Add a sample for handling hover events.

Change-Id: I9e19e09d3f5b8d0fd03f52cc8d88e6a12399d12f

samples/ApiDemos/src/com/example/android/apis/view/Hover.java

@@ -0,0 +1,106 @@
+/*
+ * 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.example.android.apis.view;
+
+import com.example.android.apis.R;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.res.Resources;
+import android.os.Bundle;
+import android.util.AttributeSet;
+import android.util.Log;
+import android.view.LayoutInflater;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.CheckBox;
+import android.widget.CompoundButton;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+
+import java.util.ArrayList;
+
+
+/**
+ * Demonstrates how to use {@link View#onHoverEvent}, {@link ViewGroup#onInterceptHoverEvent},
+ * and {@link View#setOnHoverListener}.
+ *
+ * This activity displays a few buttons and text fields and entices the user
+ * to hover over them using a mouse or touch pad.  It displays feedback reporting
+ * the position of the pointing device and the label of the view being hovered.
+ *
+ * A button changes from dark green to bright yellow when hovered.
+ * This effect is achieved by using a state-list drawable to select among different
+ * background shapes and colors based on the hover state of the button.
+ *
+ * A {@link View#OnHoverEventListener} is used to listen for hover events within the
+ * container.  The container will re
+ *
+ * A checkbox is used to control whether a special view, the Interceptor, will intercept
+ * events before they are sent to its child (a button).  When the Interceptor
+ * is intercepting events, the button will not change state as the pointer hovers
+ * over it because the interceptor itself will grab the events.
+ */
+public class Hover extends Activity {
+    private TextView mMessageTextView;
+    private CheckBox mInterceptCheckBox;
+    private HoverInterceptorView mInterceptor;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        setContentView(R.layout.hover);
+
+        mMessageTextView = (TextView) findViewById(R.id.message);
+        mInterceptCheckBox = (CheckBox) findViewById(R.id.intercept_checkbox);
+        mInterceptor = (HoverInterceptorView) findViewById(R.id.interceptor);
+
+        View container = findViewById(R.id.container);
+        container.setOnHoverListener(new View.OnHoverListener() {
+            @Override
+            public boolean onHover(View v, MotionEvent event) {
+                switch (event.getAction()) {
+                    case MotionEvent.ACTION_HOVER_ENTER:
+                        mMessageTextView.setText(Hover.this.getResources().getString(
+                                R.string.hover_message_entered_at,
+                                event.getX(), event.getY()));
+                        break;
+                    case MotionEvent.ACTION_HOVER_MOVE:
+                        mMessageTextView.setText(Hover.this.getResources().getString(
+                                R.string.hover_message_moved_at,
+                                event.getX(), event.getY()));
+                        break;
+                    case MotionEvent.ACTION_HOVER_EXIT:
+                        mMessageTextView.setText(Hover.this.getResources().getString(
+                                R.string.hover_message_exited_at,
+                                event.getX(), event.getY()));
+                        break;
+                }
+                return false;
+            }
+        });
+
+        mInterceptCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+                mInterceptor.setInterceptHover(isChecked);
+            }
+        });
+    }
+}

samples/ApiDemos/src/com/example/android/apis/view/HoverInterceptorView.java

@@ -0,0 +1,71 @@
+/*
+ * 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.example.android.apis.view;
+
+import com.example.android.apis.R;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+
+/**
+ * Part of the {@link Hover} demo activity.
+ * 
+ * The Interceptor view is a simple subclass of LinearLayout whose sole purpose
+ * is to override {@link #onInterceptHoverEvent}.  When the checkbox in the
+ * hover activity is checked, the interceptor view will intercept hover events.
+ *
+ * When this view intercepts hover events, its children will not receive
+ * hover events.  This can be useful in some cases when implementing a custom
+ * view group that would like to prevent its children from being hovered
+ * under certain situations.  Usually such custom views will be much more
+ * interesting and complex than our little Interceptor example here.
+ */
+public class HoverInterceptorView extends LinearLayout {
+    private boolean mInterceptHover;
+
+    public HoverInterceptorView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    @Override
+    public boolean onInterceptHoverEvent(MotionEvent event) {
+        if (mInterceptHover) {
+            return true;
+        }
+        return super.onInterceptHoverEvent(event);
+    }
+
+    @Override
+    public boolean onHoverEvent(MotionEvent event) {
+        TextView textView = (TextView) findViewById(R.id.intercept_message);
+        if (mInterceptHover && event.getAction() != MotionEvent.ACTION_HOVER_EXIT) {
+            textView.setText(getResources().getString(
+                    R.string.hover_intercept_message_intercepted));
+            return true;
+        }
+        textView.setText(getResources().getString(
+                R.string.hover_intercept_message_initial));
+        return super.onHoverEvent(event);
+    }
+
+    public void setInterceptHover(boolean intercept) {
+        mInterceptHover = intercept;
+    }
+}