在Windows系統(tǒng)中提供了一種系統(tǒng)消息掛鉤的(Message hook)功能，使用消息掛鉤，可以實(shí)時(shí)監(jiān)視處理系統(tǒng)中的各種消息。很多鼠標(biāo)增強(qiáng)軟件就是利用消息掛鉤來攔截所有的鼠標(biāo)消息進(jìn)行處理的。
要設(shè)置鼠標(biāo)消息掛鉤，一般先建立一個(gè)使用鼠標(biāo)消息掛鉤的動(dòng)態(tài)連接庫(DLL)文件，然后就可以在其它程序中使用這個(gè)DLL文件處理鼠標(biāo)消息。
下面的程序介紹通過鼠標(biāo)消息掛鉤監(jiān)視鼠標(biāo)消息，從而實(shí)現(xiàn)類似于一些鼠標(biāo)增強(qiáng)軟件一樣的使窗口上下左右滾動(dòng)的功能。

1．建立動(dòng)態(tài)連接庫
選擇菜單 File New ，選擇DLL產(chǎn)生一個(gè)DLL模版，保存為 MHook.Dpr
//MHook.Dpr源程序
library MHook;

uses
SysUtils,
Classes,
hkproc in 'hkproc.pas';

exports
EnableMouseHook,
DisableMouseHook;

begin
hNextHookProc:=0;
procSaveExit:=ExitProc;
ExitProc:=@HotKeyHookExit;
end.

再選擇菜單 File New ，選擇Unit建立一個(gè)Pas文件，保存為 HKProc.pas
//HKProc.pas源程序
unit hkproc;

interface
uses
Windows,Messages;
const
Move_Up = 0;

Move_Down=1;
Move_Left=2;
Move_Right=3;
var
hNextHookProc:HHook;
procSaveExit:Pointer;
M_Direct:Integer;
LPoint:TPoint;
NowWindow:Integer;

function MouseProc(iCode:Integer;wParam:WPARAM;
lParam:Pointer):LRESULT; stdcall;export;
function EnableMouseHook(WndHandle:integer):BOOL;export;

function DisableMouseHook:BOOL;export;
function GetDirect(FPoint : TPoint;LPoint : TPoint):integer;
procedure HotKeyHookExit;far;

　

implementation

//GetDirect函數(shù)根據(jù)光標(biāo)的移動(dòng)決定窗口滾動(dòng)的方向。
function GetDirect(FPoint : TPoint;LPoint : TPoint):integer;
var
iWidth,iHeight:integer;
begin
iWidth:=LPoint.x-FPoint.x;
iHeight:=lPoint.y-FPoint.y;
Result:=-1;

if ((iWidth=0)or(iHeight=0))then
exit;

if ((abs(iWidth) div abs(iHeight))>=2) then
if iWidth<0 then //Move to left
Result:=Move_Left
else
Result:=Move_Right

else if ((abs(iHeight) div abs(iWidth))>=2) then
if iHeight<0 then //Move to top
Result:=Move_Up
else
Result:=Move_Down;

end;

function MouseProc(iCode:Integer;wParam:WPARAM;
lParam:Pointer):LRESULT; stdcall;export;
var
pMouse:^MOUSEHOOKSTRUCT;
l:integer;
begin
//如果用戶按下鼠標(biāo)右鍵同時(shí)Scroll Lock鍵為按下狀態(tài)則
//滾動(dòng)窗口。
if ((wParam=WM_RBUTTONDOWN) and Boolean(GetKeyState(145))) then
begin
pMouse:=lParam;
l:=GetDirect(lPoint,pMouse.pt);
if l>=0 then
M_Direct:=l;
lPoint:=pMouse.pt;

NowWindow:=WindowFromPoint(lPoint);
if M_Direct=Move_Up then
SendMessage(NowWindow,WM_VSCROLL,SB_PAGEUP,0)
else if M_Direct=Move_Down then

SendMessage(NowWindow,WM_VSCROLL,SB_PAGEDOWN,0)
else if M_Direct=Move_Left then
SendMessage(NowWindow,WM_HSCROLL,SB_PAGELEFT,0)
else if M_Direct=Move_Right then
SendMessage(NowWindow,WM_HSCROLL,SB_PAGERIGHT,0);
Result:=1;
exit;
end
else if ((wParam=WM_RBUTTONUP) and Boolean(GetKeyState(145))) then
Result:=1
else
begin
Result:=0;
if iCode<0 then
begin
Result:=CallNextHookEx(hNextHookProc,iCode,wParam,
integer(lParam));
Exit;
end;
end;
end;

function EnableMouseHook(WndHandle:integer):BOOL;export;
begin
GetCursorPos(lPoint);
Result:=False;
if hNextHookProc<>0 then
exit;
//設(shè)置Mouse hook
hNextHookProc:=SetWindowsHookEx(WH_MOUSE,@MouseProc,
Hinstance,0);
Result:=hNextHookProc<>0;
end;

function DisableMouseHook:BOOL;export;
begin
if hNextHookProc<>0 then
begin
UnHookWindowsHookEx(hNextHookProc);
hNextHookProc:=0;
end;
Result:=hNextHookProc=0;
end;

procedure HotKeyHookExit;
begin
if hNextHookProc<>0 then
DisableMouseHook;
ExitProc:=procSaveExit;
end;

end.
在菜單中選擇 Project Build MHook建立DLL文件。

2．建立程序調(diào)用動(dòng)態(tài)連接庫
在這里我們還是使用Delphi建立程序，當(dāng)然也可以使用諸如VB等調(diào)用動(dòng)態(tài)連接庫。
在菜單中選 File New Application建立一個(gè)新程序，將工程文件保存為Project1.dpr

//project1的源程序
program Project1;

uses
Forms,
Sample1 in 'Sample1.pas' {Form1};

{$R *.RES}

begin
Application.Initialize;
//隱藏窗口
Application.ShowMainForm := False;

Application.CreateForm(TForm1, Form1);
Application.Run;
end.

將Form1的源程序文件保存成Sample1.pas

//Form1的源程序
unit Sample1;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, Menus, ImgList,ShellApi, ExtCtrls;

const
WM_ICONMESSAGE=WM_USER+$100;


type
TForm1 = class(TForm)

procedure FormClose(Sender: TObject; var Action: TCloseAction);
procedure FormCreate(Sender: TObject);
private
procedure WMBarIcon(var Message:TMessage);message WM_ICONMESSAGE;

public

end;

function EnableMouseHook(WndHandle:integer):BOOL;external 'MHook.DLL';
function DisableMouseHook:BOOL;external'MHook.DLL';

var
Form1: TForm1;

implementation

{$R *.DFM}


procedure TForm1.WMBarIcon (var Message:TMessage);
begin
//用戶雙擊任務(wù)欄圖標(biāo)則關(guān)閉程序
if Message.LParam = WM_LBUTTONDBLCLK then
close;
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
var
lpData:PNotifyIconData;
begin
//刪除任務(wù)欄圖標(biāo)
lpData := new(PNotifyIconDataA);
lpData.cbSize := 88;//SizeOf(PNotifyIconDataA);
lpData.Wnd := Form1.Handle;
lpData.hIcon := Form1.Icon.Handle;
lpData.uCallbackMessage := WM_ICONMESSAGE;
lpData.uID :=0;
lpData.szTip := '鼠標(biāo)演示';
lpData.uFlags := NIF_ICON or NIF_MESSAGE or NIF_TIP;
Shell_NotifyIcon(NIM_DELETE,lpData);
dispose(lpData);
//解除Mouse hook
DisableMouseHook;
end;

procedure TForm1.FormCreate(Sender: TObject);
var
lpData:PNotifyIconData;
begin
EnableMouseHook(Form1.Handle);
Form1.Visible := False;
lpData := new(PNotifyIconDataA);
lpData.cbSize := 88;//SizeOf(PNotifyIconDataA);
lpData.Wnd := Form1.Handle;
lpData.hIcon := Form1.Icon.Handle;
lpData.uCallbackMessage := WM_ICONMESSAGE;
lpData.uID :=0;
lpData.szTip := '鼠標(biāo)演示';
lpData.uFlags := NIF_ICON or NIF_MESSAGE or NIF_TIP;
Shell_NotifyIcon(NIM_ADD,lpData);
dispose(lpData);
end;

end.

運(yùn)行程序，按下Scroll Lock鍵使其有效，將光標(biāo)移動(dòng)到文本窗口中（如IE、Word），移動(dòng)鼠標(biāo)，點(diǎn)擊鼠標(biāo)右鍵，窗口就可以依上一次移動(dòng)的方向滾動(dòng)。
利用上面的原理，將程序做一些改動(dòng)，就可以象專業(yè)的鼠標(biāo)增強(qiáng)程序一樣做出例如縮放窗口，運(yùn)行程序等很多鼠標(biāo)增強(qiáng)效果來。
上面的程序在Windows95,Delphi4.0下運(yùn)行通過。