LXR qemu/sdl

   1/*
   2 * SDL_zoom - 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#include "sdl_zoom.h"
  15#include "osdep.h"
  16#include <stdint.h>
  17#include <stdio.h>
  18
  19static int sdl_zoom_rgb16(SDL_Surface *src, SDL_Surface *dst, int smooth,
  20                          SDL_Rect *dst_rect);
  21static int sdl_zoom_rgb32(SDL_Surface *src, SDL_Surface *dst, int smooth,
  22                          SDL_Rect *dst_rect);
  23
  24#define BPP 32
  25#include  "sdl_zoom_template.h"
  26#undef BPP
  27#define BPP 16
  28#include  "sdl_zoom_template.h"
  29#undef BPP
  30
  31int sdl_zoom_blit(SDL_Surface *src_sfc, SDL_Surface *dst_sfc, int smooth,
  32                  SDL_Rect *in_rect)
  33{
  34    SDL_Rect zoom, src_rect;
  35    int extra;
  36
  37    /* Grow the size of the modified rectangle to avoid edge artefacts */
  38    src_rect.x = (in_rect->x > 0) ? (in_rect->x - 1) : 0;
  39    src_rect.y = (in_rect->y > 0) ? (in_rect->y - 1) : 0;
  40
  41    src_rect.w = in_rect->w + 1;
  42    if (src_rect.x + src_rect.w > src_sfc->w)
  43        src_rect.w = src_sfc->w - src_rect.x;
  44
  45    src_rect.h = in_rect->h + 1;
  46    if (src_rect.y + src_rect.h > src_sfc->h)
  47        src_rect.h = src_sfc->h - src_rect.y;
  48
  49    /* (x,y) : round down */
  50    zoom.x = (int)(((float)(src_rect.x * dst_sfc->w)) / (float)(src_sfc->w));
  51    zoom.y = (int)(((float)(src_rect.y * dst_sfc->h)) / (float)(src_sfc->h));
  52
  53    /* (w,h) : round up */
  54    zoom.w = (int)( ((double)((src_rect.w * dst_sfc->w) + (src_sfc->w - 1))) /
  55                     (double)(src_sfc->w));
  56
  57    zoom.h = (int)( ((double)((src_rect.h * dst_sfc->h) + (src_sfc->h - 1))) /
  58                     (double)(src_sfc->h));
  59
  60    /* Account for any (x,y) rounding by adding one-source-pixel's worth
  61     * of destination pixels and then edge checking.
  62     */
  63
  64    extra = ((dst_sfc->w-1) / src_sfc->w) + 1;
  65
  66    if ((zoom.x + zoom.w) < (dst_sfc->w - extra))
  67        zoom.w += extra;
  68    else
  69        zoom.w = dst_sfc->w - zoom.x;
  70
  71    extra = ((dst_sfc->h-1) / src_sfc->h) + 1;
  72
  73    if ((zoom.y + zoom.h) < (dst_sfc->h - extra))
  74        zoom.h += extra;
  75    else
  76        zoom.h = dst_sfc->h - zoom.y;
  77
  78    /* The rectangle (zoom.x, zoom.y, zoom.w, zoom.h) is the area on the
  79     * destination surface that needs to be updated.
  80     */
  81    if (src_sfc->format->BitsPerPixel == 32)
  82        sdl_zoom_rgb32(src_sfc, dst_sfc, smooth, &zoom);
  83    else if (src_sfc->format->BitsPerPixel == 16)
  84        sdl_zoom_rgb16(src_sfc, dst_sfc, smooth, &zoom);
  85    else {
  86        fprintf(stderr, "pixel format not supported\n");
  87        return -1;
  88    }
  89
  90    /* Return the rectangle of the update to the caller */
  91    *in_rect = zoom;
  92
  93    return 0;
  94}
  95
  96