/* * Copyright (C) 2007 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 android.widget; import android.content.Context; import android.util.AttributeSet; import android.widget.RemoteViews.RemoteView; /** *

* Displays a button with an image (instead of text) that can be pressed * or clicked by the user. By default, an ImageButton looks like a regular * {@link android.widget.Button}, with the standard button background * that changes color during different button states. The image on the surface * of the button is defined either by the {@code android:src} attribute in the * {@code } XML element or by the * {@link #setImageResource(int)} method.

* *

To remove the standard button background image, define your own * background image or set the background color to be transparent.

*

To indicate the different button states (focused, selected, etc.), you can * define a different image for each state. E.g., a blue image by default, an * orange one for when focused, and a yellow one for when pressed. An easy way to * do this is with an XML drawable "selector." For example:

*
 * <?xml version="1.0" encoding="utf-8"?>
 * <selector xmlns:android="http://schemas.android.com/apk/res/android">
 *     <item android:state_pressed="true"
 *           android:drawable="@drawable/button_pressed" /> <!-- pressed -->
 *     <item android:state_focused="true"
 *           android:drawable="@drawable/button_focused" /> <!-- focused -->
 *     <item android:drawable="@drawable/button_normal" /> <!-- default -->
 * </selector>
* *

Save the XML file in your project {@code res/drawable/} folder and then * reference it as a drawable for the source of your ImageButton (in the * {@code android:src} attribute). Android will automatically change the image * based on the state of the button and the corresponding images * defined in the XML.

* *

The order of the {@code } elements is important because they are * evaluated in order. This is why the "normal" button image comes last, because * it will only be applied after {@code android:state_pressed} and {@code * android:state_focused} have both evaluated false.

* *

See the Buttons * guide.

* *

XML attributes

*

* See {@link android.R.styleable#ImageView Button Attributes}, * {@link android.R.styleable#View View Attributes} *

*/ @RemoteView public class ImageButton extends ImageView { public ImageButton(Context context) { this(context, null); } public ImageButton(Context context, AttributeSet attrs) { this(context, attrs, com.android.internal.R.attr.imageButtonStyle); } public ImageButton(Context context, AttributeSet attrs, int defStyleAttr) { this(context, attrs, defStyleAttr, 0); } public ImageButton(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); setFocusable(true); } @Override protected boolean onSetAlpha(int alpha) { return false; } @Override public CharSequence getAccessibilityClassName() { return ImageButton.class.getName(); } }