Fix and update internal sdl2_gfx files.

Used by default in SDL2 builds.

1 files changed, 1667 insertions, 0 deletions

diff --git a/src/sdl2gfx/SDL2_rotozoom.cpp b/src/sdl2gfx/SDL2_rotozoom.cpp
new file mode 100644
index 000000000..73461999f
--- /dev/null
+++ b/src/sdl2gfx/SDL2_rotozoom.cpp
@@ -0,0 +1,1667 @@
+/*  
+
+SDL2_rotozoom.c: rotozoomer, zoomer and shrinker for 32bit or 8bit surfaces
+
+Copyright (C) 2012-2014  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
+
+Changed for ManaPlus (C) 2013-2017  ManaPlus developers
+
+*/
+
+#ifdef WIN32
+#include <windows.h>
+#endif
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "sdl2gfx/SDL2_rotozoom.h"
+
+/* ---- 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
+*/
+static 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.
+*/
+static 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 = static_cast<tColorRGBA *>(src->pixels);
+	
+	dp = static_cast<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 = reinterpret_cast<tColorRGBA *>(reinterpret_cast<Uint8*>(sp) + (src->pitch - 4*factorx)); // next y
+			}
+			/* src dy loop */
+
+			/* next box-x */
+			sp = reinterpret_cast<tColorRGBA *>(reinterpret_cast<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 = reinterpret_cast<tColorRGBA *>(reinterpret_cast<Uint8*>(osp) + src->pitch*factory);
+
+		/*
+		* Advance destination pointers 
+		*/
+		dp = reinterpret_cast<tColorRGBA *>(reinterpret_cast<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.
+*/
+static 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 = static_cast<Uint8*>(src->pixels);
+
+	dp = static_cast<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 = static_cast<Uint8*>(static_cast<Uint8*>(sp) + (src->pitch - factorx)); 
+			} 
+			/* end src dy loop */
+
+			/* next box-x */
+			sp = static_cast<Uint8*>(static_cast<Uint8*>(oosp) + factorx);
+
+			/* Store result in destination */
+			*dp = a/n_average;
+
+			/*
+			* Advance destination pointer 
+			*/
+			dp++;
+		} 
+		/* end dst x loop */
+
+		/* next box-y */
+		sp = static_cast<Uint8*>(static_cast<Uint8*>(osp) + src->pitch*factory);
+
+		/*
+		* Advance destination pointers 
+		*/
+		dp = static_cast<Uint8*>(static_cast<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.
+*/
+static 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 = static_cast<int *>(malloc((dst->w + 1) * sizeof(Uint32)))) == nullptr) {
+		return (-1);
+	}
+	if ((say = static_cast<int *>(malloc((dst->h + 1) * sizeof(Uint32)))) == nullptr) {
+		free(sax);
+		return (-1);
+	}
+
+	/*
+	* Precalculate row increments 
+	*/
+	spixelw = (src->w - 1);
+	spixelh = (src->h - 1);
+	if (smooth) {
+		sx = static_cast<int>(65536.0 * static_cast<float>(spixelw) / static_cast<float>(dst->w - 1));
+		sy = static_cast<int>(65536.0 * static_cast<float>(spixelh) / static_cast<float>(dst->h - 1));
+	} else {
+		sx = static_cast<int>(65536.0 * static_cast<float>(src->w) / static_cast<float>(dst->w));
+		sy = static_cast<int>(65536.0 * static_cast<float>(src->h) / static_cast<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 = static_cast<tColorRGBA *>(src->pixels);
+	dp = static_cast<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 = reinterpret_cast<tColorRGBA *>(reinterpret_cast<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 = reinterpret_cast<tColorRGBA *>(reinterpret_cast<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.
+*/
+static 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 = static_cast<Uint32 *>(malloc((dst->w + 1) * sizeof(Uint32)))) == nullptr) {
+		return (-1);
+	}
+	if ((say = static_cast<Uint32 *>(malloc((dst->h + 1) * sizeof(Uint32)))) == nullptr) {
+		free(sax);
+		return (-1);
+	}
+
+	/*
+	* Pointer setup 
+	*/
+	sp = csp = static_cast<Uint8*>(src->pixels);
+	dp = static_cast<Uint8*>(dst->pixels);
+	dgap = dst->pitch - dst->w;
+
+	if (flipx) csp += (src->w-1);
+	if (flipy) csp  = (static_cast<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.
+*/
+static 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 = static_cast<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 = static_cast<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 = reinterpret_cast<tColorRGBA *>(reinterpret_cast<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 = static_cast<short>(sdx >> 16);
+				dy = static_cast<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 = reinterpret_cast<tColorRGBA *>(reinterpret_cast<Uint8*>(src->pixels) + src->pitch * dy);
+					sp += dx;
+					*pc = *sp;
+				}
+				sdx += icos;
+				sdy += isin;
+				pc++;
+			}
+			pc = reinterpret_cast<tColorRGBA *>(reinterpret_cast<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.
+*/
+static 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 = static_cast<tColorY*>(dst->pixels);
+	gap = dst->pitch - dst->w;
+	/*
+	* Clear surface to colorkey 
+	*/ 	
+	memset(pc, static_cast<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 = static_cast<short>(sdx >> 16);
+			dy = static_cast<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 = static_cast<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 nullptr 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 nullptr; 
+	}
+
+	if ((src->format->BitsPerPixel % 8) != 0) {
+		SDL_SetError("Invalid source surface bit depth");
+	    return nullptr; 
+	}
+
+	/* 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 nullptr;
+	}
+
+	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 = static_cast<Uint8*>(src->pixels);
+				dstBuf = static_cast<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 = static_cast<Uint8*>(src->pixels) + (row * src->pitch);
+				dstBuf = static_cast<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 = static_cast<Uint8*>(src->pixels) + (row * src->pitch);
+				dstBuf = static_cast<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 = static_cast<Uint8*>(src->pixels) + (row * src->pitch);
+				dstBuf = static_cast<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;
+	default:
+		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.
+
+*/
+static 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;
+
+	/*
+	* Determine destination width and height by rotating a centered source box 
+	*/
+	radangle = angle * (M_PI / 180.0);
+	*sanglezoom = sin(radangle);
+	*canglezoom = cos(radangle);
+	*sanglezoom *= zoomx;
+	*canglezoom *= zoomy;
+	x = static_cast<double>(width / 2);
+	y = static_cast<double>(height / 2);
+	cx = *canglezoom * x;
+	cy = *canglezoom * y;
+	sx = *sanglezoom * x;
+	sy = *sanglezoom * y;
+
+	dstwidthhalf = MAX(static_cast<int>(
+		ceil(MAX(MAX(MAX(fabs(cx + sy), fabs(cx - sy)), fabs(-cx + sy)), fabs(-cx - sy)))), 1);
+	dstheighthalf = MAX(static_cast<int>(
+		ceil(MAX(MAX(MAX(fabs(sx + cy), fabs(sx - cy)), fabs(-sx + cy)), fabs(-sx - cy)))), 1);
+	*dstwidth = 2 * dstwidthhalf;
+	*dstheight = 2 * dstheighthalf;
+}
+
+/*! 
+\brief Returns the size of the resulting target surface for a rotozoomSurfaceXY() call. 
+
+\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 rotozoomed destination surface.
+\param dstheight The calculated height of the rotozoomed destination surface.
+*/
+void rotozoomSurfaceSizeXY(int width, int height, double angle, double zoomx, double zoomy, int *dstwidth, int *dstheight)
+{
+	double dummy_sanglezoom, dummy_canglezoom;
+
+	_rotozoomSurfaceSizeTrig(width, height, angle, zoomx, zoomy, dstwidth, dstheight, &dummy_sanglezoom, &dummy_canglezoom);
+}
+
+/*! 
+\brief Returns the size of the resulting target surface for a rotozoomSurface() call. 
+
+\param width The source surface width.
+\param height The source surface height.
+\param angle The angle to rotate in degrees.
+\param zoom The scaling factor.
+\param dstwidth The calculated width of the rotozoomed destination surface.
+\param dstheight The calculated height of the rotozoomed destination surface.
+*/
+void rotozoomSurfaceSize(int width, int height, double angle, double zoom, int *dstwidth, int *dstheight)
+{
+	double dummy_sanglezoom, dummy_canglezoom;
+
+	_rotozoomSurfaceSizeTrig(width, height, angle, zoom, zoom, dstwidth, dstheight, &dummy_sanglezoom, &dummy_canglezoom);
+}
+
+/*!
+\brief Rotates and zooms a surface and optional anti-aliasing. 
+
+Rotates and zoomes a 32bit or 8bit 'src' surface to newly created 'dst' surface.
+'angle' is the rotation in degrees and 'zoom' a scaling factor. If 'smooth' is set
+then the destination 32bit surface is anti-aliased. If the surface is not 8bit
+or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly.
+
+\param src The surface to rotozoom.
+\param angle The angle to rotate in degrees.
+\param zoom The scaling factor.
+\param smooth Antialiasing flag; set to SMOOTHING_ON to enable.
+
+\return The new rotozoomed surface.
+*/
+SDL_Surface *rotozoomSurface(SDL_Surface * src, double angle, double zoom, int smooth)
+{
+	return rotozoomSurfaceXY(src, angle, zoom, zoom, smooth);
+}
+
+/*!
+\brief Rotates and zooms a surface with different horizontal and vertival scaling factors and optional anti-aliasing. 
+
+Rotates and zooms a 32bit or 8bit 'src' surface to newly created 'dst' surface.
+'angle' is the rotation in degrees, 'zoomx and 'zoomy' scaling factors. If 'smooth' is set
+then the destination 32bit surface is anti-aliased. If the surface is not 8bit
+or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly.
+
+\param src The surface to rotozoom.
+\param angle The angle to rotate in degrees.
+\param zoomx The horizontal scaling factor.
+\param zoomy The vertical scaling factor.
+\param smooth Antialiasing flag; set to SMOOTHING_ON to enable.
+
+\return The new rotozoomed surface.
+*/
+SDL_Surface *rotozoomSurfaceXY(SDL_Surface * src, double angle, double zoomx, double zoomy, int smooth)
+{
+	SDL_Surface *rz_src;
+	SDL_Surface *rz_dst;
+	double zoominv;
+	double sanglezoom, canglezoom, sanglezoominv, canglezoominv;
+	int dstwidthhalf, dstwidth, dstheighthalf, dstheight;
+	int is32bit;
+	int i, src_converted;
+	int flipx,flipy;
+
+	/*
+	* Sanity check 
+	*/
+	if (src == nullptr) {
+		return (nullptr);
+	}
+
+	/*
+	* Determine if source surface is 32bit or 8bit 
+	*/
+	is32bit = (src->format->BitsPerPixel == 32);
+	if ((is32bit) || (src->format->BitsPerPixel == 8)) {
+		/*
+		* Use source surface 'as is' 
+		*/
+		rz_src = src;
+		src_converted = 0;
+	} else {
+		/*
+		* New source surface is 32bit with a defined RGBA ordering 
+		*/
+		rz_src =
+			SDL_CreateRGBSurface(SDL_SWSURFACE, src->w, src->h, 32, 
+#if SDL_BYTEORDER == SDL_LIL_ENDIAN
+			0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000
+#else
+			0xff000000,  0x00ff0000, 0x0000ff00, 0x000000ff
+#endif
+			);
+
+		SDL_BlitSurface(src, nullptr, rz_src, nullptr);
+
+		src_converted = 1;
+		is32bit = 1;
+	}
+
+	/*
+	* Sanity check zoom factor 
+	*/
+	flipx = (zoomx<0.0);
+	if (flipx) zoomx=-zoomx;
+	flipy = (zoomy<0.0);
+	if (flipy) zoomy=-zoomy;
+	if (zoomx < VALUE_LIMIT) zoomx = VALUE_LIMIT;
+	if (zoomy < VALUE_LIMIT) zoomy = VALUE_LIMIT;
+	zoominv = 65536.0 / (zoomx * zoomx);
+
+	/*
+	* Check if we have a rotozoom or just a zoom 
+	*/
+	if (fabs(angle) > VALUE_LIMIT) {
+
+		/*
+		* Angle!=0: full rotozoom 
+		*/
+		/*
+		* ----------------------- 
+		*/
+
+		/* Determine target size */
+		_rotozoomSurfaceSizeTrig(rz_src->w, rz_src->h, angle, zoomx, zoomy, &dstwidth, &dstheight, &canglezoom, &sanglezoom);
+
+		/*
+		* Calculate target factors from sin/cos and zoom 
+		*/
+		sanglezoominv = sanglezoom;
+		canglezoominv = canglezoom;
+		sanglezoominv *= zoominv;
+		canglezoominv *= zoominv;
+
+		/* Calculate half size */
+		dstwidthhalf = dstwidth / 2;
+		dstheighthalf = dstheight / 2;
+
+		/*
+		* Alloc space to completely contain the rotated surface 
+		*/
+		rz_dst = nullptr;
+		if (is32bit) {
+			/*
+			* Target surface is 32bit with source RGBA/ABGR ordering 
+			*/
+			rz_dst =
+				SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight + GUARD_ROWS, 32,
+				rz_src->format->Rmask, rz_src->format->Gmask,
+				rz_src->format->Bmask, rz_src->format->Amask);
+		} else {
+			/*
+			* Target surface is 8bit 
+			*/
+			rz_dst = SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight + GUARD_ROWS, 8, 0, 0, 0, 0);
+		}
+
+		/* Check target */
+		if (rz_dst == nullptr)
+			return nullptr;
+
+		/* Adjust for guard rows */
+		rz_dst->h = dstheight;
+
+		/*
+		* Lock source surface 
+		*/
+		if (SDL_MUSTLOCK(rz_src)) {
+			SDL_LockSurface(rz_src);
+		}
+
+		/*
+		* Check which kind of surface we have 
+		*/
+		if (is32bit) {
+			/*
+			* Call the 32bit transformation routine to do the rotation (using alpha) 
+			*/
+			_transformSurfaceRGBA(rz_src, rz_dst, dstwidthhalf, dstheighthalf,
+				static_cast<int>(sanglezoominv), static_cast<int>(canglezoominv), 
+				flipx, flipy,
+				smooth);
+		} else {
+			/*
+			* Copy palette and colorkey info 
+			*/
+			for (i = 0; i < rz_src->format->palette->ncolors; i++) {
+				rz_dst->format->palette->colors[i] = rz_src->format->palette->colors[i];
+			}
+			rz_dst->format->palette->ncolors = rz_src->format->palette->ncolors;
+			/*
+			* Call the 8bit transformation routine to do the rotation 
+			*/
+			transformSurfaceY(rz_src, rz_dst, dstwidthhalf, dstheighthalf,
+				static_cast<int>(sanglezoominv), static_cast<int>(canglezoominv),
+				flipx, flipy);
+		}
+		/*
+		* Unlock source surface 
+		*/
+		if (SDL_MUSTLOCK(rz_src)) {
+			SDL_UnlockSurface(rz_src);
+		}
+
+	} else {
+
+		/*
+		* Angle=0: Just a zoom 
+		*/
+		/*
+		* -------------------- 
+		*/
+
+		/*
+		* Calculate target size
+		*/
+		zoomSurfaceSize(rz_src->w, rz_src->h, zoomx, zoomy, &dstwidth, &dstheight);
+
+		/*
+		* Alloc space to completely contain the zoomed surface 
+		*/
+		rz_dst = nullptr;
+		if (is32bit) {
+			/*
+			* Target surface is 32bit with source RGBA/ABGR ordering 
+			*/
+			rz_dst =
+				SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight + GUARD_ROWS, 32,
+				rz_src->format->Rmask, rz_src->format->Gmask,
+				rz_src->format->Bmask, rz_src->format->Amask);
+		} else {
+			/*
+			* Target surface is 8bit 
+			*/
+			rz_dst = SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight + GUARD_ROWS, 8, 0, 0, 0, 0);
+		}
+
+		/* Check target */
+		if (rz_dst == nullptr)
+			return nullptr;
+
+		/* Adjust for guard rows */
+		rz_dst->h = dstheight;
+
+		/*
+		* Lock source surface 
+		*/
+		if (SDL_MUSTLOCK(rz_src)) {
+			SDL_LockSurface(rz_src);
+		}
+
+		/*
+		* Check which kind of surface we have 
+		*/
+		if (is32bit) {
+			/*
+			* Call the 32bit transformation routine to do the zooming (using alpha) 
+			*/
+			_zoomSurfaceRGBA(rz_src, rz_dst, flipx, flipy, smooth);
+
+		} else {
+			/*
+			* Copy palette and colorkey info 
+			*/
+			for (i = 0; i < rz_src->format->palette->ncolors; i++) {
+				rz_dst->format->palette->colors[i] = rz_src->format->palette->colors[i];
+			}
+			rz_dst->format->palette->ncolors = rz_src->format->palette->ncolors;
+
+			/*
+			* Call the 8bit transformation routine to do the zooming 
+			*/
+			_zoomSurfaceY(rz_src, rz_dst, flipx, flipy);
+		}
+
+		/*
+		* Unlock source surface 
+		*/
+		if (SDL_MUSTLOCK(rz_src)) {
+			SDL_UnlockSurface(rz_src);
+		}
+	}
+
+	/*
+	* Cleanup temp surface 
+	*/
+	if (src_converted) {
+		SDL_FreeSurface(rz_src);
+	}
+
+	/*
+	* Return destination surface 
+	*/
+	return (rz_dst);
+}
+
+/*!
+\brief Calculates the size of the target surface for a zoomSurface() call.
+
+The minimum size of the target surface is 1. The input factors can be positive or negative.
+
+\param width The width of the source surface to zoom.
+\param height The height of the source surface to zoom.
+\param zoomx The horizontal zoom factor.
+\param zoomy The vertical zoom factor.
+\param dstwidth Pointer to an integer to store the calculated width of the zoomed target surface.
+\param dstheight Pointer to an integer to store the calculated height of the zoomed target surface.
+*/
+void zoomSurfaceSize(int width, int height, double zoomx, double zoomy, int *dstwidth, int *dstheight)
+{
+	/*
+	* Make zoom factors positive 
+	*/
+	int flipx, flipy;
+	flipx = (zoomx<0.0);
+	if (flipx) zoomx = -zoomx;
+	flipy = (zoomy<0.0);
+	if (flipy) zoomy = -zoomy;
+
+	/*
+	* Sanity check zoom factors 
+	*/
+	if (zoomx < VALUE_LIMIT) {
+		zoomx = VALUE_LIMIT;
+	}
+	if (zoomy < VALUE_LIMIT) {
+		zoomy = VALUE_LIMIT;
+	}
+
+	/*
+	* Calculate target size 
+	*/
+	*dstwidth = static_cast<int>(floor((static_cast<double>(width) * zoomx) + 0.5));
+	*dstheight = static_cast<int>(floor((static_cast<double>(height) * zoomy) + 0.5));
+	if (*dstwidth < 1) {
+		*dstwidth = 1;
+	}
+	if (*dstheight < 1) {
+		*dstheight = 1;
+	}
+}
+
+/*! 
+\brief Zoom a surface by independent horizontal and vertical factors with optional smoothing.
+
+Zooms a 32bit or 8bit 'src' surface to newly created 'dst' surface.
+'zoomx' and 'zoomy' are scaling factors for width and height. If 'smooth' is on
+then the destination 32bit surface is anti-aliased. If the surface is not 8bit
+or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly.
+If zoom factors are negative, the image is flipped on the axes.
+
+\param src The surface to zoom.
+\param zoomx The horizontal zoom factor.
+\param zoomy The vertical zoom factor.
+\param smooth Antialiasing flag; set to SMOOTHING_ON to enable.
+
+\return The new, zoomed surface.
+*/
+SDL_Surface *zoomSurface(SDL_Surface * src, double zoomx, double zoomy, int smooth)
+{
+	SDL_Surface *rz_src;
+	SDL_Surface *rz_dst;
+	int dstwidth, dstheight;
+	int is32bit;
+	int i, src_converted;
+	int flipx, flipy;
+
+	/*
+	* Sanity check 
+	*/
+	if (src == nullptr)
+		return (nullptr);
+
+	/*
+	* Determine if source surface is 32bit or 8bit 
+	*/
+	is32bit = (src->format->BitsPerPixel == 32);
+	if ((is32bit) || (src->format->BitsPerPixel == 8)) {
+		/*
+		* Use source surface 'as is' 
+		*/
+		rz_src = src;
+		src_converted = 0;
+	} else {
+		/*
+		* New source surface is 32bit with a defined RGBA ordering 
+		*/
+		rz_src =
+			SDL_CreateRGBSurface(SDL_SWSURFACE, src->w, src->h, 32, 
+#if SDL_BYTEORDER == SDL_LIL_ENDIAN
+			0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000
+#else
+			0xff000000,  0x00ff0000, 0x0000ff00, 0x000000ff
+#endif
+			);
+		if (rz_src == nullptr) {
+			return nullptr;
+		}
+		SDL_BlitSurface(src, nullptr, rz_src, nullptr);
+		src_converted = 1;
+		is32bit = 1;
+	}
+
+	flipx = (zoomx<0.0);
+	if (flipx) zoomx = -zoomx;
+	flipy = (zoomy<0.0);
+	if (flipy) zoomy = -zoomy;
+
+	/* Get size if target */
+	zoomSurfaceSize(rz_src->w, rz_src->h, zoomx, zoomy, &dstwidth, &dstheight);
+
+	/*
+	* Alloc space to completely contain the zoomed surface 
+	*/
+	rz_dst = nullptr;
+	if (is32bit) {
+		/*
+		* Target surface is 32bit with source RGBA/ABGR ordering 
+		*/
+		rz_dst =
+			SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight + GUARD_ROWS, 32,
+			rz_src->format->Rmask, rz_src->format->Gmask,
+			rz_src->format->Bmask, rz_src->format->Amask);
+	} else {
+		/*
+		* Target surface is 8bit 
+		*/
+		rz_dst = SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight + GUARD_ROWS, 8, 0, 0, 0, 0);
+	}
+
+	/* Check target */
+	if (rz_dst == nullptr) {
+		/*
+		* Cleanup temp surface 
+		*/
+		if (src_converted) {
+			SDL_FreeSurface(rz_src);
+		}		
+		return nullptr;
+	}
+
+	/* Adjust for guard rows */
+	rz_dst->h = dstheight;
+
+	/*
+	* Lock source surface 
+	*/
+	if (SDL_MUSTLOCK(rz_src)) {
+		SDL_LockSurface(rz_src);
+	}
+
+	/*
+	* Check which kind of surface we have 
+	*/
+	if (is32bit) {
+		/*
+		* Call the 32bit transformation routine to do the zooming (using alpha) 
+		*/
+		_zoomSurfaceRGBA(rz_src, rz_dst, flipx, flipy, smooth);
+	} else {
+		/*
+		* Copy palette and colorkey info 
+		*/
+		for (i = 0; i < rz_src->format->palette->ncolors; i++) {
+			rz_dst->format->palette->colors[i] = rz_src->format->palette->colors[i];
+		}
+		rz_dst->format->palette->ncolors = rz_src->format->palette->ncolors;
+		/*
+		* Call the 8bit transformation routine to do the zooming 
+		*/
+		_zoomSurfaceY(rz_src, rz_dst, flipx, flipy);
+	}
+	/*
+	* Unlock source surface 
+	*/
+	if (SDL_MUSTLOCK(rz_src)) {
+		SDL_UnlockSurface(rz_src);
+	}
+
+	/*
+	* Cleanup temp surface 
+	*/
+	if (src_converted) {
+		SDL_FreeSurface(rz_src);
+	}
+
+	/*
+	* Return destination surface 
+	*/
+	return (rz_dst);
+}
+
+/*! 
+\brief Shrink a surface by an integer ratio using averaging.
+
+Shrinks a 32bit or 8bit 'src' surface to a newly created 'dst' surface.
+'factorx' and 'factory' are the shrinking ratios (i.e. 2=1/2 the size,
+3=1/3 the size, etc.) The destination surface is antialiased by averaging
+the source box RGBA or Y information. If the surface is not 8bit
+or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly.
+The input surface is not modified. The output surface is newly allocated.
+
+\param src The surface to shrink.
+\param factorx The horizontal shrinking ratio.
+\param factory The vertical shrinking ratio.
+
+\return The new, shrunken surface.
+*/
+/*@nullptr@*/ 
+SDL_Surface *shrinkSurface(SDL_Surface *src, int factorx, int factory)
+{
+	int result;
+	SDL_Surface *rz_src;
+	SDL_Surface *rz_dst = nullptr;
+	int dstwidth, dstheight;
+	int is32bit;
+	int i, src_converted = 0;
+	int haveError = 0;
+
+	/*
+	* Sanity check 
+	*/
+	if (src == nullptr) {
+		return (nullptr);
+	}
+
+	/*
+	* Determine if source surface is 32bit or 8bit 
+	*/
+	is32bit = (src->format->BitsPerPixel == 32);
+	if ((is32bit) || (src->format->BitsPerPixel == 8)) {
+		/*
+		* Use source surface 'as is' 
+		*/
+		rz_src = src;
+		src_converted = 0;
+	} else {
+		/*
+		* New source surface is 32bit with a defined RGBA ordering 
+		*/
+		rz_src = SDL_CreateRGBSurface(SDL_SWSURFACE, src->w, src->h, 32, 
+#if SDL_BYTEORDER == SDL_LIL_ENDIAN
+			0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000
+#else
+			0xff000000,  0x00ff0000, 0x0000ff00, 0x000000ff
+#endif
+			);
+		if (rz_src==nullptr) {
+			haveError = 1;
+			goto exitShrinkSurface;
+		}
+
+		SDL_BlitSurface(src, nullptr, rz_src, nullptr);
+		src_converted = 1;
+		is32bit = 1;
+	}
+
+	/*
+	* Lock the surface 
+	*/
+	if (SDL_MUSTLOCK(rz_src)) {
+		if (SDL_LockSurface(rz_src) < 0) {
+			haveError = 1;
+			goto exitShrinkSurface;
+		}
+	}
+
+	/* Get size for target */
+	dstwidth=rz_src->w/factorx;
+	while (dstwidth*factorx>rz_src->w) { dstwidth--; }
+	dstheight=rz_src->h/factory;
+	while (dstheight*factory>rz_src->h) { dstheight--; }
+
+	/*
+	* Alloc space to completely contain the shrunken surface
+	* (with added guard rows)
+	*/
+	if (is32bit==1) {
+		/*
+		* Target surface is 32bit with source RGBA/ABGR ordering 
+		*/
+		rz_dst =
+			SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight + GUARD_ROWS, 32,
+			rz_src->format->Rmask, rz_src->format->Gmask,
+			rz_src->format->Bmask, rz_src->format->Amask);
+	} else {
+		/*
+		* Target surface is 8bit 
+		*/
+		rz_dst = SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight + GUARD_ROWS, 8, 0, 0, 0, 0);
+	}
+
+	/* Check target */
+	if (rz_dst == nullptr) {
+		haveError = 1;
+		goto exitShrinkSurface;
+	}
+
+	/* Adjust for guard rows */
+	rz_dst->h = dstheight;
+
+	/*
+	* Check which kind of surface we have 
+	*/
+	if (is32bit==1) {
+		/*
+		* Call the 32bit transformation routine to do the shrinking (using alpha) 
+		*/
+		result = _shrinkSurfaceRGBA(rz_src, rz_dst, factorx, factory);		
+		if ((result!=0) || (rz_dst==nullptr)) {
+			haveError = 1;
+			goto exitShrinkSurface;
+		}
+	} else {
+		/*
+		* Copy palette and colorkey info 
+		*/
+		for (i = 0; i < rz_src->format->palette->ncolors; i++) {
+			rz_dst->format->palette->colors[i] = rz_src->format->palette->colors[i];
+		}
+		rz_dst->format->palette->ncolors = rz_src->format->palette->ncolors;
+		/*
+		* Call the 8bit transformation routine to do the shrinking 
+		*/
+		result = _shrinkSurfaceY(rz_src, rz_dst, factorx, factory);
+		if (result!=0) {
+			haveError = 1;
+			goto exitShrinkSurface;
+		}
+	}
+
+exitShrinkSurface:
+	if (rz_src!=nullptr) {
+		/*
+		* Unlock source surface 
+		*/
+		if (SDL_MUSTLOCK(rz_src)) {
+			SDL_UnlockSurface(rz_src);
+		}
+
+		/*
+		* Cleanup temp surface 
+		*/
+		if (src_converted==1) {
+			SDL_FreeSurface(rz_src);
+		}
+	}
+
+	/* Check error state; maybe need to cleanup destination */
+	if (haveError==1) {
+		if (rz_dst!=nullptr) {
+			SDL_FreeSurface(rz_dst);
+		}
+		rz_dst=nullptr;
+	} 
+
+	/*
+	* Return destination surface 
+	*/
+	return (rz_dst);
+}