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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 
     20 import android.content.Context;
     21 import android.util.AttributeSet;
     22 import android.view.View;
     23 import android.view.ViewGroup;
     24 import android.view.accessibility.AccessibilityEvent;
     25 import android.view.accessibility.AccessibilityNodeInfo;
     26 
     27 /**
     28  * Specialized {@link android.widget.ViewSwitcher} that contains
     29  * only children of type {@link android.widget.TextView}.
     30  *
     31  * A TextSwitcher is useful to animate a label on screen. Whenever
     32  * {@link #setText(CharSequence)} is called, TextSwitcher animates the current text
     33  * out and animates the new text in.
     34  */
     35 public class TextSwitcher extends ViewSwitcher {
     36     /**
     37      * Creates a new empty TextSwitcher.
     38      *
     39      * @param context the application's environment
     40      */
     41     public TextSwitcher(Context context) {
     42         super(context);
     43     }
     44 
     45     /**
     46      * Creates a new empty TextSwitcher for the given context and with the
     47      * specified set attributes.
     48      *
     49      * @param context the application environment
     50      * @param attrs a collection of attributes
     51      */
     52     public TextSwitcher(Context context, AttributeSet attrs) {
     53         super(context, attrs);
     54     }
     55 
     56     /**
     57      * {@inheritDoc}
     58      *
     59      * @throws IllegalArgumentException if child is not an instance of
     60      *         {@link android.widget.TextView}
     61      */
     62     @Override
     63     public void addView(View child, int index, ViewGroup.LayoutParams params) {
     64         if (!(child instanceof TextView)) {
     65             throw new IllegalArgumentException(
     66                     "TextSwitcher children must be instances of TextView");
     67         }
     68 
     69         super.addView(child, index, params);
     70     }
     71 
     72     /**
     73      * Sets the text of the next view and switches to the next view. This can
     74      * be used to animate the old text out and animate the next text in.
     75      *
     76      * @param text the new text to display
     77      */
     78     public void setText(CharSequence text) {
     79         final TextView t = (TextView) getNextView();
     80         t.setText(text);
     81         showNext();
     82     }
     83 
     84     /**
     85      * Sets the text of the text view that is currently showing.  This does
     86      * not perform the animations.
     87      *
     88      * @param text the new text to display
     89      */
     90     public void setCurrentText(CharSequence text) {
     91         ((TextView)getCurrentView()).setText(text);
     92     }
     93 
     94     @Override
     95     public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
     96         super.onInitializeAccessibilityEvent(event);
     97         event.setClassName(TextSwitcher.class.getName());
     98     }
     99 
    100     @Override
    101     public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
    102         super.onInitializeAccessibilityNodeInfo(info);
    103         info.setClassName(TextSwitcher.class.getName());
    104     }
    105 }
    106