cameraview: fix frameskip

[deanlee]

use repaint to fix the frameskip when there are too many events in the queue (e.g. watch3)

[pd0wm]

Doesn't it make more sense to skip frames so we can keep up realtime?

[adeebshihadeh]

What events are dominating the queue? Perhaps we're spamming the queue with nonsense timer events or something else?

[deanlee]

We can easily implement an OffroadTimer like this if use singleton uistate #22789

OffroadTimer(QObject *parent) : QTimer(parent) {
  QObject::connect(uiState(), &UIState::offroadTransition, [=](bool offroad) {
    offroad ? start() : stop();
  });
}

[deanlee]

What events are dominating the queue? Perhaps we're spamming the queue with nonsense timer events or something else?

At present, this drawing problem mainly affects watch3. it is caused by many update events from the three cameras.

[pd0wm]

It seems like the video is skipping back and forth sometimes, so something goes out of order. I assume that was introduced by the async copy? Should we hold off on copying new frames if an update is still pending?

I don't like forcing a repaint in the regular ui, but it's fine in watch3. Should we make it an argument for the constructor of CameraView?

[deanlee]

Think we don't need this hack if use YUV vipc stream.

[pd0wm]

Can we ensure the texture is not being modified while Qt is actually drawing the ui? Even with YUV that might still be an issue, right?

[deanlee]

Fixed, synchronized the upload and render

[deanlee]

Can we ensure the texture is not being modified while Qt is actually drawing the ui? Even with YUV that might still be an issue, right?

YUV #22905 does not has this synchronization issue. it uploads the latest frame in the gui thread.( since the performance looks good enough , I did not do asynchronous upload for it)