This code locks up explorer. Help?

This is a discussion on This code locks up explorer. Help? within the Windows Programming forums, part of the Platform Specific Boards category; Code: ShowWindow(GetTopWindow(NULL), SW_MAXIMIZE); Any particular reason? Im trying to maximize the current window on top. I have a keyhook setup ...

  1. #1
    That Creepy Network Guy DeepBlackMagic's Avatar
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    This code locks up explorer. Help?

    Code:
    ShowWindow(GetTopWindow(NULL), SW_MAXIMIZE);
    Any particular reason? Im trying to maximize the current window on top. I have a keyhook setup to execute this statement whenever i press the "windows" key (key 91). I finally found a good use for that little bastard. As soon as some working code is posted on another thread, ill have to bind one to ctrl alt del too =P Any help would be greatly appreciated. Thanks for your time.

  2. #2
    & the hat of GPL slaying Thantos's Avatar
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    You really should have GetTopWindow pass to a hwnd so that you can do error checking.

    When troubleshooting you should really unnest your commands.

  3. #3
    That Creepy Network Guy DeepBlackMagic's Avatar
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    Im not a windows coder. I dont like the windows API. Please explain to somebody from that point of view what the problem is and how to fix it.

  4. #4
    & the hat of GPL slaying Thantos's Avatar
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    Code:
    HWND hTopWindow;
    int iError;
    TCHAR szBuffer[20];
    .......
    hTopWindow = GetTopWindow(NULL);
    
    if (hTopWindow == NULL)
      {
      wsprintf(szBuffer, TEXT("Error with GetTopWindow().  Error Number %i"), GetLastError() );
      MessageBox (NULL, szBuffer, TEXT("ERROR"), MB_ICONERROR);
      }
    
    else
      ShowWindow (hTopWindow, SW_MAXIMIZE);
    
    ......
    or something like that.

    edit: The problem could be many things. Which is why you need to un-nest (what I call it) your commands. Having GetTopWindow() seperate from ShowWindow() allows you to stop the code if there was an error. If there is no error then you have norrowed down the problem.
    Last edited by Thantos; 08-29-2003 at 08:03 PM.

  5. #5
    That Creepy Network Guy DeepBlackMagic's Avatar
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    Just tried that, the hwnd returned by gettopwindow is not null, however explorer still locks up when that showwindow command to maximize it executes.

  6. #6
    & the hat of GPL slaying Thantos's Avatar
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    Post your code please.

  7. #7
    That Creepy Network Guy DeepBlackMagic's Avatar
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    My code is far too large to post, however the relivant function goes like this:

    Code:
    LRESULT CALLBACK KeyboardFunc (int nCode, WPARAM wParam, LPARAM lParam )
    {
       HDC	       hDC;
       HWND        hwndTopWindow;
       int iError;
       TCHAR szBuffer[20];
    
       int x;
       int i = 0 ;
       x = wParam;
    
       if ( nCode >= 0 ) {
    
          if ( nCode == HC_NOREMOVE )
    		  strcpy(szType, "NOT Removed from Queue");
          else
    		 strcpy(szType, "REMOVED from Queue                                             ");
    
          wsprintf((LPSTR)szFilterLine[KEYBOARDINDEX],
    	       "KEYBOARD\tKey:%d\t%s",wParam,(LPSTR)szType);
    
    	if(x==commandkey&&!executing)
    	{
    		executing = 1;
    		executions++;
    		if(executions%2)
    		{
    			executing = 1;
    			
    			hwndTopWindow = GetTopWindow(NULL);
    			if(hwndTopWindow == NULL)
    			{
    				wsprintf(szBuffer, TEXT("Error with GetTopWindow().  Error Number %i"), GetLastError() );
    				MessageBox (NULL, szBuffer, TEXT("ERROR"), MB_ICONERROR);
    
    			}else{
    				ShowWindow(hwndTopWindow, SW_MAXIMIZE);
    			}
    			
    			executing = 0;
    			//We return here so that the command character 220 "\" isnt seen as pressed.
    			return 1;
    		}
    		executing = 0;
    	}
    
          hDC = GetDC(hwndMain);
          TabbedTextOut(hDC, 1, nLineHeight * KEYBOARDINDEX,
    	    (LPSTR)szFilterLine[KEYBOARDINDEX],
    	    strlen(szFilterLine[KEYBOARDINDEX]), 0, NULL, 1);
          ReleaseDC(hwndMain, hDC);
       }
    
       // If the message isnt for us, just peek at it and pass it on.
       //
       return( CallNextHookEx(hhookHooks[KEYBOARDINDEX], nCode, wParam, lParam));
    }
    Some of it is borrowed, other parts are poorly writen, and yes it uses global variables in parts. This code was for a personal utility and never meant to be seen by others so its not very nice. Thanks for your time.

  8. #8
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    You shouldn't be doing all that code in your keyboard hook. Send yourself a message and do your code in there so you can pass the hook straight through with minimal disruption.

  9. #9
    That Creepy Network Guy DeepBlackMagic's Avatar
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    As i stated earlyer, im not a windows coder. Im doing this the simplest way i know how. All i want to know, is why does ShowWindow(hwndTopWindow, SW_MAXIMIZE); fry my explorer process.

  10. #10
    & the hat of GPL slaying Thantos's Avatar
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    I looked at the code and tried it out. It didn't lock my explorer per say. Thought the response was screwy because it didn't maximize the only window I could see, it maximized another window handle. As such I think GetTopWindow (NULL) is not returning the window handle you want.

  11. #11
    That Creepy Network Guy DeepBlackMagic's Avatar
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    Any thoughts about how to get a better window handle? I think the probem is its using a window handle, but not a visible one. Like its trying to maximize the desktops handle or something. Explorer goes into an infinite loop eating 99% of the CPU.

  12. #12
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    I would suspect it's crashing because you are executing those calls in a system-wide hook procedure and not in the context of your own message loop.

    Try this:

    Code:
    LRESULT __stdcall LowLevelKeyboardProc (DWORD code, WPARAM wparam, LPARAM lparam)
    {
       if (code == HC_ACTION) /* A key was pressed */
       {
          KBDLLHOOKSTRUCT *hookstruct = (KBDLLHOOKSTRUCT *)lparam;
          /* Send key to our main program */
          PostMessage (hWnd, WM_U_HOOKMSG, (hookstruct->vkCode << 16) + hookstruct->scanCode, hookstruct->flags);
       }
       return (CallNextHookEx (hookHandle, code, wparam, lparam));
    }
    And then process WM_U_HOOKMSG in WndProc, rather than in the hook.

    WM_U_HOOKMSG is a userdefined message as follows:

    #define WM_U_HOOKMSG (WM_USER+0x1000)

    I know your not a Windows coder, but you should be able to get that working quite easily.

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