Draw line on image using QPainter

[JohannesMunk]

Can't you put your code into something simpler? Just one class, and without an UI-File, that you didn't provide!

Reducing complexity often helps to find problems in the first place, so you might even solve it yourself!

Johannes

PS: "Cross posting" meant, that you posted, while I was writing my message. After I posted mine.. I saw your new message and changed mine .. to "cross posting". After I read your message, I edited again :->