sdl_surface.c

Simple DirectMedia Layer - Simple DirectMedia Layer 是一个跨平台的多媒体库设计用来提供快速图形framebuffer和音频驱动。应用MPEG为软件

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    [e-mail]
*/

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id: SDL_surface.c,v 1.12 2002/08/20 16:58:49 slouken Exp $";
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "SDL_error.h"
#include "SDL_video.h"
#include "SDL_sysvideo.h"
#include "SDL_cursor_c.h"
#include "SDL_blit.h"
#include "SDL_RLEaccel_c.h"
#include "SDL_pixels_c.h"
#include "SDL_memops.h"
#include "SDL_leaks.h"

/* Public routines */
/*
 * Create an empty RGB surface of the appropriate depth
 */
SDL_Surface * SDL_CreateRGBSurface (Uint32 flags,
			int width, int height, int depth,
			Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
{
	SDL_VideoDevice *video = current_video;
	SDL_VideoDevice *this  = current_video;
	SDL_Surface *screen;
	SDL_Surface *surface;

	/* Check to see if we desire the surface in video memory */
	if ( video ) {
		screen = SDL_PublicSurface;
	} else {
		screen = NULL;
	}
	if ( screen && ((screen->flags&SDL_HWSURFACE) == SDL_HWSURFACE) ) {
		if ( (flags&(SDL_SRCCOLORKEY|SDL_SRCALPHA)) != 0 ) {
			flags |= SDL_HWSURFACE;
		}
		if ( (flags & SDL_SRCCOLORKEY) == SDL_SRCCOLORKEY ) {
			if ( ! current_video->info.blit_hw_CC ) {
				flags &= ~SDL_HWSURFACE;
			}
		}
		if ( (flags & SDL_SRCALPHA) == SDL_SRCALPHA ) {
			if ( ! current_video->info.blit_hw_A ) {
				flags &= ~SDL_HWSURFACE;
			}
		}
	} else {
		flags &= ~SDL_HWSURFACE;
	}

	/* Allocate the surface */
	surface = (SDL_Surface *)malloc(sizeof(*surface));
	if ( surface == NULL ) {
		SDL_OutOfMemory();
		return(NULL);
	}
	surface->flags = SDL_SWSURFACE;
	if ( (flags & SDL_HWSURFACE) == SDL_HWSURFACE ) {
		depth = screen->format->BitsPerPixel;
		Rmask = screen->format->Rmask;
		Gmask = screen->format->Gmask;
		Bmask = screen->format->Bmask;
		Amask = screen->format->Amask;
	}
	surface->format = SDL_AllocFormat(depth, Rmask, Gmask, Bmask, Amask);
	if ( surface->format == NULL ) {
		free(surface);
		return(NULL);
	}
	if ( Amask ) {
		surface->flags |= SDL_SRCALPHA;
	}
	surface->w = width;
	surface->h = height;
	surface->pitch = SDL_CalculatePitch(surface);
	surface->pixels = NULL;
	surface->offset = 0;
	surface->hwdata = NULL;
	surface->locked = 0;
	surface->map = NULL;
	surface->format_version = 0;
	surface->unused1 = 0;
	SDL_SetClipRect(surface, NULL);

	/* Get the pixels */
	if ( ((flags&SDL_HWSURFACE) == SDL_SWSURFACE) || 
				(video->AllocHWSurface(this, surface) < 0) ) {
		if ( surface->w && surface->h ) {
			surface->pixels = malloc(surface->h*surface->pitch);
			if ( surface->pixels == NULL ) {
				SDL_FreeSurface(surface);
				SDL_OutOfMemory();
				return(NULL);
			}
			/* This is important for bitmaps */
			memset(surface->pixels, 0, surface->h*surface->pitch);
		}
	}

	/* Allocate an empty mapping */
	surface->map = SDL_AllocBlitMap();
	if ( surface->map == NULL ) {
		SDL_FreeSurface(surface);
		return(NULL);
	}

	/* The surface is ready to go */
	surface->refcount = 1;
#ifdef CHECK_LEAKS
	++surfaces_allocated;
#endif
	return(surface);
}
/*
 * Create an RGB surface from an existing memory buffer
 */
SDL_Surface * SDL_CreateRGBSurfaceFrom (void *pixels,
			int width, int height, int depth, int pitch,
			Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
{
	SDL_Surface *surface;

	surface = SDL_CreateRGBSurface(SDL_SWSURFACE, 0, 0, depth,
	                               Rmask, Gmask, Bmask, Amask);
	if ( surface != NULL ) {
		surface->flags |= SDL_PREALLOC;
		surface->pixels = pixels;
		surface->w = width;
		surface->h = height;
		surface->pitch = pitch;
		SDL_SetClipRect(surface, NULL);
	}
	return(surface);
}
/*
 * Set the color key in a blittable surface
 */
int SDL_SetColorKey (SDL_Surface *surface, Uint32 flag, Uint32 key)
{
	/* Sanity check the flag as it gets passed in */
	if ( flag & SDL_SRCCOLORKEY ) {
		if ( flag & (SDL_RLEACCEL|SDL_RLEACCELOK) ) {
			flag = (SDL_SRCCOLORKEY | SDL_RLEACCELOK);
		} else {
			flag = SDL_SRCCOLORKEY;
		}
	} else {
		flag = 0;
	}

	/* Optimize away operations that don't change anything */
	if ( (flag == (surface->flags & (SDL_SRCCOLORKEY|SDL_RLEACCELOK))) &&
	     (key == surface->format->colorkey) ) {
		return(0);
	}

	/* UnRLE surfaces before we change the colorkey */
	if ( surface->flags & SDL_RLEACCEL ) {
	        SDL_UnRLESurface(surface, 1);
	}

	if ( flag ) {
		SDL_VideoDevice *video = current_video;
		SDL_VideoDevice *this  = current_video;


		surface->flags |= SDL_SRCCOLORKEY;
		surface->format->colorkey = key;
		if ( (surface->flags & SDL_HWACCEL) == SDL_HWACCEL ) {
			if ( (video->SetHWColorKey == NULL) ||
			     (video->SetHWColorKey(this, surface, key) < 0) ) {
				surface->flags &= ~SDL_HWACCEL;
			}
		}
		if ( flag & SDL_RLEACCELOK ) {
			surface->flags |= SDL_RLEACCELOK;
		} else {
			surface->flags &= ~SDL_RLEACCELOK;
		}
	} else {
		surface->flags &= ~(SDL_SRCCOLORKEY|SDL_RLEACCELOK);
		surface->format->colorkey = 0;
	}
	SDL_InvalidateMap(surface->map);
	return(0);
}
/* This function sets the alpha channel of a surface */
int SDL_SetAlpha (SDL_Surface *surface, Uint32 flag, Uint8 value)
{
	Uint32 oldflags = surface->flags;
	Uint32 oldalpha = surface->format->alpha;

	/* Sanity check the flag as it gets passed in */
	if ( flag & SDL_SRCALPHA ) {
		if ( flag & (SDL_RLEACCEL|SDL_RLEACCELOK) ) {
			flag = (SDL_SRCALPHA | SDL_RLEACCELOK);
		} else {
			flag = SDL_SRCALPHA;
		}
	} else {
		flag = 0;
	}

	/* Optimize away operations that don't change anything */
	if ( (flag == (surface->flags & (SDL_SRCALPHA|SDL_RLEACCELOK))) &&
	     (!flag || value == oldalpha) ) {
		return(0);
	}

	if(!(flag & SDL_RLEACCELOK) && (surface->flags & SDL_RLEACCEL))
		SDL_UnRLESurface(surface, 1);

	if ( flag ) {
		SDL_VideoDevice *video = current_video;
		SDL_VideoDevice *this  = current_video;

		surface->flags |= SDL_SRCALPHA;
		surface->format->alpha = value;
		if ( (surface->flags & SDL_HWACCEL) == SDL_HWACCEL ) {
			if ( (video->SetHWAlpha == NULL) ||
			     (video->SetHWAlpha(this, surface, value) < 0) ) {
				surface->flags &= ~SDL_HWACCEL;
			}
		}
		if ( flag & SDL_RLEACCELOK ) {
		        surface->flags |= SDL_RLEACCELOK;
		} else {
		        surface->flags &= ~SDL_RLEACCELOK;
		}
	} else {
		surface->flags &= ~SDL_SRCALPHA;
		surface->format->alpha = SDL_ALPHA_OPAQUE;
	}
	/*
	 * The representation for software surfaces is independent of
	 * per-surface alpha, so no need to invalidate the blit mapping
	 * if just the alpha value was changed. (If either is 255, we still
	 * need to invalidate.)
	 */
	if((surface->flags & SDL_HWACCEL) == SDL_HWACCEL
	   || oldflags != surface->flags
	   || (((oldalpha + 1) ^ (value + 1)) & 0x100))
		SDL_InvalidateMap(surface->map);
	return(0);
}
int SDL_SetAlphaChannel(SDL_Surface *surface, Uint8 value)
{
	int row, col;
	int offset;
	Uint8 *buf;

	if ( (surface->format->Amask != 0xFF000000) &&
	     (surface->format->Amask != 0x000000FF) ) {
		SDL_SetError("Unsupported surface alpha mask format");
		return -1;
	}

#if SDL_BYTEORDER == SDL_LIL_ENDIAN
	if ( surface->format->Amask == 0xFF000000 ) {
			offset = 3;
	} else {
			offset = 0;
	}
#else
	if ( surface->format->Amask == 0xFF000000 ) {
			offset = 0;
	} else {
			offset = 3;
	}
#endif /* Byte ordering */

	/* Quickly set the alpha channel of an RGBA or ARGB surface */
	if ( SDL_MUSTLOCK(surface) ) {
		if ( SDL_LockSurface(surface) < 0 ) {
			return -1;
		}
	}
	row = surface->h;
	while (row--) {
		col = surface->w;
		buf = (Uint8 *)surface->pixels + row * surface->pitch + offset;
		while(col--) {
			*buf = value;
			buf += 4;
		}
	}
	if ( SDL_MUSTLOCK(surface) ) {
		SDL_UnlockSurface(surface);
	}
	return 0;
}

/*
 * A function to calculate the intersection of two rectangles:
 * return true if the rectangles intersect, false otherwise
 */
static __inline__
SDL_bool SDL_IntersectRect(const SDL_Rect *A, const SDL_Rect *B, SDL_Rect *intersection)
{
	int Amin, Amax, Bmin, Bmax;

	/* Horizontal intersection */
	Amin = A->x;
	Amax = Amin + A->w;
	Bmin = B->x;
	Bmax = Bmin + B->w;
	if(Bmin > Amin)
	        Amin = Bmin;
	intersection->x = Amin;
	if(Bmax < Amax)
	        Amax = Bmax;
	intersection->w = Amax - Amin > 0 ? Amax - Amin : 0;

	/* Vertical intersection */
	Amin = A->y;
	Amax = Amin + A->h;
	Bmin = B->y;
	Bmax = Bmin + B->h;
	if(Bmin > Amin)
	        Amin = Bmin;
	intersection->y = Amin;
	if(Bmax < Amax)
	        Amax = Bmax;
	intersection->h = Amax - Amin > 0 ? Amax - Amin : 0;

	return (intersection->w && intersection->h);
}
/*
 * Set the clipping rectangle for a blittable surface
 */
SDL_bool SDL_SetClipRect(SDL_Surface *surface, const SDL_Rect *rect)
{
	SDL_Rect full_rect;

	/* Don't do anything if there's no surface to act on */
	if ( ! surface ) {
		return SDL_FALSE;
	}

	/* Set up the full surface rectangle */
	full_rect.x = 0;
	full_rect.y = 0;
	full_rect.w = surface->w;
	full_rect.h = surface->h;

	/* Set the clipping rectangle */
	if ( ! rect ) {
		surface->clip_rect = full_rect;
		return 1;
	}
	return SDL_IntersectRect(rect, &full_rect, &surface->clip_rect);
}
void SDL_GetClipRect(SDL_Surface *surface, SDL_Rect *rect)
{
	if ( surface && rect ) {
		*rect = surface->clip_rect;
	}
}
/* 
 * Set up a blit between two surfaces -- split into three parts:
 * The upper part, SDL_UpperBlit(), performs clipping and rectangle 
 * verification.  The lower part is a pointer to a low level
 * accelerated blitting function.
 *
 * These parts are separated out and each used internally by this 
 * library in the optimimum places.  They are exported so that if
 * you know exactly what you are doing, you can optimize your code
 * by calling the one(s) you need.
 */
int SDL_LowerBlit (SDL_Surface *src, SDL_Rect *srcrect,
				SDL_Surface *dst, SDL_Rect *dstrect)
{
	SDL_blit do_blit;
	SDL_Rect hw_srcrect;
	SDL_Rect hw_dstrect;

	/* Check to make sure the blit mapping is valid */
	if ( (src->map->dst != dst) ||
             (src->map->dst->format_version != src->map->format_version) ) {
		if ( SDL_MapSurface(src, dst) < 0 ) {
			return(-1);
		}
	}

	/* Figure out which blitter to use */
	if ( (src->flags & SDL_HWACCEL) == SDL_HWACCEL ) {
		if ( src == SDL_VideoSurface ) {
			hw_srcrect = *dstrect;
			hw_srcrect.x += current_video->offset_x;
			hw_srcrect.y += current_video->offset_y;
			srcrect = &hw_srcrect;
		}
		if ( dst == SDL_VideoSurface ) {
			hw_dstrect = *dstrect;
			hw_dstrect.x += current_video->offset_x;
			hw_dstrect.y += current_video->offset_y;
			dstrect = &hw_dstrect;
		}
		do_blit = src->map->hw_blit;
	} else {
		do_blit = src->map->sw_blit;
	}
	return(do_blit(src, srcrect, dst, dstrect));
}


int SDL_UpperBlit (SDL_Surface *src, SDL_Rect *srcrect,
		   SDL_Surface *dst, SDL_Rect *dstrect)
{
        SDL_Rect fulldst;
	int srcx, srcy, w, h;

	/* Make sure the surfaces aren't locked */
	if ( ! src || ! dst ) {
		SDL_SetError("SDL_UpperBlit: passed a NULL surface");
		return(-1);
	}
	if ( src->locked || dst->locked ) {
		SDL_SetError("Surfaces must not be locked during blit");
		return(-1);
	}

	/* If the destination rectangle is NULL, use the entire dest surface */
	if ( dstrect == NULL ) {
	        fulldst.x = fulldst.y = 0;
		dstrect = &fulldst;