关于 OnMouseWheelDown、OnMouseWheelUp 等事件的简单例子 - 回复 "巅枫" 的问题

问题来源: http://www.cnblogs.com/del/archive/2009/10/28/1591380.html#2006425
测试准备, 在空白窗体上添加 Memo1 和 Button1, 然后激活 Form1 的如下事件(巅枫同学关心的):
OnMouseEnter、OnMouseLeave、OnMouseWheel、OnMouseWheelDown、OnMouseWheelUp, 还用到其 OnCreate 事件.

然后根据如下测试代码, 一试便知:

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormMouseEnter(Sender: TObject);
    procedure FormMouseLeave(Sender: TObject);
    procedure FormMouseWheel(Sender: TObject; Shift: TShiftState;
      WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
    procedure FormMouseWheelDown(Sender: TObject; Shift: TShiftState;
      MousePos: TPoint; var Handled: Boolean);
    procedure FormMouseWheelUp(Sender: TObject; Shift: TShiftState;
      MousePos: TPoint; var Handled: Boolean);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  Memo1.ScrollBars := ssBoth;
  Self.AutoScroll := True;
end;

procedure TForm1.FormMouseEnter(Sender: TObject);
begin
  Memo1.Lines.Add('Form1_OnMouseEnter');
end;

procedure TForm1.FormMouseLeave(Sender: TObject);
begin
  Memo1.Lines.Add('Form1_OnMouseLeave');
end;

procedure TForm1.FormMouseWheel(Sender: TObject; Shift: TShiftState;
  WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
begin
  Memo1.Lines.Add('Form1_OnMouseWheel');
end;

procedure TForm1.FormMouseWheelDown(Sender: TObject; Shift: TShiftState;
  MousePos: TPoint; var Handled: Boolean);
begin
  Memo1.Lines.Add('Form1_OnMouseWheelDown');
  Button1.Top := Button1.Top - 4;
end;

procedure TForm1.FormMouseWheelUp(Sender: TObject; Shift: TShiftState;
  MousePos: TPoint; var Handled: Boolean);
begin
  Memo1.Lines.Add('Form1_OnMouseWheelUp');
  Button1.Top := Button1.Top + 4;
end;

end.