Allow a "ghost view" that paint a different view from the overlay.

Bug 15744995

The ghost view doesn't route touch events, but hides another
view in its normal parent, and paints it as a child of another
ViewGroup or ViewGroupOverlay.

Change-Id: I352e14c366ccfb7303cee1dbff8563c673fd12ff

2 files changed, 140 insertions, 3 deletions

diff --git a/core/java/android/view/GhostView.java b/core/java/android/view/GhostView.java
new file mode 100644
index 0000000..1aa8d99
--- /dev/null
+++ b/core/java/android/view/GhostView.java
@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package android.view;
+
+import android.graphics.Canvas;
+import android.graphics.Matrix;
+
+/**
+ * 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
+ * here using its render node. When the GhostView is set to INVISIBLE, the View it is
+ * shadowing will become VISIBLE and when the GhostView becomes VISIBLE, the shadowed
+ * view becomes INVISIBLE.
+ * @hide
+ */
+public class GhostView extends View {
+    private final Matrix mMatrix = new Matrix();
+    private final View mView;
+
+    private GhostView(View view, ViewGroup host) {
+        super(view.getContext());
+        mView = view;
+        setMatrix(host);
+        mView.mGhostView = this;
+        final ViewGroup parent = (ViewGroup) mView.getParent();
+        setLeft(0);
+        setTop(0);
+        setRight(host.getWidth());
+        setBottom(host.getHeight());
+        setGhostedVisibility(View.INVISIBLE);
+        parent.mRecreateDisplayList = true;
+        parent.getDisplayList();
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        if (canvas instanceof HardwareCanvas) {
+            HardwareCanvas hwCanvas = (HardwareCanvas) canvas;
+            int saveCount = hwCanvas.save(Canvas.MATRIX_SAVE_FLAG);
+            canvas.concat(mMatrix);
+            mView.mRecreateDisplayList = true;
+            RenderNode renderNode = mView.getDisplayList();
+            if (renderNode.isValid()) {
+                hwCanvas.drawRenderNode(renderNode);
+            }
+            hwCanvas.restoreToCount(saveCount);
+        }
+    }
+
+    @Override
+    public void setVisibility(@Visibility int visibility) {
+        super.setVisibility(visibility);
+        if (mView.mGhostView == this) {
+            int inverseVisibility = (visibility == View.VISIBLE) ? View.INVISIBLE : View.VISIBLE;
+            setGhostedVisibility(inverseVisibility);
+        }
+    }
+
+    private void setGhostedVisibility(int visibility) {
+        mView.mViewFlags = (mView.mViewFlags & ~View.VISIBILITY_MASK) | visibility;
+    }
+
+    @Override
+    protected void onDetachedFromWindow() {
+        super.onDetachedFromWindow();
+        setGhostedVisibility(View.VISIBLE);
+        mView.mGhostView = null;
+        final ViewGroup parent = (ViewGroup) mView.getParent();
+        parent.mRecreateDisplayList = true;
+        parent.getDisplayList();
+    }
+
+    private void setMatrix(ViewGroup host) {
+        host.transformMatrixToLocal(mMatrix);
+        ViewGroup parent = (ViewGroup) mView.getParent();
+        parent.transformMatrixToGlobal(mMatrix);
+        mMatrix.postTranslate(-parent.getScrollX(), -parent.getScrollY());
+    }
+
+    public static GhostView addGhost(View view, ViewGroup viewGroup) {
+        if (!(view.getParent() instanceof ViewGroup)) {
+            throw new IllegalArgumentException("Ghosted views must be parented by a ViewGroup");
+        }
+        ViewGroupOverlay overlay = viewGroup.getOverlay();
+        ViewOverlay.OverlayViewGroup overlayViewGroup = overlay.mOverlayViewGroup;
+        GhostView ghostView = view.mGhostView;
+        if (ghostView != null) {
+            ViewGroup oldParent = (ViewGroup) ghostView.getParent();
+            if (oldParent != overlayViewGroup) {
+                oldParent.removeView(ghostView);
+                ghostView = null;
+            }
+        }
+        if (ghostView == null) {
+            ghostView = new GhostView(view, (ViewGroup) overlayViewGroup.mHostView);
+            overlay.add(ghostView);
+        }
+        return ghostView;
+    }
+
+    public static void removeGhost(View view) {
+        GhostView ghostView = view.mGhostView;
+        if (ghostView != null) {
+            ViewGroup parent = (ViewGroup) ghostView.getParent();
+            parent.removeView(ghostView);
+        }
+    }
+
+    public static GhostView getGhost(View view) {
+        return view.mGhostView;
+    }
+}
diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index 4c1c2f9..81b5c20 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -17,9 +17,7 @@
 package android.view;
 
 import android.animation.AnimatorInflater;
-import android.animation.RevealAnimator;
 import android.animation.StateListAnimator;
-import android.animation.ValueAnimator;
 import android.annotation.IntDef;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
@@ -3520,6 +3518,13 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
     private int[] mTempNestedScrollConsumed;
 
     /**
+     * An overlay is going to draw this View instead of being drawn as part of this
+     * View's parent. mGhostView is the View in the Overlay that must be invalidated
+     * when this view is invalidated.
+     */
+    GhostView mGhostView;
+
+    /**
      * Simple constructor to use when creating a view from code.
      *
      * @param context The Context the view is running in, through which it can
@@ -10284,6 +10289,7 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
      *
      * @hide
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getTransitionAlpha() {
         return mTransformationInfo != null ? mTransformationInfo.mTransitionAlpha : 1;
     }
@@ -11371,6 +11377,11 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
 
     void invalidateInternal(int l, int t, int r, int b, boolean invalidateCache,
             boolean fullInvalidate) {
+        if (mGhostView != null) {
+            mGhostView.invalidate(invalidateCache);
+            return;
+        }
+
         if (skipInvalidate()) {
             return;
         }
@@ -11408,7 +11419,7 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
                 }
             }
 
-            // Damage the entire IsolatedZVolume recieving this view's shadow.
+            // Damage the entire IsolatedZVolume receiving this view's shadow.
             if (isHardwareAccelerated() && getZ() != 0) {
                 damageShadowReceiver();
             }
@@ -19397,6 +19408,7 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
      * @return The name used of the View to be used to identify Views in Transitions or null
      * if no name has been given.
      */
+    @ViewDebug.ExportedProperty
     public String getTransitionName() {
         return mTransitionName;
     }