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 
17 package com.android.launcher3;
18 
19 import android.support.v4.widget.AutoScrollHelper;
20 import android.widget.ScrollView;
21 
22 /**
23  * An implementation of {@link AutoScrollHelper} that knows how to scroll
24  * through a {@link Folder}.
25  */
26 public class FolderAutoScrollHelper extends AutoScrollHelper {
27     private static final float MAX_SCROLL_VELOCITY = 1500f;
28 
29     private final ScrollView mTarget;
30 
FolderAutoScrollHelper(ScrollView target)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
scrollTargetBy(int deltaX, int deltaY)45     public void scrollTargetBy(int deltaX, int deltaY) {
46         mTarget.scrollBy(deltaX, deltaY);
47     }
48 
49     @Override
canTargetScrollHorizontally(int direction)50     public boolean canTargetScrollHorizontally(int direction) {
51         // List do not scroll horizontally.
52         return false;
53     }
54 
55     @Override
canTargetScrollVertically(int direction)56     public boolean canTargetScrollVertically(int direction) {
57         return mTarget.canScrollVertically(direction);
58     }
59 }