SDL 2.0
SDL_rotate.h File Reference
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Macros

#define MIN(a, b)   (((a) < (b)) ? (a) : (b))
 

Functions

SDL_SurfaceSDLgfx_rotateSurface (SDL_Surface *src, double angle, int centerx, int centery, int smooth, int flipx, int flipy, int dstwidth, int dstheight, double cangle, double sangle)
 
void SDLgfx_rotozoomSurfaceSizeTrig (int width, int height, double angle, int *dstwidth, int *dstheight, double *cangle, double *sangle)
 

Macro Definition Documentation

◆ MIN

#define MIN (   a,
  b 
)    (((a) < (b)) ? (a) : (b))

Definition at line 26 of file SDL_rotate.h.

Function Documentation

◆ SDLgfx_rotateSurface()

SDL_Surface * SDLgfx_rotateSurface ( SDL_Surface src,
double  angle,
int  centerx,
int  centery,
int  smooth,
int  flipx,
int  flipy,
int  dstwidth,
int  dstheight,
double  cangle,
double  sangle 
)

Definition at line 415 of file SDL_rotate.c.

416{
417 SDL_Surface *rz_dst;
418 int is8bit, angle90;
419 int i;
420 SDL_BlendMode blendmode;
421 Uint32 colorkey = 0;
422 int colorKeyAvailable = SDL_FALSE;
423 double sangleinv, cangleinv;
424
425 /* Sanity check */
426 if (src == NULL)
427 return NULL;
428
429 if (SDL_HasColorKey(src)) {
430 if (SDL_GetColorKey(src, &colorkey) == 0) {
431 colorKeyAvailable = SDL_TRUE;
432 }
433 }
434
435 /* This function requires a 32-bit surface or 8-bit surface with a colorkey */
436 is8bit = src->format->BitsPerPixel == 8 && colorKeyAvailable;
437 if (!(is8bit || (src->format->BitsPerPixel == 32 && src->format->Amask)))
438 return NULL;
439
440 /* Calculate target factors from sin/cos and zoom */
441 sangleinv = sangle*65536.0;
442 cangleinv = cangle*65536.0;
443
444 /* Alloc space to completely contain the rotated surface */
445 rz_dst = NULL;
446 if (is8bit) {
447 /* Target surface is 8 bit */
448 rz_dst = SDL_CreateRGBSurface(0, dstwidth, dstheight + GUARD_ROWS, 8, 0, 0, 0, 0);
449 if (rz_dst != NULL) {
450 for (i = 0; i < src->format->palette->ncolors; i++) {
451 rz_dst->format->palette->colors[i] = src->format->palette->colors[i];
452 }
453 rz_dst->format->palette->ncolors = src->format->palette->ncolors;
454 }
455 } else {
456 /* Target surface is 32 bit with source RGBA ordering */
457 rz_dst = SDL_CreateRGBSurface(0, dstwidth, dstheight + GUARD_ROWS, 32,
458 src->format->Rmask, src->format->Gmask,
459 src->format->Bmask, src->format->Amask);
460 }
461
462 /* Check target */
463 if (rz_dst == NULL)
464 return NULL;
465
466 /* Adjust for guard rows */
467 rz_dst->h = dstheight;
468
469 SDL_GetSurfaceBlendMode(src, &blendmode);
470
471 if (colorKeyAvailable == SDL_TRUE) {
472 /* If available, the colorkey will be used to discard the pixels that are outside of the rotated area. */
473 SDL_SetColorKey(rz_dst, SDL_TRUE, colorkey);
474 SDL_FillRect(rz_dst, NULL, colorkey);
475 } else if (blendmode == SDL_BLENDMODE_NONE) {
476 blendmode = SDL_BLENDMODE_BLEND;
477 } else if (blendmode == SDL_BLENDMODE_MOD) {
478 /* Without a colorkey, the target texture has to be white for the MOD blend mode so
479 * that the pixels outside the rotated area don't affect the destination surface.
480 */
481 colorkey = SDL_MapRGBA(rz_dst->format, 255, 255, 255, 0);
482 SDL_FillRect(rz_dst, NULL, colorkey);
483 /* Setting a white colorkey for the destination surface makes the final blit discard
484 * all pixels outside of the rotated area. This doesn't interfere with anything because
485 * white pixels are already a no-op and the MOD blend mode does not interact with alpha.
486 */
487 SDL_SetColorKey(rz_dst, SDL_TRUE, colorkey);
488 }
489
490 SDL_SetSurfaceBlendMode(rz_dst, blendmode);
491
492 /* Lock source surface */
493 if (SDL_MUSTLOCK(src)) {
495 }
496
497 /* check if the rotation is a multiple of 90 degrees so we can take a fast path and also somewhat reduce
498 * the off-by-one problem in _transformSurfaceRGBA that expresses itself when the rotation is near
499 * multiples of 90 degrees.
500 */
501 angle90 = (int)(angle/90);
502 if (angle90 == angle/90) {
503 angle90 %= 4;
504 if (angle90 < 0) angle90 += 4; /* 0:0 deg, 1:90 deg, 2:180 deg, 3:270 deg */
505 } else {
506 angle90 = -1;
507 }
508
509 if (is8bit) {
510 /* Call the 8-bit transformation routine to do the rotation */
511 if(angle90 >= 0) {
512 transformSurfaceY90(src, rz_dst, angle90, flipx, flipy);
513 } else {
514 transformSurfaceY(src, rz_dst, centerx, centery, (int)sangleinv, (int)cangleinv,
515 flipx, flipy);
516 }
517 } else {
518 /* Call the 32-bit transformation routine to do the rotation */
519 if (angle90 >= 0) {
520 transformSurfaceRGBA90(src, rz_dst, angle90, flipx, flipy);
521 } else {
522 _transformSurfaceRGBA(src, rz_dst, centerx, centery, (int)sangleinv, (int)cangleinv,
523 flipx, flipy, smooth);
524 }
525 }
526
527 /* Unlock source surface */
528 if (SDL_MUSTLOCK(src)) {
530 }
531
532 /* Return rotated surface */
533 return rz_dst;
534}
SDL_BlendMode
The blend mode used in SDL_RenderCopy() and drawing operations.
Definition: SDL_blendmode.h:41
@ SDL_BLENDMODE_NONE
Definition: SDL_blendmode.h:42
@ SDL_BLENDMODE_BLEND
Definition: SDL_blendmode.h:44
@ SDL_BLENDMODE_MOD
Definition: SDL_blendmode.h:50
#define SDL_SetColorKey
#define SDL_GetSurfaceBlendMode
#define SDL_MapRGBA
#define SDL_SetSurfaceBlendMode
#define SDL_UnlockSurface
#define SDL_HasColorKey
#define SDL_LockSurface
#define SDL_GetColorKey
#define SDL_CreateRGBSurface
#define SDL_FillRect
GLenum src
GLfloat angle
#define GUARD_ROWS
Definition: SDL_rotate.c:77
static void _transformSurfaceRGBA(SDL_Surface *src, SDL_Surface *dst, int cx, int cy, int isin, int icos, int flipx, int flipy, int smooth)
Definition: SDL_rotate.c:230
static void transformSurfaceY90(SDL_Surface *src, SDL_Surface *dst, int angle, int flipx, int flipy)
Definition: SDL_rotate.c:203
static void transformSurfaceRGBA90(SDL_Surface *src, SDL_Surface *dst, int angle, int flipx, int flipy)
Definition: SDL_rotate.c:197
static void transformSurfaceY(SDL_Surface *src, SDL_Surface *dst, int cx, int cy, int isin, int icos, int flipx, int flipy)
Definition: SDL_rotate.c:344
@ SDL_TRUE
Definition: SDL_stdinc.h:164
@ SDL_FALSE
Definition: SDL_stdinc.h:163
uint32_t Uint32
Definition: SDL_stdinc.h:203
#define SDL_MUSTLOCK(S)
Definition: SDL_surface.h:62
return Display return Display Bool Bool int int int return Display XEvent Bool(*) XPointer return Display return Display Drawable _Xconst char unsigned int unsigned int return Display Pixmap Pixmap XColor XColor unsigned int unsigned int return Display _Xconst char char int char return Display Visual unsigned int int int char unsigned int unsigned int in i)
Definition: SDL_x11sym.h:50
#define NULL
Definition: begin_code.h:167
SDL_Color * colors
Definition: SDL_pixels.h:307
SDL_Palette * palette
Definition: SDL_pixels.h:318
A collection of pixels used in software blitting.
Definition: SDL_surface.h:71
SDL_PixelFormat * format
Definition: SDL_surface.h:73

References _transformSurfaceRGBA(), SDL_Palette::colors, SDL_Surface::format, GUARD_ROWS, SDL_Surface::h, i, SDL_Palette::ncolors, NULL, SDL_PixelFormat::palette, SDL_BLENDMODE_BLEND, SDL_BLENDMODE_MOD, SDL_BLENDMODE_NONE, SDL_CreateRGBSurface, SDL_FALSE, SDL_FillRect, SDL_GetColorKey, SDL_GetSurfaceBlendMode, SDL_HasColorKey, SDL_LockSurface, SDL_MapRGBA, SDL_MUSTLOCK, SDL_SetColorKey, SDL_SetSurfaceBlendMode, SDL_TRUE, SDL_UnlockSurface, transformSurfaceRGBA90(), transformSurfaceY(), and transformSurfaceY90().

Referenced by SW_RenderCopyEx().

◆ SDLgfx_rotozoomSurfaceSizeTrig()

void SDLgfx_rotozoomSurfaceSizeTrig ( int  width,
int  height,
double  angle,
int *  dstwidth,
int *  dstheight,
double *  cangle,
double *  sangle 
)

Definition at line 106 of file SDL_rotate.c.

109{
110 /* The trig code below gets the wrong size (due to FP inaccuracy?) when angle is a multiple of 90 degrees */
111 int angle90 = (int)(angle/90);
112 if(angle90 == angle/90) { /* if the angle is a multiple of 90 degrees */
113 angle90 %= 4;
114 if(angle90 < 0) angle90 += 4; /* 0:0 deg, 1:90 deg, 2:180 deg, 3:270 deg */
115 if(angle90 & 1) {
116 *dstwidth = height;
117 *dstheight = width;
118 *cangle = 0;
119 *sangle = angle90 == 1 ? -1 : 1; /* reversed because our rotations are clockwise */
120 } else {
121 *dstwidth = width;
122 *dstheight = height;
123 *cangle = angle90 == 0 ? 1 : -1;
124 *sangle = 0;
125 }
126 } else {
127 double x, y, cx, cy, sx, sy;
128 double radangle;
129 int dstwidthhalf, dstheighthalf;
130 /*
131 * Determine destination width and height by rotating a centered source box
132 */
133 radangle = angle * (M_PI / -180.0); /* reverse the angle because our rotations are clockwise */
134 *sangle = SDL_sin(radangle);
135 *cangle = SDL_cos(radangle);
136 x = (double)(width / 2);
137 y = (double)(height / 2);
138 cx = *cangle * x;
139 cy = *cangle * y;
140 sx = *sangle * x;
141 sy = *sangle * y;
142
143 dstwidthhalf = MAX((int)
144 SDL_ceil(MAX(MAX(MAX(SDL_fabs(cx + sy), SDL_fabs(cx - sy)), SDL_fabs(-cx + sy)), SDL_fabs(-cx - sy))), 1);
145 dstheighthalf = MAX((int)
146 SDL_ceil(MAX(MAX(MAX(SDL_fabs(sx + cy), SDL_fabs(sx - cy)), SDL_fabs(-sx + cy)), SDL_fabs(-sx - cy))), 1);
147 *dstwidth = 2 * dstwidthhalf;
148 *dstheight = 2 * dstheighthalf;
149 }
150}
#define SDL_sin
#define SDL_fabs
#define SDL_cos
#define SDL_ceil
GLint GLint GLint GLint GLint GLint y
Definition: SDL_opengl.h:1574
GLint GLint GLsizei width
Definition: SDL_opengl.h:1572
GLint GLint GLint GLint GLint x
Definition: SDL_opengl.h:1574
GLint GLint GLsizei GLsizei height
Definition: SDL_opengl.h:1572
#define MAX(a, b)
Definition: SDL_rotate.c:65

References MAX, SDL_ceil, SDL_cos, SDL_fabs, and SDL_sin.

Referenced by SW_RenderCopyEx().