perl-win32-gui-users

[perl-win32-gui-users] Having trouble Packing a string for SendMessage

[Mike C. <mc...@ro...>]

Hi all,

Trying to use Win32::GUI  Perl module to programmatically control a window in Windows from Perl. The window is a program called WinLirc which is used to control and iR Blaster for controlling equipment.

There’s already a command line program that interfaces with this window called transmit.exe, but I am trying to write a Perl version to make a web based interface.  So far, I can get the handle on the window and even issue a CloseWindow, so I know I’m hooked into it, but I am having trouble with sending the commands over WM_COPYDATA. Not sure if I’m building and packing my command line the same way transmitdoes it. Can anyone understand what they are doing by looking at the VC++ transmit.cpp code below?

Basically, you invoke transmit to send commands to the WINLirc window like this:

C:/transmit.exe Cable CHNUP 1

So, I assume in transmit.cpp, the lpCmdLine value receives the value “Cable CHNUP 1” which is what I hardcoded into my corresponding $command variable in Perl, for testing purposes.

Here’s the VC++ code from the transmit.cpp:

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
                LRESULT copyDataResult;
                HWND pOtherWnd = FindWindow(NULL, "WinLirc");
                if (pOtherWnd)
                {
                                COPYDATASTRUCT cpd;
                                cpd.dwData = 0;
                                cpd.cbData = strlen(lpCmdLine);
                                cpd.lpData = (void*)lpCmdLine;
                                copyDataResult = SendMessage(pOtherWnd,WM_COPYDATA,(WPARAM)hInstance,(LPARAM)&cpd);
        // copyDataResult has value returned by other app
                }
                else
                {
                                return 1;
                }
                return 0;
}


Anyhow here’s my best attempt at translation into Perl:

#!/usr/bin/perl
# WinLiRC Perl interface

chdir ("cgi-bin");

use Win32::GUI;

$windowtitle='WinLIRC';
$command='Cable CHNUP 1';

$handle=Win32::GUI::FindWindow('', $windowtitle);

if ($handle eq "") {print "WinLIRC window not open."; exit(0);}

$copy_data_struct=pack('L2P',0,length($command),$command);

$result=Win32::GUI::SendMessage($handle,WM_COPYDATA,0,$copy_data_struct);

print "$result"

I keep getting a result code of "0" which tells me the command is failing. More than likely it's encoded wrong...

Any help would be greatly appreciated!

Thanks,

Mike




      

Re: [perl-win32-gui-users] Having trouble Packing a string for SendMessage

[Robert M. <ro...@th...>]

2009/3/4 Mike Carambat <mc...@ro...>:
> So far, I can get the handle on the window and even issue a CloseWindow, so I know I’m hooked into it, but I
> am having trouble with sending the commands over WM_COPYDATA.

As you don't have warnings turned on, and you're using cgi, you can't
see the warnings/errors that perl is helpfully giving you:

C:\>perl -MWin32::GUI -e "print WM_COPYDATA();"
Undefined subroutine &main::WM_COPYDATA called at -e line 1.

C:\>perl -w -MWin32::GUI -e "print WM_COPYDATA();"
'use Win32::GUI;' is currently exporting constants into the callers scope. This
functionality is deprecated. Use 'use Win32::GUI();' or list your required expor
ts explicitly instead. at -e line 0
Undefined subroutine &main::WM_COPYDATA called at -e line 1.

C:\>perl -w -MWin32::GUI=WM_COPYDATA -e "print WM_COPYDATA();"
74

> #!/usr/bin/perl
> # WinLiRC Perl interface
>
> chdir ("cgi-bin");
>
> use Win32::GUI;

Try changing this line to:

  use Win32::GUI qw(WM_COPYDATA);

Win32::GUI only exports a rather small subset of the constants by
default (the original exports are maintained for backward
compatibility purposes).  Generally you want to list the constants you
require access to on the 'use Win32::GUI' line.  See
Win32::GUI::Constants and the release notes for further information.

[I haven't checked that the rest of the script works, but it looks OK
at a first glance].

Hope that helps.

Rob.