CustomOnTouchListener

CustomOnTouchListener.java

import android.os.SystemClock;
import android.support.animation.DynamicAnimation;
import android.support.animation.SpringAnimation;
import android.support.animation.SpringForce;
import android.view.MotionEvent;
import android.view.View;

import java.lang.ref.SoftReference;

/**
 * <p>
 * This class is used to set a touch listener to a View object, which helps to listen to touch events.<br/>
 * when user clicks any view having this touch listener, we create a bounce effect animation on that view.<br/>
 * This can be used on any view.<br>
 * This class is dependant on DynamicAnimationLibrary from google. So please add the library to gradle .<br><br>
 * <b>compile 'com.android.support:support-dynamic-animation:25.3.1'</b>
 * </p>
 */
public class CustomOnTouchListener implements View.OnTouchListener {
    /**
     * the view's Initial Scale
     */
    private static final float INITIAL_SCALE = 1f;
    /**
     * this is used to handle the lastClickTime to avoid multi simultaneous taps and clicks
     */
    private long mLastClickTime;
    /**
     * We need to scale the x property of view
     */
    private SpringAnimation animationX;
    /**
     * we need to scale the y property of the view
     */
    private SpringAnimation animationY;
    /**
     * Listener to listen to Animation end of the Spring animation
     */
    private AnimationEndListener mEndListener;

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        //when user has caused Action_Up event
        if (event.getAction() == MotionEvent.ACTION_UP) {
            //check if system elapsed (milliseconds - lastClick) time > LAST_CLICK_TIME
            if (SystemClock.elapsedRealtime() - mLastClickTime > 500) {//save last click time
                if (animationX == null) { // check if animation x is null... create new animation if null
                    animationX = createAnimation(v, SpringAnimation.SCALE_X);
                }
                if (animationY == null) {// check if animation is null... create new animation if null
                    animationY = createAnimation(v, SpringAnimation.SCALE_Y);
                    //check if animation end listener is null
                    if (mEndListener == null) {
                        //create the animation end listener
                        mEndListener = new AnimationEndListener();
                    }
                }
                //save last click time to disable multi touch
                mLastClickTime = SystemClock.elapsedRealtime();
                if (animationX != null && animationY != null) {
                    //add the clicked view to soft reference
                    mEndListener.addToSoftReference(v);
                    //cancel pending animations
                    animationX.cancel();
                    animationY.cancel();
                    //decrease scale x and y of the view
                    v.setScaleX(0.925f);
                    v.setScaleY(0.925f);
                    //start animation x and y
                    animationX.start();
                    animationY.start();
                    //add end listener to check end of animation
                    animationY.addEndListener(mEndListener);
                }
            }
            return true;// handle touch event
        }
        return false;//allow parent handle the touch event
    }

    /**
     * Create and initialize Spring animation
     *
     * @param v        view on which we need to add the spring effect
     * @param property x property or y property
     * @return spring animation object
     */
    private SpringAnimation createAnimation(View v, DynamicAnimation.ViewProperty property) {
        final SpringAnimation animation = new SpringAnimation(v, property);
        SpringForce springForce = new SpringForce(INITIAL_SCALE);
        springForce.setStiffness(SpringForce.STIFFNESS_MEDIUM);
        springForce.setDampingRatio(SpringForce.DAMPING_RATIO_MEDIUM_BOUNCY);
        animation.setSpring(springForce);
        return animation;
    }

    /**
     * Sole purpose of this class is call the views on click listener if present.<br>
     * The view is added to soft reference so that it can be garbage collected
     * when the animation is finished we call the view's click listener which was added to soft reference
     */
    private class AnimationEndListener implements DynamicAnimation.OnAnimationEndListener {
        SoftReference<View> weakView;

        private void addToSoftReference(View v) {
            if (weakView == null) {
                weakView = new SoftReference<>(v);
            } else {
                View view = weakView.get();
                if (view == null) {
                    weakView = new SoftReference<>(v);
                }
            }
        }

        @Override
        public void onAnimationEnd(DynamicAnimation animation, boolean canceled, float value, float velocity) {
            View view = weakView.get();
            if (view != null) {
                //call onclick listener
                view.callOnClick();
            }
        }
    }
}