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使用钩子函数[6] - 数据传递2009-12-10 博客园 万一上一个例子是从 DLL 中接受数据, 那怎么给 DLL 传递数据呢？ 还有, 在接受数据时, 让 Timer 一直在那扫描也不是个好办法呀. 本例解决了这些问题（但不知解决了博友 "鹏" 的问题没有？）.

为了方便测试, 提供一个源码下载吧: http://files.cnblogs.com/del/MouseHook_2.rar

本例效果图（和上一例是一样的）:

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.