[Development] Bug#874054: Setting QT_LINUX_ACCESSIBILITY_ALWAYS_ON=1 has a huge negative performance impact, should not be always on

Allan Sandfeld Jensen kde at carewolf.com
Sun Sep 3 20:19:31 CEST 2017


On Sonntag, 3. September 2017 19:57:55 CEST Samuel Thibault wrote:
> Allan Sandfeld Jensen, on dim. 03 sept. 2017 19:13:38 +0200, wrote:
> 
> That's Qt's fault for not taking care of EventListenerRegistered
> signals to determine whether someone is listening.
> 
So it is Qt's fault that is doing what you have told it to do? You have set 
the environment variable to ignore the absence of listeners. That is what 
QT_LINUX_ACCESSIBILITY_ALWAYS_ON does. It is an override for embedded 
applications which need to send accesibility events but for some reason can't 
autodetect the presence of a listener.

> > Note the performance impact is the same in all applications regardless of
> > framework.
> 
> No. Gtk sends only basic events (application creation notification,
> basically) when there is no screen reader.
> 
So does Qt by default, but you are forcing a special override around that. 

'Allan



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