Merge lp:~vanvugt/unity/fix-1036519 into lp:unity

[Daniel van Vugt]

Stop the launcher from overdrawing itself, hence losing transparency. It seems
to happen whenever the panel redraws but the launcher region is not damaged.
I have no idea why redrawing the panel unconditionally redraws the launcher
too, but this works around the problem for now. (LP: #1036519)

Stop the launcher from overdrawing itself, hence losing transparency. It seems
to happen whenever the panel redraws but the launcher region is not damaged.
I have no idea why redrawing the panel unconditionally redraws the launcher
too, but this works around the problem for now. (LP: #1036519)

[Daniel van Vugt (vanvugt)]

This proposal is on hold until I can prove:
  1. It doesn't affect any potential fix for bug 1036520; and
  2. It doesn't have any significant performance implications.

[Sam Spilsbury (smspillaz)]

This is fine as a stop gap for now, - we should put a bug in the bug list for lp:unity to remove this code though on figuring out what in nux is causing it.

review: Approve

[Daniel van Vugt (vanvugt)]

Actually I suspect the problem is the new version of paintDisplay. It doesn't honour the restricted paint region (which is a subset of the damage region) like the old paintDisplay does.

[Daniel van Vugt (vanvugt)]

Ignore my previous comment. paintDisplay could never handle the paint/damage region properly because Nux only allows for a rectangular clip region.

So this branch is the best solution we have for now.

=== modified file 'plugins/unityshell/src/unityshell.cpp'
--- plugins/unityshell/src/unityshell.cpp	2012-08-16 13:35:30 +0000
+++ plugins/unityshell/src/unityshell.cpp	2012-08-17 07:56:22 +0000
@@ -1358,7 +1358,9 @@
   for (ShowdesktopHandlerWindowInterface *wi : ShowdesktopHandler::animating_windows)
     wi->HandleAnimations (ms);
 
+#ifndef USE_MODERN_COMPIZ_GL
   compizDamageNux(cScreen->currentDamage());
+#endif
 
   didShellRepaint = false;
   firstWindowAboveShell = NULL;
@@ -1486,6 +1488,29 @@
 /* Grab changed nux regions and add damage rects for them */
 void UnityScreen::nuxDamageCompiz()
 {
+#ifdef USE_MODERN_COMPIZ_GL
+  /*
+   * If Nux is going to redraw anything then we have to tell Compiz to
+   * redraw everything. This is because Nux has a bad habit (bug??) of drawing
+   * more than just the regions of its DrawList. (LP: #1036519)
+   *
+   * Forunately, this does not happen on most frames. Only when the Unity
+   * Shell needs to redraw something.
+   *
+   * TODO: Try to figure out why redrawing the panel makes the launcher also
+   *       redraw even though the launcher's geometry is not in DrawList, and
+   *       stop it. Then maybe we can revert back to the old code below #else.
+   */
+  std::vector<nux::Geometry> const& dirty = wt->GetDrawList();
+  if (!dirty.empty())
+  {
+    cScreen->damageRegionSetEnabled(this, false);
+    cScreen->damageScreen();
+    cScreen->damageRegionSetEnabled(this, true);
+  }
+
+#else
+
   /*
    * WARNING: Nux bug LP: #1014610 (unbounded DrawList growth) will cause
    *          this code to be called far too often in some cases and
@@ -1536,6 +1561,7 @@
   cScreen->damageRegionSetEnabled(this, false);
   cScreen->damageRegion(nux_damage);
   cScreen->damageRegionSetEnabled(this, true);
+#endif
 }
 
 /* handle X Events */