Merge lp:~vanvugt/compiz-core/fix-877920 into lp:compiz-core/0.9.5

[Daniel van Vugt]

Prevent windows from becoming unexpectedly translucent (LP: #877920)

This can happen if plugins (like Resize Info) accidentally leave the TexEnvMode in the wrong mode. This fix ensures that glDraw always has the correct GL_TEXTURE_ENV_MODE, and that windows don't randomly become translucent (or worse).

[Daniel van Vugt (vanvugt)]

I've also proposed a fix for the resizeinfo plugin which triggered this bug...
https://code.launchpad.net/~vanvugt/compiz-resizeinfo-plugin/fix-877920/+merge/81435

We should commit both fixes.

[Sam Spilsbury (smspillaz)]

I agree with this, although I think in the future it might be more appropriate to have a state machine push/pop functionality in core - in order to change state plugins need to do it through the opengl plugin and we'll have a set of bitflags indicating what state they are changing so that core can handle the reset itself.

review: Approve

[Daniel van Vugt (vanvugt)]

push/pop as in glPushAttrib/glPopAttrib you mean? ;)
http://www.opengl.org/sdk/docs/man/xhtml/glPushAttrib.xml

=== modified file 'plugins/opengl/src/paint.cpp'
--- plugins/opengl/src/paint.cpp	2011-10-26 23:15:02 +0000
+++ plugins/opengl/src/paint.cpp	2011-11-07 10:02:23 +0000
@@ -1189,6 +1189,14 @@
 
     GLTexture::MatrixList ml (1);
 
+    //
+    // Don't assume all plugins leave TexEnvMode in a clean state (GL_REPLACE).
+    // Sometimes plugins forget to clean up correctly, so make sure we're
+    // in the correct mode or else windows could be rendered incorrectly
+    // like in LP: #877920.
+    //
+    priv->gScreen->setTexEnvMode (GL_REPLACE);
+
     if (priv->textures.size () == 1)
     {
 	ml[0] = priv->matrices[0];