Order GhostViews so that they display in their ghosted view's order.

Bug 17671834

GhostViews can be added in arbitrary order since they are added
depending on how they are insterted into the TransitionValues
maps. This CL does two things: it ensures that GhostViews are always
pulled to the top of the Overlay and inserts GhostViews into
the Overlay in the order that their ghosted views are drawn.

Change-Id: I9f68105126834cc8f30a6cfe5d58fc3c51465afd

Author: George Mount

core/java/android/view/GhostView.java

@@ -19,6 +19,8 @@
 import android.graphics.Matrix;
 import android.widget.FrameLayout;
 
+import java.util.ArrayList;
+
 /**
  * This view draws another View in an Overlay without changing the parent. It will not be drawn
  * by its parent because its visibility is set to INVISIBLE, but will be drawn
@@ -30,6 +32,7 @@
 public class GhostView extends View {
     private final View mView;
     private int mReferences;
+    private boolean mBeingMoved;
 
     private GhostView(View view) {
         super(view.getContext());
@@ -75,12 +78,14 @@ private void setGhostedVisibility(int visibility) {
     @Override
     protected void onDetachedFromWindow() {
         super.onDetachedFromWindow();
-        setGhostedVisibility(View.VISIBLE);
-        mView.mGhostView = null;
-        final ViewGroup parent = (ViewGroup) mView.getParent();
-        if (parent != null) {
-            parent.mRecreateDisplayList = true;
-            parent.getDisplayList();
+        if (!mBeingMoved) {
+            setGhostedVisibility(View.VISIBLE);
+            mView.mGhostView = null;
+            final ViewGroup parent = (ViewGroup) mView.getParent();
+            if (parent != null) {
+                parent.mRecreateDisplayList = true;
+                parent.getDisplayList();
+            }
         }
     }
 
@@ -121,7 +126,9 @@ public static GhostView addGhost(View view, ViewGroup viewGroup, Matrix matrix)
             copySize(viewGroup, parent);
             copySize(viewGroup, ghostView);
             parent.addView(ghostView);
-            overlay.add(parent);
+            ArrayList<View> tempViews = new ArrayList<View>();
+            int firstGhost = moveGhostViewsToTop(overlay.mOverlayViewGroup, tempViews);
+            insertIntoOverlay(overlay.mOverlayViewGroup, parent, ghostView, tempViews, firstGhost);
             ghostView.mReferences = previousRefCount;
         } else if (matrix != null) {
             ghostView.setMatrix(matrix);
@@ -156,4 +163,180 @@ private static void copySize(View from, View to) {
         to.setRight(from.getWidth());
         to.setBottom(from.getHeight());
     }
+
+    /**
+     * Move the GhostViews to the end so that they are on top of other views and it is easier
+     * to do binary search for the correct location for the GhostViews in insertIntoOverlay.
+     *
+     * @return The index of the first GhostView or -1 if no GhostView is in the ViewGroup
+     */
+    private static int moveGhostViewsToTop(ViewGroup viewGroup, ArrayList<View> tempViews) {
+        final int numChildren = viewGroup.getChildCount();
+        if (numChildren == 0) {
+            return -1;
+        } else if (isGhostWrapper(viewGroup.getChildAt(numChildren - 1))) {
+            // GhostViews are already at the end
+            int firstGhost = numChildren - 1;
+            for (int i = numChildren - 2; i >= 0; i--) {
+                if (!isGhostWrapper(viewGroup.getChildAt(i))) {
+                    break;
+                }
+                firstGhost = i;
+            }
+            return firstGhost;
+        }
+
+        // Remove all GhostViews from the middle
+        for (int i = numChildren - 2; i >= 0; i--) {
+            View child = viewGroup.getChildAt(i);
+            if (isGhostWrapper(child)) {
+                tempViews.add(child);
+                GhostView ghostView = (GhostView)((ViewGroup)child).getChildAt(0);
+                ghostView.mBeingMoved = true;
+                viewGroup.removeViewAt(i);
+                ghostView.mBeingMoved = false;
+            }
+        }
+
+        final int firstGhost;
+        if (tempViews.isEmpty()) {
+            firstGhost = -1;
+        } else {
+            firstGhost = viewGroup.getChildCount();
+            // Add the GhostViews to the end
+            for (int i = tempViews.size() - 1; i >= 0; i--) {
+                viewGroup.addView(tempViews.get(i));
+            }
+            tempViews.clear();
+        }
+        return firstGhost;
+    }
+
+    /**
+     * Inserts a GhostView into the overlay's ViewGroup in the order in which they
+     * should be displayed by the UI.
+     */
+    private static void insertIntoOverlay(ViewGroup viewGroup, ViewGroup wrapper,
+            GhostView ghostView, ArrayList<View> tempParents, int firstGhost) {
+        if (firstGhost == -1) {
+            viewGroup.addView(wrapper);
+        } else {
+            ArrayList<View> viewParents = new ArrayList<View>();
+            getParents(ghostView.mView, viewParents);
+
+            int index = getInsertIndex(viewGroup, viewParents, tempParents, firstGhost);
+            if (index < 0 || index >= viewGroup.getChildCount()) {
+                viewGroup.addView(wrapper);
+            } else {
+                viewGroup.addView(wrapper, index);
+            }
+        }
+    }
+
+    /**
+     * Find the index into the overlay to insert the GhostView based on the order that the
+     * views should be drawn. This keeps GhostViews layered in the same order
+     * that they are ordered in the UI.
+     */
+    private static int getInsertIndex(ViewGroup overlayViewGroup, ArrayList<View> viewParents,
+            ArrayList<View> tempParents, int firstGhost) {
+        int low = firstGhost;
+        int high = overlayViewGroup.getChildCount() - 1;
+
+        while (low <= high) {
+            int mid = (low + high) / 2;
+            ViewGroup wrapper = (ViewGroup) overlayViewGroup.getChildAt(mid);
+            GhostView midView = (GhostView) wrapper.getChildAt(0);
+            getParents(midView.mView, tempParents);
+            if (isOnTop(viewParents, tempParents)) {
+                low = mid + 1;
+            } else {
+                high = mid - 1;
+            }
+            tempParents.clear();
+        }
+
+        return low;
+    }
+
+    /**
+     * Returns true if view is a GhostView's FrameLayout wrapper.
+     */
+    private static boolean isGhostWrapper(View view) {
+        if (view instanceof FrameLayout) {
+            FrameLayout frameLayout = (FrameLayout) view;
+            if (frameLayout.getChildCount() == 1) {
+                View child = frameLayout.getChildAt(0);
+                return child instanceof GhostView;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Returns true if viewParents is from a View that is on top of the comparedWith's view.
+     * The ArrayLists contain the ancestors of views in order from top most grandparent, to
+     * the view itself, in order. The goal is to find the first matching parent and then
+     * compare the draw order of the siblings.
+     */
+    private static boolean isOnTop(ArrayList<View> viewParents, ArrayList<View> comparedWith) {
+        if (viewParents.isEmpty() || comparedWith.isEmpty() ||
+                viewParents.get(0) != comparedWith.get(0)) {
+            // Not the same decorView -- arbitrary ordering
+            return true;
+        }
+        int depth = Math.min(viewParents.size(), comparedWith.size());
+        for (int i = 1; i < depth; i++) {
+            View viewParent = viewParents.get(i);
+            View comparedWithParent = comparedWith.get(i);
+
+            if (viewParent != comparedWithParent) {
+                // i - 1 is the same parent, but these are different children.
+                return isOnTop(viewParent, comparedWithParent);
+            }
+        }
+
+        // one of these is the parent of the other
+        boolean isComparedWithTheParent = (comparedWith.size() == depth);
+        return isComparedWithTheParent;
+    }
+
+    /**
+     * Adds all the parents, grandparents, etc. of view to parents.
+     */
+    private static void getParents(View view, ArrayList<View> parents) {
+        ViewParent parent = view.getParent();
+        if (parent != null && parent instanceof ViewGroup) {
+            getParents((View) parent, parents);
+        }
+        parents.add(view);
+    }
+
+    /**
+     * Returns true if view would be drawn on top of comparedWith or false otherwise.
+     * view and comparedWith are siblings with the same parent. This uses the logic
+     * that dispatchDraw uses to determine which View should be drawn first.
+     */
+    private static boolean isOnTop(View view, View comparedWith) {
+        ViewGroup parent = (ViewGroup) view.getParent();
+
+        final int childrenCount = parent.getChildCount();
+        final ArrayList<View> preorderedList = parent.buildOrderedChildList();
+        final boolean customOrder = preorderedList == null
+                && parent.isChildrenDrawingOrderEnabled();
+        for (int i = 0; i < childrenCount; i++) {
+            int childIndex = customOrder ? parent.getChildDrawingOrder(childrenCount, i) : i;
+            final View child = (preorderedList == null)
+                    ? parent.getChildAt(childIndex) : preorderedList.get(childIndex);
+            if (child == view) {
+                return false;
+            } else if (child == comparedWith) {
+                return true;
+            }
+        }
+
+        // Shouldn't get here. Neither of the children is in the parent.
+        // Just return an arbitrary one.
+        return true;
+    }
 }

core/java/android/view/ViewGroup.java

@@ -3298,7 +3298,7 @@ private boolean hasChildWithZ() {
      * Uses a stable, insertion sort which is commonly O(n) for ViewGroups with very few elevated
      * children.
      */
-    private ArrayList<View> buildOrderedChildList() {
+    ArrayList<View> buildOrderedChildList() {
         final int count = mChildrenCount;
         if (count <= 1 || !hasChildWithZ()) return null;