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package com.almeros.android.multitouch.gesturedetectors;
import android.content.Context;
import android.graphics.PointF;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.ViewConfiguration;
/**
* @author Almer Thie (code.almeros.com) Copyright (c) 2013, Almer Thie
* (code.almeros.com)
* <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 abstract class TwoFingerGestureDetector extends BaseGestureDetector {
private final float edgeSlop;
protected float prevFingerDiffX;
protected float prevFingerDiffY;
protected float currFingerDiffX;
protected float currFingerDiffY;
private float currLen;
private float prevLen;
private PointF focus;
public TwoFingerGestureDetector(Context context) {
super(context);
ViewConfiguration config = ViewConfiguration.get(context);
edgeSlop = config.getScaledEdgeSlop();
}
@Override
protected abstract void handleStartProgressEvent(int actionCode,
MotionEvent event);
@Override
protected abstract void handleInProgressEvent(int actionCode,
MotionEvent event);
protected void updateStateByEvent(MotionEvent curr) {
super.updateStateByEvent(curr);
final MotionEvent prev = prevEvent;
currLen = -1;
prevLen = -1;
// Previous
final float px0 = prev.getX(0);
final float py0 = prev.getY(0);
final float px1 = prev.getX(1);
final float py1 = prev.getY(1);
final float pvx = px1 - px0;
final float pvy = py1 - py0;
prevFingerDiffX = pvx;
prevFingerDiffY = pvy;
// Current
final float cx0 = curr.getX(0);
final float cy0 = curr.getY(0);
final float cx1 = curr.getX(1);
final float cy1 = curr.getY(1);
final float cvx = cx1 - cx0;
final float cvy = cy1 - cy0;
currFingerDiffX = cvx;
currFingerDiffY = cvy;
focus = determineFocalPoint(curr);
}
/**
* Return the current distance between the two pointers forming the gesture
* in progress.
*
* @return Distance between pointers in pixels.
*/
public float getCurrentSpan() {
if (currLen == -1) {
final float cvx = currFingerDiffX;
final float cvy = currFingerDiffY;
currLen = (float) Math.sqrt(cvx * cvx + cvy * cvy);
}
return currLen;
}
/**
* Return the previous distance between the two pointers forming the gesture
* in progress.
*
* @return Previous distance between pointers in pixels.
*/
public float getPreviousSpan() {
if (prevLen == -1) {
final float pvx = prevFingerDiffX;
final float pvy = prevFingerDiffY;
prevLen = (float) Math.sqrt(pvx * pvx + pvy * pvy);
}
return prevLen;
}
/**
* MotionEvent has no getRawX(int) method; simulate it pending future API
* approval.
*
* @param event Motion Event
* @param pointerIndex Pointer Index
* @return Raw x value or 0
*/
protected static float getRawX(MotionEvent event, int pointerIndex) {
float offset = event.getRawX() - event.getX();
if (pointerIndex < event.getPointerCount()) {
return event.getX(pointerIndex) + offset;
}
return 0.0f;
}
/**
* MotionEvent has no getRawY(int) method; simulate it pending future API
* approval.
*
* @param event Motion Event
* @param pointerIndex Pointer Index
* @return Raw y value or 0
*/
protected static float getRawY(MotionEvent event, int pointerIndex) {
float offset = event.getRawY() - event.getY();
if (pointerIndex < event.getPointerCount()) {
return event.getY(pointerIndex) + offset;
}
return 0.0f;
}
/**
* Check if we have a sloppy gesture. Sloppy gestures can happen if the edge
* of the user's hand is touching the screen, for example.
*
* @param event Motion Event
* @return {@code true} if is sloppy gesture, {@code false} if not
*/
protected boolean isSloppyGesture(MotionEvent event) {
// As orientation can change, query the metrics in touch down
DisplayMetrics metrics = context.getResources().getDisplayMetrics();
float rightSlopEdge = metrics.widthPixels - edgeSlop;
float bottomSlopEdge = metrics.heightPixels - edgeSlop;
final float edgeSlop = this.edgeSlop;
final float x0 = event.getRawX();
final float y0 = event.getRawY();
final float x1 = getRawX(event, 1);
final float y1 = getRawY(event, 1);
boolean p0sloppy = x0 < edgeSlop || y0 < edgeSlop || x0 > rightSlopEdge
|| y0 > bottomSlopEdge;
boolean p1sloppy = x1 < edgeSlop || y1 < edgeSlop || x1 > rightSlopEdge
|| y1 > bottomSlopEdge;
if (p0sloppy && p1sloppy) {
return true;
} else if (p0sloppy) {
return true;
} else if (p1sloppy) {
return true;
}
return false;
}
/**
* Determine (multi)finger focal point (a.k.a. center point between all
* fingers)
*
* @param motionEvent Motion Event
* @return PointF focal point
*/
public static PointF determineFocalPoint(MotionEvent motionEvent) {
// Number of fingers on screen
final int pCount = motionEvent.getPointerCount();
float x = 0.0f;
float y = 0.0f;
for (int i = 0; i < pCount; i++) {
x += motionEvent.getX(i);
y += motionEvent.getY(i);
}
return new PointF(x / pCount, y / pCount);
}
public float getFocusX() {
return focus.x;
}
public float getFocusY() {
return focus.y;
}
}
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