Clear previous drawings on repaint

leochou

I have a totally transparent, top-level, sreen-sized widget, which shows some text waterwarks on macOS. I need to update the system time text on one-minutes intervals. When I call the repaint method, the previously drawn text is not erased completely. Please see the attached image and demo project.

I've seen several posts on stackoverflow about this topic, but none of them works for me. Could anyone show the most correct way to handle it with Qt? Thanks!

Leo

Demo

SGaist

Hi and welcome to devnet,

What if you paint the whole widget with a transparent rect before painting the text ?

leochou

@SGaist I've uploaded a demo project. Could you please show me what's the most correct way to clear background manually? I've tried many ways, but none of them works.

leochou

@SGaist I'm using Qt 6.2.1 on macOS Moterey. Please take a look at the uploaded screenshot. There is a text watermark in a hollow effect left on the top.

JoeCFD

change your window size setGeometry(0, 0, 950, 550); When I run your code, I can not stop it. It uses full screen of my terminal. I have to restart machine. I do not see your problem on Ubuntu 18 with Qt 5.15.2.