What is the difference between QImage and QPixmap?

Question

I do not understand what is the difference between QImage and QPixmap, they seem to offer the same functionality. When should I use a QImage and when should I use a QPixmap?

Answer 1

Important in industrial environments:

The QPixmap is stored on the video card doing the display. Not the QImage.

So if you have a server running the application, and a client station doing the display, it is very significant in term of network usage.

With a Pixmap, a Redraw consists in sending only the order to redraw (a few bytes) over the network.

With a QImage, it consists in sending the whole image (around a few MB).