What happens when Qt is compiled without corners and -no-opengl?

Question

I recently tried to compile my Qt static libraries with -no-angle and -no-opengl . At first I thought that this would not compile. But unexpectedly, Qt (5.7) compiled just fine. I could also compile my application (using a lot of QtWidgets).

To my surprise, I did not see any difference with my Angle-based Qt application. No lags, no crashes, my QtCharts did not appear, as always.

I could not find a definitive answer on the Internet. but I have two guesses:

• In the end, I did not use hardware acceleration.
• There is a mysterious backup mechanism.

What's going on here?

Answer 1

What's happening? In your case, nothing. Qt widgets do not use OpenGL behind. You must explicitly force it into the given widget stack, using QOpenGlWidget as the top-level widget. By default, you use the base component of the processor-based raster rendering - as you noticed, it works pretty well.

Compiling Qt without a corner and supporting OpenGL is a good way to downsize your application if you are not using OpenGL :)