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/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.support.v4.view;
import android.view.VelocityTracker;
/**
* Helper for accessing features in {@link VelocityTracker}
* introduced after API level 4 in a backwards compatible fashion.
*/
public class VelocityTrackerCompat {
/**
* Interface for the full API.
*/
interface VelocityTrackerVersionImpl {
public float getXVelocity(VelocityTracker tracker, int pointerId);
public float getYVelocity(VelocityTracker tracker, int pointerId);
}
/**
* Interface implementation that doesn't use anything about v4 APIs.
*/
static class BaseVelocityTrackerVersionImpl implements VelocityTrackerVersionImpl {
@Override
public float getXVelocity(VelocityTracker tracker, int pointerId) {
return tracker.getXVelocity();
}
@Override
public float getYVelocity(VelocityTracker tracker, int pointerId) {
return tracker.getYVelocity();
}
}
/**
* Interface implementation for devices with at least v11 APIs.
*/
static class HoneycombVelocityTrackerVersionImpl implements VelocityTrackerVersionImpl {
@Override
public float getXVelocity(VelocityTracker tracker, int pointerId) {
return VelocityTrackerCompatHoneycomb.getXVelocity(tracker, pointerId);
}
@Override
public float getYVelocity(VelocityTracker tracker, int pointerId) {
return VelocityTrackerCompatHoneycomb.getYVelocity(tracker, pointerId);
}
}
/**
* Select the correct implementation to use for the current platform.
*/
static final VelocityTrackerVersionImpl IMPL;
static {
if (android.os.Build.VERSION.SDK_INT >= 11) {
IMPL = new HoneycombVelocityTrackerVersionImpl();
} else {
IMPL = new BaseVelocityTrackerVersionImpl();
}
}
// -------------------------------------------------------------------
/**
* Call {@link VelocityTracker#getXVelocity(int)}.
* If running on a pre-{@link android.os.Build.VERSION_CODES#HONEYCOMB} device,
* returns {@link VelocityTracker#getXVelocity()}.
*/
public static float getXVelocity(VelocityTracker tracker, int pointerId) {
return IMPL.getXVelocity(tracker, pointerId);
}
/**
* Call {@link VelocityTracker#getYVelocity(int)}.
* If running on a pre-{@link android.os.Build.VERSION_CODES#HONEYCOMB} device,
* returns {@link VelocityTracker#getYVelocity()}.
*/
public static float getYVelocity(VelocityTracker tracker, int pointerId) {
return IMPL.getYVelocity(tracker, pointerId);
}
}
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