[PyQt] Dont understand QListView behavior after filling the QStandardItemModel is finished

[Florian Bruhin]

Hi,

On Sat, May 11, 2019 at 05:02:03PM +0200, Gottfried Müller wrote:
> The first case displays the the content of the model directly. In the second
> case a sleep command is following the filling function. In the second case
> the content appears when the sleep time ended.
> 
> But in both cases the content of QStatusBar (counter of generated items)
> appears directly after the filling process of the model is ready.
> 
> Why appears the the QListView content in the second case so late? Does an
> action exist to force the display of the items before the sleep event?

Probably due to some Qt implementation detail. Maybe QStatusBar::showMessage
forces redrawing it immediately, while QListView updates as soon as you're back
in the main loop.

> Note: You can exchange the sleep command with any procedure which needs a
> longer time. The behavior is the same.

In general, you should never block Qt's main loop, as your application will
become unresponsive. Find a way to do the same thing asynchronously, or do it
in a worker thread, or call QApplication.processEvents() regularly.

Florian

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