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/*
* Copyright (C) 2010 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 com.android.gallery3d.ui;
import android.content.Context;
import android.view.ViewConfiguration;
import com.android.gallery3d.common.OverScroller;
import com.android.gallery3d.common.Utils;
public class ScrollerHelper {
private OverScroller mScroller;
private int mOverflingDistance;
private boolean mOverflingEnabled;
public ScrollerHelper(Context context) {
mScroller = new OverScroller(context);
ViewConfiguration configuration = ViewConfiguration.get(context);
mOverflingDistance = configuration.getScaledOverflingDistance();
}
public void setOverfling(boolean enabled) {
mOverflingEnabled = enabled;
}
/**
* Call this when you want to know the new location. The position will be
* updated and can be obtained by getPosition(). Returns true if the
* animation is not yet finished.
*/
public boolean advanceAnimation(long currentTimeMillis) {
return mScroller.computeScrollOffset();
}
public boolean isFinished() {
return mScroller.isFinished();
}
public void forceFinished() {
mScroller.forceFinished(true);
}
public int getPosition() {
return mScroller.getCurrX();
}
public float getCurrVelocity() {
return mScroller.getCurrVelocity();
}
public void setPosition(int position) {
mScroller.startScroll(
position, 0, // startX, startY
0, 0, 0); // dx, dy, duration
// This forces the scroller to reach the final position.
mScroller.abortAnimation();
}
public void fling(int velocity, int min, int max) {
int currX = getPosition();
mScroller.fling(
currX, 0, // startX, startY
velocity, 0, // velocityX, velocityY
min, max, // minX, maxX
0, 0, // minY, maxY
mOverflingEnabled ? mOverflingDistance : 0, 0);
}
// Returns the distance that over the scroll limit.
public int startScroll(int distance, int min, int max) {
int currPosition = mScroller.getCurrX();
int finalPosition = mScroller.isFinished() ? currPosition :
mScroller.getFinalX();
int newPosition = Utils.clamp(finalPosition + distance, min, max);
if (newPosition != currPosition) {
mScroller.startScroll(
currPosition, 0, // startX, startY
newPosition - currPosition, 0, 0); // dx, dy, duration
}
return finalPosition + distance - newPosition;
}
}
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