如何在组件开发中定义自己的事件。

Question

加入事件和加入属性差不多,只是要响应特定的消息，写消息处理句柄，如：
TMyControl = class(Tcomponent)
  private
    FOnMouseEnter: TNotifyEvent;
    ........
    ........
    procedure FSetOnMouseEnter(value: TNotifyEvent);
  protected 
    procedure cmmouseenter(var Msg: TMessage); message CM_MOUSEENTER;
  published
    property OnMouseLeave: TNotifyEvent read FonMouseLeave write FSetOnMouseLeave;
 end;procedure TMyControl.cmmouseleave(var Msg: TMessage);
 begin
  ....
  if Assigned(FonMouseLeave) then  FOnMouseLeave(Self);
 end;

Answer 1

完整的组件例子:
unit MyLabel;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;type
  TMyLabel = class(TLabel)
  private
    { Private declarations }
    
    procedure CMMouseEnter(var Message: TMessage); message CM_MOUSEENTER;
    procedure CMMouseLeave(var Message: TMessage); message CM_MOUSELEAVE;
  protected
    { Protected declarations }
  public
    { Public declarations }
  published
    { Published declarations }
end;procedure Register;implementationprocedure Register;
begin
  RegisterComponents('Samples', [TMyLabel]);
end;procedure TMyLabel.CMMouseEnter(var message:Tmessage);
begin
    Canvas.Font.Color:=$0000FF;
    Canvas.Brush.Color:=FEntercolor;
    repaint;
end;procedure TMyLabel.CMMouseLeave(var message:Tmessage);
begin
    Canvas.Font.Color:=clBlue;
    Canvas.Brush.Color:=FLeavecolor;
    repaint;
end;
end.