src/video/SDL_pixels.c
/* [<][>][^][v][top][bottom][index][help] */
FUNCTIONS
This source file includes following functions.
- SDL_AllocFormat
- SDL_ReallocFormat
- SDL_FormatChanged
- SDL_FreeFormat
- SDL_DitherColors
- SDL_CalculatePitch
- SDL_FindColor
- SDL_MapRGB
- SDL_MapRGBA
- SDL_GetRGBA
- SDL_GetRGB
- SDL_ApplyGamma
- Map1to1
- Map1toN
- MapNto1
- SDL_AllocBlitMap
- SDL_InvalidateMap
- SDL_MapSurface
- SDL_FreeBlitMap
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: SDL_pixels.c,v 1.3.2.14 2001/02/10 07:20:05 hercules Exp $";
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,
/* [<][>][^][v][top][bottom][index][help] */
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,
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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,
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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,
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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)
/* [<][>][^][v][top][bottom][index][help] */
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 }