Need advice on virtual screens
I am developing an embedded system based on a Raspberry Pi, using a Yocto-based Linux rather than Raspbian. I'd like to use QML, but would switch to Qt Widgets if necessary. I have a fixed sized display (1920x1080), and I need to switch among a number of completely independent virtual screens. I want instant switching, no panning or other effects. Virtual screens may be written to while not visible. I want to take advantage of the GPU where possible.
First question: What's the most efficient way to switch a single display among a number of virtual screens, in QML and Qt Widgets?
Second question: I'm under the impression that a compositor like Wayland is intended to combine windows managed by independent processes, but in my system all output will be produced by a single GUI process. Do I need Wayland, or is there something simpler that still uses the GPU? Or does Wayland composite individual objects like buttons?