1/*
2 * Copyright (C) 2014 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.support.v4.view;
18
19/**
20 * An interface that can be implemented by Views to provide scroll related APIs.
21 */
22public interface ScrollingView {
23    /**
24     * <p>Compute the horizontal range that the horizontal scrollbar
25     * represents.</p>
26     *
27     * <p>The range is expressed in arbitrary units that must be the same as the
28     * units used by {@link #computeHorizontalScrollExtent()} and
29     * {@link #computeHorizontalScrollOffset()}.</p>
30     *
31     * <p>The default range is the drawing width of this view.</p>
32     *
33     * @return the total horizontal range represented by the horizontal
34     *         scrollbar
35     *
36     * @see #computeHorizontalScrollExtent()
37     * @see #computeHorizontalScrollOffset()
38     * @see android.widget.ScrollBarDrawable
39     */
40    int computeHorizontalScrollRange();
41
42    /**
43     * <p>Compute the horizontal offset of the horizontal scrollbar's thumb
44     * within the horizontal range. This value is used to compute the position
45     * of the thumb within the scrollbar's track.</p>
46     *
47     * <p>The range is expressed in arbitrary units that must be the same as the
48     * units used by {@link #computeHorizontalScrollRange()} and
49     * {@link #computeHorizontalScrollExtent()}.</p>
50     *
51     * <p>The default offset is the scroll offset of this view.</p>
52     *
53     * @return the horizontal offset of the scrollbar's thumb
54     *
55     * @see #computeHorizontalScrollRange()
56     * @see #computeHorizontalScrollExtent()
57     * @see android.widget.ScrollBarDrawable
58     */
59    int computeHorizontalScrollOffset();
60
61    /**
62     * <p>Compute the horizontal extent of the horizontal scrollbar's thumb
63     * within the horizontal range. This value is used to compute the length
64     * of the thumb within the scrollbar's track.</p>
65     *
66     * <p>The range is expressed in arbitrary units that must be the same as the
67     * units used by {@link #computeHorizontalScrollRange()} and
68     * {@link #computeHorizontalScrollOffset()}.</p>
69     *
70     * <p>The default extent is the drawing width of this view.</p>
71     *
72     * @return the horizontal extent of the scrollbar's thumb
73     *
74     * @see #computeHorizontalScrollRange()
75     * @see #computeHorizontalScrollOffset()
76     * @see android.widget.ScrollBarDrawable
77     */
78    int computeHorizontalScrollExtent();
79
80    /**
81     * <p>Compute the vertical range that the vertical scrollbar represents.</p>
82     *
83     * <p>The range is expressed in arbitrary units that must be the same as the
84     * units used by {@link #computeVerticalScrollExtent()} and
85     * {@link #computeVerticalScrollOffset()}.</p>
86     *
87     * @return the total vertical range represented by the vertical scrollbar
88     *
89     * <p>The default range is the drawing height of this view.</p>
90     *
91     * @see #computeVerticalScrollExtent()
92     * @see #computeVerticalScrollOffset()
93     * @see android.widget.ScrollBarDrawable
94     */
95    int computeVerticalScrollRange();
96
97    /**
98     * <p>Compute the vertical offset of the vertical scrollbar's thumb
99     * within the horizontal range. This value is used to compute the position
100     * of the thumb within the scrollbar's track.</p>
101     *
102     * <p>The range is expressed in arbitrary units that must be the same as the
103     * units used by {@link #computeVerticalScrollRange()} and
104     * {@link #computeVerticalScrollExtent()}.</p>
105     *
106     * <p>The default offset is the scroll offset of this view.</p>
107     *
108     * @return the vertical offset of the scrollbar's thumb
109     *
110     * @see #computeVerticalScrollRange()
111     * @see #computeVerticalScrollExtent()
112     * @see android.widget.ScrollBarDrawable
113     */
114    int computeVerticalScrollOffset();
115
116    /**
117     * <p>Compute the vertical extent of the vertical scrollbar's thumb
118     * within the vertical range. This value is used to compute the length
119     * of the thumb within the scrollbar's track.</p>
120     *
121     * <p>The range is expressed in arbitrary units that must be the same as the
122     * units used by {@link #computeVerticalScrollRange()} and
123     * {@link #computeVerticalScrollOffset()}.</p>
124     *
125     * <p>The default extent is the drawing height of this view.</p>
126     *
127     * @return the vertical extent of the scrollbar's thumb
128     *
129     * @see #computeVerticalScrollRange()
130     * @see #computeVerticalScrollOffset()
131     * @see android.widget.ScrollBarDrawable
132     */
133    int computeVerticalScrollExtent();
134}
135