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Fix bug #66887 imagescale - poor quality of scaled image

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Issue with signed char overflow.

Upstream fix:
https://bitbucket.org/libgd/gd-libgd/commits/4b86e06937bc5ff116be969137f8da9d1a7869d5
This commit is contained in:
Remi Collet
2014-03-12 17:10:51 +01:00
parent f2d5b2b6c6
commit 862c006da1
1 changed files with 6 additions and 6 deletions
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ext/gd/libgd/gd_interpolation.c
+6 -6
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@@ -1324,8 +1324,8 @@ static gdImagePtr gdImageScaleBilinearTC(gdImagePtr im, const unsigned int new_w
gdFixed f_j = gd_itofx(j);
gdFixed f_a = gd_mulfx(f_i, f_dy);
gdFixed f_b = gd_mulfx(f_j, f_dx);
const long m = gd_fxtoi(f_a);
const long n = gd_fxtoi(f_b);
const gdFixed m = gd_fxtoi(f_a);
const gdFixed n = gd_fxtoi(f_b);
gdFixed f_f = f_a - gd_itofx(m);
gdFixed f_g = f_b - gd_itofx(n);
@@ -1365,10 +1365,10 @@ static gdImagePtr gdImageScaleBilinearTC(gdImagePtr im, const unsigned int new_w
f_a3 = gd_itofx(gdTrueColorGetAlpha(pixel3));
f_a4 = gd_itofx(gdTrueColorGetAlpha(pixel4));
{
const char red = (char) gd_fxtoi(gd_mulfx(f_w1, f_r1) + gd_mulfx(f_w2, f_r2) + gd_mulfx(f_w3, f_r3) + gd_mulfx(f_w4, f_r4));
const char green = (char) gd_fxtoi(gd_mulfx(f_w1, f_g1) + gd_mulfx(f_w2, f_g2) + gd_mulfx(f_w3, f_g3) + gd_mulfx(f_w4, f_g4));
const char blue = (char) gd_fxtoi(gd_mulfx(f_w1, f_b1) + gd_mulfx(f_w2, f_b2) + gd_mulfx(f_w3, f_b3) + gd_mulfx(f_w4, f_b4));
const char alpha = (char) gd_fxtoi(gd_mulfx(f_w1, f_a1) + gd_mulfx(f_w2, f_a2) + gd_mulfx(f_w3, f_a3) + gd_mulfx(f_w4, f_a4));
const unsigned char red = (unsigned char) gd_fxtoi(gd_mulfx(f_w1, f_r1) + gd_mulfx(f_w2, f_r2) + gd_mulfx(f_w3, f_r3) + gd_mulfx(f_w4, f_r4));
const unsigned char green = (unsigned char) gd_fxtoi(gd_mulfx(f_w1, f_g1) + gd_mulfx(f_w2, f_g2) + gd_mulfx(f_w3, f_g3) + gd_mulfx(f_w4, f_g4));
const unsigned char blue = (unsigned char) gd_fxtoi(gd_mulfx(f_w1, f_b1) + gd_mulfx(f_w2, f_b2) + gd_mulfx(f_w3, f_b3) + gd_mulfx(f_w4, f_b4));
const unsigned char alpha = (unsigned char) gd_fxtoi(gd_mulfx(f_w1, f_a1) + gd_mulfx(f_w2, f_a2) + gd_mulfx(f_w3, f_a3) + gd_mulfx(f_w4, f_a4));
new_img->tpixels[dst_offset_v][dst_offset_h] = gdTrueColorAlpha(red, green, blue, alpha);
}