关于类的入门的例子(6): 类引用示例-优快云博客

本文介绍了一种使用Delphi创建动态控件的方法。通过一个简单的示例展示了如何根据用户的选择动态生成不同的控件，如按钮、编辑框和标签，并讨论了控件类引用的应用。

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    RadioGroup1: TRadioGroup;
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormCreate(Sender: TObject);
    procedure RadioGroup1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
var
  ClassRef: TControlClass;  //TControlClass 是 TControl 的类引用


procedure TForm1.FormCreate(Sender: TObject);
begin
  RadioGroup1.Width := 300;
  RadioGroup1.Columns := 3;
  RadioGroup1.Items.Add('Button');
  RadioGroup1.Items.Add('Edit');
  RadioGroup1.Items.Add('Lable');

  RadioGroup1.ItemIndex := 0;
  ClassRef := TButton;
end;

procedure TForm1.RadioGroup1Click(Sender: TObject);
begin
  case RadioGroup1.ItemIndex of
    0: ClassRef := TButton;
    1: ClassRef := TEdit;
    2: ClassRef := TLabel;
  end;
end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
var
  NewCtrl: TControl;
begin
  NewCtrl := ClassRef.Create(Self);
  NewCtrl.Name := ClassRef.ClassName + IntToStr(Self.ControlCount);
  NewCtrl.Parent := Self;
  NewCtrl.Left := X;
  NewCtrl.Top := Y;
end;

end.

转载于:https://my.oschina.net/hermer/blog/319519