58 lines
1.3 KiB
C
58 lines
1.3 KiB
C
/* scale image from SRC to DST - parameterized by type T */
|
|
|
|
/* get pixel address of point (x,y) in image t */
|
|
#define getP(t, x, y) \
|
|
(T *)(&ximage[t]->data[(ximage[t]->xoffset + (x)) * sizeof(T) + \
|
|
(y) * ximage[t]->bytes_per_line])
|
|
|
|
{
|
|
int i, j, k;
|
|
|
|
/* copy scaled lines from SRC to DST */
|
|
j = height[SRC] - 1;
|
|
|
|
do {
|
|
T *p1;
|
|
T *p2;
|
|
int p2step;
|
|
T *p1_save;
|
|
|
|
/* p1 point to begining of scanline j*magnification in DST */
|
|
p1 = getP(DST, 0, j * magnification);
|
|
p1_save = p1;
|
|
|
|
/* p2 point to begining of scanline j in SRC */
|
|
p2 = getP(SRC, 0, j);
|
|
|
|
i = width[SRC];
|
|
|
|
do {
|
|
T c = *p2++;
|
|
k = magnification;
|
|
|
|
do *p1++ = c; while (--k > 0);
|
|
} while (--i > 0);
|
|
|
|
/* duplicate that line as needed */
|
|
if (magnification > 1)
|
|
{
|
|
/* p1 point to begining of scanline j*magnification in DST */
|
|
p1 = p1_save;
|
|
|
|
/* p2 points to begining of next line */
|
|
p2 = p1;
|
|
p2step = ximage[DST]->bytes_per_line / sizeof(T);
|
|
|
|
i = width[DST] * sizeof(T);
|
|
k = magnification - 1;
|
|
|
|
do {
|
|
p2 += p2step;
|
|
memcpy(p2, p1, i);
|
|
} while (--k > 0);
|
|
}
|
|
} while (--j >= 0);
|
|
}
|
|
|
|
#undef getP
|