QT 5.13 on OS X 10.12 -- spinning ball of death

[gmbrown]

I have a relatively simple QT app that loads data from a file and displays it using qtcustom plot. Under linux it performs great. When compiled under OS X almost any GUI action -- open a file, close the application, click on a graph brings up the OS X spin ball. I'm really not sure how to start diagnosing the root cause.

[mrjj]

Hi and welcome to the forums.
First, i would try one of Qts examples to see if they also run very slowly
as to know if to look for CustomPlot issues or it's of a more general nature.
Also check you are using the right XCode.
Target Platform Architecture Build Environment
macOS 10.12, 10.13, 10.14 x86_64 and x86_64h Xcode 10 (10.14 SDK), Xcode 9* (10.13 SDK)
https://doc.qt.io/qt-5/macos.html

[gmbrown]

@mrjj

Thanks for your help. I followed your lead -- the qt examples were fine as were the qcustomplot examples. However, I finally traced the issue to the settings of the pixel buffer ratio. One line of code resolved all the problems

ui->plot->setBufferDevicePixelRatio(1.0);

It seems the default (2.0) causes drawing large graphs to go very very slowly.

Geoffrey