Simple form with pixel manipulation

[mohsenaria]

Hi guys,
I'm completely newbie to Qt
i want to create a 800X600 window that just show some circle and be able to manipulate pixels of the form. there is no interaction between user and form(no click, no dblclick,...) it just shows some circles with one color and lines with different pixel colors(each line may have different pixel colors)
also i want to be able to change the coordination system, i mean change it from top-left to the center of the window. could anyone help me do that with some sample code?
thanks in advance for your reply.

[Oleg]

Not sure about coordinate system, but for simple drawing you can use QPainter.