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# AFTERImage examples common

common functions used in other examples

libAfterImage/tutorials/common.h

- SYNOPSIS

      Generic Xlib related functionality, common for all the tutorials.

- SEE ALSO

      libAfterImage,
      ASView, ASScale, ASTile, ASMerge, ASGrad, ASFlip, ASText

libAfterImage/tutorials/_XA_WM_DELETE_WINDOW

- NAME

  _XA_WM_DELETE_WINDOW

- SYNOPSIS

      _XA_WM_DELETE_WINDOW - stores value of X Atom "WM_DELETE_WINDOW".

- DESCRIPTION

      In X all client's top level windows are managed by window manager.
      That includes moving, resizing, decorating, focusing and closing of
      windows. Interactions between window manager and client window are
      governed by ICCCM specification.
      All the parts of this specification are completely optional, but it
      is recommended that the following minimum set of hints be supplied
      for any client window:
      Window's title(WM_NAME), iconified window title(WM_ICON_NAME), class
      hint (WM_CLASS) and supported protocols (WM_PROTOCOLS). It is
      recommended also that WM_DELETE_WINDOW protocol be supported, as
      otherwise there are no way to safely close client window, but to
      kill it.
      All of the above mentioned hints are identified by atoms that have
      standard preset values, except for WM_DELETE_WINDOW. As the result we
      need to obtain WM_DELETE_WINDOW atoms ID explicitly. We use
      _XA_WM_DELETE_WINDOW to store the ID of that atom, so it is accessible
      anywhere from our application.

- SOURCE

      Atom _XA_WM_DELETE_WINDOW = None;

libAfterImage/tutorials/create_top_level_window()

- NAME

  create_top_level_window()

- SYNOPSIS

      Window create_top_level_window( ASVisual *asv, Window root,
                                      int x, int y,
                                      unsigned int width,
                                      unsigned int height,
                                      unsigned int border_width,
                                      unsigned long attr_mask,
                                      XSetWindowAttributes *attr,
                                      char *app_class );

- INPUTS

  asv
    - pointer to valid preinitialized ASVisual structure.
  root
    - root window of the screen on which to create window.
  x,
    y - desired position of the window
  width,
    height - desired window size.
  border_width
    - desired initial border width of the window (may not have any effect due to Window Manager intervention.
  attr_mask
    - mask of the attributes that has to be set on the window
  attr
    - values of the attributes to be set.
  app_class
    - title of the application to be used as its window Title and resources class.

- RETURN VALUE

      ID of the created window.

- DESCRIPTION

      create_top_level_window() is autyomating process of creating top
      level application window. It creates window for specified ASVisual,
      and then sets up basic ICCCM hints for that window, such as WM_NAME,
      WM_ICON_NAME, WM_CLASS and WM_PROTOCOLS.

- SOURCE

      Window
      create_top_level_window( ASVisual *asv, Window root, int x, int y,
                               unsigned int width, unsigned int height,
                               unsigned int border_width,
                               unsigned long attr_mask,
                               XSetWindowAttributes *attr,
                               const char *app_class, const char *app_name )
      {
          Window w = None;
      #ifndef X_DISPLAY_MISSING
          char *tmp ;
          XTextProperty name;
          XClassHint class1;

          w = create_visual_window(asv, root, x, y, width, height, border_width,
                                   InputOutput, attr_mask, attr );

          tmp = (app_name==NULL)?(char*)get_application_name():(char*)app_name;
          XStringListToTextProperty (&tmp, 1, &name);

          class1.res_name = tmp;  /* for future use */
          class1.res_class = (char*)app_class;
          XSetWMProtocols (dpy, w, &_XA_WM_DELETE_WINDOW, 1);
          XSetWMProperties (dpy, w, &name, &name, NULL, 0, NULL, NULL, &class1);
          /* final cleanup */
          XFree ((char *) name.value);

      #endif /* X_DISPLAY_MISSING */
          return w;
      }

libAfterImage/tutorials/set_window_background_and_free()

- NAME

  set_window_background_and_free()

- SYNOPSIS

      Pixmap set_window_background_and_free( Window w, Pixmap p );

- INPUTS

  w
    - ID of the window background of which we need to set.
  p
    - Pixmap to set background to.

- RETURN VALUE

      None on success. Pixmap ID of original Pixmap on failure.

- DESCRIPTION

      set_window_background_and_free() will set window's background to
      specified Pixmap, Then refresh window contents so that background
      is drawn by the server, flush all the requests to force it to be sent
      to server to be processed as fast as possible.

- NOTES

      After Window's background has been set to Pixmap - X server makes
      hidden copy of this Pixmap for later window refreshing. As the result
      original Pixmap is no longer needed and can be freed to conserve
      resources.

- SOURCE

      Pixmap
      set_window_background_and_free( Window w, Pixmap p )
      {
      #ifndef X_DISPLAY_MISSING
          if( p != None && w != None )
          {
              XSetWindowBackgroundPixmap( dpy, w, p );
              XClearWindow( dpy, w );
              XFlush( dpy );
              XFreePixmap( dpy, p );
              p = None ;
          }
      #endif /* X_DISPLAY_MISSING */
          return p ;
      }

libAfterImage/tutorials/wait_closedown()

- NAME

  wait_closedown()

- SYNOPSIS

      void wait_closedown( Window w );

- INPUTS

  w
    - ID of the window from which to wait for events.

- DESCRIPTION

      User action requesting window to be closed is generally received
      first by Window Manager. Window Manager is then handles it down to
      the window by sending it ClientMessage event with first 32 bit word
      of data set to the value of WM_DELETE_WINDOW Atom.
      Accordingly, all client has to do is wait for such event from X server
      and, when received, it should destroy its window and generally exit.

- NOTES

      It is recommended that XFlush() is issued right after XDestroyWindow()
      as Window Manager itself may attempt to do something with the window
      until it receives DestroyNotify event.

- SEE ALSO

      ICCCM, Window

- SOURCE

      void
      wait_closedown( Window w )
      {
      #ifndef X_DISPLAY_MISSING
          if( dpy == NULL || w == None )
              return ;

          XSelectInput (dpy, w, ( StructureNotifyMask |
                                  ButtonPressMask|
                                  ButtonReleaseMask));

          while(w != None)
          {
              XEvent event ;
              XNextEvent (dpy, &event);
              switch(event.type)
              {
                  case ClientMessage:
                      if ((event.xclient.format != 32) ||
                          (event.xclient.data.l[0] != _XA_WM_DELETE_WINDOW))
                          break ;
                  case ButtonPress:
                      XDestroyWindow( dpy, w );
                      XFlush( dpy );
                      w = None ;
                      break ;
              }
          }
          XCloseDisplay (dpy);
          dpy = NULL ;
      #endif
      }

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