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/*
* The Python Imaging Library
* $Id$
*
* offset an image in x and y directions
*
* history:
* 96-07-22 fl: Created
* 98-11-01 cgw@pgt.com: Fixed negative-array index bug
*
* Copyright (c) Fredrik Lundh 1996.
* Copyright (c) Secret Labs AB 1997.
*
* See the README file for information on usage and redistribution.
*/
#include "Imaging.h"
Imaging
ImagingOffset(Imaging im, int xoffset, int yoffset) {
int x, y;
Imaging imOut;
if (!im) {
return (Imaging)ImagingError_ModeError();
}
imOut = ImagingNewDirty(im->mode, im->xsize, im->ysize);
if (!imOut) {
return NULL;
}
ImagingCopyPalette(imOut, im);
/* make offsets positive to avoid negative coordinates */
xoffset %= im->xsize;
xoffset = im->xsize - xoffset;
if (xoffset < 0) {
xoffset += im->xsize;
}
yoffset %= im->ysize;
yoffset = im->ysize - yoffset;
if (yoffset < 0) {
yoffset += im->ysize;
}
#define OFFSET(image) \
for (y = 0; y < im->ysize; y++) { \
for (x = 0; x < im->xsize; x++) { \
int yi = (y + yoffset) % im->ysize; \
int xi = (x + xoffset) % im->xsize; \
imOut->image[y][x] = im->image[yi][xi]; \
} \
}
if (im->image8) {
OFFSET(image8)
} else {
OFFSET(image32)
}
return imOut;
}
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