Tk_SetClassProcs(3)   Tk Library Procedures   Tk_SetClassProcs(3)



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NAME
       Tk_SetClassProcs - register widget specific procedures

SYNOPSIS
       #include 

       Tk_SetClassProcs(tkwin, procs, instanceData)

ARGUMENTS
       Tk_Window      tkwin          (in)      Token  for  window
                                               to modify.

       Tk_ClassProcs  *procs         (in)      Pointer  to   data
                                               structure contain-
                                               ing  widget   spe-
                                               cific  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.
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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 paramter passed to
       Tk_SetClassProcs.

       createProc is used to create  platform-dependant  windows.
       It  is  invoked  by Tk_MakeWindowExist.  createProc should
       have arguments and results that match the  type  Tk_Class-
       CreateProc:
              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_Set-
       ClassProcs.   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(3)