How Can I increase the radius of the circle after each a second

Question

How Can I increase the radius of the circle after each a second? I searched about this issue in stackoverflow and I added the Thread.sleep(1000); to my code as follows:

 @Override

    public void onDraw(Canvas canvas) {

        paint.setColor(Color.BLUE);
        paint.setAntiAlias(true);
        for(int r=1;r<=70;r++)
            try {
                canvas.drawCircle(getWidth() / 2, getHeight() / 2, r, paint);
            Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

But I think that it is wrong to do this. Because when I run in my device it can not work well.

If you are worried with UI blocking then use a `Timer` or `Handler` to perform your task instead of looping. It will be more efficient. — Jibran Khan, Sep 02 '15 at 06:32
I would not suggest to use the sleep method as it would make your app lack in responsive and would block UI , I would suggest you to use timer. — Coas Mckey, Sep 02 '15 at 06:34
See here http://stackoverflow.com/questions/31219590/how-to-detect-no-touch-on-a-view-after-some-seconds/31219681#31219681 — Jibran Khan, Sep 02 '15 at 06:34

AndiGeeky · Accepted Answer · 2015-09-02T08:02:50.087

Please find custom view class to update view frequently..

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;


public class CustomView extends View {
    Paint paint;
    int radius = 0;

    public CustomView(Context context) {
        super(context);
        init();
    }

    private void init() {
        paint = new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setColor(Color.BLUE);
        paint.setAntiAlias(true);
        paint.setStrokeWidth(5f);
    }

    public void updateView(int radius) {
        this.radius = radius;
        invalidate();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawCircle(getWidth() / 2, getHeight() / 2, radius, paint);
    }
}

And call this method whenever you want to start animation :

public void startViewAnimation() {
        final Timer timer = new Timer();
        timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                if (i < 70) { // Please change '70' according to how long you want to go
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            int baseRadius=20; // base radius is basic radius of circle from which to start animation
                            customView.updateView(i+baseRadius);
                            i++;
                        }
                    });
                } else {
                    i = 0;
                }
            }
        }, 0, 500); // change '500' to milliseconds for how frequent you want to update radius
    }

And Here how to call it :

RelativeLayout relativeLayout = (RelativeLayout) findViewById(R.id.rootView);
        customView = new CustomView(this);
        relativeLayout.addView(customView);
        startViewAnimation();

And here is defined variables :

private int i = 1;
CustomView customView;

Thanks..!!

I think a part of your code is wrong. in the `startViewAnimation()` method the `i` variable is Undefined. — stackoverflow, Sep 02 '15 at 07:40

score 0 · Answer 2 · edited Sep 02 '15 at 06:37

0

You could do it with a timer. It might not be exactly a second between them (since it does some magic to save power), but it will probably work for your intended purpose.

I don't think pausing and making multiple draw calls inside the onDraw method is a good idea. Since you are pausing the GUI thread it probably won't like it (it might even wake up if someone does something to it).

edited Sep 02 '15 at 06:37

Nekresh

2,948
23
28

answered Sep 02 '15 at 06:36

Astrogat

1,617
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24

score 0 · Answer 3 · answered Sep 02 '15 at 06:38

I think you can use it here and gives time and intervals as you wanted

TimerTask doAsynchronousTask = new TimerTask() {
    @Override
    public void run() {

        //Perform background work here

        handler.post(new Runnable() {
            public void run() {
                //Perform GUI updation work here

                // increase radius with your method 
            }
        });
    }
};
timer.schedule(doAsynchronousTask, 1, 1000);

score 0 · Answer 4 · edited May 23 '17 at 10:28

0

Check out this answer here It shows the usage of Handler class wich creates such behaviour

edited May 23 '17 at 10:28

Community

1
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answered Sep 02 '15 at 06:39

Vect0rZ

401
2
6

How Can I increase the radius of the circle after each a second

4 Answers4