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SDL2_rotozoom.c
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/*
SDL2_rotozoom.c: rotozoomer, zoomer and shrinker for 32bit or 8bit surfaces
Copyright (C) 2012 Andreas Schiffler
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source
distribution.
Andreas Schiffler -- aschiffler at ferzkopp dot net
*/
#ifdef WIN32
#include <windows.h>
#endif
#include <stdlib.h>
#include <string.h>
#include "SDL2_rotozoom.h"
#include "SDL2_gfxPrimitives.h"
#define SDL_STBIMAGE_IMPLEMENTATION
#define SDL_STBIMG_DEF __attribute__ ((visibility ("default")))
#include "SDL_stbimage.h"
#define DR_MP3_IMPLEMENTATION
#include "dr_mp3.h"
SDL_STBIMG_DEF int GFX_bezierColor(SDL_Renderer* renderer, const Sint16* vx, const Sint16* vy, int n, int s, Uint32 color)
{ return bezierColor(renderer, vx, vy, n, s, color) ; }
SDL_STBIMG_DEF int GFX_filledPolyBezierColor(SDL_Renderer * renderer, const Sint16 *x, const Sint16 *y, int n, int s, Uint32 color)
{ return filledPolyBezierColor(renderer, x, y, n, s, color) ; }
SDL_STBIMG_DEF int GFX_aaFilledEllipseColor(SDL_Renderer * renderer, float cx, float cy, float rx, float ry, Uint32 color)
{ return aaFilledEllipseColor(renderer, cx, cy, rx, ry, color) ; }
SDL_STBIMG_DEF int GFX_aaFilledPolygonColor(SDL_Renderer * renderer, const double * vx, const double * vy, int n, Uint32 color)
{ return aaFilledPolygonColor(renderer, vx, vy, n, color) ; }
SDL_STBIMG_DEF int GFX_aaFilledPieColor(SDL_Renderer * renderer, float cx, float cy, float rx, float ry, float start, float end, Uint32 chord, Uint32 color)
{ return aaFilledPieColor(renderer, cx, cy, rx, ry, start, end, chord, color) ; }
SDL_STBIMG_DEF int GFX_aaArcColor(SDL_Renderer * renderer, float cx, float cy, float rx, float ry, float start, float end, float thick, Uint32 color)
{ return aaArcColor(renderer, cx, cy, rx, ry, start, end, thick, color) ; }
SDL_STBIMG_DEF int GFX_aaBezierColor(SDL_Renderer * renderer, double *x, double *y, int n, int s, float thick, Uint32 color)
{ return aaBezierColor(renderer, x, y, n, s, thick, color) ; }
SDL_STBIMG_DEF int GFX_aaFilledPolyBezierColor(SDL_Renderer * renderer, double *x, double *y, int n, int s, Uint32 color)
{ return aaFilledPolyBezierColor(renderer, x, y, n, s, color) ; }
SDL_STBIMG_DEF double GFX_EvaluateBezier(double *data, int ndata, double t)
{ return _evaluateBezier (data, ndata, t) ; }
SDL_STBIMG_DEF SDL_Surface* GFX_RotoZoomSurface(SDL_Surface * src, double angle, double zoomx, double zoomy)
{ return rotozoomSurfaceXY(src, angle, zoomx, zoomy, 0) ; }
/* ---- Internally used structures */
/*!
\brief A 32 bit RGBA pixel.
*/
typedef struct tColorRGBA {
Uint8 r;
Uint8 g;
Uint8 b;
Uint8 a;
} tColorRGBA;
/*!
\brief A 8bit Y/palette pixel.
*/
typedef struct tColorY {
Uint8 y;
} tColorY;
/*!
\brief Returns maximum of two numbers a and b.
*/
#define MAX(a,b) (((a) > (b)) ? (a) : (b))
/*!
\brief Number of guard rows added to destination surfaces.
This is a simple but effective workaround for observed issues.
These rows allocate extra memory and are then hidden from the surface.
Rows are added to the end of destination surfaces when they are allocated.
This catches any potential overflows which seem to happen with
just the right src image dimensions and scale/rotation and can lead
to a situation where the program can segfault.
*/
#define GUARD_ROWS (2)
/*!
\brief Lower limit of absolute zoom factor or rotation degrees.
*/
#define VALUE_LIMIT 0.001
/*!
\brief Returns colorkey info for a surface
*/
Uint32 _colorkey(SDL_Surface *src)
{
Uint32 key = 0;
SDL_GetColorKey(src, &key);
return key;
}
/*!
\brief Internal 32 bit integer-factor averaging Shrinker.
Shrinks 32 bit RGBA/ABGR 'src' surface to 'dst' surface.
Averages color and alpha values values of src pixels to calculate dst pixels.
Assumes src and dst surfaces are of 32 bit depth.
Assumes dst surface was allocated with the correct dimensions.
\param src The surface to shrink (input).
\param dst The shrunken surface (output).
\param factorx The horizontal shrinking ratio.
\param factory The vertical shrinking ratio.
\return 0 for success or -1 for error.
*/
int _shrinkSurfaceRGBA(SDL_Surface * src, SDL_Surface * dst, int factorx, int factory)
{
int x, y, dx, dy, dgap, ra, ga, ba, aa;
int n_average;
tColorRGBA *sp, *osp, *oosp;
tColorRGBA *dp;
/*
* Averaging integer shrink
*/
/* Precalculate division factor */
n_average = factorx*factory;
/*
* Scan destination
*/
sp = (tColorRGBA *) src->pixels;
dp = (tColorRGBA *) dst->pixels;
dgap = dst->pitch - dst->w * 4;
for (y = 0; y < dst->h; y++) {
osp=sp;
for (x = 0; x < dst->w; x++) {
/* Trace out source box and accumulate */
oosp=sp;
ra=ga=ba=aa=0;
for (dy=0; dy < factory; dy++) {
for (dx=0; dx < factorx; dx++) {
ra += sp->r;
ga += sp->g;
ba += sp->b;
aa += sp->a;
sp++;
}
/* src dx loop */
sp = (tColorRGBA *)((Uint8*)sp + (src->pitch - 4*factorx)); // next y
}
/* src dy loop */
/* next box-x */
sp = (tColorRGBA *)((Uint8*)oosp + 4*factorx);
/* Store result in destination */
dp->r = ra/n_average;
dp->g = ga/n_average;
dp->b = ba/n_average;
dp->a = aa/n_average;
/*
* Advance destination pointer
*/
dp++;
}
/* dst x loop */
/* next box-y */
sp = (tColorRGBA *)((Uint8*)osp + src->pitch*factory);
/*
* Advance destination pointers
*/
dp = (tColorRGBA *) ((Uint8 *) dp + dgap);
}
/* dst y loop */
return (0);
}
/*!
\brief Internal 8 bit integer-factor averaging shrinker.
Shrinks 8bit Y 'src' surface to 'dst' surface.
Averages color (brightness) values values of src pixels to calculate dst pixels.
Assumes src and dst surfaces are of 8 bit depth.
Assumes dst surface was allocated with the correct dimensions.
\param src The surface to shrink (input).
\param dst The shrunken surface (output).
\param factorx The horizontal shrinking ratio.
\param factory The vertical shrinking ratio.
\return 0 for success or -1 for error.
*/
int _shrinkSurfaceY(SDL_Surface * src, SDL_Surface * dst, int factorx, int factory)
{
int x, y, dx, dy, dgap, a;
int n_average;
Uint8 *sp, *osp, *oosp;
Uint8 *dp;
/*
* Averaging integer shrink
*/
/* Precalculate division factor */
n_average = factorx*factory;
/*
* Scan destination
*/
sp = (Uint8 *) src->pixels;
dp = (Uint8 *) dst->pixels;
dgap = dst->pitch - dst->w;
for (y = 0; y < dst->h; y++) {
osp=sp;
for (x = 0; x < dst->w; x++) {
/* Trace out source box and accumulate */
oosp=sp;
a=0;
for (dy=0; dy < factory; dy++) {
for (dx=0; dx < factorx; dx++) {
a += (*sp);
/* next x */
sp++;
}
/* end src dx loop */
/* next y */
sp = (Uint8 *)((Uint8*)sp + (src->pitch - factorx));
}
/* end src dy loop */
/* next box-x */
sp = (Uint8 *)((Uint8*)oosp + factorx);
/* Store result in destination */
*dp = a/n_average;
/*
* Advance destination pointer
*/
dp++;
}
/* end dst x loop */
/* next box-y */
sp = (Uint8 *)((Uint8*)osp + src->pitch*factory);
/*
* Advance destination pointers
*/
dp = (Uint8 *)((Uint8 *)dp + dgap);
}
/* end dst y loop */
return (0);
}
/*!
\brief Internal 32 bit Zoomer with optional anti-aliasing by bilinear interpolation.
Zooms 32 bit RGBA/ABGR 'src' surface to 'dst' surface.
Assumes src and dst surfaces are of 32 bit depth.
Assumes dst surface was allocated with the correct dimensions.
\param src The surface to zoom (input).
\param dst The zoomed surface (output).
\param flipx Flag indicating if the image should be horizontally flipped.
\param flipy Flag indicating if the image should be vertically flipped.
\param smooth Antialiasing flag; set to SMOOTHING_ON to enable.
\return 0 for success or -1 for error.
*/
int _zoomSurfaceRGBA(SDL_Surface * src, SDL_Surface * dst, int flipx, int flipy, int smooth)
{
int x, y, sx, sy, ssx, ssy, *sax, *say, *csax, *csay, *salast, csx, csy, ex, ey, cx, cy, sstep, sstepx, sstepy;
tColorRGBA *c00, *c01, *c10, *c11;
tColorRGBA *sp, *csp, *dp;
int spixelgap, spixelw, spixelh, dgap, t1, t2;
/*
* Allocate memory for row/column increments
*/
if ((sax = (int *) malloc((dst->w + 1) * sizeof(int))) == NULL) {
return (-1);
}
if ((say = (int *) malloc((dst->h + 1) * sizeof(int))) == NULL) {
free(sax);
return (-1);
}
/*
* Precalculate row increments
*/
spixelw = (src->w - 1);
spixelh = (src->h - 1);
if (smooth) {
sx = (int) (65536.0 * (float) spixelw / (float) (dst->w - 1));
sy = (int) (65536.0 * (float) spixelh / (float) (dst->h - 1));
} else {
sx = (int) (65536.0 * (float) (src->w) / (float) (dst->w));
sy = (int) (65536.0 * (float) (src->h) / (float) (dst->h));
}
/* Maximum scaled source size */
ssx = (src->w << 16) - 1;
ssy = (src->h << 16) - 1;
/* Precalculate horizontal row increments */
csx = 0;
csax = sax;
for (x = 0; x <= dst->w; x++) {
*csax = csx;
csax++;
csx += sx;
/* Guard from overflows */
if (csx > ssx) {
csx = ssx;
}
}
/* Precalculate vertical row increments */
csy = 0;
csay = say;
for (y = 0; y <= dst->h; y++) {
*csay = csy;
csay++;
csy += sy;
/* Guard from overflows */
if (csy > ssy) {
csy = ssy;
}
}
sp = (tColorRGBA *) src->pixels;
dp = (tColorRGBA *) dst->pixels;
dgap = dst->pitch - dst->w * 4;
spixelgap = src->pitch/4;
if (flipx) sp += spixelw;
if (flipy) sp += (spixelgap * spixelh);
/*
* Switch between interpolating and non-interpolating code
*/
if (smooth) {
/*
* Interpolating Zoom
*/
csay = say;
for (y = 0; y < dst->h; y++) {
csp = sp;
csax = sax;
for (x = 0; x < dst->w; x++) {
/*
* Setup color source pointers
*/
ex = (*csax & 0xffff);
ey = (*csay & 0xffff);
cx = (*csax >> 16);
cy = (*csay >> 16);
sstepx = cx < spixelw;
sstepy = cy < spixelh;
c00 = sp;
c01 = sp;
c10 = sp;
if (sstepy) {
if (flipy) {
c10 -= spixelgap;
} else {
c10 += spixelgap;
}
}
c11 = c10;
if (sstepx) {
if (flipx) {
c01--;
c11--;
} else {
c01++;
c11++;
}
}
/*
* Draw and interpolate colors
*/
t1 = ((((c01->r - c00->r) * ex) >> 16) + c00->r) & 0xff;
t2 = ((((c11->r - c10->r) * ex) >> 16) + c10->r) & 0xff;
dp->r = (((t2 - t1) * ey) >> 16) + t1;
t1 = ((((c01->g - c00->g) * ex) >> 16) + c00->g) & 0xff;
t2 = ((((c11->g - c10->g) * ex) >> 16) + c10->g) & 0xff;
dp->g = (((t2 - t1) * ey) >> 16) + t1;
t1 = ((((c01->b - c00->b) * ex) >> 16) + c00->b) & 0xff;
t2 = ((((c11->b - c10->b) * ex) >> 16) + c10->b) & 0xff;
dp->b = (((t2 - t1) * ey) >> 16) + t1;
t1 = ((((c01->a - c00->a) * ex) >> 16) + c00->a) & 0xff;
t2 = ((((c11->a - c10->a) * ex) >> 16) + c10->a) & 0xff;
dp->a = (((t2 - t1) * ey) >> 16) + t1;
/*
* Advance source pointer x
*/
salast = csax;
csax++;
sstep = (*csax >> 16) - (*salast >> 16);
if (flipx) {
sp -= sstep;
} else {
sp += sstep;
}
/*
* Advance destination pointer x
*/
dp++;
}
/*
* Advance source pointer y
*/
salast = csay;
csay++;
sstep = (*csay >> 16) - (*salast >> 16);
sstep *= spixelgap;
if (flipy) {
sp = csp - sstep;
} else {
sp = csp + sstep;
}
/*
* Advance destination pointer y
*/
dp = (tColorRGBA *) ((Uint8 *) dp + dgap);
}
} else {
/*
* Non-Interpolating Zoom
*/
csay = say;
for (y = 0; y < dst->h; y++) {
csp = sp;
csax = sax;
for (x = 0; x < dst->w; x++) {
/*
* Draw
*/
*dp = *sp;
/*
* Advance source pointer x
*/
salast = csax;
csax++;
sstep = (*csax >> 16) - (*salast >> 16);
if (flipx) sstep = -sstep;
sp += sstep;
/*
* Advance destination pointer x
*/
dp++;
}
/*
* Advance source pointer y
*/
salast = csay;
csay++;
sstep = (*csay >> 16) - (*salast >> 16);
sstep *= spixelgap;
if (flipy) sstep = -sstep;
sp = csp + sstep;
/*
* Advance destination pointer y
*/
dp = (tColorRGBA *) ((Uint8 *) dp + dgap);
}
}
/*
* Remove temp arrays
*/
free(sax);
free(say);
return (0);
}
/*!
\brief Internal 8 bit Zoomer without smoothing.
Zooms 8bit palette/Y 'src' surface to 'dst' surface.
Assumes src and dst surfaces are of 8 bit depth.
Assumes dst surface was allocated with the correct dimensions.
\param src The surface to zoom (input).
\param dst The zoomed surface (output).
\param flipx Flag indicating if the image should be horizontally flipped.
\param flipy Flag indicating if the image should be vertically flipped.
\return 0 for success or -1 for error.
*/
int _zoomSurfaceY(SDL_Surface * src, SDL_Surface * dst, int flipx, int flipy)
{
int x, y;
Uint32 *sax, *say, *csax, *csay;
int csx, csy;
Uint8 *sp, *dp, *csp ;
int dgap;
/*
* Allocate memory for row increments
*/
if ((sax = (Uint32 *) malloc((dst->w + 1) * sizeof(Uint32))) == NULL) {
return (-1);
}
if ((say = (Uint32 *) malloc((dst->h + 1) * sizeof(Uint32))) == NULL) {
free(sax);
return (-1);
}
/*
* Pointer setup
*/
dp = (Uint8 *) dst->pixels;
dgap = dst->pitch - dst->w;
csp = (Uint8 *) src->pixels;
if (flipx) csp += (src->w-1);
if (flipy) csp = ( (Uint8*)csp + src->pitch*(src->h-1) );
/*
* Precalculate row increments
*/
csx = 0;
csax = sax;
for (x = 0; x < dst->w; x++) {
csx += src->w;
*csax = 0;
while (csx >= dst->w) {
csx -= dst->w;
(*csax)++;
}
(*csax) = (*csax) * (flipx ? -1 : 1);
csax++;
}
csy = 0;
csay = say;
for (y = 0; y < dst->h; y++) {
csy += src->h;
*csay = 0;
while (csy >= dst->h) {
csy -= dst->h;
(*csay)++;
}
(*csay) = (*csay) * (flipy ? -1 : 1);
csay++;
}
/*
* Draw
*/
csay = say;
for (y = 0; y < dst->h; y++) {
csax = sax;
sp = csp;
for (x = 0; x < dst->w; x++) {
/*
* Draw
*/
*dp = *sp;
/*
* Advance source pointers
*/
sp += (*csax);
csax++;
/*
* Advance destination pointer
*/
dp++;
}
/*
* Advance source pointer (for row)
*/
csp += ((*csay) * src->pitch);
csay++;
/*
* Advance destination pointers
*/
dp += dgap;
}
/*
* Remove temp arrays
*/
free(sax);
free(say);
return (0);
}
/*!
\brief Internal 32 bit rotozoomer with optional anti-aliasing.
Rotates and zooms 32 bit RGBA/ABGR 'src' surface to 'dst' surface based on the control
parameters by scanning the destination surface and applying optionally anti-aliasing
by bilinear interpolation.
Assumes src and dst surfaces are of 32 bit depth.
Assumes dst surface was allocated with the correct dimensions.
\param src Source surface.
\param dst Destination surface.
\param cx Horizontal center coordinate.
\param cy Vertical center coordinate.
\param isin Integer version of sine of angle.
\param icos Integer version of cosine of angle.
\param flipx Flag indicating horizontal mirroring should be applied.
\param flipy Flag indicating vertical mirroring should be applied.
\param smooth Flag indicating anti-aliasing should be used.
*/
void _transformSurfaceRGBA(SDL_Surface * src, SDL_Surface * dst, int cx, int cy, int isin, int icos, int flipx, int flipy, int smooth)
{
int x, y, t1, t2, dx, dy, xd, yd, sdx, sdy, ax, ay, ex, ey, sw, sh;
tColorRGBA c00, c01, c10, c11, cswap;
tColorRGBA *pc, *sp;
int gap;
/*
* Variable setup
*/
xd = ((src->w - dst->w) << 15);
yd = ((src->h - dst->h) << 15);
ax = (cx << 16) - (icos * cx);
ay = (cy << 16) - (isin * cx);
sw = src->w - 1;
sh = src->h - 1;
pc = (tColorRGBA*) dst->pixels;
gap = dst->pitch - dst->w * 4;
/*
* Switch between interpolating and non-interpolating code
*/
if (smooth) {
for (y = 0; y < dst->h; y++) {
dy = cy - y;
sdx = (ax + (isin * dy)) + xd;
sdy = (ay - (icos * dy)) + yd;
for (x = 0; x < dst->w; x++) {
dx = (sdx >> 16);
dy = (sdy >> 16);
if (flipx) dx = sw - dx;
if (flipy) dy = sh - dy;
if ((dx > -1) && (dy > -1) && (dx < (src->w-1)) && (dy < (src->h-1))) {
sp = (tColorRGBA *)src->pixels;;
sp += ((src->pitch/4) * dy);
sp += dx;
c00 = *sp;
sp += 1;
c01 = *sp;
sp += (src->pitch/4);
c11 = *sp;
sp -= 1;
c10 = *sp;
if (flipx) {
cswap = c00; c00=c01; c01=cswap;
cswap = c10; c10=c11; c11=cswap;
}
if (flipy) {
cswap = c00; c00=c10; c10=cswap;
cswap = c01; c01=c11; c11=cswap;
}
/*
* Interpolate colors
*/
ex = (sdx & 0xffff);
ey = (sdy & 0xffff);
t1 = ((((c01.r - c00.r) * ex) >> 16) + c00.r) & 0xff;
t2 = ((((c11.r - c10.r) * ex) >> 16) + c10.r) & 0xff;
pc->r = (((t2 - t1) * ey) >> 16) + t1;
t1 = ((((c01.g - c00.g) * ex) >> 16) + c00.g) & 0xff;
t2 = ((((c11.g - c10.g) * ex) >> 16) + c10.g) & 0xff;
pc->g = (((t2 - t1) * ey) >> 16) + t1;
t1 = ((((c01.b - c00.b) * ex) >> 16) + c00.b) & 0xff;
t2 = ((((c11.b - c10.b) * ex) >> 16) + c10.b) & 0xff;
pc->b = (((t2 - t1) * ey) >> 16) + t1;
t1 = ((((c01.a - c00.a) * ex) >> 16) + c00.a) & 0xff;
t2 = ((((c11.a - c10.a) * ex) >> 16) + c10.a) & 0xff;
pc->a = (((t2 - t1) * ey) >> 16) + t1;
}
sdx += icos;
sdy += isin;
pc++;
}
pc = (tColorRGBA *) ((Uint8 *) pc + gap);
}
} else {
for (y = 0; y < dst->h; y++) {
dy = cy - y;
sdx = (ax + (isin * dy)) + xd;
sdy = (ay - (icos * dy)) + yd;
for (x = 0; x < dst->w; x++) {
dx = (short) (sdx >> 16);
dy = (short) (sdy >> 16);
if (flipx) dx = (src->w-1)-dx;
if (flipy) dy = (src->h-1)-dy;
if ((dx >= 0) && (dy >= 0) && (dx < src->w) && (dy < src->h)) {
sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
sp += dx;
*pc = *sp;
}
sdx += icos;
sdy += isin;
pc++;
}
pc = (tColorRGBA *) ((Uint8 *) pc + gap);
}
}
}
/*!
\brief Rotates and zooms 8 bit palette/Y 'src' surface to 'dst' surface without smoothing.
Rotates and zooms 8 bit RGBA/ABGR 'src' surface to 'dst' surface based on the control
parameters by scanning the destination surface.
Assumes src and dst surfaces are of 8 bit depth.
Assumes dst surface was allocated with the correct dimensions.
\param src Source surface.
\param dst Destination surface.
\param cx Horizontal center coordinate.
\param cy Vertical center coordinate.
\param isin Integer version of sine of angle.
\param icos Integer version of cosine of angle.
\param flipx Flag indicating horizontal mirroring should be applied.
\param flipy Flag indicating vertical mirroring should be applied.
*/
void transformSurfaceY(SDL_Surface * src, SDL_Surface * dst, int cx, int cy, int isin, int icos, int flipx, int flipy)
{
int x, y, dx, dy, xd, yd, sdx, sdy, ax, ay;
tColorY *pc, *sp;
int gap;
/*
* Variable setup
*/
xd = ((src->w - dst->w) << 15);
yd = ((src->h - dst->h) << 15);
ax = (cx << 16) - (icos * cx);
ay = (cy << 16) - (isin * cx);
pc = (tColorY*) dst->pixels;
gap = dst->pitch - dst->w;
/*
* Clear surface to colorkey
*/
memset(pc, (int)(_colorkey(src) & 0xff), dst->pitch * dst->h);
/*
* Iterate through destination surface
*/
for (y = 0; y < dst->h; y++) {
dy = cy - y;
sdx = (ax + (isin * dy)) + xd;
sdy = (ay - (icos * dy)) + yd;
for (x = 0; x < dst->w; x++) {
dx = (short) (sdx >> 16);
dy = (short) (sdy >> 16);
if (flipx) dx = (src->w-1)-dx;
if (flipy) dy = (src->h-1)-dy;
if ((dx >= 0) && (dy >= 0) && (dx < src->w) && (dy < src->h)) {
sp = (tColorY *) (src->pixels);
sp += (src->pitch * dy + dx);
*pc = *sp;
}
sdx += icos;
sdy += isin;
pc++;
}
pc += gap;
}
}
/*!
\brief Rotates a 8/16/24/32 bit surface in increments of 90 degrees.
Specialized 90 degree rotator which rotates a 'src' surface in 90 degree
increments clockwise returning a new surface. Faster than rotozoomer since
no scanning or interpolation takes place. Input surface must be 8/16/24/32 bit.
(code contributed by J. Schiller, improved by C. Allport and A. Schiffler)
\param src Source surface to rotate.
\param numClockwiseTurns Number of clockwise 90 degree turns to apply to the source.
\returns The new, rotated surface; or NULL for surfaces with incorrect input format.
*/
SDL_Surface* rotateSurface90Degrees(SDL_Surface* src, int numClockwiseTurns)
{
int row, col, newWidth, newHeight;
int bpp, bpr;
SDL_Surface* dst;
Uint8* srcBuf;
Uint8* dstBuf;
int normalizedClockwiseTurns;
/* Has to be a valid surface pointer and be a Nbit surface where n is divisible by 8 */
if (!src ||
!src->format) {
SDL_SetError("NULL source surface or source surface format");
return NULL;
}
if ((src->format->BitsPerPixel % 8) != 0) {
SDL_SetError("Invalid source surface bit depth");
return NULL;
}
/* normalize numClockwiseTurns */
normalizedClockwiseTurns = (numClockwiseTurns % 4);
if (normalizedClockwiseTurns < 0) {
normalizedClockwiseTurns += 4;
}
/* If turns are even, our new width/height will be the same as the source surface */
if (normalizedClockwiseTurns % 2) {
newWidth = src->h;
newHeight = src->w;
} else {
newWidth = src->w;
newHeight = src->h;
}
dst = SDL_CreateRGBSurface( src->flags, newWidth, newHeight, src->format->BitsPerPixel,
src->format->Rmask,
src->format->Gmask,
src->format->Bmask,
src->format->Amask);
if(!dst) {
SDL_SetError("Could not create destination surface");
return NULL;
}
if (SDL_MUSTLOCK(src)) {
SDL_LockSurface(src);
}
if (SDL_MUSTLOCK(dst)) {
SDL_LockSurface(dst);
}
/* Calculate byte-per-pixel */
bpp = src->format->BitsPerPixel / 8;
switch(normalizedClockwiseTurns) {
case 0: /* Make a copy of the surface */
{
/* Unfortunately SDL_BlitSurface cannot be used to make a copy of the surface
since it does not preserve alpha. */
if (src->pitch == dst->pitch) {
/* If the pitch is the same for both surfaces, the memory can be copied all at once. */
memcpy(dst->pixels, src->pixels, (src->h * src->pitch));
}
else
{
/* If the pitch differs, copy each row separately */
srcBuf = (Uint8*)(src->pixels);
dstBuf = (Uint8*)(dst->pixels);
bpr = src->w * bpp;
for (row = 0; row < src->h; row++) {
memcpy(dstBuf, srcBuf, bpr);
srcBuf += src->pitch;
dstBuf += dst->pitch;
}
}
}
break;
/* rotate clockwise */
case 1: /* rotated 90 degrees clockwise */
{
for (row = 0; row < src->h; ++row) {
srcBuf = (Uint8*)(src->pixels) + (row * src->pitch);
dstBuf = (Uint8*)(dst->pixels) + (dst->w - row - 1) * bpp;
for (col = 0; col < src->w; ++col) {
memcpy (dstBuf, srcBuf, bpp);
srcBuf += bpp;
dstBuf += dst->pitch;
}
}
}
break;
case 2: /* rotated 180 degrees clockwise */
{
for (row = 0; row < src->h; ++row) {
srcBuf = (Uint8*)(src->pixels) + (row * src->pitch);
dstBuf = (Uint8*)(dst->pixels) + ((dst->h - row - 1) * dst->pitch) + (dst->w - 1) * bpp;
for (col = 0; col < src->w; ++col) {
memcpy (dstBuf, srcBuf, bpp);
srcBuf += bpp;
dstBuf -= bpp;
}
}
}
break;
case 3: /* rotated 270 degrees clockwise */
{
for (row = 0; row < src->h; ++row) {
srcBuf = (Uint8*)(src->pixels) + (row * src->pitch);
dstBuf = (Uint8*)(dst->pixels) + (row * bpp) + (dst->h * dst->pitch);
for (col = 0; col < src->w; ++col) {
memcpy (dstBuf, srcBuf, bpp);
srcBuf += bpp;
dstBuf -= dst->pitch;
}
}
}
break;
}
/* end switch */
if (SDL_MUSTLOCK(src)) {
SDL_UnlockSurface(src);
}
if (SDL_MUSTLOCK(dst)) {
SDL_UnlockSurface(dst);
}
return dst;
}
/*!
\brief Internal target surface sizing function for rotozooms with trig result return.
\param width The source surface width.
\param height The source surface height.
\param angle The angle to rotate in degrees.
\param zoomx The horizontal scaling factor.
\param zoomy The vertical scaling factor.
\param dstwidth The calculated width of the destination surface.
\param dstheight The calculated height of the destination surface.
\param canglezoom The sine of the angle adjusted by the zoom factor.
\param sanglezoom The cosine of the angle adjusted by the zoom factor.
*/
void _rotozoomSurfaceSizeTrig(int width, int height, double angle, double zoomx, double zoomy,
int *dstwidth, int *dstheight,
double *canglezoom, double *sanglezoom)
{
double x, y, cx, cy, sx, sy;
double radangle;
int dstwidthhalf, dstheighthalf;
/*