[Qt-interest] Smooth UI with large QTreeView

[Wintaki Hagabashi]

Hi,

I have a GUI app that has a QTreeView with a custom model (derived from QAbstractItemModel).  At the top of the screen, there is a custom widget that is basically a scrolling ticker.  It has a QTimer and every 20 milliseconds, it updates itself (scrolls left 2 pixels).

This all works great except that once every 3 seconds the data in my QTreeView updates.  The nature of this is that the QTreeView has about 3000 rows and about 100 of them update each second.  I make the changes to my internal data structure, and then emit dataChanged().  All working perfect, except that the updates seem to block the GUI thread for a short period of time, making the scrolling ticker "pause" for a split second, making it appear jerky.

Is there a way to do the scrolling in a different thread (or the updates to the QTreeView)?  As far as I understand all GUI operations must be done in a single thread.

I tried calling posting evens to do the QTreeView updates one at a time in the hope that it would get interleaved with the timer events, smoothing out the scrolling, but this did not seem to help.

Thanks for any tips

-wayne



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