NAME

       Tk_SetClassProcs - register widget specific procedures

SYNOPSIS

       #include <tk.h>

       Tk_SetClassProcs(tkwin, procs, instanceData)

ARGUMENTS

       Tk_Window tkwin (in)                    Token for window to modify.

       const Tk_ClassProcs *procs (in)         Pointer  to data structure containing widget specific procedures.
                                               The data structure pointed to by procs must be static: Tk keeps a
                                               reference to it as long as the window exists.

       ClientData instanceData (in)            Arbitrary one-word value to pass to widget callbacks.
________________________________________________________________________________________________________________

DESCRIPTION

       Tk_SetClassProcs is called to register a set of procedures  that  are  used  as  callbacks  in  different
       places.

       The structure pointed to by procs contains the following:
              typedef struct Tk_ClassProcs {
                  unsigned int size;
                  Tk_ClassWorldChangedProc *worldChangedProc;
                  Tk_ClassCreateProc *createProc;
                  Tk_ClassModalProc *modalProc;
              } Tk_ClassProcs;
       The  size  field  is  used  to  simplify  future  expansion  of the structure. It should always be set to
       (literally) sizeof(Tk_ClassProcs).

       worldChangedProc is invoked when the system has altered in some way that requires some reaction from  the
       widget.   For  example, when a font alias (see the font manual entry) is reconfigured, widgets configured
       to use that font alias must update their display accordingly.  worldChangedProc should have arguments and
       results that match the type Tk_ClassWorldChangedProc:
              typedef void Tk_ClassWorldChangedProc(
                      ClientData instanceData);
       The instanceData parameter passed to the worldChangedProc will be identical to the instanceData parameter
       passed to Tk_SetClassProcs.

       createProc  is  used  to  create  platform-dependent  windows.   It  is  invoked  by  Tk_MakeWindowExist.
       createProc should have arguments and results that match the type Tk_ClassCreateProc:
              typedef Window Tk_ClassCreateProc(
                      Tk_Window tkwin,
                      Window parent,
                      ClientData instanceData);
       The  tkwin  and instanceData parameters will be identical to the tkwin and instanceData parameters passed
       to Tk_SetClassProcs.  The parent parameter will  be  the  parent  of  the  window  to  be  created.   The
       createProc should return the created window.

       modalProc  is invoked after all bindings on a widget have been triggered in order to handle a modal loop.
       modalProc should have arguments and results that match the type Tk_ClassModalProc:
              typedef void Tk_ClassModalProc(
                      Tk_Window tkwin,
                      XEvent *eventPtr);
       The tkwin parameter to modalProc will be identical to the tkwin  parameter  passed  to  Tk_SetClassProcs.
       The eventPtr parameter will be a pointer to an XEvent structure describing the event being processed.

KEYWORDS

       callback, class

Tk                                                     8.4                                 Tk_SetClassProcs(3tk)