Android example source code file (ImageButton.java)

This example Android source code file (ImageButton.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, attributeset, content, imagebutton, imageview, os, override, remoteview, ui, util, view

The ImageButton.java Android example source code

/*
 * 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.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.RemoteViews.RemoteView;

import java.util.Map;

/**
 * <p>
 * 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 <ImageButton>} XML element or by the 
 * {@link #setImageResource(int)} method.</p>
 * 
 * <p>To remove the standard button background image, define your own 
 * background image or set the background color to be transparent.</p>
 * <p>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:</p>
 * <pre>
 * <?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></pre>
 *
 * <p>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.</p>
 *
 * <p>The order of the {@code <item>} 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.</p>
 *
 * <p>XML attributes

 * <p>
 * See {@link android.R.styleable#ImageView Button Attributes},
 * {@link android.R.styleable#View View Attributes}
 * </p>
 */
@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 defStyle) {
        super(context, attrs, defStyle);
        setFocusable(true);
    }

    @Override
    protected boolean onSetAlpha(int alpha) {
        return false;
    }
}