OnActiveFormChange (Delphi)

Description

This example uses two forms with a button on the first form. When you click the button, the second form appears. As you switch between forms, the form that is active is colored aqua. Note: You must include the unit header for the second form to the unit file for the first form, and add the public ColorForm method to the header for the unit of the first form.

Code

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    { Private declarations }
  public
    procedure ColorForm(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses Unit2;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Form2.Show;
end;

procedure TForm1.ColorForm(Sender: TObject);
begin
  Color := clWhite;
  Form2.Color := clWhite;
  Screen.ActiveForm.Color := clAqua;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
  Screen.OnActiveFormChange := ColorForm;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  // This stops ColorForm from being called during termination.
  Screen.OnActiveFormChange := nil;
end;

Uses

• Vcl.Forms.TScreen.ActiveForm ( fr | de | ja )
• Vcl.Forms.TScreen.OnActiveFormChange ( fr | de | ja )