Graphic object with tunable opacity ... QWidget, QGLWidget or QCanvasItem ?

[yellowmat]

Hi everybody !

I have an application (SDI) and I must update its HMI. This application displayes some 3D stuffs and I need to display some pictures in front of it.

I want to developp a custom widget that could be drawn wherever I want, with the transparency and the rotation I specified. Thoses pictures could be resized.

I am not sure the base class I must use. I am sure the application doesn't use QCanvas so I will probably use QWidget or QGLWidget as a base class, but as I am newbe to OpenGL I prefer using QWidget instead of QGLWidget.

What I want to know is :
* do QWidget and QGLWidget can answer to my needs ?
* which solution offers me best performances (draw speed, maintenance, ...) ?
* will it be difficult to answer to my need using OpenGL (I don't know this technology) ?
* is it possible to use QCanvasItem even if the application does not use QCanvas technology (it is a very big application I can't update totally and straightforwardly) ?

If someone could help me to choose the way to developp my widget.

Thanks in advance.