Android Canvas Area is not full screen. How to set canvas area?

Question

Hello. I draw a rectangle overlay on Android Canvas.

canvas.drawRect(0, 0, 1000, 1000, paint);

That is my code. I set start point is (0,0) that is (left, top) coordinate. But (0,0) is not on a left-top end point of full screen. No matter how width and height are big, canvas cannot cover full screen also.

How can I solve this problem?

Did you find the solution for this? – Dhina17 Oct 01 '22 at 08:01 — Dhina17, Oct 01 '22 at 08:01

score 1 · Answer 1 · answered Mar 15 '20 at 12:05

1

If you want a fullscreen view, use the setContentView(canvas) call. That sets the full canvas view as the layout.

answered Mar 15 '20 at 12:05

770grappenmaker

292
1
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I make a class that extends View. And I make a Service class that uses the View object via WindowManager. TTTTT So I can call setContentView method because of not Activity. – Hee Joong-Dominic Kim Mar 15 '20 at 13:47

score 0 · Answer 2 · answered Mar 15 '20 at 14:16

Your issue is that by default, XML uses a thing called Titlebar, as answered here. Along with removing the Titlebar, you can set your activity to full-screen and also remove the status-bar by using this solution.

Make sure that your activity imports from Activity rather than ActionBarActivity.

Also, it is better to avoid using actual numbers when setting a position or a size, and especially when the goal is to cover the entire screen. You can get the width and height of the screen by using getWidth() and getHeight() accordingly:

canvas.drawRect(0, 0, getWidth(), getHeight());

Make sure to use these methods only in or after the onDraw method was called, else their values will be equal to 0 since the canvas was not yet initialized.

How to calculate getWidth() and getHeight() ? – K Pradeep Kumar Reddy Jul 05 '21 at 15:03 — K Pradeep Kumar Reddy, Jul 05 '21 at 15:03

Android Canvas Area is not full screen. How to set canvas area?

2 Answers2