Merge lp:~sil2100/unity/lp1071813.render-launcher-icon-drag_6.0 into lp:unity/6.0

[Łukasz Zemczak]

Cherry-picked rev 2871 from lp:unity:
Clear launcher drag icon texture before rendering to it (LP: #1071813)

Cherry-picked Nick's fix from: https://code.launchpad.net/~nick-dedekind/unity/lp1071813.render-launcher-icon-drag/+merge/132104

= Problem description =

https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1071813
Launcher drag icon textures had partial corruption due to performance optimisations in Nux r.686

= The fix =

Clear launcher drag icon texture before rendering to it.

= Test coverage =

No test.

[Nick Dedekind (nick-dedekind)]

Same as merge to trunk.
Builds OK.

LGTM.

review: Approve

[Daniel van Vugt (vanvugt)]

Tested the other proposal identical to this and it worked. So I vote yes.

review: Approve

=== modified file 'launcher/Launcher.cpp'
--- launcher/Launcher.cpp	2012-10-01 15:12:05 +0000
+++ launcher/Launcher.cpp	2012-10-30 16:57:31 +0000
@@ -2514,6 +2514,19 @@
   drag_args.push_front(arg);
 
   SetOffscreenRenderTarget(texture);
+
+  unsigned int alpha = 0, src = 0, dest = 0;
+  GfxContext.GetRenderStates().GetBlend(alpha, src, dest);
+  GfxContext.GetRenderStates().SetBlend(false);
+
+  GfxContext.QRP_Color(0,
+                      0,
+                      texture->GetWidth(),
+                      texture->GetHeight(),
+                      nux::Color(0.0f, 0.0f, 0.0f, 0.0f));
+
+  GfxContext.GetRenderStates().SetBlend(alpha, src, dest);
+
   icon_renderer->PreprocessIcons(drag_args, nux::Geometry(0, 0, _icon_size, _icon_size));
   icon_renderer->RenderIcon(nux::GetWindowThread()->GetGraphicsEngine(), arg, nux::Geometry(0, 0, _icon_size, _icon_size), nux::Geometry(0, 0, _icon_size, _icon_size));
   RestoreSystemRenderTarget();