dynamically placing forms on a pagecontrol - delphi

Question

as an extension of my previous post forms an a pagecontrol at runtime
I need a solution how to pass a buttonclick event back to the parent pagecontrol.
Do I have a assign a click function as a property and assign a new click function to all my forms for all the buttons i have placed :-( .... much work , any better solution
MyMainForm = CLass( )
....
aPagecontrol : TPageControl;
aTabForm_1 : TTabForm_1 ; // in the real case I use an dynamic array
aTabForm_2 : TTabForm_2 ;
aTabForm_3 : TTabForm_3 ;
....
UserData : TUserdata ; // lot of user data ....
function MyMainForm.CreateTabAndForm: TTabForm_1;
var
tabSheet : TTabSheet;
begin
//Create a new tab sheet
tabSheet := TTabSheet.Create(PageControl1) ;
tabSheet.PageControl := PageControl1;
//create a form
Result := TTabForm_1.Create(tabSheet) ;
Result.Parent := tabSheet;
Result.Align := alClient;
Result.BorderStyle := bsNone;
Result.Visible := true;
tabSheet.Caption := Result.Caption;
//activate the sheet
PageControl1.ActiveSheet := tabSheet;
end;
// program code , now failing :
aTabForm_1 := CreateTabAndForm;
aTabForm_1.onclick := MyButtonOnclick; // here AV happens !!
....
end;
the definition of the form
//
TTabForm_1 = class(TForm)
...
property clickButton1 : TClickfunction .......
end;
Solution #1 -> pass all the data to TTabForm_1 using properties
Solution #2 -> pass Button Click event to Mainform
target : readable code - good design

Answer 1

One way to expose events raised inside a form or control is like this :
unit Unit2;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm2 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
FButton1Clicked : TNotifyEvent; //Create a private TNotifyEvent field
public
// ...and expose it as a property
property OnButton1Click : TNotifyEvent read FButton1Clicked
write FButton1Clicked;
end;
implementation
{$R *.dfm}
procedure TForm2.Button1Click(Sender: TObject);
begin
// Execute the method if it has been assigned when Button1 is clicked.
if Assigned(FButton1Clicked) then FButton1Clicked(Sender);
end;
end.
Which you would consume like :
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, Unit2;
type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
private
FForm2 : TForm2;
procedure Form2ButtonClick(sender : TObject);//Create a TNotifyEvent handler
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.FormCreate(Sender: TObject);
begin
FForm2 := TForm2.Create(self);
//Assign a method to your custom event property
FForm2.OnButton1Click := Form2ButtonClick;
FForm2.Show;
end;
procedure TForm1.Form2ButtonClick(sender: TObject);
begin
// Do Something...
end;
end.
Of course, you don't have to use a TNotifyEvent, you can create any custom event, with parameters, that you like. For example
type
TFooEvent = procedure(ANumber : double; Sender : TObject) of object;
Which you could then use to send data with the click event :
if Assigned(FButton1Clicked) then FButton1Clicked(1.23, Button1);