XWindows- Close window event?

This is a discussion on XWindows- Close window event? within the Linux Programming forums, part of the Platform Specific Boards category; I'm just doing some basic XWindows programming, but not using any wrapper libraries (GTK, motif, QT, etc). Anyway, I can't ...

  1. #1
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    XWindows- Close window event?

    I'm just doing some basic XWindows programming, but not using any wrapper libraries (GTK, motif, QT, etc). Anyway, I can't seem to get a window close request event when I use the close button by the caption (the upper right 'X' button). In Windows you get the WM_DESTROY event, but from what I can see in XWindows I don't get anything. Based on what I've read I expected the CloseNotify event but XGetNextEvent() doesn't give anything.

    My guess is that the event should come from the window manager. If I'm not mistaken its the one that provides the caption and the close button. I was under the impression that by calling XSetWMProperties() everything should be kosher between my window and the manager. Is there something else that is required to recieve some sort of close window event? Thanks for any help.

  2. #2
    UT2004 Addict Kleid-0's Avatar
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    nvm...
    Last edited by Kleid-0; 01-09-2005 at 06:45 PM.

  3. #3
    erstwhile
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    AFAIK, you obtain an atom name for the event with XInternAtom and 'attach' it with XSetWMProtocols, eg;
    Code:
    Atom wmDelete=XInternAtom(display, "WM_DELETE_WINDOW", True);
    XSetWMProtocols(display, wnd, &wmDelete, 1);
    Then in your xevent message loop you check for ClientMessage:
    Code:
    XEvent event;
    bool loop=true;
    while (loop==true)
      {
      XNextEvent(display,&event);
      switch (event.type)
        {
        case ClientMessage:
          std::cout<<"window closed"<<std::endl;
          loop=false;
          break;
        }
      }
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  4. #4
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    Ok heres the full program I'm using:

    Code:
    #include<stdio.h>
    #include <X11/Xlib.h>
    #include <X11/Xutil.h>
    #include <X11/Xos.h>
    #include <X11/Xatom.h>
    
    int main (int ArgC, char **ArgV)
    {
        Display *cdisDisplay;
        int ciScreenNum;
        Screen *cscrScreenPtr;
        XWMHints *xwmhHints;
        XClassHint  *xchClass;
        XTextProperty xtpWinName, xtpIconName;
        XSizeHints *xshSize;
        char *pcIconName = "Icon Name?", *pcWinName = "Window Name?", *pcProgName = "Test App";
        XEvent xeEvent;
        Window Handle;
        
        cdisDisplay = XOpenDisplay(NULL);
        if (cdisDisplay == NULL)
        {//Failed to connect to an X Server
            printf("\nFailed to connect to the display\n");
            return 0;
        }
        else
        {
            ciScreenNum = DefaultScreen(cdisDisplay);
            cscrScreenPtr = DefaultScreenOfDisplay(cdisDisplay);
        }
        
        Handle = XCreateSimpleWindow(cdisDisplay, RootWindow(cdisDisplay, ciScreenNum), 0, 0, 200, 200, 0, BlackPixel(cdisDisplay, ciScreenNum), WhitePixel(cdisDisplay, ciScreenNum));
        
        //Allocate space for the hints
        xshSize = XAllocSizeHints();
        xwmhHints = XAllocWMHints();
        xchClass = XAllocClassHint();
        
        xshSize->flags = PPosition | PSize;
        
        XStringListToTextProperty(&pcWinName, 1, &xtpWinName);
        XStringListToTextProperty(&pcIconName, 1, &xtpIconName);
        
        xwmhHints->initial_state = NormalState;
        xwmhHints->input = True;
        xwmhHints->flags = StateHint | InputHint;
        
        xchClass->res_name = pcProgName;
        xchClass->res_class = "Base Win";
        
        XSetWMProperties(cdisDisplay, Handle, &xtpWinName, &xtpIconName, 0, NULL, xshSize, xwmhHints, xchClass);
    
        XSelectInput(cdisDisplay, Handle, ExposureMask | KeyPressMask | ButtonPressMask | StructureNotifyMask);
        XMapWindow(cdisDisplay, Handle); //Show the window
        
        while (1)
        {
            XNextEvent(cdisDisplay, &xeEvent);
            
            switch (xeEvent.type)
            {
                case  (ConfigureNotify) :
                {
                    printf("Window moved or resized!\n");
                    break;
                }
                case (ButtonPress) :
                {
                    printf("Mouse button %d pressed!\n", xeEvent.xbutton.button);
                    break;
                }
                case (DestroyNotify) :
                {
                    printf("Window killed!\n");
                }
                default :
                {
                    printf("Unknown event: %d (discarding)\n", xeEvent.type);
                    break;
                }
            }
        }
    }
    The output looks something like this, after moving the window a bit and clicking in it, then closing hte window using that top right 'X' button:

    Code:
    Unknown event: 21 (discarding)
    Window moved or resized!
    Unknown event: 19 (discarding)
    Unknown event: 12 (discarding)
    Window moved or resized!
    Window moved or resized!
    Window moved or resized!
    Mouse button 1 pressed!
    Mouse button 3 pressed!
    Mouse button 2 pressed!
    X connection to :0.0 broken (explicit kill or server shutdown).
    I am missing the XSetWMProtocols() call suggested by Ken Fitlike, I'll give that a shot and see how it does. From what I read that sounds like it could be hat I need.

  5. #5
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    Thanks Ken Fitlike, adding that bit of code gets me the message.

  6. #6
    UT2004 Addict Kleid-0's Avatar
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    How do you compile that code? I tried:mmm
    Code:
    kleid@Shiva:~/Programming/Laboratory$ gcc X11.c -L/usr/X11R6/lib X11.c: In function `main':
    X11.c:51: warning: passing arg 6 of `XSetWMProperties' makes integer from pointer without a cast
    /tmp/ccgYgYQ0.o(.text+0x30): In function `main':
    : undefined reference to `XOpenDisplay'
    /tmp/ccgYgYQ0.o(.text+0x112): In function `main':
    : undefined reference to `XCreateSimpleWindow'
    /tmp/ccgYgYQ0.o(.text+0x11d): In function `main':
    : undefined reference to `XAllocSizeHints'
    /tmp/ccgYgYQ0.o(.text+0x125): In function `main':
    : undefined reference to `XAllocWMHints'
    /tmp/ccgYgYQ0.o(.text+0x12d): In function `main':
    : undefined reference to `XAllocClassHint'
    /tmp/ccgYgYQ0.o(.text+0x153): In function `main':
    : undefined reference to `XStringListToTextProperty'
    /tmp/ccgYgYQ0.o(.text+0x16d): In function `main':
    : undefined reference to `XStringListToTextProperty'
    /tmp/ccgYgYQ0.o(.text+0x1e4): In function `main':
    : undefined reference to `XSetWMProperties'
    /tmp/ccgYgYQ0.o(.text+0x201): In function `main':
    : undefined reference to `XSelectInput'
    /tmp/ccgYgYQ0.o(.text+0x216): In function `main':
    : undefined reference to `XMapWindow'
    /tmp/ccgYgYQ0.o(.text+0x22b): In function `main':
    : undefined reference to `XNextEvent'
    collect2: ld returned 1 exit status
    And I also tried:
    Code:
    kleid@Shiva:~/Programming/Laboratory$ gcc X11.c -lX11
    X11.c: In function `main':
    X11.c:51: warning: passing arg 6 of `XSetWMProperties' makes integer from pointer without a cast
    /usr/bin/ld: cannot find -lX11
    collect2: ld returned 1 exit status
    What am I doing wrong :( , I know I've got the libraries.

  7. #7
    erstwhile
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    Tell the linker where to find the xlib(s) with -L path_to_xlib(s); eg. something like:
    Code:
    gcc X11.c -L /usr/X11R6/lib -lX11
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  8. #8
    UT2004 Addict Kleid-0's Avatar
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    Thank you Ken! This is awesome! My first GUI in Linux, BWHAHAHAHA!!! ... *ahem*, I like it! :)

  9. #9
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    If you try to use it for anything be sure you change line 51 from:
    Code:
    XSetWMProperties(cdisDisplay, Handle, &xtpWinName, &xtpIconName, 0, NULL, xshSize, xwmhHints, xchClass)
    To:
    Code:
    XSetWMProperties(cdisDisplay, Handle, &xtpWinName, &xtpIconName, ArgC, ArgV, xshSize, xwmhHints, xchClass)
    That functions expects to recieve the command line parameters passed to the program.

    I'll admit to being lazy when I left those out of the function call, I'm not entirely sure why the window manager needs them, but in the interest of being friendly to the manager they should be passed.

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