Merge lp:~sil2100/unity/launcher_dnd_flicker_5.0 into lp:unity/5.0

[Łukasz Zemczak]

Back-porting fix from unity trunk.
When dragging a non-application, do not saturate all icons automatically, but only those that are needed.

Eliminates flickering before 'prelighting' the Launcher icons that can handle the current drag-and-drop (LP #863230).

Copy-pasted description from the original, 6.0 MRQ.

Problem description:

When drag-and-dropping from the Dash to the Launcher a non-application icon (for instance, a PNG file), the Launcher 'flickers' a bit. This flickering means that the Launcher icons get desaturated for a moment and then loose saturation again (as originally intended), tinted (LP #863230 and more specifically - LP #971086).

The fix:

During drag and drop, instead of saturating all icons automatically when overlay is present, we only do this when we know that we're not dragging a non-application. Otherwise, only saturate the icons that we will actually 'prelight' (i.e. indicate that can handle the given file). This way, there is no flickering and all icons visualize correctly, as intended. There are no longer any tinting problems as well (as noted by JohnLea).

Test coverage:

The following fix can be tested by manual testing of the specified bugs (LP #863230, LP #971086). Problem no longer occurs.

=== modified file 'plugins/unityshell/src/Launcher.cpp'
--- plugins/unityshell/src/Launcher.cpp	2012-05-24 11:33:05 +0000
+++ plugins/unityshell/src/Launcher.cpp	2012-06-06 09:30:27 +0000
@@ -2696,9 +2696,6 @@
 
   _hide_machine->SetQuirk(LauncherHideMachine::EXTERNAL_DND_ACTIVE, true);
 
-  if (IsOverlayOpen())
-    SaturateIcons();
-
   for (auto it : _dnd_data.Uris())
   {
     if (g_str_has_suffix(it.c_str(), ".desktop"))
@@ -2713,11 +2710,21 @@
     for (auto it : *_model)
     {
       if (it->ShouldHighlightOnDrag(_dnd_data))
+      {
+        it->SetQuirk(AbstractLauncherIcon::QUIRK_DESAT, false);
         it->SetQuirk(AbstractLauncherIcon::QUIRK_DROP_PRELIGHT, true);
+      }
       else
+      {
         it->SetQuirk(AbstractLauncherIcon::QUIRK_DROP_DIM, true);
+      }
     }
   }
+  else
+  {
+    if (IsOverlayOpen())
+      SaturateIcons();
+  }
 }
 
 void