1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.widget;
18
19import android.content.Context;
20import android.os.Handler;
21import android.os.Message;
22import android.util.AttributeSet;
23import android.view.MotionEvent;
24import android.view.accessibility.AccessibilityEvent;
25import android.view.accessibility.AccessibilityNodeInfo;
26import android.widget.RemoteViews.RemoteView;
27
28import java.util.Map;
29
30/**
31 * <p>
32 * Displays a button with an image (instead of text) that can be pressed
33 * or clicked by the user. By default, an ImageButton looks like a regular
34 * {@link android.widget.Button}, with the standard button background
35 * that changes color during different button states. The image on the surface
36 * of the button is defined either by the {@code android:src} attribute in the
37 * {@code <ImageButton>} XML element or by the
38 * {@link #setImageResource(int)} method.</p>
39 *
40 * <p>To remove the standard button background image, define your own
41 * background image or set the background color to be transparent.</p>
42 * <p>To indicate the different button states (focused, selected, etc.), you can
43 * define a different image for each state. E.g., a blue image by default, an
44 * orange one for when focused, and a yellow one for when pressed. An easy way to
45 * do this is with an XML drawable "selector." For example:</p>
46 * <pre>
47 * &lt;?xml version="1.0" encoding="utf-8"?&gt;
48 * &lt;selector xmlns:android="http://schemas.android.com/apk/res/android"&gt;
49 *     &lt;item android:state_pressed="true"
50 *           android:drawable="@drawable/button_pressed" /&gt; &lt;!-- pressed --&gt;
51 *     &lt;item android:state_focused="true"
52 *           android:drawable="@drawable/button_focused" /&gt; &lt;!-- focused --&gt;
53 *     &lt;item android:drawable="@drawable/button_normal" /&gt; &lt;!-- default --&gt;
54 * &lt;/selector&gt;</pre>
55 *
56 * <p>Save the XML file in your project {@code res/drawable/} folder and then
57 * reference it as a drawable for the source of your ImageButton (in the
58 * {@code android:src} attribute). Android will automatically change the image
59 * based on the state of the button and the corresponding images
60 * defined in the XML.</p>
61 *
62 * <p>The order of the {@code <item>} elements is important because they are
63 * evaluated in order. This is why the "normal" button image comes last, because
64 * it will only be applied after {@code android:state_pressed} and {@code
65 * android:state_focused} have both evaluated false.</p>
66 *
67 * <p>See the <a href="{@docRoot}guide/topics/ui/controls/button.html">Buttons</a>
68 * guide.</p>
69 *
70 * <p><strong>XML attributes</strong></p>
71 * <p>
72 * See {@link android.R.styleable#ImageView Button Attributes},
73 * {@link android.R.styleable#View View Attributes}
74 * </p>
75 */
76@RemoteView
77public class ImageButton extends ImageView {
78    public ImageButton(Context context) {
79        this(context, null);
80    }
81
82    public ImageButton(Context context, AttributeSet attrs) {
83        this(context, attrs, com.android.internal.R.attr.imageButtonStyle);
84    }
85
86    public ImageButton(Context context, AttributeSet attrs, int defStyle) {
87        super(context, attrs, defStyle);
88        setFocusable(true);
89    }
90
91    @Override
92    protected boolean onSetAlpha(int alpha) {
93        return false;
94    }
95
96    @Override
97    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
98        super.onInitializeAccessibilityEvent(event);
99        event.setClassName(ImageButton.class.getName());
100    }
101
102    @Override
103    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
104        super.onInitializeAccessibilityNodeInfo(info);
105        info.setClassName(ImageButton.class.getName());
106    }
107}
108