使用钩子函数 - 数据传递

DLL 文件:

---

library MyHook;

uses
  SysUtils,
  Windows,
  Messages,
  Classes;

{$R *.res}

const WM_MyMessage = WM_USER + 1; {自定义消息}

var
  hook: HHOOK;
  info: string;
  h: HWND; {用作外部窗口的句柄}

{获取外部窗口的句柄}
function SetHWnd(hwnd: HWND): Boolean; stdcall;
begin
  h := hwnd;
  Result := True;
end;

function MouseHook(nCode: Integer; wParam: WPARAM; lParam: LPARAM): LRESULT; stdcall;
begin
  case wParam of
    WM_MOUSEMOVE   : info := '鼠标位置';
    WM_LBUTTONDOWN : info := '按下';
    WM_LBUTTONUp   : info := '放开';
  end;
  info := Format('%s: %d,%d', [info, PMouseHookStruct(lParam)^.pt.X, PMouseHookStruct(lParam)^.pt.Y]);

  {通过消息把数据传递给指定窗口}
  PostMessage(h, WM_MyMessage, 0, Integer(PChar(info)));

  Result := CallNextHookEx(hook, nCode, wParam, lParam);
end;

function SetHook: Boolean; stdcall;
const
  WH_MOUSE_LL =14;
begin
  hook := SetWindowsHookEx(WH_MOUSE_LL, @MouseHook, HInstance, 0);
  Result := hook <> 0;
end;

function DelHook: Boolean; stdcall;
begin
  Result := UnhookWindowsHookEx(hook);
end;

exports SetHook, DelHook, MouseHook, SetHWnd;
begin
end.

---

测试代码:

---

unit Unit1;

interface

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

const WM_MyMessage = WM_USER + 1;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure MyMessage(var msg: TMessage); message WM_MyMessage; {定义一个消息方法接受消息}
  end;

  function SetHook: Boolean; stdcall;
  function DelHook: Boolean; stdcall;
  function SetHWnd(hwnd: HWND): Boolean; stdcall;

var
  Form1: TForm1;

implementation

{$R *.dfm}

function SetHook; external 'MyHook.dll';
function DelHook; external 'MyHook.dll';
function SetHWnd; external 'MyHook.dll';

procedure TForm1.Button1Click(Sender: TObject);
begin
  SetHook;
  SetHWnd(Handle);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  DelHook;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Button1.Caption := '安装钩子';
  Button2.Caption := '载卸钩子';
  FormStyle := fsStayOnTop; {为了测试, 让窗口一直在前面}
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  DelHook;
end;

{把接受到的内容显示在窗体}
procedure TForm1.MyMessage(var msg: TMessage);
begin
  Text := PChar(msg.LParam);
end;

end.