QDirectPainter example

[ale82]

Hi,
I'm trying to speed the switch from a screen to another one, the hardware is very poor and currently it takes 2/3 second between hide of a widget and show of another one.
I know that by default Qt framework puts an intermediate layer to render the screen, it should save somewhere and then put in the frame buffer:

!http://qt-project.org/doc/qt-4.8/images/qt-embedded-clientrendering.png(default paint)!

And I read about direct paint skipping the intermediate layer using a QDirectPaint:

!http://qt-project.org/doc/qt-4.8/images/qt-embedded-reserveregion.png(with QDirectPaint)!

But it's not so clear to me how to use it, I can't find any example but a description of methods.

Basically what I have is a MainScreen for standby, when I touch the screen I have overlap another screen.
Both the screen are QWidget implemented with qt-creator, so with their UI form and so on.

Can anybody suggest me some way to use QDirectPainter?
Thanks!

[ale82]

The widget has a complex layout with stylesheet and transparency