Dogcows Code - chaz/openbox/blob - render/image.c

   1 /* -*- indent-tabs-mode: nil; tab-width: 4; c-basic-offset: 4; -*-
   2
   3    image.c for the Openbox window manager
   4    Copyright (c) 2003        Ben Jansens
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    See the COPYING file for a copy of the GNU General Public License.
  17 */
  18
  19 #include "geom.h"
  20 #include "image.h"
  21 #include "color.h"
  22
  23 #include <glib.h>
  24
  25 #define AVERAGE(a, b)   ( ((((a) ^ (b)) & 0xfefefefeL) >> 1) + ((a) & (b)) )
  26
  27 static void scale_line(RrPixel32 *dest, RrPixel32 *source, gint w, gint dw)
  28 {
  29     gint num_pixels = dw;
  30     gint int_part = w / dw;
  31     gint fract_part = w % dw;
  32     gint err = 0;
  33
  34     while (num_pixels-- > 0) {
  35         *dest++ = *source;
  36         source += int_part;
  37         err += fract_part;
  38         if (err >= dw) {
  39             err -= dw;
  40             source++;
  41         }
  42     }
  43 }
  44
  45 static RrPixel32* scale_half(RrPixel32 *source, gint w, gint h)
  46 {
  47     RrPixel32 *out, *dest, *sourceline, *sourceline2;
  48     gint dw, dh, x, y;
  49
  50     sourceline = source;
  51     sourceline2 = source + w;
  52
  53     dw = w >> 1;
  54     dh = h >> 1;
  55
  56     out = dest = g_new(RrPixel32, dw * dh);
  57
  58     for (y = 0; y < dh; ++y) {
  59         RrPixel32 *s, *s2;
  60
  61         s = sourceline;
  62         s2 = sourceline2;
  63
  64         for (x = 0; x < dw; ++x) {
  65             *dest++ = AVERAGE(AVERAGE(*s, *(s+1)),
  66                               AVERAGE(*s2, *(s2+1)));
  67             s += 2;
  68             s2 += 2;
  69         }
  70         sourceline += w << 1;
  71         sourceline2 += w << 1;
  72     }
  73     return out;
  74 }
  75
  76 static RrPixel32* scale_rect(RrPixel32 *fullsource,
  77                              gint w, gint h, gint dw, gint dh)
  78 {
  79     RrPixel32 *out, *dest;
  80     RrPixel32 *source = fullsource;
  81     RrPixel32 *oldsource = NULL;
  82     RrPixel32 *prev_source = NULL;
  83     gint num_pixels;
  84     gint int_part;
  85     gint fract_part;
  86     gint err = 0;
  87
  88     while (dw <= (w >> 1) && dh <= (h >> 1)) {
  89         source = scale_half(source, w, h);
  90         w >>= 1; h >>= 1;
  91         g_free(oldsource);
  92         oldsource = source;
  93     }
  94
  95     num_pixels = dh;
  96     int_part = (h / dh) * w;
  97     fract_part = h % dh;
  98
  99     out = dest = g_new(RrPixel32, dw * dh);
 100
 101     while (num_pixels-- > 0) {
 102         if (source == prev_source) {
 103             memcpy(dest, dest - dw, dw * sizeof(RrPixel32));
 104         } else {
 105             scale_line(dest, source, w, dw);
 106             prev_source = source;
 107         }
 108         dest += dw;
 109         source += int_part;
 110         err += fract_part;
 111         if (err >= dh) {
 112             err -= dh;
 113             source += w;
 114         }
 115     }
 116
 117     g_free(oldsource);
 118
 119     return out;
 120 }
 121
 122 void RrImageDraw(RrPixel32 *target, RrTextureRGBA *rgba,
 123                  gint target_w, gint target_h,
 124                  RrRect *area)
 125 {
 126     RrPixel32 *dest;
 127     RrPixel32 *source;
 128     gint sw, sh, dw, dh;
 129     gint col, num_pixels;
 130
 131     sw = rgba->width;
 132     sh = rgba->height;
 133
 134     /* keep the ratio */
 135     dw = area->width;
 136     dh = (gint)(dw * ((gdouble)sh / sw));
 137     if (dh > area->height) {
 138         dh = area->height;
 139         dw = (gint)(dh * ((gdouble)sw / sh));
 140     }
 141
 142     if (!(dw && dh))
 143         return; /* XXX sanity check */
 144
 145     if (sw != dw || sh != dh) {
 146         /*if (!(rgba->cache && dw == rgba->cwidth && dh == rgba->cheight))*/ {
 147             g_free(rgba->cache);
 148             rgba->cache = scale_rect(rgba->data, sw, sh, dw, dh);
 149             rgba->cwidth = dw;
 150             rgba->cheight = dh;
 151         }
 152         source = rgba->cache;
 153     } else {
 154         source = rgba->data;
 155     }
 156
 157     /* copy source -> dest, and apply the alpha channel */
 158     col = 0;
 159     num_pixels = dw * dh;
 160     dest = target + area->x + target_w * area->y;
 161     while (num_pixels-- > 0) {
 162         guchar alpha, r, g, b, bgr, bgg, bgb;
 163
 164         alpha = *source >> RrDefaultAlphaOffset;
 165         r = *source >> RrDefaultRedOffset;
 166         g = *source >> RrDefaultGreenOffset;
 167         b = *source >> RrDefaultBlueOffset;
 168
 169         /* background color */
 170         bgr = *dest >> RrDefaultRedOffset;
 171         bgg = *dest >> RrDefaultGreenOffset;
 172         bgb = *dest >> RrDefaultBlueOffset;
 173
 174         r = bgr + (((r - bgr) * alpha) >> 8);
 175         g = bgg + (((g - bgg) * alpha) >> 8);
 176         b = bgb + (((b - bgb) * alpha) >> 8);
 177
 178         *dest = ((r << RrDefaultRedOffset) |
 179                  (g << RrDefaultGreenOffset) |
 180                  (b << RrDefaultBlueOffset));
 181
 182         dest++;
 183         source++;
 184
 185         if (++col >= dw) {
 186             col = 0;
 187             dest += target_w - dw;
 188         }
 189     }
 190 }