You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
323 lines
10 KiB
323 lines
10 KiB
/*--------------------------------------------------------------------------- |
|
|
|
rpng - simple PNG display program readpng.c |
|
|
|
--------------------------------------------------------------------------- |
|
|
|
Copyright (c) 1998-2007,2017 Greg Roelofs. All rights reserved. |
|
|
|
This software is provided "as is," without warranty of any kind, |
|
express or implied. In no event shall the author or contributors |
|
be held liable for any damages arising in any way from the use of |
|
this software. |
|
|
|
The contents of this file are DUAL-LICENSED. You may modify and/or |
|
redistribute this software according to the terms of one of the |
|
following two licenses (at your option): |
|
|
|
|
|
LICENSE 1 ("BSD-like with advertising clause"): |
|
|
|
Permission is granted to anyone to use this software for any purpose, |
|
including commercial applications, and to alter it and redistribute |
|
it freely, subject to the following restrictions: |
|
|
|
1. Redistributions of source code must retain the above copyright |
|
notice, disclaimer, and this list of conditions. |
|
2. Redistributions in binary form must reproduce the above copyright |
|
notice, disclaimer, and this list of conditions in the documenta- |
|
tion and/or other materials provided with the distribution. |
|
3. All advertising materials mentioning features or use of this |
|
software must display the following acknowledgment: |
|
|
|
This product includes software developed by Greg Roelofs |
|
and contributors for the book, "PNG: The Definitive Guide," |
|
published by O'Reilly and Associates. |
|
|
|
|
|
LICENSE 2 (GNU GPL v2 or later): |
|
|
|
This program is free software; you can redistribute it and/or modify |
|
it under the terms of the GNU General Public License as published by |
|
the Free Software Foundation; either version 2 of the License, or |
|
(at your option) any later version. |
|
|
|
This program is distributed in the hope that it will be useful, |
|
but WITHOUT ANY WARRANTY; without even the implied warranty of |
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
|
GNU General Public License for more details. |
|
|
|
You should have received a copy of the GNU General Public License |
|
along with this program; if not, write to the Free Software Foundation, |
|
Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
|
|
|
---------------------------------------------------------------------------*/ |
|
|
|
#include <stdio.h> |
|
#include <stdlib.h> |
|
#include <zlib.h> |
|
|
|
#include "png.h" /* libpng header */ |
|
#include "readpng.h" /* typedefs, common macros, public prototypes */ |
|
|
|
/* future versions of libpng will provide this macro: */ |
|
#ifndef png_jmpbuf |
|
# define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf) |
|
#endif |
|
|
|
|
|
static png_structp png_ptr = NULL; |
|
static png_infop info_ptr = NULL; |
|
|
|
png_uint_32 width, height; |
|
int bit_depth, color_type; |
|
uch *image_data = NULL; |
|
|
|
|
|
void readpng_version_info(void) |
|
{ |
|
fprintf(stderr, " Compiled with libpng %s; using libpng %s.\n", |
|
PNG_LIBPNG_VER_STRING, png_libpng_ver); |
|
fprintf(stderr, " Compiled with zlib %s; using zlib %s.\n", |
|
ZLIB_VERSION, zlib_version); |
|
} |
|
|
|
|
|
/* return value = 0 for success, 1 for bad sig, 2 for bad IHDR, 4 for no mem */ |
|
|
|
int readpng_init(FILE *infile, ulg *pWidth, ulg *pHeight) |
|
{ |
|
uch sig[8]; |
|
|
|
|
|
/* first do a quick check that the file really is a PNG image; could |
|
* have used slightly more general png_sig_cmp() function instead */ |
|
|
|
fread(sig, 1, 8, infile); |
|
if (png_sig_cmp(sig, 0, 8)) |
|
return 1; /* bad signature */ |
|
|
|
|
|
/* could pass pointers to user-defined error handlers instead of NULLs: */ |
|
|
|
png_ptr = png_create_read_struct(png_get_libpng_ver(NULL), NULL, NULL, |
|
NULL); |
|
if (!png_ptr) |
|
return 4; /* out of memory */ |
|
|
|
info_ptr = png_create_info_struct(png_ptr); |
|
if (!info_ptr) { |
|
png_destroy_read_struct(&png_ptr, NULL, NULL); |
|
return 4; /* out of memory */ |
|
} |
|
|
|
|
|
/* we could create a second info struct here (end_info), but it's only |
|
* useful if we want to keep pre- and post-IDAT chunk info separated |
|
* (mainly for PNG-aware image editors and converters) */ |
|
|
|
|
|
/* setjmp() must be called in every function that calls a PNG-reading |
|
* libpng function */ |
|
|
|
if (setjmp(png_jmpbuf(png_ptr))) { |
|
png_destroy_read_struct(&png_ptr, &info_ptr, NULL); |
|
return 2; |
|
} |
|
|
|
|
|
png_init_io(png_ptr, infile); |
|
png_set_sig_bytes(png_ptr, 8); /* we already read the 8 signature bytes */ |
|
|
|
png_read_info(png_ptr, info_ptr); /* read all PNG info up to image data */ |
|
|
|
|
|
/* alternatively, could make separate calls to png_get_image_width(), |
|
* etc., but want bit_depth and color_type for later [don't care about |
|
* compression_type and filter_type => NULLs] */ |
|
|
|
png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, |
|
NULL, NULL, NULL); |
|
*pWidth = width; |
|
*pHeight = height; |
|
|
|
|
|
/* OK, that's all we need for now; return happy */ |
|
|
|
return 0; |
|
} |
|
|
|
|
|
|
|
|
|
/* returns 0 if succeeds, 1 if fails due to no bKGD chunk, 2 if libpng error; |
|
* scales values to 8-bit if necessary */ |
|
|
|
int readpng_get_bgcolor(uch *red, uch *green, uch *blue) |
|
{ |
|
png_color_16p pBackground; |
|
|
|
|
|
/* setjmp() must be called in every function that calls a PNG-reading |
|
* libpng function */ |
|
|
|
if (setjmp(png_jmpbuf(png_ptr))) { |
|
png_destroy_read_struct(&png_ptr, &info_ptr, NULL); |
|
return 2; |
|
} |
|
|
|
|
|
if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_bKGD)) |
|
return 1; |
|
|
|
/* it is not obvious from the libpng documentation, but this function |
|
* takes a pointer to a pointer, and it always returns valid red, green |
|
* and blue values, regardless of color_type: */ |
|
|
|
png_get_bKGD(png_ptr, info_ptr, &pBackground); |
|
|
|
|
|
/* however, it always returns the raw bKGD data, regardless of any |
|
* bit-depth transformations, so check depth and adjust if necessary */ |
|
|
|
if (bit_depth == 16) { |
|
*red = pBackground->red >> 8; |
|
*green = pBackground->green >> 8; |
|
*blue = pBackground->blue >> 8; |
|
} else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) { |
|
if (bit_depth == 1) |
|
*red = *green = *blue = pBackground->gray? 255 : 0; |
|
else if (bit_depth == 2) |
|
*red = *green = *blue = (255/3) * pBackground->gray; |
|
else /* bit_depth == 4 */ |
|
*red = *green = *blue = (255/15) * pBackground->gray; |
|
} else { |
|
*red = (uch)pBackground->red; |
|
*green = (uch)pBackground->green; |
|
*blue = (uch)pBackground->blue; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
|
|
|
|
|
|
/* display_exponent == LUT_exponent * CRT_exponent */ |
|
|
|
uch *readpng_get_image(double display_exponent, int *pChannels, ulg *pRowbytes) |
|
{ |
|
double gamma; |
|
png_uint_32 i, rowbytes; |
|
png_bytepp row_pointers = NULL; |
|
|
|
|
|
/* setjmp() must be called in every function that calls a PNG-reading |
|
* libpng function */ |
|
|
|
if (setjmp(png_jmpbuf(png_ptr))) { |
|
free(image_data); |
|
image_data = NULL; |
|
free(row_pointers); |
|
row_pointers = NULL; |
|
png_destroy_read_struct(&png_ptr, &info_ptr, NULL); |
|
return NULL; |
|
} |
|
|
|
|
|
/* expand palette images to RGB, low-bit-depth grayscale images to 8 bits, |
|
* transparency chunks to full alpha channel; strip 16-bit-per-sample |
|
* images to 8 bits per sample; and convert grayscale to RGB[A] */ |
|
|
|
if (color_type == PNG_COLOR_TYPE_PALETTE) |
|
png_set_expand(png_ptr); |
|
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) |
|
png_set_expand(png_ptr); |
|
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) |
|
png_set_expand(png_ptr); |
|
#ifdef PNG_READ_16_TO_8_SUPPORTED |
|
if (bit_depth == 16) |
|
# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED |
|
png_set_scale_16(png_ptr); |
|
# else |
|
png_set_strip_16(png_ptr); |
|
# endif |
|
#endif |
|
if (color_type == PNG_COLOR_TYPE_GRAY || |
|
color_type == PNG_COLOR_TYPE_GRAY_ALPHA) |
|
png_set_gray_to_rgb(png_ptr); |
|
|
|
|
|
/* unlike the example in the libpng documentation, we have *no* idea where |
|
* this file may have come from--so if it doesn't have a file gamma, don't |
|
* do any correction ("do no harm") */ |
|
|
|
if (png_get_gAMA(png_ptr, info_ptr, &gamma)) |
|
png_set_gamma(png_ptr, display_exponent, gamma); |
|
|
|
|
|
/* all transformations have been registered; now update info_ptr data, |
|
* get rowbytes and channels, and allocate image memory */ |
|
|
|
png_read_update_info(png_ptr, info_ptr); |
|
|
|
*pRowbytes = rowbytes = png_get_rowbytes(png_ptr, info_ptr); |
|
*pChannels = (int)png_get_channels(png_ptr, info_ptr); |
|
|
|
/* Guard against integer overflow */ |
|
if (height > ((size_t)(-1))/rowbytes) { |
|
fprintf(stderr, "readpng: image_data buffer would be too large\n", |
|
return NULL; |
|
} |
|
|
|
if ((image_data = (uch *)malloc(rowbytes*height)) == NULL) { |
|
png_destroy_read_struct(&png_ptr, &info_ptr, NULL); |
|
return NULL; |
|
} |
|
if ((row_pointers = (png_bytepp)malloc(height*sizeof(png_bytep))) == NULL) { |
|
png_destroy_read_struct(&png_ptr, &info_ptr, NULL); |
|
free(image_data); |
|
image_data = NULL; |
|
return NULL; |
|
} |
|
|
|
Trace((stderr, "readpng_get_image: channels = %d, rowbytes = %ld, height = %ld\n", |
|
*pChannels, rowbytes, height)); |
|
|
|
|
|
/* set the individual row_pointers to point at the correct offsets */ |
|
|
|
for (i = 0; i < height; ++i) |
|
row_pointers[i] = image_data + i*rowbytes; |
|
|
|
|
|
/* now we can go ahead and just read the whole image */ |
|
|
|
png_read_image(png_ptr, row_pointers); |
|
|
|
|
|
/* and we're done! (png_read_end() can be omitted if no processing of |
|
* post-IDAT text/time/etc. is desired) */ |
|
|
|
free(row_pointers); |
|
row_pointers = NULL; |
|
|
|
png_read_end(png_ptr, NULL); |
|
|
|
return image_data; |
|
} |
|
|
|
|
|
void readpng_cleanup(int free_image_data) |
|
{ |
|
if (free_image_data && image_data) { |
|
free(image_data); |
|
image_data = NULL; |
|
} |
|
|
|
if (png_ptr && info_ptr) { |
|
png_destroy_read_struct(&png_ptr, &info_ptr, NULL); |
|
png_ptr = NULL; |
|
info_ptr = NULL; |
|
} |
|
}
|
|
|