SeekBar.java revision b798689749c64baba81f02e10cf2157c747d6b46 
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
17package android.widget;
18
19import android.content.Context;
20import 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 */
34public 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