Home | History | Annotate | Download | only in widget 
      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.annotation.UnsupportedAppUsage;
     20 import android.content.Context;
     21 import android.util.AttributeSet;
     22 import android.view.accessibility.AccessibilityNodeInfo;
     23 
     24 
     25 /**
     26  * A SeekBar is an extension of ProgressBar that adds a draggable thumb. The user can touch
     27  * the thumb and drag left or right to set the current progress level or use the arrow keys.
     28  * Placing focusable widgets to the left or right of a SeekBar is discouraged.
     29  * <p>
     30  * Clients of the SeekBar can attach a {@link SeekBar.OnSeekBarChangeListener} to
     31  * be notified of the user's actions.
     32  *
     33  * @attr ref android.R.styleable#SeekBar_thumb
     34  */
     35 public class SeekBar extends AbsSeekBar {
     36 
     37     /**
     38      * A callback that notifies clients when the progress level has been
     39      * changed. This includes changes that were initiated by the user through a
     40      * touch gesture or arrow key/trackball as well as changes that were initiated
     41      * programmatically.
     42      */
     43     public interface OnSeekBarChangeListener {
     44 
     45         /**
     46          * Notification that the progress level has changed. Clients can use the fromUser parameter
     47          * to distinguish user-initiated changes from those that occurred programmatically.
     48          *
     49          * @param seekBar The SeekBar whose progress has changed
     50          * @param progress The current progress level. This will be in the range min..max where min
     51          *                 and max were set by {@link ProgressBar#setMin(int)} and
     52          *                 {@link ProgressBar#setMax(int)}, respectively. (The default values for
     53          *                 min is 0 and max is 100.)
     54          * @param fromUser True if the progress change was initiated by the user.
     55          */
     56         void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser);
     57 
     58         /**
     59          * Notification that the user has started a touch gesture. Clients may want to use this
     60          * to disable advancing the seekbar.
     61          * @param seekBar The SeekBar in which the touch gesture began
     62          */
     63         void onStartTrackingTouch(SeekBar seekBar);
     64 
     65         /**
     66          * Notification that the user has finished a touch gesture. Clients may want to use this
     67          * to re-enable advancing the seekbar.
     68          * @param seekBar The SeekBar in which the touch gesture began
     69          */
     70         void onStopTrackingTouch(SeekBar seekBar);
     71     }
     72 
     73     @UnsupportedAppUsage
     74     private OnSeekBarChangeListener mOnSeekBarChangeListener;
     75 
     76     public SeekBar(Context context) {
     77         this(context, null);
     78     }
     79 
     80     public SeekBar(Context context, AttributeSet attrs) {
     81         this(context, attrs, com.android.internal.R.attr.seekBarStyle);
     82     }
     83 
     84     public SeekBar(Context context, AttributeSet attrs, int defStyleAttr) {
     85         this(context, attrs, defStyleAttr, 0);
     86     }
     87 
     88     public SeekBar(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
     89         super(context, attrs, defStyleAttr, defStyleRes);
     90     }
     91 
     92     @Override
     93     @UnsupportedAppUsage
     94     void onProgressRefresh(float scale, boolean fromUser, int progress) {
     95         super.onProgressRefresh(scale, fromUser, progress);
     96 
     97         if (mOnSeekBarChangeListener != null) {
     98             mOnSeekBarChangeListener.onProgressChanged(this, progress, fromUser);
     99         }
    100     }
    101 
    102     /**
    103      * Sets a listener to receive notifications of changes to the SeekBar's progress level. Also
    104      * provides notifications of when the user starts and stops a touch gesture within the SeekBar.
    105      *
    106      * @param l The seek bar notification listener
    107      *
    108      * @see SeekBar.OnSeekBarChangeListener
    109      */
    110     public void setOnSeekBarChangeListener(OnSeekBarChangeListener l) {
    111         mOnSeekBarChangeListener = l;
    112     }
    113 
    114     @Override
    115     void onStartTrackingTouch() {
    116         super.onStartTrackingTouch();
    117         if (mOnSeekBarChangeListener != null) {
    118             mOnSeekBarChangeListener.onStartTrackingTouch(this);
    119         }
    120     }
    121 
    122     @Override
    123     void onStopTrackingTouch() {
    124         super.onStopTrackingTouch();
    125         if (mOnSeekBarChangeListener != null) {
    126             mOnSeekBarChangeListener.onStopTrackingTouch(this);
    127         }
    128     }
    129 
    130     @Override
    131     public CharSequence getAccessibilityClassName() {
    132         return SeekBar.class.getName();
    133     }
    134 
    135     /** @hide */
    136     @Override
    137     public void onInitializeAccessibilityNodeInfoInternal(AccessibilityNodeInfo info) {
    138         super.onInitializeAccessibilityNodeInfoInternal(info);
    139 
    140         if (canUserSetProgress()) {
    141             info.addAction(AccessibilityNodeInfo.AccessibilityAction.ACTION_SET_PROGRESS);
    142         }
    143     }
    144 }
    145