android - How to make view resizable on touch event

Question

See the following image

I want to change the shape of highlighted view by dragging its corner.. not necessory the view after dragging the corner should be rectangle it can be any arbitary shape

how to achive this??

now i have done the 4 corners movable on touch event but the shape is not changing

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);
    }
}

I got this code from internet.

this will able to move corners on touch event but the shape is not moving...

Answer 1

Following code is to draw rectangle on touch base.

import java.util.ArrayList;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import com.common.Utils;
import com.example.rectangleoverlay.R;

public class DrawView extends View {

    Point point1, point3;
    Point point2, point4;

    /**
     * point1 and point 3 are of same group and same as point 2 and point4
     */
    int groupId = -1;
    private ArrayList<ColorBall> colorballs = new ArrayList<ColorBall>();
    // 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.add(new ColorBall(context, R.drawable.gray_circle, point1));
        colorballs.add(new ColorBall(context, R.drawable.gray_circle, point2));
        colorballs.add(new ColorBall(context, R.drawable.gray_circle, point3));
        colorballs.add(new ColorBall(context, R.drawable.gray_circle, point4));

    }

    public DrawView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public DrawView(Context context, AttributeSet attrs) {
        super(context, attrs);
        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.add(new ColorBall(context, R.drawable.gray_circle, point1));
        colorballs.add(new ColorBall(context, R.drawable.gray_circle, point2));
        colorballs.add(new ColorBall(context, R.drawable.gray_circle, point3));
        colorballs.add(new ColorBall(context, R.drawable.gray_circle, 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.parseColor("#55000000"));
        paint.setStyle(Paint.Style.FILL);
        paint.setStrokeJoin(Paint.Join.ROUND);
        // mPaint.setStrokeCap(Paint.Cap.ROUND);
        paint.setStrokeWidth(5);

        canvas.drawPaint(paint);
        paint.setColor(Color.parseColor("#55FFFFFF"));

        if (groupId == 1) {
            canvas.drawRect(point1.x + colorballs.get(0).getWidthOfBall() / 2,
                    point3.y + colorballs.get(2).getWidthOfBall() / 2, point3.x
                            + colorballs.get(2).getWidthOfBall() / 2, point1.y
                            + colorballs.get(0).getWidthOfBall() / 2, paint);
        } else {
            canvas.drawRect(point2.x + colorballs.get(1).getWidthOfBall() / 2,
                    point4.y + colorballs.get(3).getWidthOfBall() / 2, point4.x
                            + colorballs.get(3).getWidthOfBall() / 2, point2.y
                            + colorballs.get(1).getWidthOfBall() / 2, paint);
        }
        BitmapDrawable mBitmap;
        mBitmap = new BitmapDrawable();

        // draw the balls on the canvas
        for (ColorBall ball : colorballs) {
            canvas.drawBitmap(ball.getBitmap(), ball.getX(), ball.getY(),
                    new Paint());

        }
    }

    // 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 = -1;
            groupId = -1;
            for (ColorBall ball : colorballs) {
                // check if inside the bounds of the ball (circle)
                // get the center for the ball
                Utils.logd("Id : " + ball.getID());
                Utils.logd("getX : " + ball.getX() + " getY() : " + ball.getY());
                int centerX = ball.getX() + ball.getWidthOfBall();
                int centerY = ball.getY() + ball.getHeightOfBall();
                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)));

                Utils.logd("X : " + X + " Y : " + Y + " centerX : " + centerX
                        + " CenterY : " + centerY + " radCircle : " + radCircle);

                if (radCircle < ball.getWidthOfBall()) {

                    balID = ball.getID();
                    Utils.logd("Selected ball : " + balID);
                    if (balID == 1 || balID == 3) {
                        groupId = 2;
                        canvas.drawRect(point1.x, point3.y, point3.x, point1.y,
                                paint);
                    } else {
                        groupId = 1;
                        canvas.drawRect(point2.x, point4.y, point4.x, point2.y,
                                paint);
                    }
                    invalidate();
                    break;
                }
                invalidate();
            }

            break;

        case MotionEvent.ACTION_MOVE: // touch drag with the ball
            // move the balls the same as the finger
            if (balID > -1) {
                Utils.logd("Moving Ball : " + balID);

                colorballs.get(balID).setX(X);
                colorballs.get(balID).setY(Y);

                paint.setColor(Color.CYAN);

                if (groupId == 1) {
                    colorballs.get(1).setX(colorballs.get(0).getX());
                    colorballs.get(1).setY(colorballs.get(2).getY());
                    colorballs.get(3).setX(colorballs.get(2).getX());
                    colorballs.get(3).setY(colorballs.get(0).getY());
                    canvas.drawRect(point1.x, point3.y, point3.x, point1.y,
                            paint);
                } else {
                    colorballs.get(0).setX(colorballs.get(1).getX());
                    colorballs.get(0).setY(colorballs.get(3).getY());
                    colorballs.get(2).setX(colorballs.get(3).getX());
                    colorballs.get(2).setY(colorballs.get(1).getY());
                    canvas.drawRect(point2.x, point4.y, point4.x, point2.y,
                            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, point3.y, point3.x, point1.y, paint);
    }
}

Following class is used to store objects

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Point;

public class ColorBall {

    Bitmap bitmap;
    Context mContext;
    Point point;
    int id;
    static int count = 0;

    public ColorBall(Context context, int resourceId, Point point) {
        this.id = count++;
        bitmap = BitmapFactory.decodeResource(context.getResources(),
                resourceId);
        mContext = context;
        this.point = point;
    }

    public int getWidthOfBall() {
        return bitmap.getWidth();
    }

    public int getHeightOfBall() {
        return bitmap.getHeight();
    }

    public Bitmap getBitmap() {
        return bitmap;
    }

    public int getX() {
        return point.x;
    }

    public int getY() {
        return point.y;
    }

    public int getID() {
        return id;
    }

    public void setX(int x) {
        point.x = x;
    }

    public void setY(int y) {
        point.y = y;
    }
}