Trying to understand how and where changes to an icons alpha- and saturation-value are taking place is material to get insane. By now I've spent many many many hours trying to get behind what's going on. I can't say I fully grasp

the intricate ways of icons opacity and saturation in class Launcher. As far as I can tell, there are four valid "cases" for the launcher icons in terms of alpha and saturation. To make it easier for you to follow, have a look at this table: alpha | saturation ------------------------------------------------------------------- | dash open | 0.5 | 0.0 | | dash closed | 1.0 | 1.0 | | drop-target (dragging & dash open) | 1.0 | 1.0 | | no drop-target (dragging & dash open) | 0.5 | 0.0 | ------------------------------------------------------------------- So alpha should never be outside [0.5 .. 1.0] and saturation should never be outside [0.0 .. 1.0]. From my investigation it is sufficient to protect only against the lower threshold, where alpha needs to be 0.5 and saturation 0.0 without fix: http://people.canonical.com/~mmueller/863230-issue-1.ogv with fix: http://people.canonical.com/~mmueller/after-fix-863230.ogv If anybody ever causes this to regress, I'll ... !. Fixes: https://bugs.launchpad.net/bugs/863230. Approved by Tim Penhey. (bzr r2104)

1 files changed, 14 insertions, 0 deletions

diff --git a/plugins/unityshell/src/Launcher.cpp b/plugins/unityshell/src/Launcher.cpp
index f7dd213e1..6582bd147 100644
--- a/plugins/unityshell/src/Launcher.cpp
+++ b/plugins/unityshell/src/Launcher.cpp
@@ -902,6 +902,13 @@ void Launcher::SetupRenderArg(AbstractLauncherIcon::Ptr icon, struct timespec co
 icon->GetIconType() == AbstractLauncherIcon::TYPE_DEVICE ||
 icon->GetIconType() == AbstractLauncherIcon::TYPE_EXPO;
 
+ // trying to protect against flickering when icon is dragged from dash LP: #863230
+ if (arg.alpha < 0.5)
+ {
+ arg.alpha = 0.5;
+ arg.saturation = 0.0;
+ }
+
 if (_dash_is_open)
 arg.active_arrow = icon->GetIconType() == AbstractLauncherIcon::TYPE_HOME;
 else
@@ -989,6 +996,13 @@ void Launcher::FillRenderArg(AbstractLauncherIcon::Ptr icon,
 if (drop_dim_value < 1.0f)
 arg.alpha *= drop_dim_value;
 
+ // trying to protect against flickering when icon is dragged from dash LP: #863230
+ if (arg.alpha < 0.5)
+ {
+ arg.alpha = 0.5;
+ arg.saturation = 0.0;
+ }
+
 if (icon == _drag_icon)
 {
 if (MouseBeyondDragThreshold())