简单多点测试
public class HorizontalReversePinchDetector {?
?
? ? public boolean onTouchEvent(MotionEvent e) {?
?
? ? ? ? int pointerCount = e.getPointerCount();?
?
? ? ? ? if(pointerCount != 2) {?
? ? ? ? ? ? Log.d(GESTURE, "not pinching - exactly 2 fingers are needed but have " + pointerCount);?
? ? ? ? ? ? clearPinch();?
? ? ? ? ? ? return false;?
? ? ? ? }?
?
? ? ? ? int firstIndex = e.getX(0) < e.getX(1) ? 0: 1;?
? ? ? ? int secondIndex = e.getX(0) < e.getX(1) ? 1: 0;?
?
? ? ? ? Finger currentLeftFinger = new Finger(e.getX(firstIndex), e.getY(firstIndex));?
? ? ? ? Finger currentRightFinger = new Finger(e.getX(secondIndex), e.getY(secondIndex));?
?
? ? ? ? float yDifference = Math.abs(currentLeftFinger.getY() - currentRightFinger.getY());?
? ? ? ? if(yDifference > 80) {?
? ? ? ? ? ? Log.d(GESTURE, "not pinching - fingers too vertically-oriented");?
? ? ? ? ? ? clearPinch();?
? ? ? ? ? ? return false;?
? ? ? ? }?
?
? ? ? ? if(initialLeftFinger == null) {?
? ? ? ? ? ? initialLeftFinger = currentLeftFinger;?
? ? ? ? ? ? initialRightFinger = currentRightFinger;?
? ? ? ? ? ? Log.d(GESTURE, "not pinching, but might be starting a pinch...");?
? ? ? ? ? ? return false;?
? ? ? ? }?
?
? ? ? ? float leftFingerDistance = initialLeftFinger.getX() - currentLeftFinger.getX();?
? ? ? ? float rightFingerDistance = currentRightFinger.getX() - initialRightFinger.getX();?
?
? ? ? ? float xDistanceBetweenFingers = Math.abs(currentLeftFinger.getX() - currentRightFinger.getX());?
? ? ? ? if(xDistanceBetweenFingers < minimumDistanceBetweenFingers) {?
? ? ? ? ? ? Log.d(GESTURE, "pinching, but fingers are not far enough apart...");?
? ? ? ? ? ? return true;?
? ? ? ? }?
?
? ? ? ? if(leftFingerDistance < minimumDistanceForEachFinger) {?
? ? ? ? ? ? Log.d(GESTURE, "pinching, but left finger has not moved enough...");?
? ? ? ? ? ? return true;?
? ? ? ? }?
? ? ? ? if(rightFingerDistance < minimumDistanceForEachFinger) {?
? ? ? ? ? ? Log.d(GESTURE, "pinching, but right finger has not moved enough...");?
? ? ? ? ? ? return true;?
? ? ? ? }?
?
? ? ? ? pinchCompleted();?
? ? ? ? return true;?
? ? }?
?
? ? private void pinchCompleted() {?
? ? ? ? Log.d(GESTURE, "pinch completed");?
? ? ? ? if(pinchListener != null) pinchListener.onPinch();?
? ? ? ? clearPinch();?
? ? }?
?
? ? public static interface OnPinchListener {?
? ? ? ? void onPinch();?
? ? }?
?
? ? private void clearPinch() {?
? ? ? ? initialLeftFinger = null;?
? ? ? ? initialRightFinger = null;?
? ? }?
?
? ? public void setPinchListener(OnPinchListener pinchListener) {?
? ? ? ? this.pinchListener = pinchListener;?
? ? }?
?
? ? private static class Finger {?
?
? ? ? ? private Finger(float x, float y) {?
? ? ? ? ? ? this.x = x;?
? ? ? ? ? ? this.y = y;?
? ? ? ? }?
?
? ? ? ? public float getX() {?
? ? ? ? ? ? return x;?
? ? ? ? }?
?
? ? ? ? public float getY() {?
? ? ? ? ? ? return y;?
? ? ? ? }?
?
? ? ? ? private float x;?
? ? ? ? private float y;?
? ? }?
?
? ? private Finger initialLeftFinger;?
? ? private Finger initialRightFinger;?
? ? private OnPinchListener pinchListener;?
? ? private static final float minimumDistanceForEachFinger = 30;?
? ? private static final float minimumDistanceBetweenFingers = 50;?
}?
