diff window/SDL_rotozoom.cc @ 0:223b71206888

Initial import
author thib
date Fri, 01 Aug 2008 16:32:45 +0000
parents
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new file mode 100644
--- /dev/null
+++ b/window/SDL_rotozoom.cc
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+/*  
+
+  SDL_rotozoom.c - rotozoomer for 32bit or 8bit surfaces
+
+  LGPL (c) A. Schiffler
+
+*/
+
+#ifdef WIN32
+#include <windows.h>
+#endif
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "SDL_rotozoom.h"
+
+#define MAX(a,b)    (((a) > (b)) ? (a) : (b))
+
+/* 
+ 
+ 32bit Zoomer with optional anti-aliasing by bilinear interpolation.
+
+ Zoomes 32bit RGBA/ABGR 'src' surface to 'dst' surface.
+ 
+*/
+
+int zoomSurfaceRGBA(SDL_Surface * src, SDL_Surface * dst, int smooth)
+{
+    int x, y, sx, sy, *sax, *say, *csax, *csay, csx, csy, ex, ey, t1, t2, sstep;
+    tColorRGBA *c00, *c01, *c10, *c11;
+    tColorRGBA *sp, *csp, *dp;
+    int sgap, dgap;
+
+    /*
+     * Variable setup 
+     */
+    if (smooth) {
+	/*
+	 * For interpolation: assume source dimension is one pixel 
+	 */
+	/*
+	 * smaller to avoid overflow on right and bottom edge.     
+	 */
+	sx = (int) (65536.0 * (float) (src->w - 1) / (float) dst->w);
+	sy = (int) (65536.0 * (float) (src->h - 1) / (float) dst->h);
+    } else {
+	sx = (int) (65536.0 * (float) src->w / (float) dst->w);
+	sy = (int) (65536.0 * (float) src->h / (float) dst->h);
+    }
+
+    /*
+     * Allocate memory for row increments 
+     */
+    if ((sax = (int *) malloc((dst->w + 1) * sizeof(Uint32))) == NULL) {
+	return (-1);
+    }
+    if ((say = (int *) malloc((dst->h + 1) * sizeof(Uint32))) == NULL) {
+	free(sax);
+	return (-1);
+    }
+
+    /*
+     * Precalculate row increments 
+     */
+    csx = 0;
+    csax = sax;
+    for (x = 0; x <= dst->w; x++) {
+	*csax = csx;
+	csax++;
+	csx &= 0xffff;
+	csx += sx;
+    }
+    csy = 0;
+    csay = say;
+    for (y = 0; y <= dst->h; y++) {
+	*csay = csy;
+	csay++;
+	csy &= 0xffff;
+	csy += sy;
+    }
+
+    /*
+     * Pointer setup 
+     */
+    sp = csp = (tColorRGBA *) src->pixels;
+    dp = (tColorRGBA *) dst->pixels;
+    sgap = src->pitch - src->w * 4;
+    dgap = dst->pitch - dst->w * 4;
+
+    /*
+     * Switch between interpolating and non-interpolating code 
+     */
+    if (smooth) {
+
+	/*
+	 * Interpolating Zoom 
+	 */
+
+	/*
+	 * Scan destination 
+	 */
+	csay = say;
+	for (y = 0; y < dst->h; y++) {
+	    /*
+	     * Setup color source pointers 
+	     */
+	    c00 = csp;
+	    c01 = csp;
+	    c01++;
+	    c10 = (tColorRGBA *) ((Uint8 *) csp + src->pitch);
+	    c11 = c10;
+	    c11++;
+	    csax = sax;
+	    for (x = 0; x < dst->w; x++) {
+
+		/*
+		 * Interpolate colors 
+		 */
+		ex = (*csax & 0xffff);
+		ey = (*csay & 0xffff);
+		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 pointers 
+		 */
+		csax++;
+		sstep = (*csax >> 16);
+		c00 += sstep;
+		c01 += sstep;
+		c10 += sstep;
+		c11 += sstep;
+		/*
+		 * Advance destination pointer 
+		 */
+		dp++;
+	    }
+	    /*
+	     * Advance source pointer 
+	     */
+	    csay++;
+	    csp = (tColorRGBA *) ((Uint8 *) csp + (*csay >> 16) * src->pitch);
+	    /*
+	     * Advance destination pointers 
+	     */
+	    dp = (tColorRGBA *) ((Uint8 *) dp + dgap);
+	}
+
+    } else {
+
+	/*
+	 * Non-Interpolating Zoom 
+	 */
+
+	csay = say;
+	for (y = 0; y < dst->h; y++) {
+	    sp = csp;
+	    csax = sax;
+	    for (x = 0; x < dst->w; x++) {
+		/*
+		 * Draw 
+		 */
+		*dp = *sp;
+		/*
+		 * Advance source pointers 
+		 */
+		csax++;
+		sp += (*csax >> 16);
+		/*
+		 * Advance destination pointer 
+		 */
+		dp++;
+	    }
+	    /*
+	     * Advance source pointer 
+	     */
+	    csay++;
+	    csp = (tColorRGBA *) ((Uint8 *) csp + (*csay >> 16) * src->pitch);
+	    /*
+	     * Advance destination pointers 
+	     */
+	    dp = (tColorRGBA *) ((Uint8 *) dp + dgap);
+	}
+
+    }
+
+    /*
+     * Remove temp arrays 
+     */
+    free(sax);
+    free(say);
+
+    return (0);
+}
+
+/* 
+ 
+ 8bit Zoomer without smoothing.
+
+ Zoomes 8bit palette/Y 'src' surface to 'dst' surface.
+ 
+*/
+
+int zoomSurfaceY(SDL_Surface * src, SDL_Surface * dst)
+{
+    Uint32 x, y, sx, sy, *sax, *say, *csax, *csay, csx, csy;
+    Uint8 *sp, *dp, *csp;
+    int dgap;
+
+    /*
+     * Variable setup 
+     */
+    sx = (Uint32) (65536.0 * (float) src->w / (float) dst->w);
+    sy = (Uint32) (65536.0 * (float) src->h / (float) dst->h);
+
+    /*
+     * Allocate memory for row increments 
+     */
+    if ((sax = (Uint32 *) malloc(dst->w * sizeof(Uint32))) == NULL) {
+	return (-1);
+    }
+    if ((say = (Uint32 *) malloc(dst->h * sizeof(Uint32))) == NULL) {
+	if (sax != NULL) {
+	    free(sax);
+	}
+	return (-1);
+    }
+
+    /*
+     * Precalculate row increments 
+     */
+    csx = 0;
+    csax = sax;
+    for (x = 0; x < dst->w; x++) {
+	csx += sx;
+	*csax = (csx >> 16);
+	csx &= 0xffff;
+	csax++;
+    }
+    csy = 0;
+    csay = say;
+    for (y = 0; y < dst->h; y++) {
+	csy += sy;
+	*csay = (csy >> 16);
+	csy &= 0xffff;
+	csay++;
+    }
+
+    csx = 0;
+    csax = sax;
+    for (x = 0; x < dst->w; x++) {
+	csx += (*csax);
+	csax++;
+    }
+    csy = 0;
+    csay = say;
+    for (y = 0; y < dst->h; y++) {
+	csy += (*csay);
+	csay++;
+    }
+
+    /*
+     * Pointer setup 
+     */
+    sp = csp = (Uint8 *) src->pixels;
+    dp = (Uint8 *) dst->pixels;
+    dgap = dst->pitch - dst->w;
+
+    /*
+     * 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);
+}
+
+/* 
+ 
+ 32bit Rotozoomer with optional anti-aliasing by bilinear interpolation.
+
+ Rotates and zoomes 32bit RGBA/ABGR 'src' surface to 'dst' surface.
+ 
+*/
+
+void transformSurfaceRGBA(SDL_Surface * src, SDL_Surface * dst, int cx, int cy, int isin, int icos, int smooth)
+{
+    int x, y, t1, t2, dx, dy, xd, yd, sdx, sdy, ax, ay, ex, ey, sw, sh;
+    tColorRGBA c00, c01, c10, c11;
+    tColorRGBA *pc, *sp, *spb;
+    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 ((dx >= -1) && (dy >= -1) && (dx < src->w) && (dy < src->h)) {
+		    if ((dx >= 0) && (dy >= 0) && (dx < sw) && (dy < sh)) {
+			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
+			sp += dx;
+			c00 = *sp;
+			sp += 1;
+			c01 = *sp;
+			sp = (tColorRGBA *) ((Uint8 *) sp + src->pitch);
+			sp -= 1;
+			c10 = *sp;
+			sp += 1;
+			c11 = *sp;
+		    } else if ((dx == sw) && (dy == sh)) {
+			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
+			sp += dx;
+			c00 = *sp;
+			c01 = *sp;
+			c10 = *sp;
+			c11 = *sp;
+		    } else if ((dx == -1) && (dy == -1)) {
+			sp = (tColorRGBA *) (src->pixels);
+			c00 = *sp;
+			c01 = *sp;
+			c10 = *sp;
+			c11 = *sp;
+		    } else if ((dx == -1) && (dy == sh)) {
+			sp = (tColorRGBA *) (src->pixels);
+			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
+			c00 = *sp;
+			c01 = *sp;
+			c10 = *sp;
+			c11 = *sp;
+		    } else if ((dx == sw) && (dy == -1)) {
+			sp = (tColorRGBA *) (src->pixels);
+			sp += dx;
+			c00 = *sp;
+			c01 = *sp;
+			c10 = *sp;
+			c11 = *sp;
+		    } else if (dx == -1) {
+			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
+			c00 = *sp;
+			c01 = *sp;
+			c10 = *sp;
+			sp = (tColorRGBA *) ((Uint8 *) sp + src->pitch);
+			c11 = *sp;
+		    } else if (dy == -1) {
+			sp = (tColorRGBA *) (src->pixels);
+			sp += dx;
+			c00 = *sp;
+			c01 = *sp;
+			c10 = *sp;
+			sp += 1;
+			c11 = *sp;
+		    } else if (dx == sw) {
+			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
+			sp += dx;
+			c00 = *sp;
+			c01 = *sp;
+			sp = (tColorRGBA *) ((Uint8 *) sp + src->pitch);
+			c10 = *sp;
+			c11 = *sp;
+		    } else if (dy == sh) {
+			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
+			sp += dx;
+			c00 = *sp;
+			sp += 1;
+			c01 = *sp;
+			c10 = *sp;
+			c11 = *sp;
+		    }
+		    /*
+		     * 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 ((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);
+	}
+    }
+}
+
+/* 
+ 
+ 8bit Rotozoomer without smoothing
+
+ Rotates and zoomes 8bit palette/Y 'src' surface to 'dst' surface.
+ 
+*/
+
+void transformSurfaceY(SDL_Surface * src, SDL_Surface * dst, int cx, int cy, int isin, int icos)
+{
+    int x, y, dx, dy, xd, yd, sdx, sdy, ax, ay, sw, sh;
+    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);
+    sw = src->w - 1;
+    sh = src->h - 1;
+    pc = (tColorY*)(dst->pixels);
+    gap = dst->pitch - dst->w;
+    /*
+     * Clear surface to colorkey 
+     */
+    memset(pc, (unsigned char) (src->format->colorkey & 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 ((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;
+    }
+}
+
+/* 
+ 
+ rotozoomSurface()
+
+ Rotates and zoomes a 32bit or 8bit 'src' surface to newly created 'dst' surface.
+ 'angle' is the rotation in degrees. 'zoom' a scaling factor. If 'smooth' is 1
+ 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.
+
+*/
+
+#define VALUE_LIMIT	0.001
+
+
+/* Local rotozoom-size function with trig result return */
+
+void rotozoomSurfaceSizeTrig(int width, int height, double angle, double zoom, 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 *= zoom;
+    *canglezoom *= zoom;
+    x = width / 2;
+    y = height / 2;
+    cx = *canglezoom * x;
+    cy = *canglezoom * y;
+    sx = *sanglezoom * x;
+    sy = *sanglezoom * y;
+    dstwidthhalf = MAX((int)
+		       ceil(MAX(MAX(MAX(fabs(cx + sy), fabs(cx - sy)), fabs(-cx + sy)), fabs(-cx - sy))), 1);
+    dstheighthalf = MAX((int)
+			ceil(MAX(MAX(MAX(fabs(sx + cy), fabs(sx - cy)), fabs(-sx + cy)), fabs(-sx - cy))), 1);
+    *dstwidth = 2 * dstwidthhalf;
+    *dstheight = 2 * dstheighthalf;
+}
+
+
+/* Publically available rotozoom-size function */
+
+void rotozoomSurfaceSize(int width, int height, double angle, double zoom, int *dstwidth, int *dstheight)
+{
+    double dummy_sanglezoom, dummy_canglezoom;
+
+    rotozoomSurfaceSizeTrig(width, height, angle, zoom, dstwidth, dstheight, &dummy_sanglezoom, &dummy_canglezoom);
+}
+
+
+/* Publically available rotozoom function */
+
+SDL_Surface *rotozoomSurface(SDL_Surface * src, double angle, double zoom, int smooth)
+{
+    SDL_Surface *rz_src;
+    SDL_Surface *rz_dst;
+    double zoominv;
+    double sanglezoom, canglezoom, sanglezoominv, canglezoominv;
+    int dstwidthhalf, dstwidth, dstheighthalf, dstheight;
+    double x, y, cx, cy, sx, sy;
+    int is32bit;
+    int i, src_converted;
+
+    /*
+     * Sanity check 
+     */
+    if (src == NULL)
+	return (NULL);
+
+    /*
+     * 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, 0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000);
+	SDL_BlitSurface(src, NULL, rz_src, NULL);
+	src_converted = 1;
+	is32bit = 1;
+    }
+
+    /*
+     * Sanity check zoom factor 
+     */
+    if (zoom < VALUE_LIMIT) {
+	zoom = VALUE_LIMIT;
+    }
+    zoominv = 65536.0 / (zoom * zoom);
+
+    /*
+     * 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, zoom, &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 = NULL;
+	if (is32bit) {
+	    /*
+	     * Target surface is 32bit with source RGBA/ABGR ordering 
+	     */
+	    rz_dst =
+		SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight, 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, 8, 0, 0, 0, 0);
+	}
+
+	/*
+	 * Lock source surface 
+	 */
+	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,
+				 (int) (sanglezoominv), (int) (canglezoominv), smooth);
+	    /*
+	     * Turn on source-alpha support 
+	     */
+	    SDL_SetAlpha(rz_dst, SDL_SRCALPHA, 255);
+	} 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,
+			      (int) (sanglezoominv), (int) (canglezoominv));
+	    SDL_SetColorKey(rz_dst, SDL_SRCCOLORKEY | SDL_RLEACCEL, rz_src->format->colorkey);
+	}
+	/*
+	 * Unlock source surface 
+	 */
+	SDL_UnlockSurface(rz_src);
+
+    } else {
+
+	/*
+	 * Angle=0: Just a zoom 
+	 */
+	/*
+	 * -------------------- 
+	 */
+
+	/*
+	 * Calculate target size
+	 */
+	zoomSurfaceSize(rz_src->w, rz_src->h, zoom, zoom, &dstwidth, &dstheight);
+
+	/*
+	 * Alloc space to completely contain the zoomed surface 
+	 */
+	rz_dst = NULL;
+	if (is32bit) {
+	    /*
+	     * Target surface is 32bit with source RGBA/ABGR ordering 
+	     */
+	    rz_dst =
+		SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight, 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, 8, 0, 0, 0, 0);
+	}
+
+	/*
+	 * Lock source surface 
+	 */
+	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, smooth);
+	    /*
+	     * Turn on source-alpha support 
+	     */
+	    SDL_SetAlpha(rz_dst, SDL_SRCALPHA, 255);
+	} 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);
+	    SDL_SetColorKey(rz_dst, SDL_SRCCOLORKEY | SDL_RLEACCEL, rz_src->format->colorkey);
+	}
+	/*
+	 * Unlock source surface 
+	 */
+	SDL_UnlockSurface(rz_src);
+    }
+
+    /*
+     * Cleanup temp surface 
+     */
+    if (src_converted) {
+	SDL_FreeSurface(rz_src);
+    }
+
+    /*
+     * Return destination surface 
+     */
+    return (rz_dst);
+}
+
+/* 
+ 
+ zoomSurface()
+
+ Zoomes a 32bit or 8bit 'src' surface to newly created 'dst' surface.
+ 'zoomx' and 'zoomy' are scaling factors for width and height. If 'smooth' is 1
+ 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.
+
+*/
+
+#define VALUE_LIMIT	0.001
+
+void zoomSurfaceSize(int width, int height, double zoomx, double zoomy, int *dstwidth, int *dstheight)
+{
+    /*
+     * Sanity check zoom factors 
+     */
+    if (zoomx < VALUE_LIMIT) {
+	zoomx = VALUE_LIMIT;
+    }
+    if (zoomy < VALUE_LIMIT) {
+	zoomy = VALUE_LIMIT;
+    }
+
+    /*
+     * Calculate target size 
+     */
+    *dstwidth = (int) ((double) width * zoomx);
+    *dstheight = (int) ((double) height * zoomy);
+    if (*dstwidth < 1) {
+	*dstwidth = 1;
+    }
+    if (*dstheight < 1) {
+	*dstheight = 1;
+    }
+}
+
+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;
+
+    /*
+     * Sanity check 
+     */
+    if (src == NULL)
+	return (NULL);
+
+    /*
+     * 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, 0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000);
+	SDL_BlitSurface(src, NULL, rz_src, NULL);
+	src_converted = 1;
+	is32bit = 1;
+    }
+
+    /* 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 = NULL;
+    if (is32bit) {
+	/*
+	 * Target surface is 32bit with source RGBA/ABGR ordering 
+	 */
+	rz_dst =
+	    SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth, dstheight, 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, 8, 0, 0, 0, 0);
+    }
+
+    /*
+     * Lock source surface 
+     */
+    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, smooth);
+	/*
+	 * Turn on source-alpha support 
+	 */
+	SDL_SetAlpha(rz_dst, SDL_SRCALPHA, 255);
+    } 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);
+	SDL_SetColorKey(rz_dst, SDL_SRCCOLORKEY | SDL_RLEACCEL, rz_src->format->colorkey);
+    }
+    /*
+     * Unlock source surface 
+     */
+    SDL_UnlockSurface(rz_src);
+
+    /*
+     * Cleanup temp surface 
+     */
+    if (src_converted) {
+	SDL_FreeSurface(rz_src);
+    }
+
+    /*
+     * Return destination surface 
+     */
+    return (rz_dst);
+}