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/* +-------------------------------------------------------------------+ */
/* | Copyright 1996, Greg Roelofs (newt@pobox.com) | */
/* | Last revised: 21 August 1996 | */
/* +-------------------------------------------------------------------+ */
/* $Id: readPNG.c,v 1.7 1996/08/29 05:24:48 torsten Exp $ */
#include <stdio.h>
#include <stdlib.h>
#include "png.h"
#include "image.h"
#include "rwTable.h"
#ifndef TRUE
# define TRUE 1
# define FALSE 0
#endif
#ifndef Trace
# ifdef PNG_DEBUG
# define Trace(x) fprintf x ; fflush(stderr)
# else
# define Trace(x)
# endif
#endif
int
TestPNG(char *file) /* gets called a LOT on the first image: brushes? */
{
char header[8];
FILE *fp = fopen(file, "rb"); /* libpng requires ANSI; so do we */
if (!fp)
return 0;
fread(header, 1, 8, fp);
fclose(fp);
return png_check_sig(header, 8);
}
Image *
ReadPNG(char *file)
{
FILE *fp;
png_structp png_ptr;
png_infop info_ptr;
int i, hasAlpha=FALSE;
int width, height, level, bit_depth, npasses;
Image *image = NULL;
Trace((stderr, "\nGRR ReadPNG: reading file %s\n", file));
if ((fp = fopen(file, "rb")) == (FILE *)NULL) {
RWSetMsg("Error opening input file");
return NULL;
}
png_ptr = (png_structp)malloc(sizeof(png_struct));
if (!png_ptr) {
RWSetMsg("Error allocating PNG png_ptr memory");
fclose(fp);
return NULL;
}
info_ptr = (png_infop)malloc(sizeof(png_info));
if (!info_ptr) {
RWSetMsg("Error allocating PNG info_ptr memory");
free(png_ptr);
fclose(fp);
return NULL;
}
if (setjmp(png_ptr->jmpbuf)) {
RWSetMsg("Error setting longjmp error handler");
png_read_destroy(png_ptr, info_ptr, (png_info *)0);
free(png_ptr);
free(info_ptr);
fclose(fp);
return NULL;
}
png_info_init(info_ptr);
png_read_init(png_ptr);
png_init_io(png_ptr, fp);
png_read_info(png_ptr, info_ptr);
width = info_ptr->width;
height = info_ptr->height;
Trace((stderr, "GRR ReadPNG: width = %d, height = %d\n", width, height));
switch (info_ptr->color_type) {
case PNG_COLOR_TYPE_PALETTE:
Trace((stderr, "GRR ReadPNG: PNG_COLOR_TYPE_PALETTE\n"));
image = ImageNewCmap(width, height, info_ptr->num_palette);
for (i = 0; i < info_ptr->num_palette; ++i)
ImageSetCmap(image, i, info_ptr->palette[i].red,
info_ptr->palette[i].green, info_ptr->palette[i].blue);
/* GRR: still need to get image data into `image' */
break;
case PNG_COLOR_TYPE_RGB:
Trace((stderr, "GRR ReadPNG: PNG_COLOR_TYPE_RGB\n"));
if (info_ptr->bit_depth == 16) {
RWSetMsg("Stripping 48-bit RGB image to 24 bits");
fprintf(stderr,
"ReadPNG: stripping 48-bit RGB image to 24 bits\n");
fflush(stderr);
png_set_strip_16(png_ptr);
}
image = ImageNew(width, height);
break;
case PNG_COLOR_TYPE_GRAY: /* treat grayscale as special colormap */
Trace((stderr, "GRR ReadPNG: PNG_COLOR_TYPE_GRAY\n"));
bit_depth = info_ptr->bit_depth;
if (info_ptr->bit_depth == 16) {
RWSetMsg("Stripping 16-bit grayscale image to 8 bits");
fprintf(stderr,
"ReadPNG: stripping 16-bit grayscale image to 8 bits\n");
fflush(stderr);
png_set_strip_16(png_ptr);
bit_depth = 8;
}
image = ImageNewCmap(width, height, 1 << bit_depth);
switch (bit_depth) {
case 1:
image->isBW = TRUE;
ImageSetCmap(image, 0, 0, 0, 0);
ImageSetCmap(image, 1, 255, 255, 255);
break;
case 2:
image->isGrey = TRUE;
ImageSetCmap(image, 0, 0, 0, 0);
ImageSetCmap(image, 1, 85, 85, 85); /* 255/3 */
ImageSetCmap(image, 2, 170, 170, 170);
ImageSetCmap(image, 3, 255, 255, 255);
break;
case 4:
image->isGrey = TRUE;
for (i = 0; i < 16; ++i) {
level = i * 17; /* 255/15 */
ImageSetCmap(image, i, level, level, level);
}
break;
case 8:
image->isGrey = TRUE;
for (i = 0; i < 256; ++i)
ImageSetCmap(image, i, i, i, i);
break;
}
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
Trace((stderr, "GRR ReadPNG: PNG_COLOR_TYPE_RGB_ALPHA\n"));
if (info_ptr->bit_depth == 16) {
RWSetMsg("Stripping 64-bit RGBA image to 32 bits");
png_set_strip_16(png_ptr);
}
/* need to split alpha and RGB/gray the hard way, sigh */
hasAlpha = TRUE;
image = ImageNew(width, height);
ImageMakeMask(image); /* maskData is always 1 byte deep */
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
Trace((stderr, "GRR ReadPNG: PNG_COLOR_TYPE_GRAY_ALPHA\n"));
if (info_ptr->bit_depth == 16) {
RWSetMsg("Stripping 32-bit gray+alpha image to 16 bits");
png_set_strip_16(png_ptr);
}
hasAlpha = TRUE;
image = ImageNewGrey(width, height);
ImageMakeMask(image); /* maskData is always 1 byte deep */
break;
default:
fprintf(stderr, "ReadPNG: unknown image type (%d)\n",
info_ptr->color_type);
fflush(stderr);
RWSetMsg("Unknown PNG image type");
png_read_destroy(png_ptr, info_ptr, (png_infop)NULL);
free(png_ptr);
free(info_ptr);
fclose(fp);
return image; /* NULL */
}
if (info_ptr->bit_depth < 8)
png_set_packing(png_ptr);
if (info_ptr->interlace_type)
npasses = png_set_interlace_handling(png_ptr);
png_read_update_info(png_ptr, info_ptr);
if (hasAlpha) {
png_bytep *row_pointers, png_data;
if ((row_pointers = (png_bytep *)
malloc(height * sizeof(png_bytep))) == 0) {
RWSetMsg("Out of memory in ReadPNG()");
return NULL;
}
/* very inefficient (memory-wise) to allocate entire image again, but
* no easy way around it: libpng returns the image and alpha channel
* interspersed, and interlaced alpha images just make matters worse
*/
png_data = (png_bytep)malloc(height*info_ptr->rowbytes);
if (!png_data) {
RWSetMsg("Unable to allocate temporary storage for alpha image");
fprintf(stderr, "ReadPNG error: unable to malloc png_data\n");
fflush(stderr);
ImageDelete(image);
png_read_destroy(png_ptr, info_ptr, (png_infop)NULL);
free(png_ptr);
free(info_ptr);
fclose(fp);
return NULL;
}
/* only bit depths of 8 and 16 support alpha channels */
for (i = 0; i < height; ++i)
row_pointers[i] = (png_bytep)png_data + i*info_ptr->rowbytes;
png_read_image(png_ptr, row_pointers);
if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
png_bytep png=png_data, rgb=image->data, alpha=image->maskData;
for (i = 0; i < height*width; ++i) {
*rgb++ = *png++;
*rgb++ = *png++;
*rgb++ = *png++;
*alpha++ = *png++; /* GRR: invert? doesn't seem to be used */
}
} else { /* PNG_COLOR_TYPE_GRAY_ALPHA */
png_bytep png=png_data, gray=image->data, alpha=image->maskData;
for (i = 0; i < height*width; ++i) {
*gray++ = *png++;
*alpha++ = *png++; /* GRR: invert? */
}
}
free(png_data); /* whew */
} else { /* no alpha channel */
png_bytep *row_pointers;
if ((row_pointers = (png_bytep *)
malloc(height * sizeof(png_bytep))) == 0) {
RWSetMsg("Out of memory in ReadPNG()");
return NULL;
}
for (i = 0; i < height; ++i)
row_pointers[i] = (png_bytep)image->data + i*info_ptr->rowbytes;
png_read_image(png_ptr, row_pointers);
} /* end if (hasAlpha) */
/* GRR: ideally should read all other info (text chunks, etc.) and save
* whatever ones make sense for the possible output file...but we
* don't, both because we're too darned lazy to bother and because
* XPaint is too simple-minded to be able to use it
*/
png_read_end(png_ptr, info_ptr);
png_read_destroy(png_ptr, info_ptr, (png_infop)NULL);
free(png_ptr);
free(info_ptr);
fclose(fp);
return image;
} /* end function ReadPNG() */
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