[Lazarus] animated splash screen for lengthy operation, works with windows, doesn't with linux

[Luca Olivetti]

El 27/3/23 a les 11:06, Sven Barth via lazarus ha escrit:
> Luca Olivetti via lazarus <lazarus at lists.lazarus-ide.org 
> <mailto:lazarus at lists.lazarus-ide.org>> schrieb am Mo., 27. März 2023, 
> 10:34:
> 
>     El 27/3/23 a les 10:13, Jean SUZINEAU via lazarus ha escrit:
>      >
>      > Le 27/03/2023 à 09:46, Luca Olivetti via lazarus a écrit :
>      >> procedure TUpdateThread.Execute;
>      >> begin
>      >>   while not Terminated do
>      >>   begin
>      >>     FWaitForm.ShowProgress;
>      >>     Sleep(30);
>      >>   end;
>      >> end;
>      >
>      > Usually I use TThread.Synchronize to ensure that the graphic code
>     is run
>      > by the main thread.
>      >
>      > But it won't work if your main thread is blocking.
> 
>     Exactly
> 
>      >
>      > May be you should do the inverse move the lengthy operation to a
>      > separate thread and keep the main thread for the splash screen ?
> 
>     Yes, I usually do that, but in this case it's not possible (the lengthy
>     operation is just a  TSQLQuery.open that I cannot delegate to a
>     different thread).
> 
> 
> You need to find a way then, because the GUI handling *must* be done in 
> the main thread.

Opening the query in a thread[*] seems to have no ill effects, so that's 
what I'm doing now.


[*] instead of opening the query I spawn a thread that opens it, wait 
for it to finish while executing Application.ProcessMessages and 
eventually reraise the exception that was generated inside the thread.

Bye
-- 
Luca Olivetti
Wetron Automation Technology http://www.wetron.es/
Tel. +34 93 5883004 (Ext.3010)  Fax +34 93 5883007