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95 lines
2.8 KiB
C
95 lines
2.8 KiB
C
/*
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* SDL_zoom - surface scaling
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*
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* Copyright (c) 2009 Citrix Systems, Inc.
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*
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* Derived from: SDL_rotozoom, LGPL (c) A. Schiffler from the SDL_gfx library.
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* Modifications by Stefano Stabellini.
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*
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* This work is licensed under the terms of the GNU GPL version 2.
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* See the COPYING file in the top-level directory.
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*
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*/
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#include "sdl_zoom.h"
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#include "osdep.h"
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#include <stdint.h>
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#include <stdio.h>
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static int sdl_zoom_rgb16(SDL_Surface *src, SDL_Surface *dst, int smooth,
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SDL_Rect *dst_rect);
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static int sdl_zoom_rgb32(SDL_Surface *src, SDL_Surface *dst, int smooth,
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SDL_Rect *dst_rect);
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#define BPP 32
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#include "sdl_zoom_template.h"
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#undef BPP
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#define BPP 16
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#include "sdl_zoom_template.h"
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#undef BPP
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int sdl_zoom_blit(SDL_Surface *src_sfc, SDL_Surface *dst_sfc, int smooth,
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SDL_Rect *in_rect)
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{
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SDL_Rect zoom, src_rect;
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int extra;
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/* Grow the size of the modified rectangle to avoid edge artefacts */
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src_rect.x = (in_rect->x > 0) ? (in_rect->x - 1) : 0;
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src_rect.y = (in_rect->y > 0) ? (in_rect->y - 1) : 0;
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src_rect.w = in_rect->w + 1;
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if (src_rect.x + src_rect.w > src_sfc->w)
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src_rect.w = src_sfc->w - src_rect.x;
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src_rect.h = in_rect->h + 1;
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if (src_rect.y + src_rect.h > src_sfc->h)
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src_rect.h = src_sfc->h - src_rect.y;
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/* (x,y) : round down */
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zoom.x = (int)(((float)(src_rect.x * dst_sfc->w)) / (float)(src_sfc->w));
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zoom.y = (int)(((float)(src_rect.y * dst_sfc->h)) / (float)(src_sfc->h));
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/* (w,h) : round up */
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zoom.w = (int)( ((double)((src_rect.w * dst_sfc->w) + (src_sfc->w - 1))) /
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(double)(src_sfc->w));
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zoom.h = (int)( ((double)((src_rect.h * dst_sfc->h) + (src_sfc->h - 1))) /
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(double)(src_sfc->h));
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/* Account for any (x,y) rounding by adding one-source-pixel's worth
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* of destination pixels and then edge checking.
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*/
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extra = ((dst_sfc->w-1) / src_sfc->w) + 1;
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if ((zoom.x + zoom.w) < (dst_sfc->w - extra))
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zoom.w += extra;
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else
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zoom.w = dst_sfc->w - zoom.x;
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extra = ((dst_sfc->h-1) / src_sfc->h) + 1;
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if ((zoom.y + zoom.h) < (dst_sfc->h - extra))
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zoom.h += extra;
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else
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zoom.h = dst_sfc->h - zoom.y;
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/* The rectangle (zoom.x, zoom.y, zoom.w, zoom.h) is the area on the
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* destination surface that needs to be updated.
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*/
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if (src_sfc->format->BitsPerPixel == 32)
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sdl_zoom_rgb32(src_sfc, dst_sfc, smooth, &zoom);
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else if (src_sfc->format->BitsPerPixel == 16)
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sdl_zoom_rgb16(src_sfc, dst_sfc, smooth, &zoom);
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else {
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fprintf(stderr, "pixel format not supported\n");
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return -1;
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}
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/* Return the rectangle of the update to the caller */
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*in_rect = zoom;
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return 0;
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}
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