1/*
2 * Copyright (C) 2014 Google Inc.
3 * Licensed to The Android Open Source Project.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18package com.android.mail.ui;
19
20import android.content.Context;
21import android.database.Observable;
22import android.util.AttributeSet;
23import android.widget.ListView;
24
25import com.android.mail.browse.ScrollNotifier;
26
27/**
28 * Ordinary list view with extra boilerplate to notify on scrollbar-related events (unrelated to
29 * {@link android.widget.AbsListView.OnScrollListener}!)
30 */
31public class ScrollNotifyingListView extends ListView implements ScrollNotifier {
32
33    private final ScrollObservable mObservable = new ScrollObservable();
34
35    public ScrollNotifyingListView(Context c) {
36        this(c, null);
37    }
38
39    public ScrollNotifyingListView(Context c, AttributeSet attrs) {
40        super(c, attrs);
41    }
42
43    @Override
44    public void addScrollListener(ScrollListener l) {
45        mObservable.registerObserver(l);
46    }
47
48    @Override
49    public void removeScrollListener(ScrollListener l) {
50        mObservable.unregisterObserver(l);
51    }
52
53    @Override
54    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
55        super.onScrollChanged(l, t, oldl, oldt);
56        mObservable.onScrollChanged(l, t, oldl, oldt);
57    }
58
59    @Override
60    public int computeVerticalScrollRange() {
61        return super.computeVerticalScrollRange();
62    }
63
64    @Override
65    public int computeVerticalScrollOffset() {
66        return super.computeVerticalScrollOffset();
67    }
68
69    @Override
70    public int computeVerticalScrollExtent() {
71        return super.computeVerticalScrollExtent();
72    }
73
74    @Override
75    public int computeHorizontalScrollRange() {
76        return super.computeHorizontalScrollRange();
77    }
78
79    @Override
80    public int computeHorizontalScrollOffset() {
81        return super.computeHorizontalScrollOffset();
82    }
83
84    @Override
85    public int computeHorizontalScrollExtent() {
86        return super.computeHorizontalScrollExtent();
87    }
88
89    private static class ScrollObservable extends Observable<ScrollListener> {
90
91        @SuppressWarnings("unused")
92        public void onScrollChanged(int l, int t, int oldl, int oldt) {
93            for (ScrollListener sl : mObservers) {
94                sl.onNotifierScroll(t);
95            }
96        }
97
98    }
99
100}
101