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package com.almeros.android.multitouch.gesturedetectors;
import android.content.Context;
import android.view.MotionEvent;
/**
* @author Robert Nordan (robert.nordan@norkart.no)
* <p>
* Copyright (c) 2013, Norkart AS
* <p>
* All rights reserved.
* <p>
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* <p>
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* <p>
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
* WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
public class ShoveGestureDetector extends TwoFingerGestureDetector {
/**
* Listener which must be implemented which is used by ShoveGestureDetector
* to perform callbacks to any implementing class which is registered to a
* ShoveGestureDetector via the constructor.
*
* @see ShoveGestureDetector.SimpleOnShoveGestureListener
*/
public interface OnShoveGestureListener {
public boolean onShove(ShoveGestureDetector detector);
public boolean onShoveBegin(ShoveGestureDetector detector);
public void onShoveEnd(ShoveGestureDetector detector);
}
/**
* Helper class which may be extended and where the methods may be
* implemented. This way it is not necessary to implement all methods of
* OnShoveGestureListener.
*/
public static class SimpleOnShoveGestureListener implements
OnShoveGestureListener {
public boolean onShove(ShoveGestureDetector detector) {
return false;
}
public boolean onShoveBegin(ShoveGestureDetector detector) {
return true;
}
public void onShoveEnd(ShoveGestureDetector detector) {
// Do nothing, overridden implementation may be used
}
}
private float prevAverageY;
private float currAverageY;
private final OnShoveGestureListener listener;
private boolean sloppyGesture;
public ShoveGestureDetector(Context context, OnShoveGestureListener listener) {
super(context);
this.listener = listener;
}
@Override
protected void handleStartProgressEvent(int actionCode, MotionEvent event) {
switch (actionCode) {
case MotionEvent.ACTION_POINTER_DOWN:
// At least the second finger is on screen now
resetState(); // In case we missed an UP/CANCEL event
prevEvent = MotionEvent.obtain(event);
timeDelta = 0;
updateStateByEvent(event);
// See if we have a sloppy gesture
sloppyGesture = isSloppyGesture(event);
if (!sloppyGesture) {
// No, start gesture now
gestureInProgress = listener.onShoveBegin(this);
}
break;
case MotionEvent.ACTION_MOVE:
if (!sloppyGesture) {
break;
}
// See if we still have a sloppy gesture
sloppyGesture = isSloppyGesture(event);
if (!sloppyGesture) {
// No, start normal gesture now
gestureInProgress = listener.onShoveBegin(this);
}
break;
case MotionEvent.ACTION_POINTER_UP:
if (!sloppyGesture) {
break;
}
break;
}
}
@Override
protected void handleInProgressEvent(int actionCode, MotionEvent event) {
switch (actionCode) {
case MotionEvent.ACTION_POINTER_UP:
// Gesture ended but
updateStateByEvent(event);
if (!sloppyGesture) {
listener.onShoveEnd(this);
}
resetState();
break;
case MotionEvent.ACTION_CANCEL:
if (!sloppyGesture) {
listener.onShoveEnd(this);
}
resetState();
break;
case MotionEvent.ACTION_MOVE:
updateStateByEvent(event);
// Only accept the event if our relative pressure is within
// a certain limit. This can help filter shaky data as a
// finger is lifted. Also check that shove is meaningful.
if (currPressure / prevPressure > PRESSURE_THRESHOLD
&& Math.abs(getShovePixelsDelta()) > 0.5f) {
final boolean updatePrevious = listener.onShove(this);
if (updatePrevious) {
prevEvent.recycle();
prevEvent = MotionEvent.obtain(event);
}
}
break;
}
}
@Override
protected void resetState() {
super.resetState();
sloppyGesture = false;
prevAverageY = 0.0f;
currAverageY = 0.0f;
}
@Override
protected void updateStateByEvent(MotionEvent curr) {
super.updateStateByEvent(curr);
final MotionEvent prev = prevEvent;
float py0 = prev.getY(0);
float py1 = prev.getY(1);
prevAverageY = (py0 + py1) / 2.0f;
float cy0 = curr.getY(0);
float cy1 = curr.getY(1);
currAverageY = (cy0 + cy1) / 2.0f;
}
@Override
protected boolean isSloppyGesture(MotionEvent event) {
boolean sloppy = super.isSloppyGesture(event);
if (sloppy) {
return true;
}
// If it's not traditionally sloppy, we check if the angle between
// fingers
// is acceptable.
double angle = Math.abs(Math.atan2(currFingerDiffY, currFingerDiffX));
// about 20 degrees, left or right
return !((0.0f < angle && angle < 0.35f) || 2.79f < angle
&& angle < Math.PI);
}
/**
* Return the distance in pixels from the previous shove event to the
* current event.
*
* @return The current distance in pixels.
*/
public float getShovePixelsDelta() {
return currAverageY - prevAverageY;
}
}
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