Proposing that we implement a new "FrameTimer" (or other suitable named) Qt Quick element which would help synchronizing with the scene refresh. Currently this isn't easy to do, see comments from QTBUG-98339.

The API could contain at least these:

Properties:

• int frame (Frame number 0..inf while animation is running)
• real frameTime (Time in seconds since the previous screen update)
• real elapsedTime (Time in seconds since the start)
• bool running
• bool paused

Slots:

• pause()
• restart()
• resume()
• start()
• stop()

Here are few use-cases for this element:

1) Animate things freely in-sync with other animations. NumberAnimations etc. can't be really used if "speed" can be freely changed.

FrameTimer {
  running: true
  onFrameChanged: {
    // Move item speed px/s, no matter what the speed, screen Hz or fps is.
    myItem.x += frameTime * speed;
  }
}

2) Get fps without "dummy rotating item" hack.

property real fps
 
FrameTimer {
  running: true
  onFrameChanged: {
    // Get current fps
    fps = 1.0 / frameTime;
    // Easy to calculate also average fps from longer period
  }
}

3) Get real frame number for ShaderEffect (see e.g. how Shadertoy uses this). Also get elapsed time easily (Timer doesn't expose this, so need to maintain it manually, or e.g. use NumberAnimation or JS Date) as well as time delta (frame time).

FrameTimer {
  id: frameTimer
  running: true
  // Allow (re)starting and stopping this
}
ShaderEffect {
  property int iFrame: frameTimer.frame
  property real iTime: frameTimer.elapsedTime
  property real iTimeDelta: frameTimer.frameTime
  ...
}