VelocityTrackerCompat.java revision eedc67283a5a49dce86c625e54596dfdea9465a7 
1/*
2 * Copyright (C) 2011 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
19import android.view.VelocityTracker;
20
21/**
22 * Helper for accessing newer features in VelocityTracker.
23 */
24public class VelocityTrackerCompat {
25    /**
26     * Interface for the full API.
27     */
28    interface VelocityTrackerVersionImpl {
29        public float getXVelocity(VelocityTracker tracker, int pointerId);
30        public float getYVelocity(VelocityTracker tracker, int pointerId);
31    }
32
33    /**
34     * Interface implementation that doesn't use anything about v4 APIs.
35     */
36    static class BaseVelocityTrackerVersionImpl implements VelocityTrackerVersionImpl {
37        @Override
38        public float getXVelocity(VelocityTracker tracker, int pointerId) {
39            return tracker.getXVelocity();
40        }
41        @Override
42        public float getYVelocity(VelocityTracker tracker, int pointerId) {
43            return tracker.getYVelocity();
44        }
45    }
46
47    /**
48     * Interface implementation for devices with at least v11 APIs.
49     */
50    static class HoneycombVelocityTrackerVersionImpl implements VelocityTrackerVersionImpl {
51        @Override
52        public float getXVelocity(VelocityTracker tracker, int pointerId) {
53            return VelocityTrackerCompatHoneycomb.getXVelocity(tracker, pointerId);
54        }
55        @Override
56        public float getYVelocity(VelocityTracker tracker, int pointerId) {
57            return VelocityTrackerCompatHoneycomb.getYVelocity(tracker, pointerId);
58        }
59    }
60
61    /**
62     * Select the correct implementation to use for the current platform.
63     */
64    static final VelocityTrackerVersionImpl IMPL;
65    static {
66        if (android.os.Build.VERSION.SDK_INT >= 11) {
67            IMPL = new HoneycombVelocityTrackerVersionImpl();
68        } else {
69            IMPL = new BaseVelocityTrackerVersionImpl();
70        }
71    }
72
73    // -------------------------------------------------------------------
74
75    /**
76     * Call {@link VelocityTracker#getXVelocity(int)}.
77     * If running on a pre-{@android.os.Build.VERSION_CODES#HONEYCOMB} device,
78     * returns {@link VelocityTracker#getXVelocity()}.
79     */
80    public static float getXVelocity(VelocityTracker tracker, int pointerId) {
81        return IMPL.getXVelocity(tracker, pointerId);
82    }
83
84    /**
85     * Call {@link VelocityTracker#getYVelocity(int)}.
86     * If running on a pre-{@android.os.Build.VERSION_CODES#HONEYCOMB} device,
87     * returns {@link VelocityTracker#getYVelocity()}.
88     */
89    public static float getYVelocity(VelocityTracker tracker, int pointerId) {
90        return IMPL.getYVelocity(tracker, pointerId);
91    }
92}
93