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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 
     22 
     23 
     24 /**
     25  * A SeekBar is an extension of ProgressBar that adds a draggable thumb. The user can touch
     26  * the thumb and drag left or right to set the current progress level or use the arrow keys.
     27  * Placing focusable widgets to the left or right of a SeekBar is discouraged.
     28  * <p>
     29  * Clients of the SeekBar can attach a {@link SeekBar.OnSeekBarChangeListener} to
     30  * be notified of the user's actions.
     31  *
     32  * @attr ref android.R.styleable#SeekBar_thumb
     33  */
     34 public class SeekBar extends AbsSeekBar {
     35 
     36     /**
     37      * A callback that notifies clients when the progress level has been
     38      * changed. This includes changes that were initiated by the user through a
     39      * touch gesture or arrow key/trackball as well as changes that were initiated
     40      * programmatically.
     41      */
     42     public interface OnSeekBarChangeListener {
     43 
     44         /**
     45          * Notification that the progress level has changed. Clients can use the fromUser parameter
     46          * to distinguish user-initiated changes from those that occurred programmatically.
     47          *
     48          * @param seekBar The SeekBar whose progress has changed
     49          * @param progress The current progress level. This will be in the range 0..max where max
     50          *        was set by {@link ProgressBar#setMax(int)}. (The default value for max is 100.)
     51          * @param fromUser True if the progress change was initiated by the user.
     52          */
     53         void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser);
     54 
     55         /**
     56          * Notification that the user has started a touch gesture. Clients may want to use this
     57          * to disable advancing the seekbar.
     58          * @param seekBar The SeekBar in which the touch gesture began
     59          */
     60         void onStartTrackingTouch(SeekBar seekBar);
     61 
     62         /**
     63          * Notification that the user has finished a touch gesture. Clients may want to use this
     64          * to re-enable advancing the seekbar.
     65          * @param seekBar The SeekBar in which the touch gesture began
     66          */
     67         void onStopTrackingTouch(SeekBar seekBar);
     68     }
     69 
     70     private OnSeekBarChangeListener mOnSeekBarChangeListener;
     71 
     72     public SeekBar(Context context) {
     73         this(context, null);
     74     }
     75 
     76     public SeekBar(Context context, AttributeSet attrs) {
     77         this(context, attrs, com.android.internal.R.attr.seekBarStyle);
     78     }
     79 
     80     public SeekBar(Context context, AttributeSet attrs, int defStyle) {
     81         super(context, attrs, defStyle);
     82     }
     83 
     84     @Override
     85     void onProgressRefresh(float scale, boolean fromUser) {
     86         super.onProgressRefresh(scale, fromUser);
     87 
     88         if (mOnSeekBarChangeListener != null) {
     89             mOnSeekBarChangeListener.onProgressChanged(this, getProgress(), fromUser);
     90         }
     91     }
     92 
     93     /**
     94      * Sets a listener to receive notifications of changes to the SeekBar's progress level. Also
     95      * provides notifications of when the user starts and stops a touch gesture within the SeekBar.
     96      *
     97      * @param l The seek bar notification listener
     98      *
     99      * @see SeekBar.OnSeekBarChangeListener
    100      */
    101     public void setOnSeekBarChangeListener(OnSeekBarChangeListener l) {
    102         mOnSeekBarChangeListener = l;
    103     }
    104 
    105     @Override
    106     void onStartTrackingTouch() {
    107         if (mOnSeekBarChangeListener != null) {
    108             mOnSeekBarChangeListener.onStartTrackingTouch(this);
    109         }
    110     }
    111 
    112     @Override
    113     void onStopTrackingTouch() {
    114         if (mOnSeekBarChangeListener != null) {
    115             mOnSeekBarChangeListener.onStopTrackingTouch(this);
    116         }
    117     }
    118 
    119 }
    120