ImageView supporting single finger sliding and double finger scaling

Support single finger sliding and double finger scaling ImageView

import android.content.Context;
import android.graphics.Point;
import android.os.Build;
import android.support.annotation.Nullable;
import android.support.annotation.RequiresApi;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;

/** *  Use and normal imageview It doesn't make any difference , And this imageview It supports two finger scaling , Put it in any layout , The problem of gesture conflict such as nested sliding has been solved  *  Need to cooperate with  MakeUpZoomImage  Use  * * @see MakeUpZoomImage */
public class ZoomImageView extends android.support.v7.widget.AppCompatImageView {
    
    private static final String TAG = "ZoomImageView";
    private double lastD;
    private Point lastCenter;
    private int pCont;

    public ZoomImageView(Context context) {
    
        super(context);
        setClickable(true);
    }

    public ZoomImageView(Context context, @Nullable AttributeSet attrs) {
    
        super(context, attrs);
        setClickable(true);
    }

    public ZoomImageView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    
        super(context, attrs, defStyleAttr);
        setClickable(true);
    }

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    @Override
    public boolean onTouchEvent(MotionEvent event) {
    
        switch (event.getAction() & MotionEvent.ACTION_MASK) {
    
            case MotionEvent.ACTION_DOWN:
                pCont = 1;
                return true;
            case MotionEvent.ACTION_POINTER_DOWN:
                pCont++;
                if (pCont >= 2) {
    
                    setElevation(100);
                    bringToFront();
                    getParent().requestDisallowInterceptTouchEvent(true);
                    lastD = getDistance(event);
                    lastCenter = getCurrentPoint(event);
                }
                return true;
            case MotionEvent.ACTION_POINTER_UP:
                pCont--;
                return true;
            case MotionEvent.ACTION_MOVE:
                if (event.getPointerCount() >= 2) {
    
                    double moved = getDistance(event) - lastD;
                    double viewSize = Math.sqrt(getWidth() * getWidth() + getHeight() * getHeight());
                    double scale = (moved / viewSize);
                    Log.d(TAG, scale + " " + lastD);
                    setVisibility(INVISIBLE);
                    Point point = getCurrentPoint(event);
                    float tx = point.x - lastCenter.x;
                    float ty = point.y - lastCenter.y;
                    MakeUpZoomImage.get().update(this, getDrawable(), scale + 1, tx, ty);
                    return true;
                }
                return true;
            case MotionEvent.ACTION_UP:
                MakeUpZoomImage.get().remove();
                setVisibility(VISIBLE);
                getParent().requestDisallowInterceptTouchEvent(false);
                pCont = 0;
                setScaleX(1);
                setScaleY(1);
                return true;
            default:
                break;
        }
        return super.onTouchEvent(event);
    }

    private Point getCurrentPoint(MotionEvent event) {
    
        float x0 = event.getX(0);
        float y0 = event.getY(0);
        float x1 = event.getX(1);
        float y1 = event.getY(1);
        Point point = new Point(((int) (x1 + x0) / 2), ((int) (y1 + y0) / 2));
        return point;
    }

    private double getDistance(MotionEvent event) {
    
        float x0 = event.getX(0);
        float y0 = event.getY(0);
        float x1 = event.getX(1);
        float y1 = event.getY(1);

        return Math.sqrt((
                (y1 - y0) * (y1 - y0))
                + ((x1 - x0) * (x1 - x0))
        );
    }

}

import android.app.Activity;
import android.content.res.Resources;
import android.graphics.drawable.Drawable;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

public class MakeUpZoomImage {
    
    private Activity activity;
    private volatile static MakeUpZoomImage makeUpZoomImage;
    private ImageView imageView;

    private MakeUpZoomImage(Activity activity) {
    
        this.activity = activity;
        imageView = new ImageView(activity);
        activity.addContentView(imageView, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.MATCH_PARENT));
        imageView.setVisibility(View.GONE);
    }

    public static MakeUpZoomImage attach(Activity activity) {
    
        if (makeUpZoomImage == null) {
    
            synchronized (MakeUpZoomImage.class) {
    
                if (makeUpZoomImage == null) {
    
                    makeUpZoomImage = new MakeUpZoomImage(activity);
                }
            }
        }
        return makeUpZoomImage;
    }

    public static MakeUpZoomImage get() {
    
        if (makeUpZoomImage == null) {
    
            synchronized (MakeUpZoomImage.class) {
    
                if (makeUpZoomImage == null) {
    
                    throw new IllegalStateException("Must be initialized");
                }
            }
        }
        return makeUpZoomImage;
    }

    public void release() {
    
        remove();
        makeUpZoomImage = null;
    }

    public void update(View view, Drawable drawable, double zoom, float tx, float ty) {
    
        if (view == null) {
    
            return;
        }
        int[] location = new int[2];
        view.getLocationInWindow(location);

        ViewGroup.LayoutParams lp = imageView.getLayoutParams();
        lp.width = view.getWidth();
        lp.height = view.getHeight();
        imageView.setLayoutParams(lp);
        imageView.setX(location[0] + tx);
        imageView.setY(location[1] - getNotificationBarHeight() + ty);

        imageView.setVisibility(View.VISIBLE);
        imageView.setImageDrawable(drawable);
        imageView.setScaleX((float) zoom);
        imageView.setScaleY((float) zoom);
    }

    private int getNotificationBarHeight() {
    
        Resources resources = activity.getResources();
        int resourceId = resources.getIdentifier("status_bar_height", "dimen", "android");
        int height = resources.getDimensionPixelSize(resourceId);
        return height;
    }

    public void remove() {
    
        imageView.setVisibility(View.GONE);
        imageView.setImageDrawable(null);
    }
}