Preventing dock target from showing for single tasks.

Change-Id: I2a73c085e3777ac79f2846e1ba59f7c65bc3f9d0
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
index 501f052..0d9a1c4 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
@@ -93,12 +93,6 @@
 
     private RecentsTransitionHelper mTransitionHelper;
     private RecentsViewTouchHandler mTouchHandler;
-    private TaskStack.DockState[] mVisibleDockStates = {
-            TaskStack.DockState.LEFT,
-            TaskStack.DockState.TOP,
-            TaskStack.DockState.RIGHT,
-            TaskStack.DockState.BOTTOM,
-    };
 
     private final Interpolator mFastOutSlowInInterpolator;
     private final Interpolator mFastOutLinearInInterpolator;
@@ -435,8 +429,9 @@
     @Override
     protected void dispatchDraw(Canvas canvas) {
         super.dispatchDraw(canvas);
-        for (int i = mVisibleDockStates.length - 1; i >= 0; i--) {
-            Drawable d = mVisibleDockStates[i].viewState.dockAreaOverlay;
+        ArrayList<TaskStack.DockState> visDockStates = mTouchHandler.getVisibleDockStates();
+        for (int i = visDockStates.size() - 1; i >= 0; i--) {
+            Drawable d = visDockStates.get(i).viewState.dockAreaOverlay;
             if (d.getAlpha() > 0) {
                 d.draw(canvas);
             }
@@ -445,8 +440,9 @@
 
     @Override
     protected boolean verifyDrawable(Drawable who) {
-        for (int i = mVisibleDockStates.length - 1; i >= 0; i--) {
-            Drawable d = mVisibleDockStates[i].viewState.dockAreaOverlay;
+        ArrayList<TaskStack.DockState> visDockStates = mTouchHandler.getVisibleDockStates();
+        for (int i = visDockStates.size() - 1; i >= 0; i--) {
+            Drawable d = visDockStates.get(i).viewState.dockAreaOverlay;
             if (d == who) {
                 return true;
             }
@@ -674,7 +670,9 @@
         if (newDockStates != null) {
             Collections.addAll(newDockStatesSet, newDockStates);
         }
-        for (TaskStack.DockState dockState : mVisibleDockStates) {
+        ArrayList<TaskStack.DockState> visDockStates = mTouchHandler.getVisibleDockStates();
+        for (int i = visDockStates.size() - 1; i >= 0; i--) {
+            TaskStack.DockState dockState = visDockStates.get(i);
             TaskStack.DockState.ViewState viewState = dockState.viewState;
             if (newDockStates == null || !newDockStatesSet.contains(dockState)) {
                 // This is no longer visible, so hide it
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsViewTouchHandler.java b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsViewTouchHandler.java
index 0ca46a0..d8698ee 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsViewTouchHandler.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsViewTouchHandler.java
@@ -71,6 +71,7 @@
 
     private DropTarget mLastDropTarget;
     private ArrayList<DropTarget> mDropTargets = new ArrayList<>();
+    private ArrayList<TaskStack.DockState> mVisibleDockStates = new ArrayList<>();
 
     public RecentsViewTouchHandler(RecentsView rv) {
         mRv = rv;
@@ -97,6 +98,13 @@
         return dockStates;
     }
 
+    /**
+     * Returns the set of visible dock states for this current drag.
+     */
+    public ArrayList<TaskStack.DockState> getVisibleDockStates() {
+        return mVisibleDockStates;
+    }
+
     /** Touch preprocessing for handling below */
     public boolean onInterceptTouchEvent(MotionEvent ev) {
         handleTouchEvent(ev);
@@ -130,11 +138,13 @@
         mTaskView.setTranslationX(x);
         mTaskView.setTranslationY(y);
 
-        if (!ssp.hasDockedTask()) {
+        mVisibleDockStates.clear();
+        if (!ssp.hasDockedTask() && mRv.getTaskStack().getTaskCount() > 1) {
             // Add the dock state drop targets (these take priority)
             TaskStack.DockState[] dockStates = getDockStatesForCurrentOrientation();
             for (TaskStack.DockState dockState : dockStates) {
                 registerDropTargetForCurrentDrag(dockState);
+                mVisibleDockStates.add(dockState);
             }
         }