Delphi中继承方式使用控件

Delphi中继承方式使用控件2013-12-12 博客园万一以前写代码, 总是把主单元弄得满满当当; 现在更喜欢把控件比较独立的功能写成一个单元, 改写属性、重载方法...哪怕只有一点点和默认不同, 也喜欢独立出来. 刚刚用到 TListBox, 需要能拖动元素、双击删除.

unit ListBox2; interfaceusesSystem.Classes, Vcl.Controls, Vcl.StdCtrls, System.Types; typeTListBox2 = class（TCustomListBox）protectedprocedure DragOver（Source: TObject; X: Integer; Y: Integer; State: TDragState; var Accept: Boolean）; override;procedure DblClick; override;publicconstructor Create（AOwner: TComponent）; override;procedure DragDrop（Source: TObject; X: Integer; Y: Integer）; override;end; implementation{ TListBox2 }constructor TListBox2.Create（AOwner: TComponent）;begininherited;DragMode := dmAutomatic;end; procedure TListBox2.DblClick;begininherited;Items.Delete（ItemIndex）;end; procedure TListBox2.DragDrop（Source: TObject; X, Y: Integer）;begininherited;Items.Exchange（ItemIndex, ItemAtPos（Point（X,Y）, True））;end; procedure TListBox2.DragOver（Source: TObject; X, Y: Integer; State: TDragState; var Accept: Boolean）;begininherited;Accept := True;end; end.

测试:

uses ListBox2; procedure TForm1.FormCreate（Sender: TObject）;beginwith TListBox2.Create（Self） dobeginParent := Self;Align := alLeft;Items.CommaText := "A,B,C,D,E,F,G";end;end;