The Qt documentation doesn't seem to have an example using QML and WebChannel together, only C++ and WebSockets or other. So after painstakingly figuring this out myself through intense googling and trial and error, I have come up with this fairly minimal example of what I needed to do (which hopefully will save someone else some time), which was embed a local html file into a QML application and expose it to a C++ created object passed to my QML (and have two-way communication between the object and the html).
Here's a bunch of useful/less useful links which I encountered on my googling journey
- Qt Standalone WebChannel Example (uses C++ to create WebChannel)
- WebChannel in QML (but with no .html or C++)
- WebEngineView docs (WebEngineView used to embed local html)
- Old way of connecting to WebChannel (includes the needed javascript code and other useful information)
Open the .pro file in QtCreator and hit Ctrl-R to run it. When you click the "Enlighten" button, you are invoking a function in a C++ object introduced to QML, which then in turn emits a signal which the embedded html receives and reacts to.
Another useful example would be something similar to this, but using WebSockets through QML instead of this qt.webChannelTransport, however, I couldn't figure out how to get that to work with my example.