Tweaks to ViewOverlay.

* Clarify Javadocs for add / remove when called with the same
Drawable.
* Add @NonNull annotation to all add / remove APIs and throw
IllegalArgumentException when null value is passed.

Bug: 27528798
Change-Id: Ied8f28c70775309e4fa85aff6a7202c1a0eb6aa3

diff --git a/core/java/android/view/ViewGroupOverlay.java b/core/java/android/view/ViewGroupOverlay.java
index 16afc5d..c2807ba 100644 (file)
--- a/core/java/android/view/ViewGroupOverlay.java
+++ b/core/java/android/view/ViewGroupOverlay.java
@@ -15,6 +15,7 @@
  */
 package android.view;
 
+import android.annotation.NonNull;
 import android.content.Context;
 import android.graphics.drawable.Drawable;
 
@@ -37,7 +38,7 @@ public class ViewGroupOverlay extends ViewOverlay {
     }
 
     /**
-     * Adds a View to the overlay. The bounds of the added view should be
+     * Adds a {@code View} to the overlay. The bounds of the added view should be
      * relative to the host view. Any view added to the overlay should be
      * removed when it is no longer needed or no longer visible.
      *
@@ -54,23 +55,32 @@ public class ViewGroupOverlay extends ViewOverlay {
      * and 200 pixels down from the origin of the overlay's
      * host view, then the view will be offset by (100, 200).</p>
      *
-     * @param view The View to be added to the overlay. The added view will be
+     * <p>{@code View}s added with this API will be drawn in the order they were
+     * added. Drawing of the overlay views will happen before drawing of any of the
+     * {@code Drawable}s added with {@link #add(Drawable)} API even if a call to
+     * this API happened after the call to {@link #add(Drawable)}.</p>
+     *
+     * <p>Passing <code>null</code> parameter will result in an
+     * {@link IllegalArgumentException} being thrown.</p>
+     *
+     * @param view The {@code View} to be added to the overlay. The added view will be
      * drawn when the overlay is drawn.
      * @see #remove(View)
      * @see ViewOverlay#add(Drawable)
      */
-    public void add(View view) {
+    public void add(@NonNull View view) {
         mOverlayViewGroup.add(view);
     }
 
     /**
-     * Removes the specified View from the overlay.
+     * Removes the specified {@code View} from the overlay. Passing <code>null</code> parameter
+     * will result in an {@link IllegalArgumentException} being thrown.
      *
-     * @param view The View to be removed from the overlay.
+     * @param view The {@code View} to be removed from the overlay.
      * @see #add(View)
      * @see ViewOverlay#remove(Drawable)
      */
-    public void remove(View view) {
+    public void remove(@NonNull View view) {
         mOverlayViewGroup.remove(view);
     }
 }

diff --git a/core/java/android/view/ViewOverlay.java b/core/java/android/view/ViewOverlay.java
index 5e5ef29..0d05c54 100644 (file)
--- a/core/java/android/view/ViewOverlay.java
+++ b/core/java/android/view/ViewOverlay.java
@@ -16,6 +16,7 @@
 package android.view;
 
 import android.animation.LayoutTransition;
+import android.annotation.NonNull;
 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Rect;
@@ -59,25 +60,30 @@ public class ViewOverlay {
     }
 
     /**
-     * Adds a Drawable to the overlay. The bounds of the drawable should be relative to
+     * Adds a {@link Drawable} to the overlay. The bounds of the drawable should be relative to
      * the host view. Any drawable added to the overlay should be removed when it is no longer
-     * needed or no longer visible.
+     * needed or no longer visible. Adding an already existing {@link Drawable}
+     * is a no-op. Passing <code>null</code> parameter will result in an
+     * {@link IllegalArgumentException} being thrown.
      *
-     * @param drawable The Drawable to be added to the overlay. This drawable will be
-     * drawn when the view redraws its overlay.
+     * @param drawable The {@link Drawable} to be added to the overlay. This drawable will be
+     * drawn when the view redraws its overlay. {@link Drawable}s will be drawn in the order that
+     * they were added.
      * @see #remove(Drawable)
      */
-    public void add(Drawable drawable) {
+    public void add(@NonNull Drawable drawable) {
         mOverlayViewGroup.add(drawable);
     }
 
     /**
-     * Removes the specified Drawable from the overlay.
+     * Removes the specified {@link Drawable} from the overlay. Removing a {@link Drawable} that was
+     * not added with {@link #add(Drawable)} is a no-op. Passing <code>null</code> parameter will
+     * result in an {@link IllegalArgumentException} being thrown.
      *
-     * @param drawable The Drawable to be removed from the overlay.
+     * @param drawable The {@link Drawable} to be removed from the overlay.
      * @see #add(Drawable)
      */
-    public void remove(Drawable drawable) {
+    public void remove(@NonNull Drawable drawable) {
         mOverlayViewGroup.remove(drawable);
     }
 
@@ -119,7 +125,7 @@ public class ViewOverlay {
          * The View for which this is an overlay. Invalidations of the overlay are redirected to
          * this host view.
          */
-        View mHostView;
+        final View mHostView;
 
         /**
          * The set of drawables to draw when the overlay is rendered.
@@ -137,10 +143,12 @@ public class ViewOverlay {
             mRenderNode.setLeftTopRightBottom(0, 0, mRight, mBottom);
         }
 
-        public void add(Drawable drawable) {
+        public void add(@NonNull Drawable drawable) {
+            if (drawable == null) {
+                throw new IllegalArgumentException("drawable must be non-null");
+            }
             if (mDrawables == null) {
-
-                mDrawables = new ArrayList<Drawable>();
+                mDrawables = new ArrayList<>();
             }
             if (!mDrawables.contains(drawable)) {
                 // Make each drawable unique in the overlay; can't add it more than once
@@ -150,7 +158,10 @@ public class ViewOverlay {
             }
         }
 
-        public void remove(Drawable drawable) {
+        public void remove(@NonNull Drawable drawable) {
+            if (drawable == null) {
+                throw new IllegalArgumentException("drawable must be non-null");
+            }
             if (mDrawables != null) {
                 mDrawables.remove(drawable);
                 invalidate(drawable.getBounds());
@@ -163,7 +174,11 @@ public class ViewOverlay {
             return super.verifyDrawable(who) || (mDrawables != null && mDrawables.contains(who));
         }
 
-        public void add(View child) {
+        public void add(@NonNull View child) {
+            if (child == null) {
+                throw new IllegalArgumentException("view must be non-null");
+            }
+
             if (child.getParent() instanceof ViewGroup) {
                 ViewGroup parent = (ViewGroup) child.getParent();
                 if (parent != mHostView && parent.getParent() != null &&
@@ -190,7 +205,11 @@ public class ViewOverlay {
             super.addView(child);
         }
 
-        public void remove(View view) {
+        public void remove(@NonNull View view) {
+            if (view == null) {
+                throw new IllegalArgumentException("view must be non-null");
+            }
+
             super.removeView(view);
         }