How to keep the FPS stable at 60fps when using QML to draw animations

[QTAndy]

Hi,
I‘am developing an QT Cluster App by QML on an 8Gb Board like below:

1. Using two QML's Canvas to draw Cluster animations
2. Set QQuickWindow::setSceneGraphBackend(QSGRendererInterface::OpenGL)
3. Calling method requestPaint() from c++ thread to render Cluster page per 16ms by asynchronous way.

When running QT Cluster App, the FPS of Cluster is about 30-40fps and it is not stable. After tuning, we found there are some reasons caused the low FPS, the main reasons are below:

1. Render rate(16ms)
2. Multi Canvas

But if we reduce the render rate to 100ms or more, although FPS will up to 60fps, but the QT Annimations looks very slow.
So, I want to confirm that if there any way to keep my App's FPS stable at 60fps when setting the render frequency as 16ms .
By the way, the OS and S/W are below:
OS:

1. QNX Hypervisor
2. QXN Host(QT Cluster App) + Guest Android(IVI Launcher App)

S/W:

1. QT open source Library 5.11.2
2. Qtcreator 4.11.1

that's all.

[QTAndy]

I tried the Qt5.14.2\Examples\Qt-5.14.2\quickcontrols\extras\dashboard in my enviornment. I fount it runs in scope 55-60fps.
I found there is a module named "QT for mcu" in QT site. And I found some demos runs smoothly with it.
Should I use the "QT for mcu" library to improve my Cluster app?

[J.Hilk]

Hi @QTAndy

using a Canvas element seems like one of the slowest way to implement custom drawings.

have you considered subclassing
https://doc.qt.io/qt-5/qquickitem.html
or
https://doc.qt.io/qt-5/qquickpainteditem.html

and doing your drawing directly in updatePaintNode ?

In theory, that should be a lot faster!

[QTAndy]

@J-Hilk
Thanks for your reply.
I tried Scene Graph and used QQuickItem's updatePaintNode().
It works well. The FPS has been improved although it is still less than 60fps.
But the edges of the graphic are jagged.
I tried setAntialiasing(true) and setSmooth(true), but they don't seem to work.
Is there any method to fix this issue?