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

Luca Olivetti luca at wetron.es
Mon Mar 27 16:17:22 CEST 2023

El 27/3/23 a les 16:13, Michael Van Canneyt via lazarus ha escrit:
> On Mon, 27 Mar 2023, Luca Olivetti via lazarus wrote:
>> El 27/3/23 a les 11:59, Luca Olivetti via lazarus ha escrit:
>>> [*] 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.
>> Speaking of which, I encapsulated it in a procedure (TWaitForm is the 
>> spash screen, Aproc is a procedure of object, TExecInThread simply 
>> calls AProc in its execute method):
>> procedure ExecWithSplash(AProc:TThreadProc);
>> var wf:TWaitForm;
>>    ut:TExecInThread;
>> begin
>>  Wf:=TWaitForm.Create(Application);
>>  WF.Show;
>>  ut:=TExecInThread.create(AProc);
>>  while not ut.Finished
>>    Application.ProcessMessages
>>  wf.free;
>>  if ut.FatalException<>nil then
>>    raise(ut.FatalException);
>>  ut.free;
> Ehm. In case of an exception, ut will never be freed ?

That's what I said.
I was looking for a way to free it *and* raise the exception in the 
context of the main thread.
If I move the ut.free before the raise, the exception has already been 
freed and it's invalid, causing a sigsev, if I enclose it in a 
try..finally the exception handler will be called after the finally has 
freed the thread (and the exception, so it's the same problem).

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

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