Windows全局鍵盤鉤子 - Delphi

Question

我創建了一個GLOBAL鍵盤鉤子DLL，使用在互聯網上找到的源代碼。對於最好的部分來說，除了涉及到瀏覽器以外，它的功能非常出色。

它接收瀏覽器中的每個按鍵，但看起來，當瀏覽器獲得焦點時，它會丟失按下的第一個按鍵。在IE和Firefox中測試過它，兩者似乎都是一樣的。

例如，如果我打開IE並開始輸入www。 ，我只能回來ww。如果瀏覽器窗口始終處於焦點狀態，則不會再有密鑰丟失。一旦瀏覽器失去焦點並重新獲得焦點，第一個關鍵就會再次失蹤。

難道是因爲只使用WH_KEYDOWN而不是WH_KEYPRESS/WH_KEYUP？任何人都可以對此有所瞭解嗎？

謝謝

PS：鉤子函數本身就是下圖：DLL發送了一份備忘錄箱和應用程序句柄至極DLL將發送消息，以及一個usermessage。

function KeyHookFunc(Code, VirtualKey, KeyStroke: Integer): LRESULT; stdcall; 
var 
    KeyState1: TKeyBoardState; 
    AryChar: array[0..1] of Char; 
    Count: Integer; 
begin 
    Result := 0; 
    if Code = HC_NOREMOVE then Exit; 

    Result := CallNextHookEx(hKeyHook, Code, VirtualKey, KeyStroke); 
    {I moved the CallNextHookEx up here but if you want to block 
    or change any keys then move it back down} 
    if Code < 0 then 
    Exit; 
    if Code = HC_ACTION then 
    begin 
    if ((KeyStroke and (1 shl 30)) <> 0) then 
     if not IsWindow(hMemo) then 
     begin 
     {I moved the OpenFileMapping up here so it would not be opened 
     unless the app the DLL is attatched to gets some Key messages} 
     hMemFile := OpenFileMapping(FILE_MAP_WRITE, False, 'NetParentMAP');//Global7v9k 
     PHookRec1 := MapViewOfFile(hMemFile, FILE_MAP_WRITE, 0, 0, 0); 
     if PHookRec1 <> nil then 
     begin 
      hMemo := PHookRec1.MemoHnd; 
      hApp := PHookRec1.AppHnd; 
     end; 
     end; 
    if ((KeyStroke AND (1 shl 31)) = 0) then //if ((KeyStroke and (1 shl 30)) <> 0) then 
    begin 
     GetKeyboardState(KeyState1); 
     Count := ToAscii(VirtualKey, KeyStroke, KeyState1, AryChar, 0); 
     if Count = 1 then 
     begin 
     SendMessage(hMemo, WM_CHAR, Ord(AryChar[0]), 0); 
     {I included 2 ways to get the Charaters, a Memo Hnadle and 
     a WM_USER+1678 message to the program} 
     PostMessage(hApp, WM_USER + 1678, Ord(AryChar[0]), 0); 
     end; 
    end; 
    end; 
end; 

Answer 1

你是不是你的分配和hMemo值hApp足夠早。您正在等待，直到通知的「先前狀態」標誌爲1，表示按鍵已按住至少1次重複計數，或正在釋放，以先發生者爲準。因此，hMemo和hApp在您的掛鉤檢測到第一次按下鍵通知時尚不可用。這就是你錯過角色的原因。試試這個：

function KeyHookFunc(Code, VirtualKey, KeyStroke: Integer): LRESULT; stdcall; 
var 
    KeyState1: TKeyBoardState; 
    AryChar: array[0..1] of Char; 
    Count: Integer; 
begin 
    Result := CallNextHookEx(hKeyHook, Code, VirtualKey, KeyStroke); 
    if Code <> HC_ACTION then Exit; 

    { a key notification had occured, prepare the HWNDs 
    before checking the actual key state } 
    if (hMemo = 0) or (hApp = 0) then 
    begin 
    if hMemFile = 0 then 
    begin 
     hMemFile := OpenFileMapping(FILE_MAP_WRITE, False, 'NetParentMAP'); 
     if hMemFile = 0 then Exit; 
    end; 
    if PHookRec1 = nil then 
    begin 
     PHookRec1 := MapViewOfFile(hMemFile, FILE_MAP_WRITE, 0, 0, 0); 
     if PHookRec1 = nil then Exit; 
    end; 
    hMemo := PHookRec1.MemoHnd; 
    hApp := PHookRec1.AppHnd; 
    if (hMemo = 0) and (hApp = 0) then Exit; 
    end; 

    if ((KeyStroke and (1 shl 31)) = 0) then // a key is down 
    begin 
    GetKeyboardState(KeyState1); 
    Count := ToAscii(VirtualKey, KeyStroke, KeyState1, AryChar, 0); 
    if Count = 1 then 
    begin 
     if hMemo <> 0 then SendMessage(hMemo, WM_CHAR, Ord(AryChar[0]), 0); 
     if hApp <> 0 then PostMessage(hApp, WM_USER + 1678, Ord(AryChar[0]), 0); 
    end; 
    end; 
end;