif /* PNG_INFO_IMAGE_SUPPORTED */ #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ #ifdef PNG_SIMPLIFIED_READ_SUPPORTED /* SIMPLIFIED READ * * This code currently relies on the sequential reader, though it could easily * be made to work with the progressive one. */ /* Do all the *safe* initialization - 'safe' means that png_error won't be * called, so setting up the jmp_buf is not required. This means that anything * called from here must *not* call png_malloc - it has to call png_malloc_warn * instead so that control is returned safely back to this routine. */ static int png_image_read_init(png_imagep image) { png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image, png_safe_error, png_safe_warning); if (png_ptr != NULL) { png_infop info_ptr = png_create_info_struct(png_ptr); if (info_ptr != NULL) { png_controlp control = png_voidcast(png_controlp, png_malloc_warn(png_ptr, sizeof *control)); if (control != NULL) { png_memset(control, 0, sizeof *control); control->png_ptr = png_ptr; control->info_ptr = info_ptr; control->for_write = 0; image->opaque = control; return 1; } /* Error clean up */ png_destroy_info_struct(png_ptr, &info_ptr); } png_destroy_read_struct(&png_ptr, NULL, NULL); } return png_image_error(image, "png_image_read: out of memory"); } /* Utility to find the base format of a PNG file from a png_struct. */ static png_uint_32 png_image_format(png_structp png_ptr, png_infop info_ptr) { png_uint_32 format = 0; if (png_ptr->color_type & PNG_COLOR_MASK_COLOR) format |= PNG_FORMAT_FLAG_COLOR; if (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) format |= PNG_FORMAT_FLAG_ALPHA; else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS)) format |= PNG_FORMAT_FLAG_ALPHA; if (png_ptr->bit_depth == 16) format |= PNG_FORMAT_FLAG_LINEAR; return format; } /* Do the main body of a 'png_image_begin_read' function; read the PNG file * header and fill in all the information. This is executed in a safe context, * unlike the init routine above. */ static int png_image_read_header(png_voidp argument) { png_imagep image = png_voidcast(png_imagep, argument); png_structp png_ptr = image->opaque->png_ptr; png_infop info_ptr = image->opaque->info_ptr; png_read_info(png_ptr, info_ptr); /* Do this the fast way; just read directly out of png_struct. */ image->width = png_ptr->width; image->height = png_ptr->height; { png_uint_32 format = png_image_format(png_ptr, info_ptr); image->format = format; image->flags = 0; /* Now try to work out whether the color data does not match sRGB. */ if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && (info_ptr->valid & PNG_INFO_sRGB) == 0) { /* gamma is irrelevant because libpng does gamma correction, what * matters is if the cHRM chunk doesn't match or, in the absence of * cRHM, if the iCCP profile appears to have different end points. */ if (info_ptr->valid & PNG_INFO_cHRM) { /* TODO: this is a copy'n'paste from pngrutil.c, make a common * checking function. This checks for a 1% error. */ /* The cHRM chunk is used in preference to iCCP */ if (PNG_OUT_OF_RANGE(info_ptr->x_white, 31270, 1000) || PNG_OUT_OF_RANGE(info_ptr->y_white, 32900, 1000) || PNG_OUT_OF_RANGE(info_ptr->x_red, 64000, 1000) || PNG_OUT_OF_RANGE(info_ptr->y_red, 33000, 1000) || PNG_OUT_OF_RANGE(info_ptr->x_green, 30000, 1000) || PNG_OUT_OF_RANGE(info_ptr->y_green, 60000, 1000) || PNG_OUT_OF_RANGE(info_ptr->x_blue, 15000, 1000) || PNG_OUT_OF_RANGE(info_ptr->y_blue, 6000, 1000)) image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB; } else if (info_ptr->valid & PNG_INFO_iCCP) { # if 0 /* TODO: IMPLEMENT THIS! Remember to remove iCCP from the chunks_to_ignore list */ /* Here if we just have an iCCP chunk. */ if (!png_iCCP_is_sRGB(png_ptr, info_ptr)) # endif image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB; } } } return 1; } #ifdef PNG_STDIO_SUPPORTED int PNGAPI png_image_begin_read_from_stdio(png_imagep image, FILE* file) { if (image != NULL) { if (file != NULL) { if (png_image_read_init(image)) { /* This is slightly evil, but png_init_io doesn't do anything other * than this and we haven't changed the standard IO functions so * this saves a 'safe' function. */ image->opaque->png_ptr->io_ptr = file; return png_safe_execute(image, png_image_read_header, image); } } else return png_image_error(image, "png_image_begin_read_from_stdio: invalid argument"); } return 0; } int PNGAPI png_image_begin_read_from_file(png_imagep image, const char *file_name) { if (image != NULL) { if (file_name != NULL) { FILE *fp = fopen(file_name, "rb"); if (fp != NULL) { if (png_image_read_init(image)) { image->opaque->png_ptr->io_ptr = fp; image->opaque->owned_file = 1; return png_safe_execute(image, png_image_read_header, image); } /* Clean up: just the opened file. */ (void)fclose(fp); } else return png_image_error(image, strerror(errno)); } else return png_image_error(image, "png_image_begin_read_from_file: invalid argument"); } return 0; } #endif /* PNG_STDIO_SUPPORTED */ static void PNGCBAPI png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need) { if (png_ptr != NULL) { png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr); if (image != NULL) { png_controlp cp = image->opaque; if (cp != NULL) { png_const_bytep memory = cp->memory; png_size_t size = cp->size; if (memory != NULL && size >= need) { png_memcpy(out, memory, need); cp->memory = memory + need; cp->size = size - need; return; } png_error(png_ptr, "read beyond end of data"); } } png_error(png_ptr, "invalid memory read"); } } int PNGAPI png_image_begin_read_from_memory(png_imagep image, png_const_voidp memory, png_size_t size) { if (image != NULL) { if (memory != NULL && size > 0) { if (png_image_read_init(image)) { /* Now set the IO functions to read from the memory buffer and * store it into io_ptr. Again do this in-place to avoid calling a * libpng function that requires error handling. */ image->opaque->memory = png_voidcast(png_const_bytep, memory); image->opaque->size = size; image->opaque->png_ptr->io_ptr = image; image->opaque->png_ptr->read_data_fn = png_image_memory_read; return png_safe_execute(image, png_image_read_header, image); } } else return png_image_error(image, "png_image_begin_read_from_memory: invalid argument"); } return 0; } /* Arguments to png_image_finish_read: */ typedef struct { /* Arguments: */ png_imagep image; png_voidp buffer; png_int_32 row_stride; png_colorp background; /* Local variables: */ png_bytep local_row; png_bytep first_row; ptrdiff_t row_bytes; /* unsigned arithmetic step between rows */ } png_image_read_control; /* Just the row reading part of png_image_read. */ static int png_image_read_composite(png_voidp argument) { png_image_read_control *display = png_voidcast(png_image_read_control*, argument); png_imagep image = display->image; png_structp png_ptr = image->opaque->png_ptr; png_byte interlace_type = png_ptr->interlaced; int passes; switch (interlace_type) { case PNG_INTERLACE_NONE: passes = 1; break; case PNG_INTERLACE_ADAM7: passes = PNG_INTERLACE_ADAM7_PASSES; break; default: png_error(png_ptr, "unknown interlace type"); } { png_uint_32 height = image->height; png_uint_32 width = image->width; unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1; int pass; for (pass = 0; pass < passes; ++pass) { png_bytep row = display->first_row; unsigned int startx, stepx, stepy; png_uint_32 y; if (interlace_type == PNG_INTERLACE_ADAM7) { /* The row may be empty for a short image: */ if (PNG_PASS_COLS(width, pass) == 0) continue; startx = PNG_PASS_START_COL(pass); stepx = PNG_PASS_COL_OFFSET(pass); y = PNG_PASS_START_ROW(pass); stepy = PNG_PASS_ROW_OFFSET(pass); } else { y = 0; startx = 0; stepx = stepy = 1; } /* The following are invariants across all the rows: */ startx *= channels; stepx *= channels; for (; ylocal_row; png_bytep outrow = row + startx; png_const_bytep end_row = row + width * channels; /* Read the row, which is packed: */ png_read_row(png_ptr, inrow, NULL); /* Now do the composition on each pixel in this row. */ for (; outrow < end_row; outrow += stepx) { png_byte alpha = inrow[channels]; if (alpha > 0) /* else no change to the output */ { unsigned int c; for (c=0; crow_bytes; } } } return 1; } /* The do_local_background case; called when all the following transforms are to * be done: * * PNG_RGB_TO_GRAY * PNG_COMPOSITE * PNG_GAMMA * * This is a work-round for the fact that both the PNG_RGB_TO_GRAY and * PNG_COMPOSITE code performs gamma correction, so we get double gamma * correction. The fix-up is to prevent the PNG_COMPOSITE operation happening * inside libpng, so this routine sees an 8 or 16-bit gray+alpha row and handles * the removal or pre-multiplication of the alpha channel. */ static int png_image_read_background(png_voidp argument) { png_image_read_control *display = png_voidcast(png_image_read_control*, argument); png_imagep image = display->image; png_structp png_ptr = image->opaque->png_ptr; png_infop info_ptr = image->opaque->info_ptr; png_byte interlace_type = png_ptr->interlaced; png_uint_32 height = image->height; png_uint_32 width = image->width; int pass, passes; /* Double check the convoluted logic below. We expect to get here with * libpng doing rgb to gray and gamma correction but background processing * left to the png_image_read_background function. The rows libpng produce * might be 8 or 16-bit but should always have two channels; gray plus alpha. */ if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0) png_error(png_ptr, "lost rgb to gray"); if ((png_ptr->transformations & PNG_COMPOSE) != 0) png_error(png_ptr, "unexpected compose"); /* The palette code zaps PNG_GAMMA in place... */ if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) == 0 && (png_ptr->transformations & PNG_GAMMA) == 0) png_error(png_ptr, "lost gamma correction"); if (png_get_channels(png_ptr, info_ptr) != 2) png_error(png_ptr, "lost/gained channels"); switch (interlace_type) { case PNG_INTERLACE_NONE: passes = 1; break; case PNG_INTERLACE_ADAM7: passes = PNG_INTERLACE_ADAM7_PASSES; break; default: png_error(png_ptr, "unknown interlace type"); } switch (png_get_bit_depth(png_ptr, info_ptr)) { default: png_error(png_ptr, "unexpected bit depth"); break; case 8: /* 8-bit sRGB gray values with an alpha channel; the alpha channel is * to be removed by composing on a backgroundi: either the row if * display->background is NULL or display->background.green if not. * Unlike the code above ALPHA_OPTIMIZED has *not* been done. */ for (pass = 0; pass < passes; ++pass) { png_bytep row = display->first_row; unsigned int startx, stepx, stepy; png_uint_32 y; if (interlace_type == PNG_INTERLACE_ADAM7) { /* The row may be empty for a short image: */ if (PNG_PASS_COLS(width, pass) == 0) continue; startx = PNG_PASS_START_COL(pass); stepx = PNG_PASS_COL_OFFSET(pass); y = PNG_PASS_START_ROW(pass); stepy = PNG_PASS_ROW_OFFSET(pass); } else { y = 0; startx = 0; stepx = stepy = 1; } if (display->background == NULL) { for (; ylocal_row; png_bytep outrow = row + startx; png_const_bytep end_row = row + width; /* Read the row, which is packed: */ png_read_row(png_ptr, inrow, NULL); /* Now do the composition on each pixel in this row. */ for (; outrow < end_row; outrow += stepx) { png_byte alpha = inrow[1]; if (alpha > 0) /* else no change to the output */ { png_uint_32 component = inrow[0]; if (alpha < 255) /* else just use component */ { /* Since PNG_OPTIMIZED_ALPHA was not set it is * necessary to invert the sRGB transfer * function and multiply the alpha out. */ component = png_sRGB_table[component] * alpha; component += png_sRGB_table[outrow[0]] * (255-alpha); component = PNG_sRGB_FROM_LINEAR(component); } outrow[0] = (png_byte)component; } inrow += 2; /* gray and alpha channel */ } row += display->row_bytes; } } else /* constant background value */ { png_byte background8 = display->background->green; png_uint_16 background = png_sRGB_table[background8]; for (; ylocal_row; png_bytep outrow = row + startx; png_const_bytep end_row = row + width; /* Read the row, which is packed: */ png_read_row(png_ptr, inrow, NULL); /* Now do the composition on each pixel in this row. */ for (; outrow < end_row; outrow += stepx) { png_byte alpha = inrow[1]; if (alpha > 0) /* else use background */ { png_uint_32 component = inrow[0]; if (alpha < 255) /* else just use component */ { component = png_sRGB_table[component] * alpha; component += background * (255-alpha); component = PNG_sRGB_FROM_LINEAR(component); } outrow[0] = (png_byte)component; } else outrow[0] = background8; inrow += 2; /* gray and alpha channel */ } row += display->row_bytes; } } } break; case 16: /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must * still be done and, maybe, the alpha channel removed. This code also * handles the alpha-first option. */ { unsigned int outchannels = png_get_channels(png_ptr, info_ptr); int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0; int swap_alpha = 0; if (preserve_alpha && (image->format & PNG_FORMAT_FLAG_AFIRST)) swap_alpha = 1; for (pass = 0; pass < passes; ++pass) { png_uint_16p row = (png_uint_16p)display->first_row; unsigned int startx, stepx, stepy; /* all in pixels */ png_uint_32 y; if (interlace_type == PNG_INTERLACE_ADAM7) { /* The row may be empty for a short image: */ if (PNG_PASS_COLS(width, pass) == 0) continue; startx = PNG_PASS_START_COL(pass); stepx = PNG_PASS_COL_OFFSET(pass); y = PNG_PASS_START_ROW(pass); stepy = PNG_PASS_ROW_OFFSET(pass); } else { y = 0; startx = 0; stepx = stepy = 1; } startx *= outchannels; stepx *= outchannels; for (; ylocal_row, NULL); inrow = (png_uint_16p)display->local_row; /* Now do the pre-multiplication on each pixel in this row. */ for (; outrow < end_row; outrow += stepx) { png_uint_32 component = inrow[0]; png_uint_16 alpha = inrow[1]; if (alpha > 0) /* else 0 */ { if (alpha < 65535) /* else just use component */ { component *= alpha; component += 32767; component /= 65535; } } else component = 0; outrow[swap_alpha] = (png_uint_16)component; if (outchannels > 1) outrow[1 ^ swap_alpha] = alpha; inrow += 2; /* components and alpha channel */ } row += display->row_bytes; } } } break; } return 1; } /* The guts of png_image_finish_read as a png_safe_execute callback. */ static int png_image_read_end(png_voidp argument) { png_image_read_control *display = png_voidcast(png_image_read_control*, argument); png_imagep image = display->image; png_structp png_ptr = image->opaque->png_ptr; png_infop info_ptr = image->opaque->info_ptr; png_uint_32 format = image->format; int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0; int do_local_compose = 0; int do_local_background = 0; /* to avoid double gamma correction bug */ int passes = 0; /* Add transforms to ensure the correct output format is produced then check * that the required implementation support is there. Always expand; always * need 8 bits minimum, no palette and expanded tRNS. */ png_set_expand(png_ptr); /* Now check the format to see if it was modified. */ { png_uint_32 base_format = png_image_format(png_ptr, info_ptr); png_uint_32 change = format ^ base_format; png_fixed_point output_gamma; int mode; /* alpha mode */ /* Do this first so that we have a record if rgb to gray is happening. */ if (change & PNG_FORMAT_FLAG_COLOR) { /* gray<->color transformation required. */ if (format & PNG_FORMAT_FLAG_COLOR) png_set_gray_to_rgb(png_ptr); else { /* libpng can't do both rgb to gray and * background/pre-multiplication if there is also significant gamma * correction, because both operations require linear colors and * the code only supports one transform doing the gamma correction. * Handle this by doing the pre-multiplication or background * operation in this code, if necessary. * * TODO: fix this by rewriting pngrtran.c (!) * * For the moment (given that fixing this in pngrtran.c is an * enormous change) 'do_local_background' is used to indicate that * the problem exists. */ if (base_format & PNG_FORMAT_FLAG_ALPHA) do_local_background = 1/*maybe*/; png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT); } change &= ~PNG_FORMAT_FLAG_COLOR; } /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise. */ { png_fixed_point input_gamma_default; if (base_format & PNG_FORMAT_FLAG_LINEAR) input_gamma_default = PNG_GAMMA_LINEAR; else input_gamma_default = PNG_DEFAULT_sRGB; /* Call png_set_alpha_mode to set the default for the input gamma; the * output gamma is set by a second call below. */ png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default); } if (linear) { /* If there *is* an alpha channel in the input it must be multiplied * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG. */ if (base_format & PNG_FORMAT_FLAG_ALPHA) mode = PNG_ALPHA_STANDARD; /* associated alpha */ else mode = PNG_ALPHA_PNG; output_gamma = PNG_GAMMA_LINEAR; } else { mode = PNG_ALPHA_PNG; output_gamma = PNG_DEFAULT_sRGB; } /* If 'do_local_background' is set check for the presence of gamma * correction; this is part of the work-round for the libpng bug * described above. * * TODO: fix libpng and remove this. */ if (do_local_background) { png_fixed_point gtest; /* This is 'png_gamma_threshold' from pngrtran.c; the test used for * gamma correction, the screen gamma hasn't been set on png_struct * yet; it's set below. png_struct::gamma, however, is set to the * final value. */ if (png_muldiv(>est, output_gamma, png_ptr->gamma, PNG_FP_1) && !png_gamma_significant(gtest)) do_local_background = 0; else if (mode == PNG_ALPHA_STANDARD) { do_local_background = 2/*required*/; mode = PNG_ALPHA_PNG; /* prevent libpng doing it */ } /* else leave as 1 for the checks below */ } /* If the bit-depth changes then handle that here. */ if (change & PNG_FORMAT_FLAG_LINEAR) { if (linear /*16-bit output*/) png_set_expand_16(png_ptr); else /* 8-bit output */ png_set_scale_16(png_ptr); change &= ~PNG_FORMAT_FLAG_LINEAR; } /* Now the background/alpha channel changes. */ if (change & PNG_FORMAT_FLAG_ALPHA) { /* Removing an alpha channel requires composition for the 8-bit * formats; for the 16-bit it is already done, above, by the * pre-multiplication and the channel just needs to be stripped. */ if (base_format & PNG_FORMAT_FLAG_ALPHA) { /* If RGB->gray is happening the alpha channel must be left and the * operation completed locally. * * TODO: fix libpng and remove this. */ if (do_local_background) do_local_background = 2/*required*/; /* 16-bit output: just remove the channel */ else if (linear) /* compose on black (well, pre-multiply) */ png_set_strip_alpha(png_ptr); /* 8-bit output: do an appropriate compose */ else if (display->background != NULL) { png_color_16 c; c.index = 0; /*unused*/ c.red = display->background->red; c.green = display->background->green; c.blue = display->background->blue; c.gray = display->background->green; /* This is always an 8-bit sRGB value, using the 'green' channel * for gray is much better than calculating the luminance here; * we can get off-by-one errors in that calculation relative to * the app expectations and that will show up in transparent * pixels. */ png_set_background_fixed(png_ptr, &c, PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 0/*gamma: not used*/); } else /* compose on row: implemented below. */ { do_local_compose = 1; /* This leaves the alpha channel in the output, so it has to be * removed by the code below. Set the encoding to the 'OPTIMIZE' * one so the code only has to hack on the pixels that require * composition. */ mode = PNG_ALPHA_OPTIMIZED; } } else /* output needs an alpha channel */ { /* This is tricky because it happens before the swap operation has * been accomplished; however, the swap does *not* swap the added * alpha channel (weird API), so it must be added in the correct * place. */ png_uint_32 filler; /* opaque filler */ int where; if (linear) filler = 65535; else filler = 255; # ifdef PNG_FORMAT_AFIRST_SUPPORTED if (format & PNG_FORMAT_FLAG_AFIRST) { where = PNG_FILLER_BEFORE; change &= ~PNG_FORMAT_FLAG_AFIRST; } else # endif where = PNG_FILLER_AFTER; png_set_add_alpha(png_ptr, filler, where); } /* This stops the (irrelevant) call to swap_alpha below. */ change &= ~PNG_FORMAT_FLAG_ALPHA; } /* Now set the alpha mode correctly; this is always done, even if there is * no alpha channel in either the input or the output because it correctly * sets the output gamma. */ png_set_alpha_mode_fixed(png_ptr, mode, output_gamma); # ifdef PNG_FORMAT_BGR_SUPPORTED if (change & PNG_FORMAT_FLAG_BGR) { /* Check only the output format; PNG is never BGR; don't do this if * the output is gray, but fix up the 'format' value in that case. */ if (format & PNG_FORMAT_FLAG_COLOR) png_set_bgr(png_ptr); else format &= ~PNG_FORMAT_FLAG_BGR; change &= ~PNG_FORMAT_FLAG_BGR; } # endif # ifdef PNG_FORMAT_AFIRST_SUPPORTED if (change & PNG_FORMAT_FLAG_AFIRST) { /* Only relevant if there is an alpha channel - it's particularly * important to handle this correctly because do_local_compose may * be set above and then libpng will keep the alpha channel for this * code to remove. */ if (format & PNG_FORMAT_FLAG_ALPHA) { /* Disable this if doing a local background, * TODO: remove this when local background is no longer required. */ if (do_local_background != 2) png_set_swap_alpha(png_ptr); } else format &= ~PNG_FORMAT_FLAG_AFIRST; change &= ~PNG_FORMAT_FLAG_AFIRST; } # endif /* If the *output* is 16-bit then we need to check for a byte-swap on this * architecture. */ if (linear) { PNG_CONST png_uint_16 le = 0x0001; if (*(png_const_bytep)&le) png_set_swap(png_ptr); } /* If change is not now 0 some transformation is missing - error out. */ if (change) png_error(png_ptr, "png_read_image: unsupported transformation"); } # ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED /* Prepare the reader to ignore all recognized chunks whose data will not * be used, i.e., all chunks recognized by libpng except for those * involved in basic image reading: * * IHDR, PLTE, IDAT, IEND * * Or image data handling: * * tRNS, bKGD, gAMA, cHRM, sRGB, iCCP and sBIT. * * This provides a small performance improvement and eliminates any * potential vulnerability to security problems in the unused chunks. * * TODO: make it so that this is an explicit list to process, not a list * to ignore? */ { static PNG_CONST png_byte chunks_to_ignore[] = { 104, 73, 83, 84, '\0', /* hIST */ 105, 84, 88, 116, '\0', /* iTXt */ 111, 70, 70, 115, '\0', /* oFFs */ 112, 67, 65, 76, '\0', /* pCAL */ 112, 72, 89, 115, '\0', /* pHYs */ 115, 67, 65, 76, '\0', /* sCAL */ 115, 80, 76, 84, '\0', /* sPLT */ 116, 69, 88, 116, '\0', /* tEXt */ 116, 73, 77, 69, '\0', /* tIME */ 122, 84, 88, 116, '\0' /* zTXt */ }; /* Ignore unknown chunks */ png_set_keep_unknown_chunks(png_ptr, 1 /* PNG_HANDLE_CHUNK_NEVER */, NULL, 0); /* Ignore known but unused chunks */ png_set_keep_unknown_chunks(png_ptr, 1 /* PNG_HANDLE_CHUNK_NEVER */, chunks_to_ignore, (sizeof chunks_to_ignore)/5); } # endif /* PNG_HANDLE_AS_UNKNOWN_SUPPORTED */ /* Update the 'info' structure and make sure the result is as required; first * make sure to turn on the interlace handling if it will be required * (because it can't be turned on *after* the call to png_read_update_info!) * * TODO: remove the do_local_background fixup below. */ if (!do_local_compose && do_local_background != 2) passes = png_set_interlace_handling(png_ptr); png_read_update_info(png_ptr, info_ptr); { png_uint_32 info_format = 0; if (info_ptr->color_type & PNG_COLOR_MASK_COLOR) info_format |= PNG_FORMAT_FLAG_COLOR; if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA) { /* do_local_compose removes this channel below. */ if (!do_local_compose) { /* do_local_background does the same if required. */ if (do_local_background != 2 || (format & PNG_FORMAT_FLAG_ALPHA) != 0) info_format |= PNG_FORMAT_FLAG_ALPHA; } } else if (do_local_compose) /* internal error */ png_error(png_ptr, "png_image_read: alpha channel lost"); if (info_ptr->bit_depth == 16) info_format |= PNG_FORMAT_FLAG_LINEAR; # ifdef PNG_FORMAT_BGR_SUPPORTED if (png_ptr->transformations & PNG_BGR) info_format |= PNG_FORMAT_FLAG_BGR; # endif # ifdef PNG_FORMAT_AFIRST_SUPPORTED if (png_ptr->transformations & PNG_SWAP_ALPHA || ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 && (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0)) info_format |= PNG_FORMAT_FLAG_AFIRST; # endif /* This is actually an internal error. */ if (info_format != format) png_error(png_ptr, "png_read_image: invalid transformations"); } /* Now read the rows. If do_local_compose is set then it is necessary to use * a local row buffer. The output will be GA, RGBA or BGRA and must be * converted to G, RGB or BGR as appropriate. The 'local_row' member of the * display acts as a flag. */ { png_bytep first_row = png_voidcast(png_bytep, display->buffer); ptrdiff_t row_bytes = display->row_stride; if (linear) row_bytes *= sizeof (png_uint_16); /* The following expression is designed to work correctly whether it gives * a signed or an unsigned result. */ if (row_bytes < 0) first_row += (image->height-1) * (-row_bytes); display->first_row = first_row; display->row_bytes = row_bytes; } if (do_local_compose) { int result; png_bytep row = png_voidcast(png_bytep, png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr))); display->local_row = row; result = png_safe_execute(image, png_image_read_composite, display); display->local_row = NULL; png_free(png_ptr, row); return result; } else if (do_local_background == 2) { int result; png_bytep row = png_voidcast(png_bytep, png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr))); display->local_row = row; result = png_safe_execute(image, png_image_read_background, display); display->local_row = NULL; png_free(png_ptr, row); return result; } else { png_alloc_size_t row_bytes = display->row_bytes; while (--passes >= 0) { png_uint_32 y = image->height; png_bytep row = display->first_row; while (y-- > 0) { png_read_row(png_ptr, row, NULL); row += row_bytes; } } return 1; } } int PNGAPI png_image_finish_read(png_imagep image, png_colorp background, void *buffer, png_int_32 row_stride) { if (image != NULL) { png_uint_32 check; if (row_stride == 0) row_stride = PNG_IMAGE_ROW_STRIDE(*image); if (row_stride < 0) check = -row_stride; else check = row_stride; if (buffer != NULL && check >= PNG_IMAGE_ROW_STRIDE(*image)) { int result; png_image_read_control display; png_memset(&display, 0, sizeof display); display.image = image; display.buffer = buffer; display.row_stride = row_stride; display.background = background; display.local_row = NULL; result = png_safe_execute(image, png_image_read_end, &display); png_image_free(image); return result; } else return png_image_error(image, "png_image_finish_read: invalid argument"); } return 0; } #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */ #endif /* PNG_READ_SUPPORTED */