Default RotateDrawable's pivot set to (50%, 50%)

In order to define the pivot in an XML-instanciated RotateDrawable, android:pivotX
and android:pivotY had to be set in your XML. Forgetting to set those attributes
ended up in a NullPointerException (tv = null) that were caught by the Resources.getDrawable()
method (caught as an Exception). As a result a not-very-accurate message was logged:
"Resource not found ...". Defining a default pivot value seems like a great fix.
Some other fixes would be to modify the documentation or notify the user with a better
explanation than "Resource not found ...".

Author: Cyril Mottier

graphics/java/android/graphics/drawable/RotateDrawable.java

@@ -204,13 +204,27 @@ public void inflate(Resources r, XmlPullParser parser, AttributeSet attrs)
                 com.android.internal.R.styleable.RotateDrawable_visible);
 
         TypedValue tv = a.peekValue(com.android.internal.R.styleable.RotateDrawable_pivotX);
-        boolean pivotXRel = tv.type == TypedValue.TYPE_FRACTION;
-        float pivotX = pivotXRel ? tv.getFraction(1.0f, 1.0f) : tv.getFloat();
+        boolean pivotXRel;
+        float pivotX;
+        if (tv == null) {
+            pivotXRel = true;
+            pivotX = 0.5f;
+        } else {
+            pivotXRel = tv.type == TypedValue.TYPE_FRACTION;
+            pivotX = pivotXRel ? tv.getFraction(1.0f, 1.0f) : tv.getFloat();
+        }
 
         tv = a.peekValue(com.android.internal.R.styleable.RotateDrawable_pivotY);
-        boolean pivotYRel = tv.type == TypedValue.TYPE_FRACTION;
-        float pivotY = pivotYRel ? tv.getFraction(1.0f, 1.0f) : tv.getFloat();
-        
+        boolean pivotYRel;
+        float pivotY;
+        if (tv == null) {
+            pivotYRel = true;
+            pivotY = 0.5f;
+        } else {
+            pivotYRel = tv.type == TypedValue.TYPE_FRACTION;
+            pivotY = pivotYRel ? tv.getFraction(1.0f, 1.0f) : tv.getFloat();
+        }
+
         float fromDegrees = a.getFloat(
                 com.android.internal.R.styleable.RotateDrawable_fromDegrees, 0.0f);
         float toDegrees = a.getFloat(