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/*
* Copyright (C) 2008 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.launcher2;
import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.util.Log;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.ViewConfiguration;
import java.util.ArrayList;
public class SwipeController {
private static final String TAG = "Launcher.SwipeController";
private static final int FRAME_DELAY = 1000 / 30;
private static final float DECAY_CONSTANT = 0.65f;
private static final float SPRING_CONSTANT = 0.0009f;
// configuration
private SwipeListener mListener;
private int mSlop;
private float mSwipeDistance;
// state
private VelocityTracker mVelocityTracker;
private boolean mCanceled;
private boolean mTracking;
private int mDownX;
private int mDownY;
private float mMinDest;
private float mMaxDest;
private long mFlingTime;
private long mLastTime;
private int mDirection;
private float mVelocity;
private float mDest;
private float mAmount;
public interface SwipeListener {
public void onStartSwipe();
public void onFinishSwipe(int amount);
public void onSwipe(float amount);
}
public SwipeController(Context context, SwipeListener listener) {
ViewConfiguration config = ViewConfiguration.get(context);
mSlop = config.getScaledTouchSlop();
DisplayMetrics display = context.getResources().getDisplayMetrics();
mSwipeDistance = display.heightPixels / 2; // one half of the screen
mListener = listener;
}
public void setRange(float min, float max) {
mMinDest = min;
mMaxDest = max;
}
public void cancelSwipe() {
mCanceled = true;
}
public boolean onInterceptTouchEvent(MotionEvent ev) {
onTouchEvent(ev);
// After we return true, onIntercept doesn't get called any more, so this is
// a good place to do the callback.
if (mTracking) {
mListener.onStartSwipe();
}
return mTracking;
}
public boolean onTouchEvent(MotionEvent ev) {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
final int screenX = (int)ev.getRawX();
final int screenY = (int)ev.getRawY();
final int deltaX = screenX - mDownX;
final int deltaY = screenY - mDownY;
final int action = ev.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
// Remember location of down touch
mCanceled = false;
mTracking = false;
mDownX = screenX;
mDownY = screenY;
break;
case MotionEvent.ACTION_MOVE:
if (!mCanceled && !mTracking) {
if (Math.abs(deltaX) > mSlop) {
mCanceled = true;
mTracking = false;
}
if (Math.abs(deltaY) > mSlop) {
mTracking = true;
}
}
if (mTracking && !mCanceled) {
track(screenY);
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
if (mTracking && !mCanceled) {
fling(screenY);
}
mVelocityTracker.recycle();
mVelocityTracker = null;
break;
}
return mTracking || mCanceled;
}
private float clamp(float v) {
if (v < mMinDest) {
return mMinDest;
} else if (v > mMaxDest) {
return mMaxDest;
} else {
return v;
}
}
/**
* Perform the callbacks.
*/
private void track(int screenY) {
mAmount = clamp((screenY - mDownY) / mSwipeDistance);
mListener.onSwipe(mAmount);
}
private void fling(int screenY) {
mVelocityTracker.computeCurrentVelocity(1);
mVelocity = mVelocityTracker.getYVelocity() / mSwipeDistance;
mDirection = mVelocity >= 0.0f ? 1 : -1;
mAmount = clamp((screenY-mDownY)/mSwipeDistance);
if (mAmount < 0) {
mDest = clamp(mVelocity < 0 ? -1.0f : 0.0f);
} else {
mDest = clamp(mVelocity < 0 ? 0.0f : 1.0f);
}
mFlingTime = SystemClock.uptimeMillis();
mLastTime = 0;
scheduleAnim();
}
private void scheduleAnim() {
boolean send = true;
if (mDirection > 0) {
if (mAmount > (mDest - 0.01f)) {
send = false;
}
} else {
if (mAmount < (mDest + 0.01f)) {
send = false;
}
}
if (send) {
mHandler.sendEmptyMessageDelayed(1, FRAME_DELAY);
} else {
mListener.onFinishSwipe((int)(mAmount >= 0 ? (mAmount+0.5f) : (mAmount-0.5f)));
}
}
Handler mHandler = new Handler() {
public void handleMessage(Message msg) {
long now = SystemClock.uptimeMillis();
final long t = now - mFlingTime;
final long dt = t - mLastTime;
mLastTime = t;
final float timeSlices = dt / (float)FRAME_DELAY;
float distance = mDest - mAmount;
mVelocity += timeSlices * mDirection * SPRING_CONSTANT * distance * distance / 2;
mVelocity *= (timeSlices * DECAY_CONSTANT);
mAmount += timeSlices * mVelocity;
mAmount += distance * timeSlices * 0.2f; // cheat
mListener.onSwipe(mAmount);
scheduleAnim();
}
};
}
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