Solved

MDI application with childwins in dll's

Posted on 1998-10-07
10
220 Views
Last Modified: 2010-04-06
Hi!

I'm having a problem with an MDI application. The child windows are defined in a .dll or .bpl and I can't make it
work. In the .dll I have a function that shows the window and set's the application.handle property for the .dll to
the MDI-applications handle. When creating the window I get the following message:
    Project raised exception class EInvalidOperation with message 'Cannot create form. No MDI forms are
currently active'

Is it possible to do this? If it is, any ideas?
/Per
0
Comment
Question by:peed112097
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 3
  • 2
  • +1
10 Comments
 
LVL 10

Expert Comment

by:Jacco
ID: 1342109
A bit more down the list Westy asks the same question!

Just a remark :)

I am looking into the problem.

Regards Jacco
0
 

Author Comment

by:peed112097
ID: 1342110
I've solved the problem when using a dll,but look into my other Q if you have any idea's there! I'll be deleting this Q soon!

/Per
0
 
LVL 10

Expert Comment

by:Jacco
ID: 1342111
What was the solution?
0
[Live Webinar] The Cloud Skills Gap

As Cloud technologies come of age, business leaders grapple with the impact it has on their team's skills and the gap associated with the use of a cloud platform.

Join experts from 451 Research and Concerto Cloud Services on July 27th where we will examine fact and fiction.

 

Author Comment

by:peed112097
ID: 1342112
Look at westys Q!
0
 
LVL 10

Expert Comment

by:Jacco
ID: 1342113
I can't get your solution to work. Are you sure the MDI child form is not compiled into the main EXE? I get a resource error because the application handle is wrong.

Regards Jacco
0
 

Author Comment

by:peed112097
ID: 1342114
Ok, if you send me your e-mail address I'll mail the project to you. I'm sure that the child's not in the .exe.

0
 
LVL 10

Expert Comment

by:Jacco
ID: 1342115
Jacco@HotelConcepts.COM

Thanks in advance!

Regards Jacco
0
 
LVL 2

Accepted Solution

by:
Hagen040798 earned 200 total points
ID: 1342116
Hi peed

The answer for the problem is the same answer for your question with the dynamicly loading packages and includeds Objects.
I have for my Firma yust this programmed.
TForms in Librarys-DLL's and the Loading, Creation, Destroying and unloading from the Librarys at Runtime.
Post me your E-Mail-Address and i send your a Example from my Project.
my E-Mail is HaReddmann@AOL.COM

Hagen.

0
 
LVL 2

Expert Comment

by:Thaddy
ID: 1342117
You might be interest in this little snippet.
Design your form, add action:=caFree to the formclose event!
and compile it in this dll framework. You call the dll form from your main app like so: ShowMDIChildForm(Application);

library MDIForms;
uses
  SysUtils, Classes,Forms,Windows,ChildU in 'ChildU.pas' {ChildForm};
var
  DLLApp : TApplication;
procedure MyDLLProc(Reason: Integer);
begin
  if Reason = DLL_PROCESS_DETACH then
    if Assigned(DllApp) then
      Application := DllApp;
end;
procedure ShowMDIChildForm(MainApp : TApplication);
var
  Child : TChildForm;
begin
  if not Assigned(DllApp) then begin
    DllApp := Application;
    Application := MainApp;
  end;
  Child :=TChildForm.Create(Application.MainForm);
  Child.Show;
end;
exports
  ShowMDIChildForm;
begin
  DllApp := nil;
  DLLProc := @MyDLLProc;
end.
0
 
LVL 2

Expert Comment

by:Hagen040798
ID: 1342118
Hi Per.

Have You reseived me Mail ?

Hagen.
0

Featured Post

Announcing the Most Valuable Experts of 2016

MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
Introduction Raise your hands if you were as upset with FireMonkey as I was when I discovered that there was no TListview.  I use TListView in almost all of my applications I've written, and I was not going to compromise by resorting to TStringGrid…
In this video, viewers are given an introduction to using the Windows 10 Snipping Tool, how to quickly locate it when it's needed and also how make it always available with a single click of a mouse button, by pinning it to the Desktop Task Bar. Int…
If you’ve ever visited a web page and noticed a cool font that you really liked the look of, but couldn’t figure out which font it was so that you could use it for your own work, then this video is for you! In this Micro Tutorial, you'll learn yo…
Suggested Courses
Course of the Month7 days, 21 hours left to enroll

617 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question