content: /*
   * 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.view.MotionEvent;
  import android.view.PointerIcon;
  import android.widget.RemoteViews.RemoteView;
  
  /**
   * <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>
   * &lt;?xml version="1.0" encoding="utf-8"?&gt;
   * &lt;selector xmlns:android="http://schemas.android.com/apk/res/android"&gt;
   *     &lt;item android:state_pressed="true"
   *           android:drawable="@drawable/button_pressed" /&gt; &lt;!-- pressed --&gt;
   *     &lt;item android:state_focused="true"
   *           android:drawable="@drawable/button_focused" /&gt; &lt;!-- focused --&gt;
   *     &lt;item android:drawable="@drawable/button_normal" /&gt; &lt;!-- default --&gt;
   * &lt;/selector&gt;</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>
   */
  @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();
      }
  
      @Override
      public PointerIcon onResolvePointerIcon(MotionEvent event, int pointerIndex) {
          if (getPointerIcon() == null && isClickable() && isEnabled()) {
              return PointerIcon.getSystemIcon(getContext(), PointerIcon.TYPE_HAND);
          }
          return super.onResolvePointerIcon(event, pointerIndex);
      }
  }
  