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Annotation of qemu/ui/sdl_zoom.c, revision 1.1

1.1     ! root        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: 
        !            19: static int sdl_zoom_rgb16(SDL_Surface *src, SDL_Surface *dst, int smooth,
        !            20:                           SDL_Rect *dst_rect);
        !            21: static 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: 
        !            31: int 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: 

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