Re: [fltk.general] Re: Window is frozen - Forums

On Sun, 28 Nov 2021, 20:46 supsm17 wrote:

As for lock and unlock, they kind of work? The window is very laggy and takes some time to update. After the thread finishes executing it appears that the window is completely frozen.

Hm, OK, I suspect this comes under the heading of "threads are hard", basically.

I'm on my phone, so can't really code up an example just now.

It would be helpful if you could post a minimal, compilable, example of what you are doing that manifests the failure state, so that we can advise on how to proceed.

This can (and should) work fine - that it does not tells us that there's something awry in your code, so we need to see what you are doing, so we can figure out what.
--
Ian
From my Fairphone FP3

On Sunday, November 28, 2021 at 3:43:51 AM UTC-8 Ian MacArthur wrote:

On Sun, 28 Nov 2021, 10:39 Manolo wrote:
To call Fl_Browser::add() from a worker thread, you have to call Fl::lock() before and Fl::unlock() after.
See an example of how it's done in demo program test/threads.
Also, make sure you follow guidelines given in :
https://fltk.gitlab.io/fltk/advanced.html

Yes, as Manolo says, the crux is that the render context on WIN32 is basically single threaded and can only safely be accessed from the main thread of each process.

So to access rendering from a worker thread, you need to lock, or (better) use the FL::awake callback mechanism.

--
Ian
From my Fairphone FP3

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