android中的ImageButton

/* * 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.view.accessibility.AccessibilityEvent;import android.view.accessibility.AccessibilityNodeInfo;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>See the <a href="{@docRoot}guide/topics/ui/controls/button.html">Buttons</a> * guide.</p> * * <p><strong>XML attributes</strong></p> * <p> * See {@link android.R.styleable#ImageView Button Attributes}, * {@link android.R.styleable#View View Attributes} * </p> */@RemoteViewpublic 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;    }    @Override    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {        super.onInitializeAccessibilityEvent(event);        event.setClassName(ImageButton.class.getName());    }    @Override    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {        super.onInitializeAccessibilityNodeInfo(info);        info.setClassName(ImageButton.class.getName());    }}
更多相关文章

随机推荐
