ExactCalculator: Add haptic button widget

This is a basic extension of Button that provides haptic feedback when
the user touches the button (*not* when they release, to reduce latency).
It uses the system's predefined virtual key haptic feedback effect for
modern vibration effects that the user is already familiar with and
automatic response to changes in system vibration settings.

Change-Id: I55982d5cc3a982a2aa8d9d053af6dddb4438f6f7

1 files changed, 64 insertions, 0 deletions

diff --git a/src/com/android/calculator2/HapticButton.java b/src/com/android/calculator2/HapticButton.java
new file mode 100644
index 0000000..a1f8c90
--- /dev/null
+++ b/src/com/android/calculator2/HapticButton.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2006 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.widget.Button;
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.View;
+import android.view.LayoutInflater;
+import android.view.MotionEvent;
+import android.view.HapticFeedbackConstants;
+
+/**
+ * A basic Button that vibrates on finger down.
+ */
+public class HapticButton extends Button {
+    public HapticButton(Context context) {
+        super(context);
+        initVibration(context);
+    }
+
+    public HapticButton(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        initVibration(context);
+    }
+
+    public HapticButton(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        initVibration(context);
+    }
+
+    public HapticButton(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
+        super(context, attrs, defStyleAttr, defStyleRes);
+        initVibration(context);
+    }
+
+    private void initVibration(Context context) {
+        setOnTouchListener(new View.OnTouchListener() {
+            @Override
+            public boolean onTouch(View v, MotionEvent event) {
+                if (event.getAction() == MotionEvent.ACTION_DOWN) {
+                    performHapticFeedback(HapticFeedbackConstants.VIRTUAL_KEY);
+                }
+
+                // Passthrough
+                return false;
+            }
+        });
+    }
+}