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/* zoom.c - Copyright (C) 2001-2002 Jacob Kroon, see COPYING for details */
/* Zoom code originally by A. Schiffler, aschiffler@cogeco.ca */
#include <stdlib.h>
#include <SDL_video.h>
/* defines */
#define VALUE_LIMIT 0.001
/* zoom code */
static 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);
}
SDL_Surface *zoomSurface(SDL_Surface * src, float zoom)
{
SDL_Surface *rz_src;
SDL_Surface *rz_dst;
int dstwidth, dstheight;
int i;
/* Sanity check */
if (src == NULL)
return (NULL);
if (src->format->BitsPerPixel != 8)
return NULL;
rz_src = src;
/* Sanity check zoom factors */
if (zoom < VALUE_LIMIT) {
zoom = VALUE_LIMIT;
}
/* Calculate target size and set rect */
dstwidth = (int) ((double) rz_src->w * zoom);
dstheight = (int) ((double) rz_src->h * zoom);
if (dstwidth < 1) {
dstwidth = 1;
}
if (dstheight < 1) {
dstheight = 1;
}
/* Alloc space to completely contain the zoomed surface */
rz_dst = NULL;
/* 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 */
/* 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);
/* Return destination surface */
return (rz_dst);
}
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