在指定窗口上安装HOOK函数

procedure HookProc(nCode, wParam, lParam: LongWORD);stdcall;
begin
if not DLLData^.Hooked then
begin
  HookAPI;
  DLLData^.Hooked := True;
end;
//调用下一个Hook
CallNextHookEx(DLLData^.Hook, nCode, wParam, lParam);
end;


{------------------------------------}
{函数名:InstallHook
{函数功能:在指定窗口上安装HOOK
{函数参数:sWindow:要安装HOOK的窗口
{返回值:成功返回TRUE,失败返回FALSE
{------------------------------------}
function InstallHook(SWindow: LongWORD):Boolean;stdcall;
var
ThreadID: LongWORD;
begin
Result := False;

DLLData^.Hook := 0;
ThreadID := GetWindowThreadProcessId(sWindow, nil);
//给指定窗口挂上钩子
DLLData^.Hook := SetWindowsHookEx(WH_GETMESSAGE, @HookProc, Hinstance, ThreadID);
if DLLData^.Hook > 0 then
  Result := True //是否成功HOOK
else
  exit;
end;

{------------------------------------}
{过程名:UnHook
{过程功能:卸载HOOK
{过程参数:无
{------------------------------------}
procedure UnHook;stdcall;
begin
UnHookAPI;
//卸载Hook
UnhookWindowsHookEx(DLLData^.Hook);
end;

{------------------------------------}
{过程名:DLL入口函数
{过程功能:进行DLL初始化,释放等
{过程参数:DLL状态
{------------------------------------}
procedure MyDLLHandler(Reason: Integer);
var
FHandle: LongWORD;
begin
case Reason of
  DLL_PROCESS_ATTACH:
  begin         //建立文件映射,以实现DLL中的全局变量
    FHandle := CreateFileMapping($FFFFFFFF, nil, PAGE_READWRITE, 0, $ffff, 'MYDLLDATA');
    if FHandle = 0 then
    if GetLastError = ERROR_ALREADY_EXISTS then
    begin
    FHandle := OpenFileMapping(FILE_MAP_ALL_ACCESS, False, 'MYDLLDATA');
    if FHandle = 0 then Exit;
    end else Exit;
    DLLData := MapViewOfFile(FHandle, FILE_MAP_ALL_ACCESS, 0, 0, 0);
    if DLLData = nil then
    CloseHandle(FHandle);
  end;
  DLL_PROCESS_DETACH:
  begin
    if Assigned(DLLData) then
    begin
    UnmapViewOfFile(DLLData);
    DLLData := nil;
    end;
  end;
end;
end;



exports sethook, endhook,installhook,unhook;
begin
hNextHookProc := 0;
procSaveExit := ExitProc;
ExitProc := @HotKeyHookExit;

DLLProc := @MyDLLHandler;
MyDLLhandler(DLL_PROCESS_ATTACH);
DLLData^.Hooked := False;
end.