Register/Unregister observer on window visibility change

If the ThemeChooser is in a paused state, the ThemeObserver in the
component selector will still fire off when a theme is added or
removed.  This causes an NPE when the loader is restarted.

This patch unregisters the content observer when the window is no
longer visible and then re-registers it once the window is visible
again.

Change-Id: I628b269eb95a7fb521470ff3b33845086ee30461
TICKET: CHOOSER-108

1 files changed, 13 insertions, 0 deletions

diff --git a/src/com/cyngn/theme/chooser/ComponentSelector.java b/src/com/cyngn/theme/chooser/ComponentSelector.java
index 5c59b31..f3f4af2 100644
--- a/src/com/cyngn/theme/chooser/ComponentSelector.java
+++ b/src/com/cyngn/theme/chooser/ComponentSelector.java
@@ -197,6 +197,19 @@ public class ComponentSelector extends LinearLayout
         mThemesObserver.unregister();
     }
 
+    @Override
+    protected void onWindowVisibilityChanged(int visibility) {
+        super.onWindowVisibilityChanged(visibility);
+        // Window visibility transitions as follows
+        // VISIBLE -> INVISIBLE -> GONE
+        // GONE -> INVISIBLE -> VISIBLE
+        if (visibility == View.GONE) {
+            mThemesObserver.unregister();
+        } else if (visibility == View.VISIBLE) {
+            mThemesObserver.register();
+        }
+    }
+
     public void setComponentType(String component) {
         setComponentType(component, null, DEFAULT_COMPONENT_ID);
     }