sdl_zoom_template.h

   1 /*
   2  * SDL_zoom_template - surface scaling
   3  *
   4  * Copyright (c) 2009 Citrix Systems, Inc.
   5  *
   6  * Derived from: SDL_rotozoom,  LGPL (c) A. Schiffler from the SDL_gfx library.
   7  * Modifications by Stefano Stabellini.
   8  *
   9  * This work is licensed under the terms of the GNU GPL version 2.
  10  * See the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #if BPP == 16
  15 #define SDL_TYPE Uint16
  16 #elif BPP == 32
  17 #define SDL_TYPE Uint32
  18 #else
  19 #error unsupport depth
  20 #endif
  21
  22 /*
  23  *  Simple helper functions to make the code looks nicer
  24  *
  25  *  Assume spf = source SDL_PixelFormat
  26  *         dpf = dest SDL_PixelFormat
  27  *
  28  */
  29 #define getRed(color)   (((color) & spf->Rmask) >> spf->Rshift)
  30 #define getGreen(color) (((color) & spf->Gmask) >> spf->Gshift)
  31 #define getBlue(color)  (((color) & spf->Bmask) >> spf->Bshift)
  32 #define getAlpha(color) (((color) & spf->Amask) >> spf->Ashift)
  33
  34 #define setRed(r, pcolor) do { \
  35     *pcolor = ((*pcolor) & (~(dpf->Rmask))) + \
  36               (((r) & (dpf->Rmask >> dpf->Rshift)) << dpf->Rshift); \
  37 } while (0);
  38
  39 #define setGreen(g, pcolor) do { \
  40     *pcolor = ((*pcolor) & (~(dpf->Gmask))) + \
  41               (((g) & (dpf->Gmask >> dpf->Gshift)) << dpf->Gshift); \
  42 } while (0);
  43
  44 #define setBlue(b, pcolor) do { \
  45     *pcolor = ((*pcolor) & (~(dpf->Bmask))) + \
  46               (((b) & (dpf->Bmask >> dpf->Bshift)) << dpf->Bshift); \
  47 } while (0);
  48
  49 #define setAlpha(a, pcolor) do { \
  50     *pcolor = ((*pcolor) & (~(dpf->Amask))) + \
  51               (((a) & (dpf->Amask >> dpf->Ashift)) << dpf->Ashift); \
  52 } while (0);
  53
  54 static int glue(sdl_zoom_rgb, BPP)(SDL_Surface *src, SDL_Surface *dst, int smooth,
  55                                    SDL_Rect *dst_rect)
  56 {
  57     int x, y, sx, sy, *sax, *say, *csax, *csay, csx, csy, ex, ey, t1, t2, sstep, sstep_jump;
  58     SDL_TYPE *c00, *c01, *c10, *c11, *sp, *csp, *dp;
  59     int d_gap;
  60     SDL_PixelFormat *spf = src->format;
  61     SDL_PixelFormat *dpf = dst->format;
  62
  63     if (smooth) {
  64         /* For interpolation: assume source dimension is one pixel.
  65          * Smaller here to avoid overflow on right and bottom edge.
  66          */
  67         sx = (int) (65536.0 * (float) (src->w - 1) / (float) dst->w);
  68         sy = (int) (65536.0 * (float) (src->h - 1) / (float) dst->h);
  69     } else {
  70         sx = (int) (65536.0 * (float) src->w / (float) dst->w);
  71         sy = (int) (65536.0 * (float) src->h / (float) dst->h);
  72     }
  73
  74     if ((sax = (int *) malloc((dst->w + 1) * sizeof(Uint32))) == NULL) {
  75         return (-1);
  76     }
  77     if ((say = (int *) malloc((dst->h + 1) * sizeof(Uint32))) == NULL) {
  78         free(sax);
  79         return (-1);
  80     }
  81
  82     sp = csp = (SDL_TYPE *) src->pixels;
  83     dp = (SDL_TYPE *) (dst->pixels + dst_rect->y * dst->pitch +
  84                        dst_rect->x * dst->format->BytesPerPixel);
  85
  86     csx = 0;
  87     csax = sax;
  88     for (x = 0; x <= dst->w; x++) {
  89         *csax = csx;
  90         csax++;
  91         csx &= 0xffff;
  92         csx += sx;
  93     }
  94     csy = 0;
  95     csay = say;
  96     for (y = 0; y <= dst->h; y++) {
  97         *csay = csy;
  98         csay++;
  99         csy &= 0xffff;
 100         csy += sy;
 101     }
 102
 103     d_gap = dst->pitch - dst_rect->w * dst->format->BytesPerPixel;
 104
 105     if (smooth) {
 106         csay = say;
 107         for (y = 0; y < dst_rect->y; y++) {
 108             csay++;
 109             sstep = (*csay >> 16) * src->pitch;
 110             csp = (SDL_TYPE *) ((Uint8 *) csp + sstep);
 111         }
 112
 113         /* Calculate sstep_jump */
 114         csax = sax;
 115         sstep_jump = 0;
 116         for (x = 0; x < dst_rect->x; x++) {
 117             csax++;
 118             sstep = (*csax >> 16);
 119             sstep_jump += sstep;
 120         }
 121
 122         for (y = 0; y < dst_rect->h ; y++) {
 123             /* Setup colour source pointers */
 124             c00 = csp + sstep_jump;
 125             c01 = c00 + 1;
 126             c10 = (SDL_TYPE *) ((Uint8 *) csp + src->pitch) + sstep_jump;
 127             c11 = c10 + 1;
 128             csax = sax + dst_rect->x;
 129
 130             for (x = 0; x < dst_rect->w; x++) {
 131
 132                 /* Interpolate colours */
 133                 ex = (*csax & 0xffff);
 134                 ey = (*csay & 0xffff);
 135                 t1 = ((((getRed(*c01) - getRed(*c00)) * ex) >> 16) +
 136                      getRed(*c00)) & (dpf->Rmask >> dpf->Rshift);
 137                 t2 = ((((getRed(*c11) - getRed(*c10)) * ex) >> 16) +
 138                      getRed(*c10)) & (dpf->Rmask >> dpf->Rshift);
 139                 setRed((((t2 - t1) * ey) >> 16) + t1, dp);
 140                 t1 = ((((getGreen(*c01) - getGreen(*c00)) * ex) >> 16) +
 141                      getGreen(*c00)) & (dpf->Gmask >> dpf->Gshift);
 142                 t2 = ((((getGreen(*c11) - getGreen(*c10)) * ex) >> 16) +
 143                      getGreen(*c10)) & (dpf->Gmask >> dpf->Gshift);
 144                 setGreen((((t2 - t1) * ey) >> 16) + t1, dp);
 145                 t1 = ((((getBlue(*c01) - getBlue(*c00)) * ex) >> 16) +
 146                      getBlue(*c00)) & (dpf->Bmask >> dpf->Bshift);
 147                 t2 = ((((getBlue(*c11) - getBlue(*c10)) * ex) >> 16) +
 148                      getBlue(*c10)) & (dpf->Bmask >> dpf->Bshift);
 149                 setBlue((((t2 - t1) * ey) >> 16) + t1, dp);
 150                 t1 = ((((getAlpha(*c01) - getAlpha(*c00)) * ex) >> 16) +
 151                      getAlpha(*c00)) & (dpf->Amask >> dpf->Ashift);
 152                 t2 = ((((getAlpha(*c11) - getAlpha(*c10)) * ex) >> 16) +
 153                      getAlpha(*c10)) & (dpf->Amask >> dpf->Ashift);
 154                 setAlpha((((t2 - t1) * ey) >> 16) + t1, dp);
 155
 156                 /* Advance source pointers */
 157                 csax++;
 158                 sstep = (*csax >> 16);
 159                 c00 += sstep;
 160                 c01 += sstep;
 161                 c10 += sstep;
 162                 c11 += sstep;
 163                 /* Advance destination pointer */
 164                 dp++;
 165             }
 166             /* Advance source pointer */
 167             csay++;
 168             csp = (SDL_TYPE *) ((Uint8 *) csp + (*csay >> 16) * src->pitch);
 169             /* Advance destination pointers */
 170             dp = (SDL_TYPE *) ((Uint8 *) dp + d_gap);
 171         }
 172
 173
 174     } else {
 175         csay = say;
 176
 177         for (y = 0; y < dst_rect->y; y++) {
 178             csay++;
 179             sstep = (*csay >> 16) * src->pitch;
 180             csp = (SDL_TYPE *) ((Uint8 *) csp + sstep);
 181         }
 182
 183         /* Calculate sstep_jump */
 184         csax = sax;
 185         sstep_jump = 0;
 186         for (x = 0; x < dst_rect->x; x++) {
 187             csax++;
 188             sstep = (*csax >> 16);
 189             sstep_jump += sstep;
 190         }
 191
 192         for (y = 0 ; y < dst_rect->h ; y++) {
 193             sp = csp + sstep_jump;
 194             csax = sax + dst_rect->x;
 195
 196             for (x = 0; x < dst_rect->w; x++) {
 197
 198                 /* Draw */
 199                 *dp = *sp;
 200
 201                 /* Advance source pointers */
 202                 csax++;
 203                 sstep = (*csax >> 16);
 204                 sp += sstep;
 205
 206                 /* Advance destination pointer */
 207                 dp++;
 208             }
 209             /* Advance source pointers */
 210             csay++;
 211             sstep = (*csay >> 16) * src->pitch;
 212             csp = (SDL_TYPE *) ((Uint8 *) csp + sstep);
 213
 214             /* Advance destination pointer */
 215             dp = (SDL_TYPE *) ((Uint8 *) dp + d_gap);
 216         }
 217     }
 218
 219     free(sax);
 220     free(say);
 221     return (0);
 222 }
 223
 224 #undef SDL_TYPE
 225