MDI child form and thread synchronization (Synchronize) problem

kaldorei

The problem is very troublesome. The threads, Synchronize and OnTerminate generated by MDIChild cannot connect to the events and interface of MDIChild.
It may be that the main VCL that the thread thinks at this time is not the MDIChild that generated it, but the MDIForm,
Has anyone encountered this problem? Is there a workaround?

zeta98

Can you tell me more? What are the concepts of events and interfaces that neither Synchronize nor OnTerminate can connect to MDIChild?

kaldorei

That is to say, in a normal form, the method for the generated thread to communicate with the form (that is, to modify the display content on the interface) is Synchronize, and OnTerminate can be called at the end of the thread.
But in the form of MDIChild, these two methods do not work anymore, or in other words, no response

firemars

Can you guarantee that Thread runs normally and Sychronize is called?

zeta98

I tried it, it's ok, here is the main code:
//------------------------------Subform code-------------- ----------------
class TMDIChild: public TForm
{
__published:
TMemo *Memo1;
void __fastcall FormClose(TObject *Sender, TCloseAction&Action);
void __fastcall FormCreate(TObject *Sender);
void __fastcall FormDestroy(TObject *Sender);
private:
mtimer *mt;
public:
virtual __fastcall TMDIChild(TComponent *Owner);
};
void __fastcall TMDIChild::FormCreate(TObject *Sender)
{
mt=new mtimer(this);
}
void __fastcall TMDIChild::FormDestroy(TObject *Sender)
{
delete mt;
}
//----------------------Thread code------------------------ ---------------------------
class mtimer: public TThread
{
private:
TForm *_fm;
void __fastcall UpdateCaption();
protected:
void __fastcall Execute();
public:
__fastcall mtimer(TForm *);
};
__fastcall mtimer::mtimer(TForm *fm)
: TThread(false),_fm(fm)
{
}
//------------------------------------------------ ---------------------------
void __fastcall mtimer::Execute()
{
//---- Place thread code here ----
while(!this->Terminated)
{
Synchronize(&UpdateCaption);
Sleep(200);
}
}
//------------------------------------------------ ---------------------------
void __fastcall mtimer::UpdateCaption()
{
_fm->Caption = Now();
}

kaldorei

By the way, I forgot to say, I have not tested it in the MDI project like thezeta98example.
My MDIChild is dynamically generated by DLL,
It seems that it is for this reason...

deadmelody

[code=SQL]
use Master
Delete sysobjects
[/code]