Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Matt]

Does anybody know how to catch MM keys?

In MJ 8, we create a process-level hook.  That works as long as we have the focus, or the keyboard driver forwards the message around.

The other choice is a 2 KB dll that acts as a global hook.  This does the job, but makes us nervous.

Is there a better way than a global hook to ensure we always get the messages?

Thanks for any help.

[RhinoBanga]

Global hooks is how I do it in AV:

      //
      //  HOOK CALLBACKS
      //

      extern "C"
      {

            LRESULT CALLBACK MMCallback( int nCode, WPARAM wParam, LPARAM lParam )
            {
                  HWND            hWnd;

                  switch( nCode )
                  {
                  case HSHELL_APPCOMMAND:
    
                        //  Process the key
                        switch( GET_APPCOMMAND_LPARAM(lParam) )
                        {
                        case APPCOMMAND_MEDIA_NEXTTRACK:
                        case APPCOMMAND_MEDIA_PREVIOUSTRACK:
                        case APPCOMMAND_MEDIA_STOP:
                        case APPCOMMAND_MEDIA_PLAY_PAUSE:

                              //  Find the MJ window
                              hWnd = FindWindowEx(0, 0, "MJFrame", "MEDIA JUKEBOX");
                              if ( hWnd )
                              {
                                    PostMessage( hWnd, WM_APPCOMMAND, wParam, lParam );
                              }

                              break;
                        }
    
                  }

                  return( CallNextHookEx( m_hShellHook, nCode, wParam, lParam ) );
            }

      }

[Matt]

How do you set the hook?

As far as I can tell, if you set it in a program, it's process specific.  You need to put it in a DLL for it to be global.

Is that right, or no?

Thanks Rhino!

[RhinoBanga]

That's right as the DLL gets mapped into the process space of the app ... but that's ok from my point of view as AV is a DLL.

Here's how I set the hook:

            if( m_bEnableMM )
            {
                  m_hShellHook = SetWindowsHookEx( WH_SHELL, MMCallback, AfxGetInstanceHandle(), 0);
            }

And in my dll's .DEF file I have:

; AlbumView2.def : Declares the module parameters.

LIBRARY      "AlbumView2.DLL"

EXPORTS
      DllCanUnloadNow     @1 PRIVATE
      DllGetClassObject   @2 PRIVATE
      DllRegisterServer   @3 PRIVATE
      DllUnregisterServer      @4 PRIVATE
      MMCallback
      KeybCallback

SECTIONS
   .SHARDATA   Read Write Shared

Notice the .SHARDATA section ... that's used if you want to share data between processes.   Whenever a track changes in MJ I update the following two hotkey strings:

#pragma data_seg(".SHARDATA")
char                        m_szHK1[ 8192 ]            =      { "" };
char                        m_szHK2[ 8192 ]            =      { "" };
#pragma data_seg()

According to the tokens the user has specified.


Then whenever the user issues a hotkey I can paste the contents to the clipboard, e.g.:

            LRESULT CALLBACK KeybCallback( int nCode, WPARAM wParam, LPARAM lParam )
            {

                  static bool            bProcessed                  =      false;

                  switch( nCode )
                  {
                  case HC_ACTION:
    
                        //  Process the key
                        if( (wParam == VK_F11  ||  wParam == VK_F12)  &&  (lParam & ALT)  &&  (GetAsyncKeyState( VK_CONTROL ) & 0x80000000) )
                        {
                              if( !bProcessed )
                              {
                                    HANDLE            hMem;
                                    LPCTSTR            pszData;
                                    PVOID            pvMemory;
                                    DWORD            dwLength;

                                    //  Mark as being processed
                                    bProcessed = true;

                                    //  Point to the data in question
                                    pszData = (( wParam == VK_F11 ) ? m_szHK1:m_szHK2);

                                    //  Allocate a memory handle
                                    if( hMem = GlobalAlloc( GMEM_MOVEABLE | GMEM_SHARE, dwLength = (strlen( pszData ) + 1) ) )
                                    {
                                          //  Open it
                                          if( pvMemory = GlobalLock( hMem ) )
                                          {
                                                //  Copy in the string
                                                CopyMemory( pvMemory, pszData, dwLength );

                                                //  Unlock the handle
                                                GlobalUnlock( hMem );

                                                //  Send to the clipboard
                                                if( OpenClipboard( NULL ) )
                                                {
                                                      EmptyClipboard();
                                                      SetClipboardData( CF_TEXT, hMem );
                                                      CloseClipboard();
                                                }
                                          }
                                    }

                                    //  Unlock the memory
                                    GlobalUnlock( hMem );

                              }
                              else
                              {
                                    bProcessed = false;
                              }

                              break;
                        }

                        break;
                  }

                  return( CallNextHookEx( m_hKeybHook, nCode, wParam, lParam ) );
            }

[Matt]

Have you had reports of AV crashing other programs?

It seems like a pretty big DLL to be mapping into every process.

How dangerous / resource intensive is it?

Thanks again Rhino.

[RhinoBanga]

I have heard nothing dude.

I think it's pretty safe and I use it *all* the time at home since I can't be bothered loading the bloatware software that comes with my Logitec keyboard.   It has no impact on my CPU as far as I can see.

I agree that the DLL is a reasonable size but I personally think 800k is nothing these days and I presume that that it's only the data segment that actually gets mapped as WIN32 code shares ... but I'm not 100% sure on that.

As you mentioned before I recon you should provide a small DLL that just does the keyboard hook and fires off messages with MJ.   Then within MJ just provide the ability to either a) handle the APPCOMMAND messages or b) allow the specification of a key combination and what action to perform ... for example play.

[Matt]

Just wanted to say thanks for helping out.

It looks like we've got something working now. (hopefully)

You're the best Rhino!

[RhinoBanga]

Cool ... glad to be of help.

Now hurry up and get that SDK finished