Fix the feel of Calculator buttons

- Make them more responsive to clicks
- If you touch down on a button and then move onto another target, we should not show any feedback after the click

Change-Id: I129fad65fafd051d534ecde8a2b6cfb78d29df08

res/layout-land/main.xml

@@ -76,7 +76,7 @@
         </FrameLayout>
     </LinearLayout>
 
-    <android.support.v4.view.ViewPager
+    <com.android.calculator2.CalculatorViewPager
          android:id="@+id/panelswitch"
          android:layout_width="match_parent"
          android:layout_height="0dp"

res/layout-port/main.xml

@@ -93,7 +93,7 @@
         </FrameLayout>
 
     </LinearLayout>
-    <android.support.v4.view.ViewPager
+    <com.android.calculator2.CalculatorViewPager
          android:id="@+id/panelswitch"
          android:layout_width="match_parent"
          android:layout_height="0dp"

src/com/android/calculator2/CalculatorViewPager.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2011 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 com.android.calculator2;
+
+import android.content.Context;
+import android.support.v4.view.ViewPager;
+import android.util.AttributeSet;
+
+public class CalculatorViewPager extends ViewPager {
+    public CalculatorViewPager(Context context) {
+        super(context);
+    }
+
+    public CalculatorViewPager(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    /**
+     * ViewPager inherits ViewGroup's default behavior of delayed clicks
+     * on its children, but in order to make the calc buttons more responsive
+     * we disable that here.
+     */
+    public boolean shouldDelayChildPressedState() {
+        return false;
+    }
+}

src/com/android/calculator2/ColorButton.java

@@ -120,7 +120,11 @@ public boolean onTouchEvent(MotionEvent event) {
 
         switch (event.getAction()) {
             case MotionEvent.ACTION_UP:
-                animateClickFeedback();
+                if (isPressed()) {
+                    animateClickFeedback();
+                } else {
+                    invalidate();
+                }
                 break;
             case MotionEvent.ACTION_DOWN:
             case MotionEvent.ACTION_CANCEL: