Delphi实现全局鼠标钩子

PMouseHookStruct = ^TMouseHookStruct;
{$EXTERNALSYM tagMOUSEHOOKSTRUCT}
tagMOUSEHOOKSTRUCT = packed record
pt: TPoint;
hwnd: HWND;
wHitTestCode: UINT;
dwExtraInfo: DWORD;
end;
TMouseHookStruct = tagMOUSEHOOKSTRUCT;

library Mouse_HookDLL;

{ Important note about DLL memory management: ShareMem must be the
  first unit in your library's USES clause AND your project's (select
  Project-View Source) USES clause if your DLL exports any procedures or
  functions that pass strings as parameters or function results. This
  applies to all strings passed to and from your DLL--even those that
  are nested in records and classes. ShareMem is the interface unit to
  the BORLNDMM.DLL shared memory manager, which must be deployed along
  with your DLL. To avoid using BORLNDMM.DLL, pass string information
  using PChar or ShortString parameters. }

uses
  SysUtils,
  Windows,
  Messages,
  Classes;

{$R *.res}

var
  NextHook : HHook;
  //调用者的Handle，用来给其发消息
  CallHandle : HWND;
  //通知调用者的消息，由调用者传进来
  MessageID : Word;

//挂钩子函数 ,这里只处理鼠标移动，其他的鼠标动作，道理一样
function HookProc(code:Integer;wParam:WPARAM;lParam:LPARAM):LRESULT;stdcall;
begin
  Result := 0;
  if code < 0 then
    Result := CallNextHookEx(NextHook,code,wParam,lParam);
  case wParam of
    WM_NCMOUSEMOVE,WM_MOUSEMOVE:
    begin
      //给调用者发消息
      SendMessage(CallHandle,MessageID,wParam,Integer(@pMouseHookStruct(lParam)^));
    end;
  end;
end;

//启动钩子
function StartHook(MsgID:Word):Bool;stdcall;
begin
  Result := False;
  if NextHook <> 0 then
    Exit;
  MessageID := MsgID;
  //挂钩,SetWindowsHookEx的参数dwThreadId=0，表示挂全局的,不知道为什么，我系统是2003，用WH_MOUSE只能在本进程中实现钩子，WH_MOUSE_LL可以实现全局，在Delphi7中，是没有WH_MOUSE_LL定义的，你可以自己定义，值是14
  NextHook := SetWindowsHookEx(WH_MOUSE_LL,@HookProc,HInstance,0);
  Result := NextHook <> 0;
end;

//脱钩
function StopHook:Bool;stdcall;
begin
  if NextHook <> 0 then
  begin
    UnHookWindowsHookEx(NextHook);
    NextHook := 0;
  end;
  Result := NextHook = 0;
end;

//传递调用者句柄
procedure SetCallHandle(sender:HWND);stdcall;
begin
  CallHandle := sender;
  NextHook := 0;
end;

exports
  StartHook name 'StartHook',
  StopHook name 'StopHook',
  SetCallHandle name 'SetCallHandle';

begin
end.

unit HookTest;

interface

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

type
  TfrmHookTest = class(TForm)
    Label1: TLabel;
    procedure FormCreate(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    { Private declarations }
    //重载消息处理
    procedure WndProc(var Message: TMessage);override;
  public
    { Public declarations }
  end;

var
  frmHookTest: TfrmHookTest;

const
  WM_TestMsg = WM_User + 100;

implementation

{$R *.dfm}
function StartHook(MsgID:Word):Bool;stdcall;external 'Mouse_HookDLL.dll';
function StopHook:Bool;stdcall;external 'Mouse_HookDLL.dll';
procedure SetCallHandle(sender:HWND);stdcall;external 'Mouse_HookDLL.dll';

procedure TfrmHookTest.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  StopHook;
end;

procedure TfrmHookTest.FormCreate(Sender: TObject);
begin
  SetCallHandle(Self.Handle);
  if not StartHook(WM_TestMsg) then
  begin
    ShowMessage('挂钩失败！');
  end;
end;

procedure TfrmHookTest.WndProc(var Message: TMessage);
var
  x,y:integer;
begin
  //得到符合条件的钩子
  if Message.Msg = WM_TestMsg then
  begin
    x := pMouseHookStruct(Message.LParam)^.pt.X;
    y := pMouseHookStruct(Message.LParam)^.pt.Y;
    //显示x，y坐标
    Self.Label1.Caption := '鼠标当前位置：x='+IntToStr(x)+' : y='+IntToStr(y);
  end;
  inherited;
end;

end.