Tk_SetClassProcs(3) Tk Library Procedures Tk_SetClassProcs(3)

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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.
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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 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(3)