Steve Gatenby schrieb:
Hoping somebody may be able to explain why the following doesn't stop
the Form closing.
Button1 sets the method pointer correctly (I believe), as when closing
the form the showmessage occurs as expected (and shows the correct form
name).
But the form closes anyway.
procedure MyFormCloseQuery(Sender: TObject; var CanClose: boolean);
begin
ShowMessage('MyCloseQuery:'+TControl(Sender).Name);
CanClose := FALSE;
end;
procedure TformMain.Button1Click(Sender: TObject);
var
OnCloseQueryMethod :TCloseQueryEvent;
begin
TMethod(OnCloseQueryMethod).Code := @MyFormCloseQuery;
TMethod(OnCloseQueryMethod).Data := formMain;
TForm(formMain).OnCloseQuery := OnCloseQueryMethod;
end;
Here formMain.OnCloseQuery := @MyFormCloseQuery should be sufficient,
unless the OnCloseQuery handler deals with data in the form. But in this
case the handler should be made part of the formMain code, so that it
can access the form's fields and methods.
When your formMain closes anyway, I'd suggest to write an OnClose
handler and set CloseAction to caNone there.
AFAIR OnCloseQuery is intended for ending an application, where the
application denies ending when any form reports CanClose=False. Closing
individual forms instead should be handled in OnClose.
DoDi
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