This patch fixes a problem with imagecopyresampled() when copying an image
with a non-constant alpha layer. If nobody objects, I'll commit this.
Tim
Index: gd.c
===================================================================
RCS file: /repository/php4/ext/gd/libgd/gd.c,v
retrieving revision 1.15
diff -u -r1.15 gd.c
--- gd.c 22 Aug 2002 16:21:32 -0000 1.15
+++ gd.c 29 Sep 2002 06:36:35 -0000
@@ -2038,6 +2038,7 @@
float sx, sy;
float spixels = 0.0f;
float red = 0.0f, green = 0.0f, blue = 0.0f, alpha = 0.0f;
+ float alpha_factor, alpha_sum = 0.0f, contrib_sum = 0.0f;
sy1 = ((float)(y - dstY)) * (float)srcH /
(float)dstH;
sy2 = ((float)(y + 1 - dstY)) * (float) srcH /
@@ -2095,10 +2096,13 @@
src,
(int) sx + srcX,
(int) sy + srcY);
- red += gdTrueColorGetRed (p) * pcontribution;
- green += gdTrueColorGetGreen (p) * pcontribution;
- blue += gdTrueColorGetBlue (p) * pcontribution;
+ alpha_factor = ((gdAlphaMax - gdTrueColorGetAlpha(p))) * pcontribution;
+ red += gdTrueColorGetRed (p) * alpha_factor;
+ green += gdTrueColorGetGreen (p) * alpha_factor;
+ blue += gdTrueColorGetBlue (p) * alpha_factor;
alpha += gdTrueColorGetAlpha (p) * pcontribution;
+ alpha_sum += alpha_factor;
+ contrib_sum += pcontribution;
spixels += xportion * yportion;
sx += 1.0f;
}
@@ -2113,6 +2117,13 @@
blue /= spixels;
alpha /= spixels;
}
+ if ( alpha_sum != 0.0f)
+ {
+ if( contrib_sum != 0.0f ) alpha_sum /= contrib_sum;
+ red /= alpha_sum;
+ green /= alpha_sum;
+ blue /= alpha_sum;
+ }
/* Clamping to allow for rounding errors above */
if (red > 255.0f)
{
--
PHP Development Mailing List <http://www.php.net/>
To unsubscribe, visit: http://www.php.net/unsub.php
