FolderAutoScrollHelper.java revision b66773cfb9aee1e99b21e8cbac58043bb1ec32a9 
1/*
2 * Copyright (C) 2013 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 com.android.launcher3;
18
19import android.support.v4.widget.AutoScrollHelper;
20import android.widget.ScrollView;
21
22/**
23 * An implementation of {@link AutoScrollHelper} that knows how to scroll
24 * through a {@link Folder}.
25 */
26public class FolderAutoScrollHelper extends AutoScrollHelper {
27    private static final float MAX_SCROLL_VELOCITY = 1500f;
28
29    private final ScrollView mTarget;
30
31    public FolderAutoScrollHelper(ScrollView target) {
32        super(target);
33
34        mTarget = target;
35
36        setActivationDelay(0);
37        setEdgeType(EDGE_TYPE_INSIDE_EXTEND);
38        setExclusive(true);
39        setMaximumVelocity(MAX_SCROLL_VELOCITY, MAX_SCROLL_VELOCITY);
40        setRampDownDuration(0);
41        setRampUpDuration(0);
42    }
43
44    @Override
45    public void scrollTargetBy(int deltaX, int deltaY) {
46        mTarget.scrollBy(deltaX, deltaY);
47    }
48
49    @Override
50    public boolean canTargetScrollHorizontally(int direction) {
51        // List do not scroll horizontally.
52        return false;
53    }
54
55    @Override
56    public boolean canTargetScrollVertically(int direction) {
57        return mTarget.canScrollVertically(direction);
58    }
59}