Ctrl+C

[Guest]

I read from the winapi help file that ctrl+c, if I understand it
correctly, is treated as a signal and not as keyboard input. I
have a paste button on a toolbar that is disabled if the clipboard
does not contain any text. What api call do I need to use to
see if the ctrl+c signal has been generated so I then can enable the paste button
as a result of it.

Regards,
Adam

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[Lance Edmonds]

The following is off the top of my head, so E&OE please...

Normally, the control with keyboard focus will deal with Copy, Cut and Paste messages itself.

It is usual design practice to enable/disable the copy/cut/paste toolbar buttons when processing Notification Messages from edit controls (and any other controls that can use Cut/Copy/Paste functions). For example, by capturing %WM_COMMAND|%EN_SETFOCUS and %WM_COMMAND|%EN_KILLFOCUS messages.

For example, when an edit control gains keyboard focus, your callback will receive a %WM_COMMAND|%EN_SETFOCUS message. In response to this message, you would query the state of the text in the clipboard... if text was found to be present, then you would enable the Paste button (or disable it if there was no text on the clipboard).

If you also examine the "current selection" state, and some text is found to be selected (ie, blue high-light), then you would enable the Cut/Copy buttons, otherwise disable them. This would usually be done in response to %EN_SETFOCUS notification and also in response to %EN_CHANGE, etc.

Also, when focus is lost (%WM_COMMAND|%EN_KILLFOCUS), you would disable the toobar buttons, etc.

In essence, you don't need to look at the keyboard activity to handle the operations... you only need to enable/disable the toolbar buttons according to the conditions of the current {edit} control.

If you ignore the state of the actual clipboard and enabled the Paste button in response to a Cut/Copy "action", then your app will not accurately reflect the state of affairs if another application clears the clipboard, your app would need to readjust the toolbar button state when the control regains focus again. If you did not do it this way, then your button would remain enabled yet there would be no text to paste - this design would then not adhere to standard GUI "design concepts".

One final note: I don't have my copy here to confirm, but IIRC Charles Petzolds "Programming Windows" book does discuss these concepts (or it could be in the Rector/Newcomer "Win32 Programming" book). When I get back to my office, I'll check it out (pls remind me if I forget! Thanks!)

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Borje Hagsten]

Yes, and you can use the IsClipboardFormatAvailable API to check
if the clipboard contains anything to paste, for plain text like:

CanPasteText = IsClipboardFormatAvailable(%CF_TEXT)



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[This message has been edited by Borje Hagsten (edited October 09, 2000).]

[Semen Matusovski]

I think that most of program use SetClipboardViewer.
This short sample registrates (see caption) any change of Clipboard.

   #Compile Exe
   #Dim All
   #Register None
   #Include "Win32Api.Inc"

   CallBack Function DlgProc
      Static hwndNextViewer As Long
      Select Case CbMsg
         Case %WM_INITDIALOG
            hwndNextViewer = SetClipboardViewer(CbHndl)
         Case %WM_CHANGECBCHAIN
            If CbWparam = hwndNextViewer Then hwndNextViewer = CbLparam Else _
            If hwndNextViewer <> 0 Then SendMessage hwndNextViewer, CbMsg, CbWparam, CbLparam
         Case %WM_DESTROY
            ChangeClipboardChain CbHndl, hwndNextViewer
         Case %WM_DRAWCLIPBOARD
            Static n As Long: Incr n: SetWindowText CbHndl, Str$(n)
            SendMessage hwndNextViewer, CbMsg, CbWparam, CbLparam
      End Select
  End Function

  Function PbMain
     Local hDlg As Long
     Dialog New 0, "Test", ,, 100, 100, %WS_CAPTION Or %WS_SYSMENU, %WS_EX_TOPMOST To hDlg
     Dialog Show Modal hDlg Call DlgProc
  End Function

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E-MAIL: [email protected]

[Guest]

I am already using IsClipboardFormatAvailable api to check the
clipboard so I can enable the Paste command in the edit menu as a
repsonse to a %WM_INITMENU messaqge which does exactly what I
want for it. I use a mousemove procedure to enable the cut,copy buttons
on the toolbar as well. I am also already processing the %EN_SETFOCUS message
to check the state of the clipboard to enable the paste button on the toolbar. I am sorry for not clarifying, I didn't mean to directly
enable the paste button in response to the ctrl+c signal, I wanted
to do a ctrl+c, check the clipbaord to see if there was text and
then enable the paste button based on the contents of the clipboard.
The edit control is the only control on the window, and oh by the way
this is not a DDT app, and what if the window is maximaized. The edit
control automatically gets the focus when the window gets the
focus, so I am only getting one %EN_FOCUS message generated when
the window gets the focus, correct? If there is no text on the
clipboard to start with when the window gets the focus and I highlight
some text and press ctrl+c, I want the paste button, like my paste command to become
enabled. Like I said I have the paste menu item doing this by processing
the %WM_INIMENU message. Now processing
the %WM_KEYUP message(0r %WM_KEYDOWN), if I check to see if the "c" key
or anyother key for that fact is pressed then I enable it just fine; of couse,
no text is copied to the clipboard, because it is not ctrl+c,for me to check first. Since the
ctrl+c is treated as a signal instead of keyboard input,according the help guide then I am out-of-luck at the moment.

Regards,
Adam

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[Semen Matusovski]

Adam --
I modified one old training code

   #Compile Exe
   #Register None
   #Dim All
   #Include "win32Api.inc"

   Global ghKbrdHook As Long, hDlg As Long
   Function KeyboardHook(ByVal iCode As Integer, ByVal wParam As Long, ByVal lParam As Long) As Dword
      Dim w As String, ww As Static String
      If iCode = %HC_ACTION Then
         If (lParam And &H80000000) = 0 Then ' Pressed
            If Asc(Mkl$(lParam), 3) = 46 Then
               If (GetKeyState(%VK_LCONTROL) And &H80000000) Or _
                  (GetKeyState(%VK_RCONTROL) And &H80000000) Then w$ = "Ctrl-C"
            End If
         End If
         If w$ <> ww$ Then ww$ = w$: SetWindowText hDlg, ByCopy w$
      End If
      Function = CallNextHookEx(ghKbrdHook, iCode, wParam, lParam)
   End Function

   Function PbMain      
      ghKbrdHook = SetWindowsHookEx(%WH_KEYBOARD, CodePtr(KeyboardHook), 0, GetCurrentThreadId)
      Dialog New 0,"Test",,, 50, 50, %WS_CAPTION Or %WS_SYSMENU To hdlg
      Dialog Show Modal hdlg
      UnhookWindowsHookEx ghKbrdHook
   End Function

but sure that there is a lot of other ways, how to detect Ctrl-C.


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E-MAIL: [email protected]

[Guest]

Thanks for the code Semen but I could never get it to work - maybe
it's a Windows ME issue, but I doubt it. If other windows apps
can do this, then there is obviously a way to do it, hmmmm....

Regards,
Adam

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[Borje Hagsten]

Why not simply use IsClipboardFormatAvailable in WM_KEYUP? Also,
remember that Ctrl+Ins also works like Ctrl+C, Shift+Ins like
Ctrl+V and Shift+Delete like Ctrl+X..

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[Guest]

Hi Borje,
Thanks for the suggestion but I tried that and it did not work
either. The hlp guide says this about ctrl+c and ctrl+break:

The CTRL+C and CTRL+BREAK key combinations receive special
handling by console processes. By default, when a console
window has the keyboard focus, CTRL+C or CTRL+BREAK is treated
as a signal (SIGINT or SIGBREAK) and not as keyboard input.
By default, these signals are passed to all console processes
that are attached to the console, causing the system to call
the control handler function or functions associated with these
processes. Detached processes (GUI processes or console processes
started with the DETACHED_PROCESS or CREATE_NEW_CONSOLE flag)
are not affected.

So Other keystrokes work but not ctrl+c. I will keep playing with it
though and see if something "pops up".

Regards,
Adam

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[Eric Pearson]

Adam --

Ah, you didn't mention until now that you were talking about a console window!

PB/CC automatically handles the function that allows Ctrl-C to be passed to your program instead of acting like a Ctrl-Break "signal".

If you are using PB/DLL and creating a console window with AllocConsole, check out the SetConsoleMode(ENABLE_PROCESSED_INPUT) API.

-- Eric

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Perfect Sync: Perfect Sync Development Tools
Email: mailto:[email protected][email protected]</A>



[This message has been edited by Eric Pearson (edited October 09, 2000).]

[Semen Matusovski]

Adam -
Initial code was tested under 2000.
I forgot about differences with 9x.
In this form it works under 98SE.
Under 2000 - it's necessary to change VK_CONTROL to VK_LCONTROL.

   #Compile Exe
   #Register None
   #Dim All
   #Include "win32Api.inc"
   Global ghKbrdHook As Long, hDlg As Long
   Function KeyboardHook(ByVal iCode As Integer, ByVal wParam As Long, ByVal lParam As Long) As Dword
      Dim w As String, ww As Static String
      If iCode = %HC_ACTION Then
         If (lParam And &H80000000) = 0 Then ' Pressed
            If Asc(Mkl$(lParam), 3) = 46 Then
               If (GetAsyncKeyState(%VK_CONTROL) And &H80000000) Or _
                  (GetAsyncKeyState(%VK_RCONTROL) And &H80000000) Then w$ = "Ctrl-C"
            End If
         End If
         If w$ <> ww$ Then ww$ = w$: SetWindowText hDlg, ByCopy w$
      End If
      Function = CallNextHookEx(ghKbrdHook, iCode, wParam, lParam)
   End Function
   Function PbMain
      ghKbrdHook = SetWindowsHookEx(%WH_KEYBOARD, CodePtr(KeyboardHook), 0, GetCurrentThreadId)
      Dialog New 0,"Test",,, 50, 50, %WS_CAPTION Or %WS_SYSMENU To hdlg
      Dialog Show Modal hdlg
      UnhookWindowsHookEx ghKbrdHook
   End Function

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E-MAIL: [email protected]

[Guest]

Thanks for the suggeston Eric, but right after I posted my last
message I fixed the problem and it is working now. It turned out
to be a logic problem(Hello, earth to Adam - come in Adam). I also
misread the help guide about mentioning about a CONSOLE window -
DUHHHHHHHH. Sometimes it takes awhile for certain words to sink
in I guess. I am not working with a console window. Well at least
it is working now. Thank you gentlemen for offering to help though.

Regards,
Adam


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