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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 
     24 
     25 
     26 /**
     27  * A SeekBar is an extension of ProgressBar that adds a draggable thumb. The user can touch
     28  * the thumb and drag left or right to set the current progress level or use the arrow keys.
     29  * Placing focusable widgets to the left or right of a SeekBar is discouraged.
     30  * <p>
     31  * Clients of the SeekBar can attach a {@link SeekBar.OnSeekBarChangeListener} to
     32  * be notified of the user's actions.
     33  *
     34  * @attr ref android.R.styleable#SeekBar_thumb
     35  */
     36 public class SeekBar extends AbsSeekBar {
     37 
     38     /**
     39      * A callback that notifies clients when the progress level has been
     40      * changed. This includes changes that were initiated by the user through a
     41      * touch gesture or arrow key/trackball as well as changes that were initiated
     42      * programmatically.
     43      */
     44     public interface OnSeekBarChangeListener {
     45 
     46         /**
     47          * Notification that the progress level has changed. Clients can use the fromUser parameter
     48          * to distinguish user-initiated changes from those that occurred programmatically.
     49          *
     50          * @param seekBar The SeekBar whose progress has changed
     51          * @param progress The current progress level. This will be in the range 0..max where max
     52          *        was set by {@link ProgressBar#setMax(int)}. (The default value for max is 100.)
     53          * @param fromUser True if the progress change was initiated by the user.
     54          */
     55         void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser);
     56 
     57         /**
     58          * Notification that the user has started a touch gesture. Clients may want to use this
     59          * to disable advancing the seekbar.
     60          * @param seekBar The SeekBar in which the touch gesture began
     61          */
     62         void onStartTrackingTouch(SeekBar seekBar);
     63 
     64         /**
     65          * Notification that the user has finished a touch gesture. Clients may want to use this
     66          * to re-enable advancing the seekbar.
     67          * @param seekBar The SeekBar in which the touch gesture began
     68          */
     69         void onStopTrackingTouch(SeekBar seekBar);
     70     }
     71 
     72     private OnSeekBarChangeListener mOnSeekBarChangeListener;
     73 
     74     public SeekBar(Context context) {
     75         this(context, null);
     76     }
     77 
     78     public SeekBar(Context context, AttributeSet attrs) {
     79         this(context, attrs, com.android.internal.R.attr.seekBarStyle);
     80     }
     81 
     82     public SeekBar(Context context, AttributeSet attrs, int defStyle) {
     83         super(context, attrs, defStyle);
     84     }
     85 
     86     @Override
     87     void onProgressRefresh(float scale, boolean fromUser) {
     88         super.onProgressRefresh(scale, fromUser);
     89 
     90         if (mOnSeekBarChangeListener != null) {
     91             mOnSeekBarChangeListener.onProgressChanged(this, getProgress(), fromUser);
     92         }
     93     }
     94 
     95     /**
     96      * Sets a listener to receive notifications of changes to the SeekBar's progress level. Also
     97      * provides notifications of when the user starts and stops a touch gesture within the SeekBar.
     98      *
     99      * @param l The seek bar notification listener
    100      *
    101      * @see SeekBar.OnSeekBarChangeListener
    102      */
    103     public void setOnSeekBarChangeListener(OnSeekBarChangeListener l) {
    104         mOnSeekBarChangeListener = l;
    105     }
    106 
    107     @Override
    108     void onStartTrackingTouch() {
    109         super.onStartTrackingTouch();
    110         if (mOnSeekBarChangeListener != null) {
    111             mOnSeekBarChangeListener.onStartTrackingTouch(this);
    112         }
    113     }
    114 
    115     @Override
    116     void onStopTrackingTouch() {
    117         super.onStopTrackingTouch();
    118         if (mOnSeekBarChangeListener != null) {
    119             mOnSeekBarChangeListener.onStopTrackingTouch(this);
    120         }
    121     }
    122 
    123     @Override
    124     public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
    125         super.onInitializeAccessibilityEvent(event);
    126         event.setClassName(SeekBar.class.getName());
    127     }
    128 
    129     @Override
    130     public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
    131         super.onInitializeAccessibilityNodeInfo(info);
    132         info.setClassName(SeekBar.class.getName());
    133     }
    134 }
    135