catch key press  messages
lazarus / 67-Windows

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laggyluk · 2017-11-10 09:11

Hi
What I'm trying to do is capture all key presses on form and send them
to chromium osr component for processing.

tried
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
WndProc(var Message: TLMessage); override; but no luck, then I've
tried
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i function
WndCallback(Ahwnd: HWND; uMsg: UINT; wParam: WParam; lParam:
LParam):LRESULT; stdcall;
They both captured windows messages, mouse clicks etc but neither was
receiving any of key press messages I'm interested in:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i WM_CHAR,
WM_SYSCHAR,WM_SYSKEYDOWN,WM_SYSKEYUP,WM_KEYDOWN,WM_KEYUPWhy is that?

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laggyluk · 2017-11-10 09:21

I think I know why but still don't know the solution

https://stackoverflow.com/questions/20408071/form-wm-keydown-and-wm-
keyup-messages-arent-captured-in-wndproc

there is no ProcessCmdKey method to override

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balazsszekely · 2017-11-10 10:44

Works fine here. Just press different keys or key combinations like
Alt + F, etc...
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses
Windows; var  FPrevWndProc: WNDPROC; function WndCallback(AHWND: HWND;
uMsg: UINT; wParam: WParam; lParam: LParam): LRESULT; stdcall;begin 
case uMsg of    WM_CHAR: Form1.Caption := 'WM_CHAR';    WM_SYSCHAR:
Form1.Caption := 'WM_SYSCHAR';    WM_SYSKEYDOWN: Form1.Caption :=
'WM_SYSKEYDOWN';    WM_SYSKEYUP: Form1.Caption := 'WM_SYSKEYUP';   
WM_KEYDOWN: Form1.Caption := 'WM_KEYDOWN';    WM_KEYUP: Form1.Caption
:= 'WM_KEYUP';  end;  Result := CallWindowProc(FPrevWndProc, Ahwnd,
uMsg, WParam, LParam);end; procedure TForm1.FormCreate(Sender:
TObject);begin  FPrevWndProc :=
Windows.WNDPROC(SetWindowLongPtr(Self.Handle, GWL_WNDPROC,
PtrUInt(@WndCallback)));end;

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laggyluk · 2017-11-10 11:08

does work in blank project, dropping tmemo on form breaks it

I'm using memo for logging only, can it be prevented from stealing
messages?

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balazsszekely · 2017-11-10 11:11

You have a window handle, change it when the focus shifts from one
control to another.

FPrevWndProc := Windows.WNDPROC(SetWindowLongPtr(Self.Handle,
GWL_WNDPROC, PtrUInt(@WndCallback)));

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laggyluk · 2017-11-10 11:22

solved, thanks!

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.OnFocusChange(sender: tobject);begin  if screen.ActiveControl
<>nil then   FPrevWndProc :=
Windows.WNDPROC(SetWindowLongPtr(screen.ActiveControl.Handle,
GWL_WNDPROC, PtrUInt(@WndCallback)));end;

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ASerge · 2017-11-11 02:39

Quote from: laggyluk on November 10, 2017, 12:22:36 pmCode: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.OnFocusChange(sender: tobject);begin  if screen.ActiveControl
<>nil then   FPrevWndProc :=
Windows.WNDPROC(SetWindowLongPtr(screen.ActiveControl.Handle,
GWL_WNDPROC, PtrUInt(@WndCallback)));end; Very bad decision. You
overwrite the variable FPrevWndProc, and the WndCallback procedure
calls the code not for its own window class.
Use message hooks:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i   private 
 procedure KeyMessage(const Msg: TMsg);  end; var  Form1:
TForm1; implementation uses Windows; {$R *.lfm} var  GHook:
HHOOK; function MessageHookProc(nCode: Integer; wParam: WPARAM; 
lParam: LPARAM): LRESULT; stdcall;var  Msg: LCLType.PMsg absolute
lParam;begin  if nCode >= 0 then    case Msg^.message of     
WM_KEYDOWN, WM_KEYUP, WM_SYSKEYDOWN, WM_SYSKEYUP, WM_CHAR,
WM_SYSCHAR:        Form1.KeyMessage(Msg^);    end;  Result :=
CallNextHookEx(GHook, nCode, wParam, lParam);end; procedure
TForm1.FormCreate(Sender: TObject);begin  GHook :=
SetWindowsHookEx(WH_GETMESSAGE, @MessageHookProc, 0, MainThreadID); 
if GHook = 0 then    RaiseLastOSError;end; procedure
TForm1.FormDestroy(Sender: TObject);begin  if GHook <> 0 then  begin 
 UnhookWindowsHookEx(GHook);    GHook := 0;  end;end; procedure
TForm1.KeyMessage(const Msg: LCLType.TMsg);begin  case Msg.message of 
  WM_KEYDOWN:      Memo1.Append('WM_KEYDOWN: ' +
IntToStr(Msg.wParam));    WM_KEYUP:      Memo1.Append('WM_KEYUP: ' +
IntToStr(Msg.wParam));    WM_SYSKEYDOWN:     
Memo1.Append('WM_SYSKEYDOWN: ' + IntToStr(Msg.wParam));   
WM_SYSKEYUP:      Memo1.Append('WM_SYSKEYUP: ' +
IntToStr(Msg.wParam));    WM_CHAR:      Memo1.Append('WM_CHAR: ' +
IntToStr(Msg.wParam) + ' "' + Chr(Msg.wParam) + '"');    WM_SYSCHAR: 
   Memo1.Append('WM_SYSCHAR: ' + IntToStr(Msg.wParam) + ' "' +
Chr(Msg.wParam) + '"');  end;end;

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laggyluk · 2017-11-15 12:52

True and it resulted in occasional crashes. Your solution works
better.