Fix NPE in RippleDrawable

Invalidate was called while we were busy clearing the list of
animating ripples, which led to an inconsistency between the
ripple count and actual state of the ripple list.

BUG: 17136636
BUG: 17281011
Change-Id: Ifb7be7eb334ad9a44cc3a1e6f55ad1e35218989a
diff --git a/graphics/java/android/graphics/drawable/RippleDrawable.java b/graphics/java/android/graphics/drawable/RippleDrawable.java
index ca32751..7402bdb 100644
--- a/graphics/java/android/graphics/drawable/RippleDrawable.java
+++ b/graphics/java/android/graphics/drawable/RippleDrawable.java
@@ -33,7 +33,6 @@
 import android.graphics.Rect;
 import android.util.AttributeSet;
 import android.util.DisplayMetrics;
-import android.util.Log;
 
 import com.android.internal.R;
 
@@ -41,6 +40,7 @@
 import org.xmlpull.v1.XmlPullParserException;
 
 import java.io.IOException;
+import java.util.Arrays;
 
 /**
  * Drawable that shows a ripple effect in response to state changes. The
@@ -88,7 +88,6 @@
  * @attr ref android.R.styleable#RippleDrawable_color
  */
 public class RippleDrawable extends LayerDrawable {
-    private static final String LOG_TAG = RippleDrawable.class.getSimpleName();
     private static final PorterDuffXfermode DST_IN = new PorterDuffXfermode(Mode.DST_IN);
     private static final PorterDuffXfermode SRC_ATOP = new PorterDuffXfermode(Mode.SRC_ATOP);
     private static final PorterDuffXfermode SRC_OVER = new PorterDuffXfermode(Mode.SRC_OVER);
@@ -215,10 +214,14 @@
         final Ripple[] ripples = mAnimatingRipples;
         for (int i = 0; i < count; i++) {
             ripples[i].jump();
-            ripples[i] = null;
+        }
+        if (ripples != null) {
+            Arrays.fill(ripples, 0, count, null);
         }
         mAnimatingRipplesCount = 0;
         mClearingHotspots = false;
+
+        invalidateSelf();
     }
 
     @Override
@@ -549,6 +552,15 @@
         mAnimatingRipples[mAnimatingRipplesCount++] = mRipple;
     }
 
+    @Override
+    public void invalidateSelf() {
+        // Don't invalidate when we're clearing hotspots. We'll handle that
+        // manually when we're done.
+        if (!mClearingHotspots) {
+            super.invalidateSelf();
+        }
+    }
+
     private void removeRipple() {
         if (mRipple != null) {
             mRipple.exit();
@@ -572,7 +584,9 @@
         final Ripple[] ripples = mAnimatingRipples;
         for (int i = 0; i < count; i++) {
             ripples[i].cancel();
-            ripples[i] = null;
+        }
+        if (ripples != null) {
+            Arrays.fill(ripples, 0, count, null);
         }
         mAnimatingRipplesCount = 0;
         mClearingHotspots = false;
@@ -680,7 +694,7 @@
             final int count = mAnimatingRipplesCount;
             final int index = getRippleIndex(ripple);
             if (index >= 0) {
-                System.arraycopy(ripples, index + 1, ripples, index + 1 - 1, count - (index + 1));
+                System.arraycopy(ripples, index + 1, ripples, index, count - (index + 1));
                 ripples[count - 1] = null;
                 mAnimatingRipplesCount--;
                 invalidateSelf();