text: /*
      SDL - Simple DirectMedia Layer
      Copyright (C) 1997-2009 Sam Lantinga
  
      This library is free software; you can redistribute it and/or
      modify it under the terms of the GNU Lesser General Public
      License as published by the Free Software Foundation; either
      version 2.1 of the License, or (at your option) any later version.
  
      This library is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      Lesser General Public License for more details.
  
      You should have received a copy of the GNU Lesser General Public
      License along with this library; if not, write to the Free Software
      Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  
      Sam Lantinga
      slouken@libsdl.org
  */
  #include "SDL_config.h"
  
  /* This is the implementation of the YUV video surface support */
  
  #include "SDL_video.h"
  #include "SDL_sysvideo.h"
  #include "SDL_yuvfuncs.h"
  #include "SDL_yuv_sw_c.h"
  
  
  SDL_Overlay *SDL_CreateYUVOverlay(int w, int h, Uint32 format,
                                    SDL_Surface *display)
  {
  	SDL_VideoDevice *video = current_video;
  	SDL_VideoDevice *this  = current_video;
  	const char *yuv_hwaccel;
  	SDL_Overlay *overlay;
  
  	if ( (display->flags & SDL_OPENGL) == SDL_OPENGL ) {
  		SDL_SetError("YUV overlays are not supported in OpenGL mode");
  		return NULL;
  	}
  
  	/* Display directly on video surface, if possible */
  	if ( SDL_getenv("SDL_VIDEO_YUV_DIRECT") ) {
  		if ( (display == SDL_PublicSurface) &&
  		     ((SDL_VideoSurface->format->BytesPerPixel == 2) ||
  		      (SDL_VideoSurface->format->BytesPerPixel == 4)) ) {
  			display = SDL_VideoSurface;
  		}
  	}
  	overlay = NULL;
          yuv_hwaccel = SDL_getenv("SDL_VIDEO_YUV_HWACCEL");
  	if ( ((display == SDL_VideoSurface) && video->CreateYUVOverlay) &&
  	     (!yuv_hwaccel || (SDL_atoi(yuv_hwaccel) > 0)) ) {
  		overlay = video->CreateYUVOverlay(this, w, h, format, display);
  	}
  	/* If hardware YUV overlay failed ... */
  	if ( overlay == NULL ) {
  		overlay = SDL_CreateYUV_SW(this, w, h, format, display);
  	}
  	return overlay;
  }
  
  int SDL_LockYUVOverlay(SDL_Overlay *overlay)
  {
  	if ( overlay == NULL ) {
  		SDL_SetError("Passed NULL overlay");
  		return -1;
  	}
  	return overlay->hwfuncs->Lock(current_video, overlay);
  }
  
  void SDL_UnlockYUVOverlay(SDL_Overlay *overlay)
  {
  	if ( overlay == NULL ) {
  		return;
  	}
  	overlay->hwfuncs->Unlock(current_video, overlay);
  }
  
  int SDL_DisplayYUVOverlay(SDL_Overlay *overlay, SDL_Rect *dstrect)
  {
  	SDL_Rect src, dst;
  	int srcx, srcy, srcw, srch;
  	int dstx, dsty, dstw, dsth;
  
  	if ( overlay == NULL || dstrect == NULL ) {
  		SDL_SetError("Passed NULL overlay or dstrect");
  		return -1;
  	}
  
  	/* Clip the rectangle to the screen area */
  	srcx = 0;
  	srcy = 0;
  	srcw = overlay->w;
  	srch = overlay->h;
  	dstx = dstrect->x;
  	dsty = dstrect->y;
  	dstw = dstrect->w;
  	dsth = dstrect->h;
  	if ( dstx < 0 ) {
  		srcw += (dstx * overlay->w) / dstrect->w;
  		dstw += dstx;
  		srcx -= (dstx * overlay->w) / dstrect->w;
  		dstx = 0;
  	}
  	if ( (dstx+dstw) > current_video->screen->w ) {
  		int extra = (dstx+dstw - current_video->screen->w);
  		srcw -= (extra * overlay->w) / dstrect->w;
  		dstw -= extra;
  	}
  	if ( dsty < 0 ) {
  		srch += (dsty * overlay->h) / dstrect->h;
  		dsth += dsty;
  		srcy -= (dsty * overlay->h) / dstrect->h;
  		dsty = 0;
  	}
  	if ( (dsty+dsth) > current_video->screen->h ) {
  		int extra = (dsty+dsth - current_video->screen->h);
  		srch -= (extra * overlay->h) / dstrect->h;
  		dsth -= extra;
  	}
  	if ( srcw <= 0 || srch <= 0 ||
  	     srch <= 0 || dsth <= 0 ) {
  		return 0;
  	}
  	/* Ugh, I can't wait for SDL_Rect to be int values */
  	src.x = srcx;
  	src.y = srcy;
  	src.w = srcw;
  	src.h = srch;
  	dst.x = dstx;
  	dst.y = dsty;
  	dst.w = dstw;
  	dst.h = dsth;
  	return overlay->hwfuncs->Display(current_video, overlay, &src, &dst);
  }
  
  void SDL_FreeYUVOverlay(SDL_Overlay *overlay)
  {
  	if ( overlay == NULL ) {
  		return;
  	}
  	if ( overlay->hwfuncs ) {
  		overlay->hwfuncs->FreeHW(current_video, overlay);
  	}
  	SDL_free(overlay);
  }
  