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