Fix stutter when swiping workspace first time

Bug # 5366313

Change-Id: If4212d0cd626d0829e3e4487da52f455b0b89983

src/com/android/launcher2/Launcher.java

@@ -244,6 +244,12 @@ public final class Launcher extends Activity
 
     private BubbleTextView mWaitingForResume;
 
+    private Runnable mBuildLayersRunnable = new Runnable() {
+        public void run() {
+            mWorkspace.buildPageHardwareLayers();
+        }
+    };
+
     private static ArrayList<PendingAddArguments> sPendingAddList
             = new ArrayList<PendingAddArguments>();
 
@@ -550,6 +556,9 @@ public final class Launcher extends Activity
         // When we resume Launcher, a different Activity might be responsible for the app
         // market intent, so refresh the icon
         updateAppMarketIcon();
+        if (!mWorkspaceLoading) {
+            mWorkspace.post(mBuildLayersRunnable);
+        }
     }
 
     @Override
@@ -2964,6 +2973,8 @@ public final class Launcher extends Activity
         // Update the market app icon as necessary (the other icons will be managed in response to
         // package changes in bindSearchablesChanged()
         updateAppMarketIcon();
+
+        mWorkspace.post(mBuildLayersRunnable);
     }
 
     @Override

src/com/android/launcher2/Workspace.java

@@ -313,6 +313,16 @@ public class Workspace extends SmoothPagedView
         setMotionEventSplittingEnabled(true);
     }
 
+    public void buildPageHardwareLayers() {
+        if (getWindowToken() != null) {
+            final int childCount = getChildCount();
+            for (int i = 0; i < childCount; i++) {
+                CellLayout cl = (CellLayout) getChildAt(i);
+                cl.buildChildrenLayer();
+            }
+        }
+    }
+
     public void onDragStart(DragSource source, Object info, int dragAction) {
         mIsDragOccuring = true;
         updateChildrenLayersEnabled();