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scottc
243
wrlib/png.c
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243
wrlib/png.c
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/* png.c - load PNG image from file
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*
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* Raster graphics library
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*
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* Copyright (c) 1997 Alfredo K. Kojima
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free
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* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <config.h>
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/* AIX requires this to be the first thing in the file. */
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#ifdef __GNUC__
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# define alloca __builtin_alloca
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#else
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# if HAVE_ALLOCA_H
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# include <alloca.h>
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# else
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# ifdef _AIX
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# pragma alloca
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# else
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# ifndef alloca /* predefined by HP cc +Olibcalls */
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char *alloca ();
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# endif
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# endif
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# endif
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#endif
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#ifdef USE_PNG
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <png.h>
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#if PNG_LIBPNG_VER < 96
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#error libpng_must_be_more_at_least_0_96
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#endif
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#include "wraster.h"
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RImage*
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RLoadPNG(RContext *context, char *file, int index)
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{
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char *tmp;
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RImage *image=NULL;
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FILE *f;
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png_structp png;
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png_infop pinfo, einfo;
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png_color_16p bkcolor;
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int alpha;
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int x, y, i;
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double gamma, sgamma;
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png_uint_32 width, height;
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int depth, junk, color_type;
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png_bytep *png_rows;
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unsigned char *r, *g, *b, *a;
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f = fopen(file, "r");
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if (!f) {
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sprintf(RErrorString, "could not open file \"%s\"", file);
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return NULL;
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}
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png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
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(png_error_ptr)NULL, (png_error_ptr)NULL);
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if (!png) {
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sprintf(RErrorString, "error loading PNG file \"%s\"", file);
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fclose(f);
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return NULL;
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}
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pinfo = png_create_info_struct(png);
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if (!pinfo) {
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sprintf(RErrorString, "error loading PNG file \"%s\"", file);
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fclose(f);
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png_destroy_read_struct(&png, NULL, NULL);
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return NULL;
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}
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einfo = png_create_info_struct(png);
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if (!einfo) {
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sprintf(RErrorString, "error loading PNG file \"%s\"", file);
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fclose(f);
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png_destroy_read_struct(&png, &pinfo, NULL);
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return NULL;
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}
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if (setjmp(png->jmpbuf)) {
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sprintf(RErrorString, "error loading PNG file \"%s\"", file);
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fclose(f);
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png_destroy_read_struct(&png, &pinfo, &einfo);
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if (image)
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RDestroyImage(image);
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return NULL;
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}
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png_init_io(png, f);
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png_read_info(png, pinfo);
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png_get_IHDR(png, pinfo, &width, &height, &depth, &color_type,
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&junk, &junk, &junk);
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/* check for an alpha channel */
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if (png_get_valid(png, pinfo, PNG_INFO_tRNS))
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alpha = True;
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else
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alpha = (color_type & PNG_COLOR_MASK_ALPHA);
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/* allocate RImage */
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image = RCreateImage(width, height, alpha);
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if (!image) {
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sprintf(RErrorString, "could not create RImage");
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fclose(f);
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png_destroy_read_struct(&png, &pinfo, &einfo);
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return NULL;
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}
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/* normalize to 8bpp with alpha channel */
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if (color_type == PNG_COLOR_TYPE_PALETTE && depth < 8)
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png_set_expand(png);
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if (color_type == PNG_COLOR_TYPE_GRAY && depth < 8)
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png_set_expand(png);
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if (png_get_valid(png, pinfo, PNG_INFO_tRNS))
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png_set_expand(png);
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if (depth == 16)
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png_set_strip_16(png);
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if (color_type == PNG_COLOR_TYPE_GRAY ||
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color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
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png_set_gray_to_rgb(png);
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/* set gamma correction */
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if ((context->attribs->flags & RC_GammaCorrection)
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&& context->depth != 8) {
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sgamma = (context->attribs->rgamma + context->attribs->ggamma +
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context->attribs->bgamma) / 3;
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} else if ((tmp = getenv("DISPLAY_GAMMA")) != NULL) {
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sgamma = atof(tmp);
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if (sgamma==0)
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sgamma = 1;
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} else {
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sgamma = 2.0;
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}
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if (png_get_gAMA(png, pinfo, &gamma))
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png_set_gamma(png, sgamma, gamma);
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else
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png_set_gamma(png, sgamma, 0.45);
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/* do the transforms */
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png_read_update_info(png, pinfo);
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/* set background color */
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if (png_get_bKGD(png, pinfo, &bkcolor)) {
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image->background.red = bkcolor->red >> 8;
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image->background.green = bkcolor->green >> 8;
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image->background.blue = bkcolor->blue >> 8;
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}
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png_rows = alloca(sizeof(char*)*height);
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if (!png_rows) {
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sprintf(RErrorString, "out of memory loading \"%s\"", file);
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fclose(f);
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RDestroyImage(image);
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png_destroy_read_struct(&png, &pinfo, &einfo);
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#ifdef C_ALLOCA
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alloca(0);
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#endif
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return NULL;
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}
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for (y=0; y<height; y++) {
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png_rows[y] = alloca(png_get_rowbytes(png, pinfo));
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if (!png_rows[y]) {
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sprintf(RErrorString, "out of memory loading \"%s\"", file);
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fclose(f);
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RDestroyImage(image);
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png_destroy_read_struct(&png, &pinfo, &einfo);
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#ifdef C_ALLOCA
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alloca(0);
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#endif
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return NULL;
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}
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}
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/* read data */
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png_read_image(png, png_rows);
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png_read_end(png, einfo);
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png_destroy_read_struct(&png, &pinfo, &einfo);
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fclose(f);
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r = image->data[0];
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g = image->data[1];
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b = image->data[2];
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a = image->data[3];
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/* convert to RImage */
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if (alpha) {
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for (y=0; y<height; y++) {
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for (x=0, i=0; x<width; x++) {
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*(r++) = *(png_rows[y]+i++);
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*(g++) = *(png_rows[y]+i++);
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*(b++) = *(png_rows[y]+i++);
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*(a++) = *(png_rows[y]+i++);
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}
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}
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} else {
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for (y=0; y<height; y++) {
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for (x=0, i=0; x<width; x++) {
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*(r++) = *(png_rows[y]+i++);
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*(g++) = *(png_rows[y]+i++);
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*(b++) = *(png_rows[y]+i++);
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}
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}
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}
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#ifdef C_ALLOCA
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alloca(0);
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#endif
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return image;
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}
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#endif /* USE_PNG */
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