src/video/SDL_pixels.c
changeset 0 74212992fb08
child 48 f97decee03a9
equal deleted inserted replaced
-1:000000000000 0:74212992fb08
       
     1 /*
       
     2     SDL - Simple DirectMedia Layer
       
     3     Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga
       
     4 
       
     5     This library is free software; you can redistribute it and/or
       
     6     modify it under the terms of the GNU Library General Public
       
     7     License as published by the Free Software Foundation; either
       
     8     version 2 of the License, or (at your option) any later version.
       
     9 
       
    10     This library is distributed in the hope that it will be useful,
       
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
       
    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
       
    13     Library General Public License for more details.
       
    14 
       
    15     You should have received a copy of the GNU Library General Public
       
    16     License along with this library; if not, write to the Free
       
    17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
       
    18 
       
    19     Sam Lantinga
       
    20     slouken@devolution.com
       
    21 */
       
    22 
       
    23 #ifdef SAVE_RCSID
       
    24 static char rcsid =
       
    25  "@(#) $Id$";
       
    26 #endif
       
    27 
       
    28 /* General (mostly internal) pixel/color manipulation routines for SDL */
       
    29 
       
    30 #include <stdio.h>
       
    31 #include <stdlib.h>
       
    32 #include <string.h>
       
    33 
       
    34 #include "SDL_error.h"
       
    35 #include "SDL_endian.h"
       
    36 #include "SDL_video.h"
       
    37 #include "SDL_sysvideo.h"
       
    38 #include "SDL_blit.h"
       
    39 #include "SDL_pixels_c.h"
       
    40 #include "SDL_RLEaccel_c.h"
       
    41 
       
    42 /* Helper functions */
       
    43 /*
       
    44  * Allocate a pixel format structure and fill it according to the given info.
       
    45  */
       
    46 SDL_PixelFormat *SDL_AllocFormat(int bpp,
       
    47 			Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
       
    48 {
       
    49 	SDL_PixelFormat *format;
       
    50 	Uint32 mask;
       
    51 
       
    52 	/* Allocate an empty pixel format structure */
       
    53 	format = malloc(sizeof(*format));
       
    54 	if ( format == NULL ) {
       
    55 		SDL_OutOfMemory();
       
    56 		return(NULL);
       
    57 	}
       
    58 	memset(format, 0, sizeof(*format));
       
    59 	format->alpha = SDL_ALPHA_OPAQUE;
       
    60 
       
    61 	/* Set up the format */
       
    62 	format->BitsPerPixel = bpp;
       
    63 	format->BytesPerPixel = (bpp+7)/8;
       
    64 	switch (bpp) {
       
    65 		case 1:
       
    66 			/* Create the 2 color black-white palette */
       
    67 			format->palette = (SDL_Palette *)malloc(
       
    68 							sizeof(SDL_Palette));
       
    69 			if ( format->palette == NULL ) {
       
    70 				SDL_FreeFormat(format);
       
    71 				SDL_OutOfMemory();
       
    72 				return(NULL);
       
    73 			}
       
    74 			(format->palette)->ncolors = 2;
       
    75 			(format->palette)->colors = (SDL_Color *)malloc(
       
    76 				(format->palette)->ncolors*sizeof(SDL_Color));
       
    77 			if ( (format->palette)->colors == NULL ) {
       
    78 				SDL_FreeFormat(format);
       
    79 				SDL_OutOfMemory();
       
    80 				return(NULL);
       
    81 			}
       
    82 			format->palette->colors[0].r = 0xFF;
       
    83 			format->palette->colors[0].g = 0xFF;
       
    84 			format->palette->colors[0].b = 0xFF;
       
    85 			format->palette->colors[1].r = 0x00;
       
    86 			format->palette->colors[1].g = 0x00;
       
    87 			format->palette->colors[1].b = 0x00;
       
    88 			format->Rloss = 8;
       
    89 			format->Gloss = 8;
       
    90 			format->Bloss = 8;
       
    91 			format->Aloss = 8;
       
    92 			format->Rshift = 0;
       
    93 			format->Gshift = 0;
       
    94 			format->Bshift = 0;
       
    95 			format->Ashift = 0;
       
    96 			format->Rmask = 0;
       
    97 			format->Gmask = 0;
       
    98 			format->Bmask = 0;
       
    99 			format->Amask = 0;
       
   100 			break;
       
   101 
       
   102 		case 4:
       
   103 			/* Create the 16 color VGA palette */
       
   104 			format->palette = (SDL_Palette *)malloc(
       
   105 							sizeof(SDL_Palette));
       
   106 			if ( format->palette == NULL ) {
       
   107 				SDL_FreeFormat(format);
       
   108 				SDL_OutOfMemory();
       
   109 				return(NULL);
       
   110 			}
       
   111 			(format->palette)->ncolors = 16;
       
   112 			(format->palette)->colors = (SDL_Color *)malloc(
       
   113 				(format->palette)->ncolors*sizeof(SDL_Color));
       
   114 			if ( (format->palette)->colors == NULL ) {
       
   115 				SDL_FreeFormat(format);
       
   116 				SDL_OutOfMemory();
       
   117 				return(NULL);
       
   118 			}
       
   119 			/* Punt for now, will this ever be used? */
       
   120 			memset((format->palette)->colors, 0,
       
   121 				(format->palette)->ncolors*sizeof(SDL_Color));
       
   122 
       
   123 			/* Palettized formats have no mask info */
       
   124 			format->Rloss = 8;
       
   125 			format->Gloss = 8;
       
   126 			format->Bloss = 8;
       
   127 			format->Aloss = 8;
       
   128 			format->Rshift = 0;
       
   129 			format->Gshift = 0;
       
   130 			format->Bshift = 0;
       
   131 			format->Ashift = 0;
       
   132 			format->Rmask = 0;
       
   133 			format->Gmask = 0;
       
   134 			format->Bmask = 0;
       
   135 			format->Amask = 0;
       
   136 			break;
       
   137 
       
   138 		case 8:
       
   139 			/* Create an empty 256 color palette */
       
   140 			format->palette = (SDL_Palette *)malloc(
       
   141 							sizeof(SDL_Palette));
       
   142 			if ( format->palette == NULL ) {
       
   143 				SDL_FreeFormat(format);
       
   144 				SDL_OutOfMemory();
       
   145 				return(NULL);
       
   146 			}
       
   147 			(format->palette)->ncolors = 256;
       
   148 			(format->palette)->colors = (SDL_Color *)malloc(
       
   149 				(format->palette)->ncolors*sizeof(SDL_Color));
       
   150 			if ( (format->palette)->colors == NULL ) {
       
   151 				SDL_FreeFormat(format);
       
   152 				SDL_OutOfMemory();
       
   153 				return(NULL);
       
   154 			}
       
   155 			memset((format->palette)->colors, 0,
       
   156 				(format->palette)->ncolors*sizeof(SDL_Color));
       
   157 
       
   158 			/* Palettized formats have no mask info */
       
   159 			format->Rloss = 8;
       
   160 			format->Gloss = 8;
       
   161 			format->Bloss = 8;
       
   162 			format->Aloss = 8;
       
   163 			format->Rshift = 0;
       
   164 			format->Gshift = 0;
       
   165 			format->Bshift = 0;
       
   166 			format->Ashift = 0;
       
   167 			format->Rmask = 0;
       
   168 			format->Gmask = 0;
       
   169 			format->Bmask = 0;
       
   170 			format->Amask = 0;
       
   171 			break;
       
   172 
       
   173 		default:
       
   174 			/* No palette, just packed pixel info */
       
   175 			format->palette = NULL;
       
   176 			format->Rshift = 0;
       
   177 			format->Rloss = 8;
       
   178 			if ( Rmask ) {
       
   179 				for ( mask = Rmask; !(mask&0x01); mask >>= 1 )
       
   180 					++format->Rshift;
       
   181 				for ( ; (mask&0x01); mask >>= 1 )
       
   182 					--format->Rloss;
       
   183 			}
       
   184 			format->Gshift = 0;
       
   185 			format->Gloss = 8;
       
   186 			if ( Gmask ) {
       
   187 				for ( mask = Gmask; !(mask&0x01); mask >>= 1 )
       
   188 					++format->Gshift;
       
   189 				for ( ; (mask&0x01); mask >>= 1 )
       
   190 					--format->Gloss;
       
   191 			}
       
   192 			format->Bshift = 0;
       
   193 			format->Bloss = 8;
       
   194 			if ( Bmask ) {
       
   195 				for ( mask = Bmask; !(mask&0x01); mask >>= 1 )
       
   196 					++format->Bshift;
       
   197 				for ( ; (mask&0x01); mask >>= 1 )
       
   198 					--format->Bloss;
       
   199 			}
       
   200 			format->Ashift = 0;
       
   201 			format->Aloss = 8;
       
   202 			if ( Amask ) {
       
   203 				for ( mask = Amask; !(mask&0x01); mask >>= 1 )
       
   204 					++format->Ashift;
       
   205 				for ( ; (mask&0x01); mask >>= 1 )
       
   206 					--format->Aloss;
       
   207 			}
       
   208 			format->Rmask = Rmask;
       
   209 			format->Gmask = Gmask;
       
   210 			format->Bmask = Bmask;
       
   211 			format->Amask = Amask;
       
   212 			break;
       
   213 	}
       
   214 	/* Calculate some standard bitmasks, if necessary 
       
   215 	 * Note:  This could conflict with an alpha mask, if given.
       
   216 	 */
       
   217 	if ( (bpp > 8) && !format->Rmask && !format->Gmask && !format->Bmask ) {
       
   218 		/* R-G-B */
       
   219 		if ( bpp > 24 )
       
   220 			bpp = 24;
       
   221 		format->Rloss = 8-(bpp/3);
       
   222 		format->Gloss = 8-(bpp/3)-(bpp%3);
       
   223 		format->Bloss = 8-(bpp/3);
       
   224 		format->Rshift = ((bpp/3)+(bpp%3))+(bpp/3);
       
   225 		format->Gshift = (bpp/3);
       
   226 		format->Bshift = 0;
       
   227 		format->Rmask = ((0xFF>>format->Rloss)<<format->Rshift);
       
   228 		format->Gmask = ((0xFF>>format->Gloss)<<format->Gshift);
       
   229 		format->Bmask = ((0xFF>>format->Bloss)<<format->Bshift);
       
   230 	}
       
   231 	return(format);
       
   232 }
       
   233 SDL_PixelFormat *SDL_ReallocFormat(SDL_Surface *surface, int bpp,
       
   234 			Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
       
   235 {
       
   236 	if ( surface->format ) {
       
   237 		SDL_FreeFormat(surface->format);
       
   238 		SDL_FormatChanged(surface);
       
   239 	}
       
   240 	surface->format = SDL_AllocFormat(bpp, Rmask, Gmask, Bmask, Amask);
       
   241 	return surface->format;
       
   242 }
       
   243 
       
   244 /*
       
   245  * Change any previous mappings from/to the new surface format
       
   246  */
       
   247 void SDL_FormatChanged(SDL_Surface *surface)
       
   248 {
       
   249 	surface->format_version++;
       
   250 	SDL_InvalidateMap(surface->map);
       
   251 }
       
   252 /*
       
   253  * Free a previously allocated format structure
       
   254  */
       
   255 void SDL_FreeFormat(SDL_PixelFormat *format)
       
   256 {
       
   257 	if ( format ) {
       
   258 		if ( format->palette ) {
       
   259 			if ( format->palette->colors ) {
       
   260 				free(format->palette->colors);
       
   261 			}
       
   262 			free(format->palette);
       
   263 		}
       
   264 		free(format);
       
   265 	}
       
   266 }
       
   267 /*
       
   268  * Calculate an 8-bit (3 red, 3 green, 2 blue) dithered palette of colors
       
   269  */
       
   270 void SDL_DitherColors(SDL_Color *colors, int bpp)
       
   271 {
       
   272 	int i;
       
   273 	if(bpp != 8)
       
   274 		return;		/* only 8bpp supported right now */
       
   275 
       
   276 	for(i = 0; i < 256; i++) {
       
   277 		int r, g, b;
       
   278 		/* map each bit field to the full [0, 255] interval,
       
   279 		   so 0 is mapped to (0, 0, 0) and 255 to (255, 255, 255) */
       
   280 		r = i & 0xe0;
       
   281 		r |= r >> 3 | r >> 6;
       
   282 		colors[i].r = r;
       
   283 		g = (i << 3) & 0xe0;
       
   284 		g |= g >> 3 | g >> 6;
       
   285 		colors[i].g = g;
       
   286 		b = i & 0x3;
       
   287 		b |= b << 2;
       
   288 		b |= b << 4;
       
   289 		colors[i].b = b;
       
   290 	}
       
   291 }
       
   292 /* 
       
   293  * Calculate the pad-aligned scanline width of a surface
       
   294  */
       
   295 Uint16 SDL_CalculatePitch(SDL_Surface *surface)
       
   296 {
       
   297 	Uint16 pitch;
       
   298 
       
   299 	/* Surface should be 4-byte aligned for speed */
       
   300 	pitch = surface->w*surface->format->BytesPerPixel;
       
   301 	switch (surface->format->BitsPerPixel) {
       
   302 		case 1:
       
   303 			pitch = (pitch+7)/8;
       
   304 			break;
       
   305 		case 4:
       
   306 			pitch = (pitch+1)/2;
       
   307 			break;
       
   308 		default:
       
   309 			break;
       
   310 	}
       
   311 	pitch = (pitch + 3) & ~3;	/* 4-byte aligning */
       
   312 	return(pitch);
       
   313 }
       
   314 /*
       
   315  * Match an RGB value to a particular palette index
       
   316  */
       
   317 Uint8 SDL_FindColor(SDL_Palette *pal, Uint8 r, Uint8 g, Uint8 b)
       
   318 {
       
   319 	/* Do colorspace distance matching */
       
   320 	unsigned int smallest;
       
   321 	unsigned int distance;
       
   322 	int rd, gd, bd;
       
   323 	int i;
       
   324 	Uint8 pixel=0;
       
   325 		
       
   326 	smallest = ~0;
       
   327 	for ( i=0; i<pal->ncolors; ++i ) {
       
   328 		rd = pal->colors[i].r - r;
       
   329 		gd = pal->colors[i].g - g;
       
   330 		bd = pal->colors[i].b - b;
       
   331 		distance = (rd*rd)+(gd*gd)+(bd*bd);
       
   332 		if ( distance < smallest ) {
       
   333 			pixel = i;
       
   334 			if ( distance == 0 ) { /* Perfect match! */
       
   335 				break;
       
   336 			}
       
   337 			smallest = distance;
       
   338 		}
       
   339 	}
       
   340 	return(pixel);
       
   341 }
       
   342 
       
   343 /* Find the opaque pixel value corresponding to an RGB triple */
       
   344 Uint32 SDL_MapRGB(SDL_PixelFormat *format, Uint8 r, Uint8 g, Uint8 b)
       
   345 {
       
   346 	if ( format->palette == NULL ) {
       
   347 		return (r >> format->Rloss) << format->Rshift
       
   348 		       | (g >> format->Gloss) << format->Gshift
       
   349 		       | (b >> format->Bloss) << format->Bshift
       
   350 		       | format->Amask;
       
   351 	} else {
       
   352 		return SDL_FindColor(format->palette, r, g, b);
       
   353 	}
       
   354 }
       
   355 
       
   356 /* Find the pixel value corresponding to an RGBA quadruple */
       
   357 Uint32 SDL_MapRGBA(SDL_PixelFormat *format, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
       
   358 {
       
   359 	if ( format->palette == NULL ) {
       
   360 	        return (r >> format->Rloss) << format->Rshift
       
   361 		    | (g >> format->Gloss) << format->Gshift
       
   362 		    | (b >> format->Bloss) << format->Bshift
       
   363 		    | ((a >> format->Aloss) << format->Ashift & format->Amask);
       
   364 	} else {
       
   365 		return SDL_FindColor(format->palette, r, g, b);
       
   366 	}
       
   367 }
       
   368 
       
   369 void SDL_GetRGBA(Uint32 pixel, SDL_PixelFormat *fmt,
       
   370 		 Uint8 *r, Uint8 *g, Uint8 *b, Uint8 *a)
       
   371 {
       
   372 	if ( fmt->palette == NULL ) {
       
   373 	        /*
       
   374 		 * This makes sure that the result is mapped to the
       
   375 		 * interval [0..255], and the maximum value for each
       
   376 		 * component is 255. This is important to make sure
       
   377 		 * that white is indeed reported as (255, 255, 255),
       
   378 		 * and that opaque alpha is 255.
       
   379 		 * This only works for RGB bit fields at least 4 bit
       
   380 		 * wide, which is almost always the case.
       
   381 		 */
       
   382 	        unsigned rv, gv, bv, av;
       
   383 		rv = (pixel & fmt->Rmask) >> fmt->Rshift;
       
   384 		*r = (rv << fmt->Rloss) + (rv >> (8 - fmt->Rloss));
       
   385 		gv = (pixel & fmt->Gmask) >> fmt->Gshift;
       
   386 		*g = (gv << fmt->Gloss) + (gv >> (8 - fmt->Gloss));
       
   387 		bv = (pixel & fmt->Bmask) >> fmt->Bshift;
       
   388 		*b = (bv << fmt->Bloss) + (bv >> (8 - fmt->Bloss));
       
   389 		if(fmt->Amask) {
       
   390 		        av = (pixel & fmt->Amask) >> fmt->Ashift;
       
   391 			*a = (av << fmt->Aloss) + (av >> (8 - fmt->Aloss));
       
   392 		} else
       
   393 		        *a = SDL_ALPHA_OPAQUE;
       
   394 	} else {
       
   395 		*r = fmt->palette->colors[pixel].r;
       
   396 		*g = fmt->palette->colors[pixel].g;
       
   397 		*b = fmt->palette->colors[pixel].b;
       
   398 		*a = SDL_ALPHA_OPAQUE;
       
   399 	}
       
   400 }
       
   401 
       
   402 void SDL_GetRGB(Uint32 pixel, SDL_PixelFormat *fmt, Uint8 *r,Uint8 *g,Uint8 *b)
       
   403 {
       
   404 	if ( fmt->palette == NULL ) {
       
   405 	        /* the note for SDL_GetRGBA above applies here too */
       
   406 	        unsigned rv, gv, bv;
       
   407 		rv = (pixel & fmt->Rmask) >> fmt->Rshift;
       
   408 		*r = (rv << fmt->Rloss) + (rv >> (8 - fmt->Rloss));
       
   409 		gv = (pixel & fmt->Gmask) >> fmt->Gshift;
       
   410 		*g = (gv << fmt->Gloss) + (gv >> (8 - fmt->Gloss));
       
   411 		bv = (pixel & fmt->Bmask) >> fmt->Bshift;
       
   412 		*b = (bv << fmt->Bloss) + (bv >> (8 - fmt->Bloss));
       
   413 	} else {
       
   414 		*r = fmt->palette->colors[pixel].r;
       
   415 		*g = fmt->palette->colors[pixel].g;
       
   416 		*b = fmt->palette->colors[pixel].b;
       
   417 	}
       
   418 }
       
   419 
       
   420 /* Apply gamma to a set of colors - this is easy. :) */
       
   421 void SDL_ApplyGamma(Uint16 *gamma, SDL_Color *colors, SDL_Color *output,
       
   422 							int ncolors)
       
   423 {
       
   424 	int i;
       
   425 
       
   426 	for ( i=0; i<ncolors; ++i ) {
       
   427 		output[i].r = gamma[0*256 + colors[i].r] >> 8;
       
   428 		output[i].g = gamma[1*256 + colors[i].g] >> 8;
       
   429 		output[i].b = gamma[2*256 + colors[i].b] >> 8;
       
   430 	}
       
   431 }
       
   432 
       
   433 /* Map from Palette to Palette */
       
   434 static Uint8 *Map1to1(SDL_Palette *src, SDL_Palette *dst, int *identical)
       
   435 {
       
   436 	Uint8 *map;
       
   437 	int i;
       
   438 
       
   439 	if ( identical ) {
       
   440 		if ( src->ncolors <= dst->ncolors ) {
       
   441 			/* If an identical palette, no need to map */
       
   442 			if ( memcmp(src->colors, dst->colors, src->ncolors*
       
   443 						sizeof(SDL_Color)) == 0 ) {
       
   444 				*identical = 1;
       
   445 				return(NULL);
       
   446 			}
       
   447 		}
       
   448 		*identical = 0;
       
   449 	}
       
   450 	map = (Uint8 *)malloc(src->ncolors);
       
   451 	if ( map == NULL ) {
       
   452 		SDL_OutOfMemory();
       
   453 		return(NULL);
       
   454 	}
       
   455 	for ( i=0; i<src->ncolors; ++i ) {
       
   456 		map[i] = SDL_FindColor(dst,
       
   457 			src->colors[i].r, src->colors[i].g, src->colors[i].b);
       
   458 	}
       
   459 	return(map);
       
   460 }
       
   461 /* Map from Palette to BitField */
       
   462 static Uint8 *Map1toN(SDL_Palette *src, SDL_PixelFormat *dst)
       
   463 {
       
   464 	Uint8 *map;
       
   465 	int i;
       
   466 	int  bpp;
       
   467 	unsigned alpha;
       
   468 
       
   469 	bpp = ((dst->BytesPerPixel == 3) ? 4 : dst->BytesPerPixel);
       
   470 	map = (Uint8 *)malloc(src->ncolors*bpp);
       
   471 	if ( map == NULL ) {
       
   472 		SDL_OutOfMemory();
       
   473 		return(NULL);
       
   474 	}
       
   475 
       
   476 	alpha = dst->Amask ? SDL_ALPHA_OPAQUE : 0;
       
   477 	/* We memory copy to the pixel map so the endianness is preserved */
       
   478 	for ( i=0; i<src->ncolors; ++i ) {
       
   479 		ASSEMBLE_RGBA(&map[i*bpp], dst->BytesPerPixel, dst,
       
   480 			      src->colors[i].r, src->colors[i].g,
       
   481 			      src->colors[i].b, alpha);
       
   482 	}
       
   483 	return(map);
       
   484 }
       
   485 /* Map from BitField to Dithered-Palette to Palette */
       
   486 static Uint8 *MapNto1(SDL_PixelFormat *src, SDL_Palette *dst, int *identical)
       
   487 {
       
   488 	/* Generate a 256 color dither palette */
       
   489 	SDL_Palette dithered;
       
   490 	SDL_Color colors[256];
       
   491 
       
   492 	dithered.ncolors = 256;
       
   493 	SDL_DitherColors(colors, 8);
       
   494 	dithered.colors = colors;
       
   495 	return(Map1to1(&dithered, dst, identical));
       
   496 }
       
   497 
       
   498 SDL_BlitMap *SDL_AllocBlitMap(void)
       
   499 {
       
   500 	SDL_BlitMap *map;
       
   501 
       
   502 	/* Allocate the empty map */
       
   503 	map = (SDL_BlitMap *)malloc(sizeof(*map));
       
   504 	if ( map == NULL ) {
       
   505 		SDL_OutOfMemory();
       
   506 		return(NULL);
       
   507 	}
       
   508 	memset(map, 0, sizeof(*map));
       
   509 
       
   510 	/* Allocate the software blit data */
       
   511 	map->sw_data = (struct private_swaccel *)malloc(sizeof(*map->sw_data));
       
   512 	if ( map->sw_data == NULL ) {
       
   513 		SDL_FreeBlitMap(map);
       
   514 		SDL_OutOfMemory();
       
   515 		return(NULL);
       
   516 	}
       
   517 	memset(map->sw_data, 0, sizeof(*map->sw_data));
       
   518 
       
   519 	/* It's ready to go */
       
   520 	return(map);
       
   521 }
       
   522 void SDL_InvalidateMap(SDL_BlitMap *map)
       
   523 {
       
   524 	if ( ! map ) {
       
   525 		return;
       
   526 	}
       
   527 	map->dst = NULL;
       
   528 	map->format_version = (unsigned int)-1;
       
   529 	if ( map->table ) {
       
   530 		free(map->table);
       
   531 		map->table = NULL;
       
   532 	}
       
   533 }
       
   534 int SDL_MapSurface (SDL_Surface *src, SDL_Surface *dst)
       
   535 {
       
   536 	SDL_PixelFormat *srcfmt;
       
   537 	SDL_PixelFormat *dstfmt;
       
   538 	SDL_BlitMap *map;
       
   539 
       
   540 	/* Clear out any previous mapping */
       
   541 	map = src->map;
       
   542 	if ( (src->flags & SDL_RLEACCEL) == SDL_RLEACCEL ) {
       
   543 		SDL_UnRLESurface(src, 1);
       
   544 	}
       
   545 	SDL_InvalidateMap(map);
       
   546 
       
   547 	/* Figure out what kind of mapping we're doing */
       
   548 	map->identity = 0;
       
   549 	srcfmt = src->format;
       
   550 	dstfmt = dst->format;
       
   551 	switch (srcfmt->BytesPerPixel) {
       
   552 	    case 1:
       
   553 		switch (dstfmt->BytesPerPixel) {
       
   554 		    case 1:
       
   555 			/* Palette --> Palette */
       
   556 			/* If both SDL_HWSURFACE, assume have same palette */
       
   557 			if ( ((src->flags & SDL_HWSURFACE) == SDL_HWSURFACE) &&
       
   558 			     ((dst->flags & SDL_HWSURFACE) == SDL_HWSURFACE) ) {
       
   559 				map->identity = 1;
       
   560 			} else {
       
   561 				map->table = Map1to1(srcfmt->palette,
       
   562 					dstfmt->palette, &map->identity);
       
   563 			}
       
   564 			if ( ! map->identity ) {
       
   565 				if ( map->table == NULL ) {
       
   566 					return(-1);
       
   567 				}
       
   568 			}
       
   569 			if (srcfmt->BitsPerPixel!=dstfmt->BitsPerPixel)
       
   570 				map->identity = 0;
       
   571 			break;
       
   572 
       
   573 		    default:
       
   574 			/* Palette --> BitField */
       
   575 			map->table = Map1toN(srcfmt->palette, dstfmt);
       
   576 			if ( map->table == NULL ) {
       
   577 				return(-1);
       
   578 			}
       
   579 			break;
       
   580 		}
       
   581 		break;
       
   582 	default:
       
   583 		switch (dstfmt->BytesPerPixel) {
       
   584 		    case 1:
       
   585 			/* BitField --> Palette */
       
   586 			map->table = MapNto1(srcfmt,
       
   587 					dstfmt->palette, &map->identity);
       
   588 			if ( ! map->identity ) {
       
   589 				if ( map->table == NULL ) {
       
   590 					return(-1);
       
   591 				}
       
   592 			}
       
   593 			map->identity = 0;	/* Don't optimize to copy */
       
   594 			break;
       
   595 		    default:
       
   596 			/* BitField --> BitField */
       
   597 			if ( FORMAT_EQUAL(srcfmt, dstfmt) )
       
   598 				map->identity = 1;
       
   599 			break;
       
   600 		}
       
   601 		break;
       
   602 	}
       
   603 
       
   604 	map->dst = dst;
       
   605 	map->format_version = dst->format_version;
       
   606 
       
   607 	/* Choose your blitters wisely */
       
   608 	return(SDL_CalculateBlit(src));
       
   609 }
       
   610 void SDL_FreeBlitMap(SDL_BlitMap *map)
       
   611 {
       
   612 	if ( map ) {
       
   613 		SDL_InvalidateMap(map);
       
   614 		if ( map->sw_data != NULL ) {
       
   615 			free(map->sw_data);
       
   616 		}
       
   617 		free(map);
       
   618 	}
       
   619 }