Add a form before Mainform - forms

Question

I would like to program a small advertising form, which let's me easily implement it to any of my other projects.
The ad form should appear before my real project/app starts.
Some requirements have to be met:
Easy to implement to any project without any hassle - add form/unit and almost everything takes care of the rest.
My app's MainForm (Application.MainForm) shall be created during runtime AFTER my ad form has been successfully closed (or requirements have been met)
Adding only 1 unit/form should be enough to implement
My progress so far is:
I create an empty main form which is hidden (Application.MainForm)
Then I create a modalform, which is the actual Ad-Form - on the right modalresult, free my welcomescreen and proceed to the "main app"
I need to remove all auto-create forms from my project
I open a procedure in my project's source file with some parameters, including the app's main form (see source)
Unfortunately I have to add all units/forms to the project instead of just one (recursive path problem?)
That's what I have so far:
Project Source:
program MyTestProgram;
uses
Vcl.Forms,
Windows,
uMainWindow in 'uMainWindow.pas' {Form1},
uEmptyForm in '..\AdProject\uEmptyForm.pas' {AdEmptyMainForm},
uWelcomeScreen in '..\AdProject\uWelcomeScreen.pas' {WelcomeScreen}; // shouldn't be here
{$R *.res}
begin
Application.Initialize;
Application.MainFormOnTaskbar := True;
Application.Run;
LoadAdWindow('Title of my app', uMainWindow.TForm1, uMainWindow.Form1);
end.
EmptyForm Unit:
unit uEmptyForm;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs;
type
TAdEmptyMainForm = class(TForm)
private
{ Private declarations }
public
{ Public declarations }
end;
var
AdEmptyMainForm: TAdEmptyMainForm;
procedure LoadAdWindow (Appname: string; InstanceClass: TComponentClass; var Reference);
implementation
{$R *.dfm}
uses
uWelcomeScreen; // Has to be added to the project, otherwise it doesn't detect the unit in the same path as this unit
procedure LoadAdWindow (Appname: string; InstanceClass: TComponentClass; var Reference);
begin
Application.MainFormOnTaskbar := True;
Application.ShowMainForm := False;
Application.Title := Appname;
Application.CreateForm(TAdEmptyMainForm, AdEmptyMainForm);
with uWelcomeScreen.TWelcomeScreen.Create(Application.MainForm) do
begin
Caption := Appname;
if ShowModal <> 1337 then ExitProcess(0);
Free;
end;
Application.CreateForm(InstanceClass, Reference);
end;
end.
After the welcome screen succeeds, the application closes.
Is this even the right way to it?
Any help is appreciated!

Answer 1

The Application.MainForm is established by the first call to Application.CreateForm() for a TForm-derived class. Application.Run() exits immediately if Application.MainForm is not assigned.
To do what you are attempting, you should do it more like the following instead. You don't need a blank MainForm, simply create and show the ad window before creating the real MainForm. Only the project main source needs to be changed:
program MyTestProgram;
uses
Vcl.Forms,
Windows,
uMainWindow in 'uMainWindow.pas' {Form1},
uWelcomeScreen in '..\AdProject\uWelcomeScreen.pas' {WelcomeScreen};
{$R *.res}
begin
Application.Initialize;
Application.MainFormOnTaskbar := True;
Application.Title := 'Title of my app';
with TWelcomeScreen.Create(Application) do
try
Caption := Application.Title;
if ShowModal <> 1337 then
Exit;
finally
Free;
end;
Application.CreateForm(TForm1, Form1);
Application.Run;
end.

Answer 2

You can easily create and show the Ad Form and after it create and show the main form, like this :
var
FAdFrm : TAdFrm;
begin
FAdFrm := TAdFrm.Create(nil);
if FAdFrm.ShowModal = mrOK then
begin
FAdFrm.Free;
Application.Initialize;
Application.MainFormOnTaskbar := True;
Application.CreateForm(TMainFrm, MainFrm);
Application.Run;
end
else
FAdFrm.Free;
Be careful that the Main Form of your project is the first form that created with Application.CreateForm method

Answer 3

An alternative is to create the advertising form on MainForm's create event. I do this on my own projects.
procedure TMainForm.FormCreate(Sender: TObject);
begin
AdvForm := TAdvForm.Create(Self);
Try
AdvForm.ShowModal;
finally
AdvForm.Free;
end;
end;