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/*
Copyright (C) 2008 Fons Adriaensen <fons@kokkinizita.net>
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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <png.h>
#include <clxclient.h>
XImage *mkimage (const char *file, X_display *disp, XftColor *bgnd)
{
FILE *F;
png_byte hdr [8];
png_structp png_ptr;
png_infop png_info;
const unsigned char **data, *p;
int dx, dy, x, y, dp;
float vr, vg, vb, va, br, bg, bb;
unsigned long mr, mg, mb, pix;
XImage *image;
F = fopen (file, "r");
if (!F)
{
fprintf (stderr, "Can't open '%s'\n", file);
return 0;
}
fread (hdr, 1, 8, F);
if (png_sig_cmp (hdr, 0, 8))
{
fprintf (stderr, "'%s' is not a PNG file\n", file);
return 0;
}
fseek (F, 0, SEEK_SET);
png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING, 0, 0, 0);
if (! png_ptr)
{
fclose (F);
return 0;
}
png_info = png_create_info_struct (png_ptr);
if (! png_info)
{
png_destroy_read_struct (&png_ptr, 0, 0);
fclose (F);
return 0;
}
if (setjmp (png_jmpbuf (png_ptr)))
{
png_destroy_read_struct (&png_ptr, &png_info, 0);
fclose (F);
fprintf (stderr, "png:longjmp()\n");
return 0;
}
png_init_io (png_ptr, F);
png_read_png (png_ptr, png_info,
PNG_TRANSFORM_STRIP_16 | PNG_TRANSFORM_PACKING | PNG_TRANSFORM_EXPAND,
0);
dx = png_info->width;
dy = png_info->height;
dp = (png_info->color_type & PNG_COLOR_MASK_ALPHA) ? 4 : 3;
data = (const unsigned char **)(png_get_rows (png_ptr, png_info));
image = XCreateImage (disp->dpy (),
disp->dvi (),
DefaultDepth (disp->dpy (), disp->dsn ()),
ZPixmap, 0, 0, dx, dy, 32, 0);
image->data = new char [image->height * image->bytes_per_line];
mr = image->red_mask;
mg = image->green_mask;
mb = image->blue_mask;
vr = mr / 255.0f;
vg = mg / 255.0f;
vb = mb / 255.0f;
if (bgnd)
{
br = bgnd->color.red >> 8;
bg = bgnd->color.green >> 8;
bb = bgnd->color.blue >> 8;
}
else br = bg = bb = 0;
for (y = 0; y < dy; y++)
{
p = data [y];
for (x = 0; x < dx; x++)
{
va = (dp == 4) ? (p [3] / 255.0f) : 1;
pix = ((unsigned long)((p [0] * va + (1 - va) * br) * vr) & mr)
| ((unsigned long)((p [1] * va + (1 - va) * bg) * vg) & mg)
| ((unsigned long)((p [2] * va + (1 - va) * bb) * vb) & mb);
XPutPixel (image, x, y, pix);
p += dp;
}
}
png_destroy_read_struct (&png_ptr, &png_info, 0);
fclose (F);
return image;
}
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