nx-X11: Fix alpha premultiplication in XRenderParseColor. Fixes: #893.

debian/changelog

@@ -237,6 +237,14 @@ nx-libs (2:3.5.0.32-0x2go1) UNRELEASED; urgency=low
     Adds:
     - 0660_nxcomp_fix-negotiation-in-stage-10-error.full+lite.patch
 
+  [ Emanuele Giaquinta ]
+  * nx-X11: Fix alpha premultiplication in XRenderParseColor.
+    Fixes: #893.
+    v2: backport to nx-libs 3.6.x (Mike Gabriel)
+    v3: backport to nx-libs 3.5.0.x (Mihai Moldovan)
+    Adds:
+    - 0040_nx-X11_Fix-alpha-premultiplication-in-XRenderPa.full.patch
+
  -- X2Go Release Manager <git-admin@x2go.org>  Tue, 17 Mar 2015 19:19:32 +0100
 
 nx-libs (2:3.5.0.31-0x2go1) unstable; urgency=low

debian/patches/0040_nx-X11_Fix-alpha-premultiplication-in-XRenderPa.full.patch

+commit ffc87da60b2262432d56f15332b3edd15b7e00b2
+Author: Emanuele Giaquinta <emanuele.giaquinta@gmail.com>
+Date:   Tue Jun 23 16:09:50 2015 +0200
+
+    Fix alpha premultiplication in XRenderParseColor.
+    
+     Due to C arithmetic conversion rules we must use an unsigned constant (or a
+     cast) to perform the multiplication using unsigned arithmetic.
+    
+     Fixes ArcticaProject/nx-libs#55.
+    
+     Author: Emanuele Giaquinta <emanuele.giaquinta@gmail.com>
+     Reviewed-by: Jeremy Huddleston <jeremyhu@apple.com>
+     Rebased against NX: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>
+
+     v3: backport to nx-libs 3.5.0.x (Mihai Moldovan)
+
+--- a/nx-X11/lib/Xrender/Color.c
++++ b/nx-X11/lib/Xrender/Color.c
+@@ -85,8 +85,8 @@ XRenderParseColor(Display *dpy, char *spec, XRenderColor *def)
+ 	def->blue = coreColor.blue;
+ 	def->alpha = 0xffff;
+     }
+-    def->red = (def->red * def->alpha) / 65535;
+-    def->green = (def->green * def->alpha) / 65535;
+-    def->blue = (def->blue * def->alpha) / 65535;
++    def->red = (def->red * def->alpha) / 0xffffU;
++    def->green = (def->green * def->alpha) / 0xffffU;
++    def->blue = (def->blue * def->alpha) / 0xffffU;
+     return 1;
+ }

debian/patches/series

@@ -26,6 +26,7 @@
 0029_nxcomp_ppc64.full+lite.patch
 0030_nx-X11_configure-args.full.patch
 0031_nx-X11_parallel-make.full.patch
+0040_nx-X11_Fix-alpha-premultiplication-in-XRenderPa.full.patch
 0051_nxcomp_macos105-fdisset.full+lite.patch
 0052_nxcomp_macos10-nxauth-location.full+lite.patch
 0053_nx-X11_no-xcomp1-install-target.full.patch