Windows 全局键盘挂钩 - Delphi

Question

我使用互联网上的源代码创建了一个 GLOBAL 键盘挂钩 DLL。最好的部分是它工作得很好，除了浏览器。

它会拾取浏览器中的每个键，但似乎当浏览器获得焦点时，它会丢失第一个被按下的键。在 IE 和 Firefox 中测试过，似乎两者都一样。

例如，如果我打开 IE 并开始输入 www。 ，我只回来了ww。如果浏览器窗口保持焦点，则不会丢失更多键。一旦浏览器失去焦点并重新获得焦点，第一个键就会再次丢失。

可能是因为只使用 WH_KEYDOWN 而不是 WH_KEYPRESS / WH_KEYUP ？有人能解释一下吗？

谢谢

PS：钩子函数本身如下：向 DLL 发送一个备忘录框和应用程序句柄，DLL 将发送消息和用户消息。

    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

您没有足够早地分配 hMemo 和 hApp 值。您正在等待“先前状态”标志为 1 的通知，这表明一个键已被按住至少 1 次重复计数，或者正在被释放，以先发生者为准。因此，hMemo 和 hApp 在你的钩子检测到它的第一个按键通知时还不可用。这就是为什么你会错过角色。试试这个：

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;