[Interest] Guide me through the Qt offerings for GUIs

[Shawn Rutledge]

> On 2021 Apr 15, at 12:25, Rui Oliveira <ruilvo at hotmail.com> wrote:
> 
> Hey,
> As per the title implies, I would like some comments on the GUI offerings Qt currently has. 
> 
> I'll share my own assessments and needs, and I'd like very much to hear your comments.
> 
> So:
> 
> I want to write a desktop application. This desktop application would not involve displaying lists of things, which seems to be what all tutorials/guides/courses are about, especially on the QML side. This application would involve some "custom graphics", namely a FFT display, and a "waterfall" display. You can google for "GQRX" and you'll know what I want.
> 
You probably want to go with a shader-based solution for rendering those displays really fast on the GPU, without a high CPU load, assuming that you are rendering them from raw data, not generating images with some other library, and assuming that your users tend to have GPUs.  I think Qt Quick (and Controls) is a good fit, but check out the qtdeclarative/examples/quick/scenegraph/graph example and see if you’d like to render your displays like that.  It is more work than using QPainter, but probably worth it if the data is updating quickly.

If it turns out that you need to use QPainter for some reason, it’s going to be slower, higher CPU load, even higher if you want antialiasing; in that case, widgets are OK, or you can still use Qt Quick and subclass QQuickPaintedItem to do the custom rendering.  But it wouldn’t be my first choice.