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 17 package android.widget; 18 19 import android.content.Context; 20 import android.util.AttributeSet; 21 import android.widget.RemoteViews.RemoteView; 22 23 /** 24 * <p> 25 * Displays a button with an image (instead of text) that can be pressed 26 * or clicked by the user. By default, an ImageButton looks like a regular 27 * {@link android.widget.Button}, with the standard button background 28 * that changes color during different button states. The image on the surface 29 * of the button is defined either by the {@code android:src} attribute in the 30 * {@code <ImageButton>} XML element or by the 31 * {@link #setImageResource(int)} method.</p> 32 * 33 * <p>To remove the standard button background image, define your own 34 * background image or set the background color to be transparent.</p> 35 * <p>To indicate the different button states (focused, selected, etc.), you can 36 * define a different image for each state. E.g., a blue image by default, an 37 * orange one for when focused, and a yellow one for when pressed. An easy way to 38 * do this is with an XML drawable "selector." For example:</p> 39 * <pre> 40 * <?xml version="1.0" encoding="utf-8"?> 41 * <selector xmlns:android="http://schemas.android.com/apk/res/android"> 42 * <item android:state_pressed="true" 43 * android:drawable="@drawable/button_pressed" /> <!-- pressed --> 44 * <item android:state_focused="true" 45 * android:drawable="@drawable/button_focused" /> <!-- focused --> 46 * <item android:drawable="@drawable/button_normal" /> <!-- default --> 47 * </selector></pre> 48 * 49 * <p>Save the XML file in your project {@code res/drawable/} folder and then 50 * reference it as a drawable for the source of your ImageButton (in the 51 * {@code android:src} attribute). Android will automatically change the image 52 * based on the state of the button and the corresponding images 53 * defined in the XML.</p> 54 * 55 * <p>The order of the {@code <item>} elements is important because they are 56 * evaluated in order. This is why the "normal" button image comes last, because 57 * it will only be applied after {@code android:state_pressed} and {@code 58 * android:state_focused} have both evaluated false.</p> 59 * 60 * <p>See the <a href="{@docRoot}guide/topics/ui/controls/button.html">Buttons</a> 61 * guide.</p> 62 * 63 * <p><strong>XML attributes</strong></p> 64 * <p> 65 * See {@link android.R.styleable#ImageView Button Attributes}, 66 * {@link android.R.styleable#View View Attributes} 67 * </p> 68 */ 69 @RemoteView 70 public class ImageButton extends ImageView { 71 public ImageButton(Context context) { 72 this(context, null); 73 } 74 75 public ImageButton(Context context, AttributeSet attrs) { 76 this(context, attrs, com.android.internal.R.attr.imageButtonStyle); 77 } 78 79 public ImageButton(Context context, AttributeSet attrs, int defStyleAttr) { 80 this(context, attrs, defStyleAttr, 0); 81 } 82 83 public ImageButton(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { 84 super(context, attrs, defStyleAttr, defStyleRes); 85 setFocusable(true); 86 } 87 88 @Override 89 protected boolean onSetAlpha(int alpha) { 90 return false; 91 } 92 93 @Override 94 public CharSequence getAccessibilityClassName() { 95 return ImageButton.class.getName(); 96 } 97 } 98
