Siehe folgendes Bild

Ich möchte die Form der hervorgehobenen Ansicht durch Ziehen der Ecke ändern. Es ist nicht erforderlich, dass die Ansicht nach dem Ziehen der Ecke rechteckig ist. Es kann sich um eine beliebige beliebige Form handeln

wie kommt man dahin ??

Jetzt habe ich die 4 Ecken bei Berührung beweglich gemacht, aber die Form ändert sich nicht

<code>package com.assignment.DragDrop;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;

public class DrawView extends View {


    Point point1,point2,point3,point4;
    private ColorBall[] colorballs = new ColorBall[4]; // array that holds the balls
    private int balID = 0; // variable to know what ball is being dragged
    Paint paint;
    Canvas canvas;
    public DrawView(Context context) {
        super(context);
         paint=new Paint();
        setFocusable(true); //necessary for getting the touch events
        canvas= new Canvas();
        // setting the start point for the balls
        point1 = new Point();
        point1.x = 50;
        point1.y = 20;

        point2 = new Point();
        point2.x = 150;
        point2.y = 20;

        point3 = new Point();
        point3.x = 150;
        point3.y = 120;

        point4 = new Point();
        point4.x = 50;
        point4.y = 120;


        // declare each ball with the ColorBall class
        colorballs[0] = new ColorBall(context,R.drawable.bol_blauw, point1);
        colorballs[1] = new ColorBall(context,R.drawable.bol_blauw, point2);
        colorballs[2] = new ColorBall(context,R.drawable.bol_groen, point3);
        colorballs[3] = new ColorBall(context,R.drawable.bol_geel, point4);


    }

    // the method that draws the balls
    @Override protected void onDraw(Canvas canvas) {
        //canvas.drawColor(0xFFCCCCCC);     //if you want another background color       

        paint.setAntiAlias(true);
        paint.setDither(true);
        paint.setColor(Color.BLACK);
        paint.setStyle(Paint.Style.FILL);
        paint.setStrokeJoin(Paint.Join.ROUND);
       // mPaint.setStrokeCap(Paint.Cap.ROUND);
        paint.setStrokeWidth(5);


          canvas.drawPaint(paint);
          paint.setColor(Color.WHITE);

          canvas.drawRect(point1.x+25, point2.x, point3.x+25, point4.x, paint);
          BitmapDrawable mBitmap;
          mBitmap= new BitmapDrawable();

        //  canvas.drawBitmap(bitmap, left, top, paint)
        // shade_region_between_points();
         // canvas.drawLine(point1.x, point1.y, point2.x, point2.y, paint);
        //  canvas.drawLine(point1.x, point1.y, point4.x, point4.y, paint);

        //  canvas.drawLine(point4.x, point4.y, point3.x, point3.y, paint);
        // canvas.drawLine(point2.x, point2.y, point3.x, point3.y, paint);
          //draw the balls on the canvas
        for (ColorBall ball : colorballs) {
            canvas.drawBitmap(ball.getBitmap(), ball.getX(), ball.getY(), paint);
             // canvas.drawLine(point1.x, point1.y, point2.x, point2.y, paint);

    //  canvas.drawRect(point1.x, point2.x, point3.x, point4.x, paint);



        }
        /*Drawable drawable = getResources().getDrawable(R.drawable.ic_launcher);
        drawable.setBounds( point1.x+25, point2.x, point3.x+25, point4.x);
        drawable.draw(canvas);*/
    }

    // events when touching the screen
    public boolean onTouchEvent(MotionEvent event) {
        int eventaction = event.getAction(); 

        int X = (int)event.getX(); 
        int Y = (int)event.getY(); 

        switch (eventaction ) { 

        case MotionEvent.ACTION_DOWN: // touch down so check if the finger is on a ball
            balID = 0;
            for (ColorBall ball : colorballs) {
                // check if inside the bounds of the ball (circle)
                // get the center for the ball
                int centerX = ball.getX() + 25;
                int centerY = ball.getY() + 25;
                paint.setColor(Color.CYAN);
                // calculate the radius from the touch to the center of the ball
                double radCircle  = Math.sqrt( (double) (((centerX-X)*(centerX-X)) + (centerY-Y)*(centerY-Y)));
                //  canvas.drawLine(point1.x, point1.y, point2.x, point2.y, paint);

                // if the radius is smaller then 23 (radius of a ball is 22), then it must be on the ball
                if (radCircle < 23){

                    balID = ball.getID();
                    canvas.drawRect(point1.x, point2.x, point3.x, point4.x, paint);

                    invalidate(); 
                    break;
                }
                invalidate(); 

                //canvas.drawRect(point1.x, point2.x, point3.x, point4.x, paint);
                // check all the bounds of the ball (square)
                //if (X > ball.getX() && X < ball.getX()+50 && Y > ball.getY() && Y < ball.getY()+50){
                //  balID = ball.getID();
                //  break;
                //}
            }

            break; 


        case MotionEvent.ACTION_MOVE:   // touch drag with the ball
            // move the balls the same as the finger
            if (balID > 0) {
            try {
                colorballs[balID-1].setX(X-25);
                    colorballs[balID-1].setY(Y-25);
                     // canvas.drawLine(point1.x, point1.y, point2.x, point2.y, paint);

            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            paint.setColor(Color.CYAN);
            canvas.drawRect(point1.x, point2.x, point3.x, point4.x, paint);
            invalidate(); 
            }

            break; 

        case MotionEvent.ACTION_UP: 
            // touch drop - just do things here after dropping

            break; 
        } 
        // redraw the canvas
        invalidate(); 
        return true; 

    }


    public void shade_region_between_points()
    {
        canvas.drawRect(point1.x, point2.x, point3.x, point4.x, paint);
    }
}
</code>

Ich habe diesen Code aus dem Internet erhalten.

Dadurch können Ecken bei Berührung verschoben werden, aber die Form bewegt sich nicht ...