Question

I mean I want to drawline but slowly.
I write this code to draw line in ondraw method.

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caneta.setARGB(255, 255, 0,0);caneta.setStrokeWidth(10); 
canvas.drawLine(0, ys * 1/2, this.getWidth(), ys * 1/2, caneta);
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how I did it slowly?

Answer 1

That’s nearly like a gameloop works:

-invalidate your canvas ever X milliseconds (using a loop and Thread.sleep())

-increment your X/Y coords after every loop

-handle the new coords in onDraw() again

Example:

private int x1, x2;
    private int y1, y2;
    private View v;

    public void start()
    {
        for (int i = 0; i <= 250; i++)
        {
             v.invalidate();

             x2 += 1;

            try
            {
                Thread.sleep(50);
            }
            catch (InterruptedException e)
            {
            }
        }
    }

in your existing view class, where you already have your onDraw method

 protected void onDraw(Canvas canvas)
        {
        //draw your line here using your X and Y member
                canvas.drawLine(x1, y1, x2, y2, caneta);
        }