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/*
* The Python Imaging Library
* $Id: Offset.c 2134 2004-10-06 08:55:20Z fredrik $
*
* 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 = ImagingNew(im->mode, im->xsize, im->ysize);
if (!imOut)
return NULL;
ImagingCopyInfo(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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