Surface View draws only in breakpoint debugging

Question

I want to control drawing on Surface View from MainActivity. (user) Github link of the project is given at the end of the post.

MainActivity calls draw(Drawing) method on SurfaceView instance.

I have following code, the surface view only draws when I enabled breakpoint debugging.

I already visited these links, no solution found:

Android SurfaceView empty

Drawing using the Surfaceview creates blank screen

Android drawing on surfaceview and canvas

Tutorials I folowed:

Drawing Triangles, Rhombuses and Other Custom Shapes on an Android Canvas

Android Coding - Drawing on SurfaceView

I thought it was a matter of view creation being in the process so I added checks for creation:

public void draw(Drawing drawing) {    

        this.drawing = drawing;    

        if (surfaceHolder.isCreating()) {

            surfaceHolder.addCallback(new SurfaceHolder.Callback() {
                @Override
                public void surfaceCreated(SurfaceHolder holder) {   

                    thread = new Thread(LushSurfaceView.this);
                    thread.start();    
                }    

            });


        } else {


            thread = new Thread(this);
            thread.start();   

        }    
    }

Here is thread:

 @Override
    public void run() {
        if (drawing != null) {


            switch (drawing) {


                case RECT:
                    drawRectShape();
                    break;
            }


        }
    }

Also I added delays deliberately to wait for the surface view initialization.

private void drawRectShape() {

        if (surfaceHolder.getSurface().isValid()) {


            Canvas canvas = surfaceHolder.lockCanvas();
            try {
                Thread.sleep(300);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            if (canvas != null && !surfaceHolder.isCreating()) {
                Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
                paint.setStyle(Paint.Style.STROKE);
                paint.setStrokeWidth(30);


                Random random = new Random();

                int w = canvas.getWidth();
                int h = canvas.getHeight();
                int left = Math.round(w/2);
                int top = Math.round(h/2);
                int right = 200;
                int bottom =200;

                int r = random.nextInt(255);
                int g = random.nextInt(255);
                int b = random.nextInt(255);
                paint.setColor(0xff000000 + (r << 16) + (g << 8) + b);
                canvas.drawRect(new Rect(left, top, right, bottom), paint);

                surfaceHolder.unlockCanvasAndPost(canvas);
            }
        }

    }

Code works when: I enable breakpoint debugging.
Simple debugging does not show anything drawn.
I recreated this scenario several times.

I am using Nexus 6 (OS 7.1.1) as testing device. (Not Emulator).

Project source at github.

Surface View draws only in breakpoint debugging

0 Answers0