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      1 /*
      2  * Copyright (C) 2006 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.view.accessibility.AccessibilityEvent;
     22 import android.view.accessibility.AccessibilityNodeInfo;
     23 import android.widget.RemoteViews.RemoteView;
     24 
     25 
     26 /**
     27  * Represents a push-button widget. Push-buttons can be
     28  * pressed, or clicked, by the user to perform an action.
     29 
     30  * <p>A typical use of a push-button in an activity would be the following:
     31  * </p>
     32  *
     33  * <pre>
     34  * public class MyActivity extends Activity {
     35  *     protected void onCreate(Bundle icicle) {
     36  *         super.onCreate(icicle);
     37  *
     38  *         setContentView(R.layout.content_layout_id);
     39  *
     40  *         final Button button = (Button) findViewById(R.id.button_id);
     41  *         button.setOnClickListener(new View.OnClickListener() {
     42  *             public void onClick(View v) {
     43  *                 // Perform action on click
     44  *             }
     45  *         });
     46  *     }
     47  * }</pre>
     48  *
     49  * <p>However, instead of applying an {@link android.view.View.OnClickListener OnClickListener} to
     50  * the button in your activity, you can assign a method to your button in the XML layout,
     51  * using the {@link android.R.attr#onClick android:onClick} attribute. For example:</p>
     52  *
     53  * <pre>
     54  * &lt;Button
     55  *     android:layout_height="wrap_content"
     56  *     android:layout_width="wrap_content"
     57  *     android:text="@string/self_destruct"
     58  *     android:onClick="selfDestruct" /&gt;</pre>
     59  *
     60  * <p>Now, when a user clicks the button, the Android system calls the activity's {@code
     61  * selfDestruct(View)} method. In order for this to work, the method must be public and accept
     62  * a {@link android.view.View} as its only parameter. For example:</p>
     63  *
     64  * <pre>
     65  * public void selfDestruct(View view) {
     66  *     // Kabloey
     67  * }</pre>
     68  *
     69  * <p>The {@link android.view.View} passed into the method is a reference to the widget
     70  * that was clicked.</p>
     71  *
     72  * <h3>Button style</h3>
     73  *
     74  * <p>Every Button is styled using the system's default button background, which is often different
     75  * from one device to another and from one version of the platform to another. If you're not
     76  * satisfied with the default button style and want to customize it to match the design of your
     77  * application, then you can replace the button's background image with a <a
     78  * href="{@docRoot}guide/topics/resources/drawable-resource.html#StateList">state list drawable</a>.
     79  * A state list drawable is a drawable resource defined in XML that changes its image based on
     80  * the current state of the button. Once you've defined a state list drawable in XML, you can apply
     81  * it to your Button with the {@link android.R.attr#background android:background}
     82  * attribute. For more information and an example, see <a
     83  * href="{@docRoot}guide/topics/resources/drawable-resource.html#StateList">State List
     84  * Drawable</a>.</p>
     85  *
     86  * <p>See the <a href="{@docRoot}guide/topics/ui/controls/button.html">Buttons</a>
     87  * guide.</p>
     88  *
     89  * <p><strong>XML attributes</strong></p>
     90  * <p>
     91  * See {@link android.R.styleable#Button Button Attributes},
     92  * {@link android.R.styleable#TextView TextView Attributes},
     93  * {@link android.R.styleable#View View Attributes}
     94  * </p>
     95  */
     96 @RemoteView
     97 public class Button extends TextView {
     98     public Button(Context context) {
     99         this(context, null);
    100     }
    101 
    102     public Button(Context context, AttributeSet attrs) {
    103         this(context, attrs, com.android.internal.R.attr.buttonStyle);
    104     }
    105 
    106     public Button(Context context, AttributeSet attrs, int defStyleAttr) {
    107         this(context, attrs, defStyleAttr, 0);
    108     }
    109 
    110     public Button(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
    111         super(context, attrs, defStyleAttr, defStyleRes);
    112     }
    113 
    114     @Override
    115     public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
    116         super.onInitializeAccessibilityEvent(event);
    117         event.setClassName(Button.class.getName());
    118     }
    119 
    120     @Override
    121     public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
    122         super.onInitializeAccessibilityNodeInfo(info);
    123         info.setClassName(Button.class.getName());
    124     }
    125 }
    126