Golang : Qt update UI elements with core.QCoreApplication_ProcessEvents


Tags : golang Qt progress-dialog-bar qt-core-process-events update-elements

Not a tutorial, but putting this here in case I need to refer back in future. While developing a Golang-Qt application recently, I found out that UI elements such as progress bar or progress dialog will not be updated without this line:

core.QCoreApplication_ProcessEvents(core.QEventLoop__AllEvents)

Why? Basically, a graphical user interface(GUI) Qt application needs to update/redraw itself....but doing so every second can be a resource hogging process.

From http://doc.qt.io/qt-5/qcoreapplication.html#processEvents:

In the event that you are running a local loop which calls this function continuously, without an event loop, the DeferredDelete events will not be processed. This can affect the behaviour of widgets, e.g. QToolTip, that rely on DeferredDelete events to function properly. An alternative would be to call sendPostedEvents() from within that local loop.

Calling this function processes events only for the calling thread.

Therefore, need to invoke the core.QCoreApplication_ProcessEvents(core.QEventLoop__AllEvents) function to get Qt to update the UI elements such as a progress bar.

References:

http://doc.qt.io/qt-5/qcoreapplication.html#processEvents

https://www.socketloop.com/tutorials/golang-qt-progress-dialog-example

http://stackoverflow.com/questions/8399349/simple-example-using-qprogressdialog-any-ideas-why-this-doesnt-work-properly

  See also : Golang : Qt progress dialog example



Tags : golang Qt progress-dialog-bar qt-core-process-events update-elements

By Adam Ng

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