VCL Form Basics

Code

unit MainFormUnit;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, Vcl.Forms, Vcl.StdCtrls;

type
  TMainForm = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    FClickCount: Integer;
  public
    property ClickCount: Integer read FClickCount;
  end;

var
  MainForm: TMainForm;

implementation

{$R *.dfm}

procedure TMainForm.FormCreate(Sender: TObject);
begin
  FClickCount := 0;
  Caption := 'My Delphi App';
end;

procedure TMainForm.Button1Click(Sender: TObject);
begin
  Inc(FClickCount);
  Button1.Caption := 'Clicked ' + IntToStr(FClickCount) + ' times';
end;

end.

Explanation

VCL forms are .pas (code) + .dfm (designer) pairs. {$R *.dfm} links the form resources. Event handlers use Sender (the component that fired). Common events: OnClick, OnCreate, OnShow, OnClose. Components are dropped on the form at design time; properties set in Object Inspector.

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