Lock screen slide view

SlideView.java

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.annotation.TargetApi;
import android.content.Context;
import android.os.Build;
import android.support.annotation.Nullable;
import android.support.v4.view.MotionEventCompat;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;

public class SlideView extends View {

    public interface IOnFinishListener {
        void finish();
    }

    private float mMotionDownX, mMotionDownY;
    private IOnFinishListener mFinishListener;

    private GestureDetector.OnGestureListener mGestureListener = new GestureDetector.SimpleOnGestureListener() {

        @TargetApi(Build.VERSION_CODES.HONEYCOMB)
        @Override
        public boolean onDown(MotionEvent e) {
            mMotionDownX = e.getRawX() - getTranslationX();
            mMotionDownY = e.getRawY() - getTranslationY();
            return true;
        }

        @TargetApi(Build.VERSION_CODES.HONEYCOMB)
        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
            float duration = e2.getRawX() - mMotionDownX;
            duration = duration < 0 ? 0 : duration;
            setTranslationX(duration);
            //setTranslationY(e2.getRawY() - mMotionDownY);
            if (getBackground() != null) {
                getBackground().setAlpha((int) ((mScreenWidth - getTranslationX()) / mScreenWidth * 200));
            }
            return true;
        }
    };

    private GestureDetector mGestureDetector;
    private int mScreenWidth;

    public SlideView(Context context) {
        this(context, null);
    }

    public SlideView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public SlideView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        init();
    }

    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    private void init() {
        mGestureDetector = new GestureDetector(getContext(), mGestureListener);
        mScreenWidth = getResources().getDisplayMetrics().widthPixels;
        if (getBackground() != null) {
            getBackground().setAlpha((int) ((mScreenWidth - getTranslationX()) / mScreenWidth * 200));
        }
    }

    public void setmFinishListener(IOnFinishListener mFinishListener) {
        this.mFinishListener = mFinishListener;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        final int action = MotionEventCompat.getActionMasked(event);
        if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) {
            doTriggerEvent(event.getRawX());
            return true;
        }
        return mGestureDetector.onTouchEvent(event);
    }

    private void doTriggerEvent(float x) {
        float movex = x - mMotionDownX;
        if (movex > (mScreenWidth * 0.4)) {
            moveMoveView(mScreenWidth - getLeft(), true);
        } else {
            moveMoveView(-getLeft(), false);
        }
    }

    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    private void moveMoveView(float to, boolean finish) {
        ObjectAnimator animator = ObjectAnimator.ofFloat(this, "translationX", to);
        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                if (getBackground() != null) {
                    getBackground().setAlpha((int) ((mScreenWidth - getTranslationX()) / mScreenWidth * 200));
                }
            }
        });
        if (finish) {
            animator.addListener(new AnimatorListenerAdapter() {
                @Override
                public void onAnimationEnd(Animator animation) {
                    super.onAnimationEnd(animation);
                    if (mFinishListener != null) {
                        mFinishListener.finish();
                    }
                }
            });
        }
        animator.setDuration(250).start();
    }
}