低级鼠标键盘钩子的疑问。

unit LLKBMouthHook;



interface



uses

  Windows, Messages, SysUtils;



function StartHookKeyMouse: boolean;

function StopHookKeyMouse: boolean;



implementation



type

  tagKBDLLHOOKSTRUCT = packed record 

    vkCode: DWORD; 

    scanCode: DWORD; 

    flags: DWORD; 

    time: DWORD; 

    dwExtraInfo: DWORD; 

  end;

  KBDLLHOOKSTRUCT = tagKBDLLHOOKSTRUCT;

  PKBDLLHOOKSTRUCT = ^KBDLLHOOKSTRUCT;



type

  PMSLLHOOKSTRUCT = ^MSLLHOOKSTRUCT;

  MSLLHOOKSTRUCT = record

    pt: TPoint;

    hwnd:HWND;

    mouseData: DWORD;

    flags: DWORD;

    time: DWORD;

    dwExtraInfo: DWORD;

  end;



const

  WH_KEYBOARD_LL = 13; 

  WH_MOUSE_LL = 14;



var

  hhkLowLevelKybd: HHook = 0;

  hhkLowLevelMouse: HHook = 0;



procedure WriteScreen(TmpStr:string);

var

  ScreenDC: HDC;

begin

 // 输出到屏幕

  ScreenDC := GetDC(0);

  TextOut(ScreenDC, 0, 0, PChar(TmpStr), Length(TmpStr));

  ReleaseDC(0, ScreenDC);

end;



  // 取窗口类名

function GetWinClass(hWnd: HWnd): string;

var

  szClassName: array[0..20] of Char;

begin

  szClassName[GetClassName(hWnd, szClassName, 20)] := #0;

  Result := szClassName;

end;



  // 取窗体文字

function GetWinTitle(hWnd: HWnd): string;

var

  szWindowText: array[0..20] of Char;

  szTextLength: Integer;

begin

  szTextLength := SendMessage(hWnd, WM_GETTEXT, 20, Integer(@szWindowText[0]));

  szWindowText[szTextLength] := #0;

  Result := szWindowText;

end;





function LowLevelKeyboardProc(nCode: Integer; WParam: WPARAM; LParam: LPARAM): LRESULT; stdcall;

var

  p: PKBDLLHOOKSTRUCT;

  fEatKeystroke: BOOL;

begin

  if (nCode = HC_ACTION) then 

  begin

    p := PKBDLLHOOKSTRUCT(lParam);

    case wParam of

      WM_KEYDOWN:

        begin

          //键盘按下事件

          if p.vkCode = VK_RETURN then WriteScreen('回车按下');

        end;

    end;

  end;

  Result := 0;

  Result := CallNextHookEx(0, nCode, WParam, LParam);

end;



function LowLevelMouseProc(nCode: Integer; WParam: WPARAM; LParam: LPARAM): LRESULT; stdcall;

var

  p: PMSLLHOOKSTRUCT;

begin

  if (nCode = HC_ACTION) then

  begin

    p := PMSLLHOOKSTRUCT(lParam);

    case wParam of

      WM_LBUTTONDOWN:

        begin

          if p.hwnd<>0 then Writescreen('有句柄') else WriteScreen('无句柄');



          //无论鼠标点什么程序上的按钮，都取不到鼠标下控件的句柄，为什么呢？

        end;

    end;

    Result := 0;

    Result := CallNextHookEx(0, nCode, WParam, LParam);

  end;

end;





function StartHookKeyMouse: boolean;

begin

  if hhkLowLevelKybd = 0 then hhkLowLevelKybd := SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, Hinstance, 0);

  if hhkLowLevelMouse = 0 then hhkLowLevelMouse := SetWindowsHookEx(WH_MOUSE_LL, LowlevelMouseProc, HInstance, 0);

  result := (hhkLowLevelKybd <> 0) or (hhkLowLevelMouse <> 0);

end;



function StopHookKeyMouse: boolean;

begin

  if hhkLowLevelKybd <> 0 then

  begin

    UnhookWindowsHookEx(hhkLowLevelKybd);

    hhkLowLevelKybd := 0;

  end;

  if hhkLowLevelMouse <> 0 then

  begin

    UnHookWindowsHookEx(hhkLowLevelMouse);

    hhkLowLevelMouse := 0;

  end;

  result := true;

end;



initialization

  hhkLowLevelKybd := 0;

  hhkLowLevelMouse := 0;

finalization

  if hhkLowLevelKybd <> 0 then UnhookWindowsHookEx(hhkLowLevelKybd);

  if hhkLowLevelMouse <> 0 then UnhookWindowsHookEx(hhkLowLevelMouse);

end.