Hi Rob. The problem was in the Notification procedure: the AComponent received as parameter is not ready (created). Fixed now. Now I can create the MDI forms and a button for each of them without much overhead.
Thank for the answer. Rob Kennedy wrote: > CubicDesign wrote: > >> Do you know the WindowMenu property of a (parent) form? >> It links to a menu that lists all current MDI children of an application. >> >> I want to list all existing children also in other place. More exactly I >> want to create an interface similar with Macromedia Dreamweaver or >> Delphi 7, where each MDI child has its own tab from where it can be >> quickly accessed. >> > > Delphi 7 does not use MDI. > > If you want tabs, then go ahead and use tabs. Don't try to take an MDI > application and force it into tabs. > > >> I started the work from TForm.Notification but something went wrong. The >> idea was to create a new tab in a TPageControl every time a TForm was >> created at runtime. >> > > If you plan to do this by taking forms and re-parenting them into tabs, > I think you're going to have problems. Have you considered using frames? > You can design them visually just like forms, but they don't carry the > extra burden by trying to act like standalone forms. > > >> Somebody came with idea of adding a routine in each MDI form (in Create >> and Destroy) that will create and delete its corresponding tab, but I >> don't like the idea because I have many different forms derived from >> TFrom in my application and I have to modify them all. >> > > If they're all supposed to act a certain way, then make them all descend > from a common base class that acts that way. Then your modification > simply consists of changing all their ancestors to be that new class > instead of TForm. > > >> The code that I tried is: >> >> VAR >> Initializing: Boolean= True; >> FormID: Integer= 0; >> >> procedure TfrmMain.Button1Click(Sender: TObject); >> VAR F: TForm; >> begin >> F:= TForm.Create(Self); >> F.Caption:= 'xx'; >> F.Name:= 'Form'+ i2s(FormID); >> F.Tag:= FormID; >> F.FormStyle:= fsMDIChild; >> F.Show; >> F.BringToFront; >> end; >> > > Since you're creating the form here, in the MDI parent's code, why don't > you also create the button here? You have all the information you need, > so why rely on some underdocumented internal VCL notification to tell > you about it? > > >> procedure TfrmMain.FormCreate(Sender: TObject); >> begin >> Initializing:= FALSE; >> end; >> >> >> procedure TfrmMain.Notification(AComponent: TComponent; Operation: >> TOperation); >> VAR btn: TButton; >> begin >> inherited; >> if NOT Initializing >> AND (Operation= opInsert) >> AND (AComponent is TForm) >> then >> begin >> inc(FormID); >> >> btn:= TButton.Create(Self); >> btn.Parent:= Self; >> btn.Visible:= TRUE; >> btn.BringToFront; >> btn.Top := 1; >> btn.Caption:= (AComponent as TForm).Caption; <--- AV here >> btn.Tag:= FormID; >> AComponent.Tag:= FormID; >> end; >> >> if (Operation= opRemove) then RemoveAsocButton; >> end; >> >> >> The code creates a Tform MDI child when you push the button. >> At this moment the Notification is aware that a new component is ready >> to be created. Here I want to create the list of existing MDI children - >> the above code tries to create a button for each of these MDI children. >> However it fails when at this line (AComponent as TForm).Caption. The >> AComponent seems to be un-initialized. >> > > Which part causes the access violation? There are three things on that line: > > 1. Casting AComponent to TForm > 2. Reading the Caption property from the result of that cast > 3. Writing the Caption property of the button > > >> Delphi's documentation doesn't tell you big deal about Notification so I >> kinda got stuck. >> > > > _______________________________________________ Delphi mailing list -> [email protected] http://lists.elists.org/cgi-bin/mailman/listinfo/delphi
