给DBGrid添加鼠标滚动事件

学习利用TApplicaiton的OnMessage方法来添加控件的消息响应！

unit Unit1;

interface

uses
     Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, DB,     ADODB, Grids, DBGrids;

type
    TForm1 = class(TForm)
    DBGrid1: TDBGrid;
    ADOTable1: TADOTable;
    DataSource1: TDataSource;
    procedure FormCreate(Sender: TObject);
    private
    Procedure OnMouseWheel(Var Msg :TMsg;var Handled:Boolean);
     { Private declarations }
    public
      { Public declarations }
    end;

var

   Form1: TForm1;

   implementation

  {$R *.dfm}
    //------------------------------------------------------------------------------
Procedure TForm1.OnMouseWheel(Var Msg :TMsg;var Handled:Boolean);
  begin
     if Msg.message = WM_MouseWheel then 
  begin
     if Msg.wParam > 0 then
  begin
     if DBGrid1.Focused then
       SendMessage(DBGrid1.Handle,WM_VSCROLL,SB_PAGEUP,0);
    end
  else
     begin
         if DBGrid1.Focused then
            SendMessage(DBGrid1.Handle,WM_VSCROLL,SB_PAGEDOWN,0);
         end;
      Handled:= True;
    end;
end;

procedure TForm1.FormCreate(Sender: TObject);
  begin
      Application.OnMessage:=OnMouseWheel; // 截获鼠标滚动事件
  end;