Tk_SetOptions(3) Tk Library Procedures Tk_SetOptions(3) ______________________________________________________________________________
NAME
Tk_CreateOptionTable, Tk_DeleteOptionTable, Tk_InitOptions,
Tk_SetOptions, Tk_FreeSavedOptions, Tk_RestoreSavedOptions,
Tk_GetOptionValue, Tk_GetOptionInfo, Tk_FreeConfigOptions, Tk_Offset -
process configuration options
SYNOPSIS
#include <tk.h>
Tk_OptionTable
Tk_CreateOptionTable(interp, templatePtr)
Tk_DeleteOptionTable(optionTable)
int
Tk_InitOptions(interp, recordPtr, optionTable, tkwin)
int
Tk_SetOptions(interp, recordPtr, optionTable, objc, objv, tkwin, savePtr, maskPtr)
Tk_FreeSavedOptions(savedPtr)
Tk_RestoreSavedOptions(savedPtr)
Tcl_Obj *
Tk_GetOptionValue(interp, recordPtr, optionTable, namePtr, tkwin)
Tcl_Obj *
Tk_GetOptionInfo(interp, recordPtr, optionTable, namePtr, tkwin)
Tk_FreeConfigOptions(recordPtr, optionTable, tkwin)
int
Tk_Offset(type, field)
ARGUMENTS
Tcl_Interp *interp (in) A Tcl interpreter. Most
procedures use this only
for returning error
messages; if it is NULL
then no error messages are
returned. For
Tk_CreateOptionTable the
value cannot be NULL; it
gives the interpreter in
which the option table will
be used.
const Tk_OptionSpec *templatePtr (in) Points to an array of
static information that
describes the configuration
options that are supported.
Used to build a
Tk_OptionTable. The
information pointed to by
this argument must exist
for the lifetime of the
Tk_OptionTable.
Tk_OptionTable optionTable (in) Token for an option table.
Must have been returned by
a previous call to
Tk_CreateOptionTable.
char *recordPtr (in/out) Points to structure in
which values of
configuration options are
stored; fields of this
record are modified by
procedures such as
Tk_SetOptions and read by
procedures such as
Tk_GetOptionValue.
Tk_Window tkwin (in) For options such as
TK_OPTION_COLOR, this
argument indicates the
window in which the option
will be used. If
optionTable uses no window-
dependent options, then a
NULL value may be supplied
for this argument.
int objc (in) Number of values in objv.
Tcl_Obj *const *objv (in) Command-line arguments for
setting configuring
options.
Tk_SavedOptions *savePtr (out) If not NULL, the structure
pointed to by this argument
is filled in with the old
values of any options that
were modified and old
values are restored
automatically if an error
occurs in Tk_SetOptions.
int *maskPtr (out) If not NULL, the word
pointed to by maskPtr is
filled in with the bit-wise
OR of the typeMask fields
for the options that were
modified.
Tk_SavedOptions *savedPtr (in/out) Points to a structure
previously filled in by
Tk_SetOptions with old
values of modified options.
Tcl_Obj *namePtr (in) The value of this object is
the name of a particular
option. If NULL is passed
to Tk_GetOptionInfo then
information is returned for
all options. Must not be
NULL when Tk_GetOptionValue
is called.
type name type (in) The name of the type of a
record.
field name field (in) The name of a field in
records of type type.
______________________________________________________________________________
DESCRIPTION
These procedures handle most of the details of parsing configuration
options such as those for Tk widgets. Given a description of what
options are supported, these procedures handle all the details of
parsing options and storing their values into a C structure associated
with the widget or object. The procedures were designed primarily for
widgets in Tk, but they can also be used for other kinds of objects
that have configuration options. In the rest of this manual page
"widget" will be used to refer to the object whose options are being
managed; in practice the object may not actually be a widget. The term
"widget record" is used to refer to the C-level structure in which
information about a particular widget or object is stored.
Note that the easiest way to learn how to use these procedures is to
look at a working example. In Tk, the simplest example is the code
that implements the button family of widgets, which is in tkButton.c.
Other examples are in tkSquare.c and tkMenu.c.
In order to use these procedures, the code that implements the widget
must contain a static array of Tk_OptionSpec structures. This is a
template that describes the various options supported by that class of
widget; there is a separate template for each kind of widget. The
template contains information such as the name of each option, its
type, its default value, and where the value of the option is stored in
the widget record. See TEMPLATES below for more detail.
In order to process configuration options efficiently, the static
template must be augmented with additional information that is
available only at runtime. The procedure Tk_CreateOptionTable creates
this dynamic information from the template and returns a Tk_OptionTable
token that describes both the static and dynamic information. All of
the other procedures, such as Tk_SetOptions, take a Tk_OptionTable
token as argument. Typically, Tk_CreateOptionTable is called the first
time that a widget of a particular class is created and the resulting
Tk_OptionTable is used in the future for all widgets of that class. A
Tk_OptionTable may be used only in a single interpreter, given by the
interp argument to Tk_CreateOptionTable. When an option table is no
longer needed Tk_DeleteOptionTable should be called to free all of its
resources. All of the option tables for a Tcl interpreter are freed
automatically if the interpreter is deleted.
Tk_InitOptions is invoked when a new widget is created to set the
default values. Tk_InitOptions is passed a token for an option table
(optionTable) and a pointer to a widget record (recordPtr), which is
the C structure that holds information about this widget.
Tk_InitOptions uses the information in the option table to choose an
appropriate default for each option, then it stores the default value
directly into the widget record, overwriting any information that was
already present in the widget record. Tk_InitOptions normally returns
TCL_OK. If an error occurred while setting the default values (e.g.,
because a default value was erroneous) then TCL_ERROR is returned and
an error message is left in interp's result if interp is not NULL. For
any widget's configuration option that has TK_OPTION_DONT_SET_DEFAULT
set in its flags field, the above initialization is fully skipped, see
below.
Tk_SetOptions is invoked to modify configuration options based on
information specified in a Tcl command. The command might be one that
creates a new widget, or a command that modifies options on an existing
widget. The objc and objv arguments describe the values of the
arguments from the Tcl command. Objv must contain an even number of
objects: the first object of each pair gives the name of an option and
the second object gives the new value for that option. Tk_SetOptions
looks up each name in optionTable, checks that the new value of the
option conforms to the type in optionTable, and stores the value of the
option into the widget record given by recordPtr. Tk_SetOptions
normally returns TCL_OK. If an error occurred (such as an unknown
option name or an illegal option value) then TCL_ERROR is returned and
an error message is left in interp's result if interp is not NULL.
Tk_SetOptions has two additional features. First, if the maskPtr
argument is not NULL then it points to an integer value that is filled
in with information about the options that were modified. For each
option in the template passed to Tk_CreateOptionTable there is a
typeMask field. The bits of this field are defined by the code that
implements the widget; for example, each bit might correspond to a
particular configuration option. Alternatively, bits might be used
functionally. For example, one bit might be used for redisplay: all
options that affect the widget's display, such that changing the option
requires the widget to be redisplayed, might have that bit set.
Another bit might indicate that the geometry of the widget must be
recomputed, and so on. Tk_SetOptions OR's together the typeMask fields
from all the options that were modified and returns this value at
*maskPtr; the caller can then use this information to optimize itself
so that, for example, it does not redisplay the widget if the modified
options do not affect the widget's appearance.
The second additional feature of Tk_SetOptions has to do with error
recovery. If an error occurs while processing configuration options,
this feature makes it possible to restore all the configuration options
to their previous values. Errors can occur either while processing
options in Tk_SetOptions or later in the caller. In many cases the
caller does additional processing after Tk_SetOptions returns; for
example, it might use an option value to set a trace on a variable and
may detect an error if the variable is an array instead of a scalar.
Error recovery is enabled by passing in a non-NULL value for the
savePtr argument to Tk_SetOptions; this should be a pointer to an
uninitialized Tk_SavedOptions structure on the caller's stack.
Tk_SetOptions overwrites the structure pointed to by savePtr with
information about the old values of any options modified by the
procedure. If Tk_SetOptions returns successfully, the caller uses the
structure in one of two ways. If the caller completes its processing
of the new options without any errors, then it must pass the structure
to Tk_FreeSavedOptions so that the old values can be freed. If the
caller detects an error in its processing of the new options, then it
should pass the structure to Tk_RestoreSavedOptions, which will copy
the old values back into the widget record and free the new values. If
Tk_SetOptions detects an error then it automatically restores any
options that had already been modified and leaves *savePtr in an empty
state: the caller need not call either Tk_FreeSavedOptions or
Tk_RestoreSavedOptions. If the savePtr argument to Tk_SetOptions is
NULL then Tk_SetOptions frees each old option value immediately when it
sets a new value for the option. In this case, if an error occurs in
the third option, the old values for the first two options cannot be
restored.
Tk_GetOptionValue returns the current value of a configuration option
for a particular widget. The namePtr argument contains the name of an
option; Tk_GetOptionValue uses optionTable to lookup the option and
extract its value from the widget record pointed to by recordPtr, then
it returns an object containing that value. If an error occurs (e.g.,
because namePtr contains an unknown option name) then NULL is returned
and an error message is left in interp's result unless interp is NULL.
Tk_GetOptionInfo returns information about configuration options in a
form suitable for configure widget commands. If the namePtr argument
is not NULL, it points to an object that gives the name of a
configuration option; Tk_GetOptionInfo returns an object containing a
list with five elements, which are the name of the option, the name and
class used for the option in the option database, the default value for
the option, and the current value for the option. If the namePtr
argument is NULL, then Tk_GetOptionInfo returns information about all
options in the form of a list of lists; each sublist describes one
option. Synonym options are handled differently depending on whether
namePtr is NULL: if namePtr is NULL then the sublist for each synonym
option has only two elements, which are the name of the option and the
name of the other option that it refers to; if namePtr is non-NULL and
names a synonym option then the object returned is the five-element
list for the other option that the synonym refers to. If an error
occurs (e.g., because namePtr contains an unknown option name) then
NULL is returned and an error message is left in interp's result unless
interp is NULL.
Tk_FreeConfigOptions must be invoked when a widget is deleted. It
frees all of the resources associated with any of the configuration
options defined in recordPtr by optionTable.
The Tk_Offset macro is provided as a safe way of generating the
objOffset and internalOffset values for entries in Tk_OptionSpec
structures. It takes two arguments: the name of a type of record, and
the name of a field in that record. It returns the byte offset of the
named field in records of the given type.
TEMPLATES
The array of Tk_OptionSpec structures passed to Tk_CreateOptionTable
via its templatePtr argument describes the configuration options
supported by a particular class of widgets. Each structure specifies
one configuration option and has the following fields:
typedef struct {
Tk_OptionType type;
const char *optionName;
const char *dbName;
const char *dbClass;
const char *defValue;
int objOffset;
int internalOffset;
int flags;
const void *clientData;
int typeMask;
} Tk_OptionSpec;
The type field indicates what kind of configuration option this is
(e.g. TK_OPTION_COLOR for a color value, or TK_OPTION_INT for an
integer value). Type determines how the value of the option is parsed
(more on this below). The optionName field is a string such as -font
or -bg; it is the name used for the option in Tcl commands and passed
to procedures via the objc or namePtr arguments. The dbName and
dbClass fields are used by Tk_InitOptions to look up a default value
for this option in the option database; if dbName is NULL then the
option database is not used by Tk_InitOptions for this option. The
defValue field specifies a default value for this configuration option
if no value is specified in the option database. The objOffset and
internalOffset fields indicate where to store the value of this option
in widget records (more on this below); values for the objOffset and
internalOffset fields should always be generated with the Tk_Offset
macro. The flags field contains additional information to control the
processing of this configuration option (see below for details).
ClientData provides additional type-specific data needed by certain
types. For instance, for TK_OPTION_COLOR types, clientData is a string
giving the default value to use on monochrome displays. See the
descriptions of the different types below for details. The last field,
typeMask, is used by Tk_SetOptions to return information about which
options were modified; see the description of Tk_SetOptions above for
details.
When Tk_InitOptions and Tk_SetOptions store the value of an option into
the widget record, they can do it in either of two ways. If the
objOffset field of the Tk_OptionSpec is greater than or equal to zero,
then the value of the option is stored as a (Tcl_Obj *) at the location
in the widget record given by objOffset. If the internalOffset field
of the Tk_OptionSpec is greater than or equal to zero, then the value
of the option is stored in a type-specific internal form at the
location in the widget record given by internalOffset. For example, if
the option's type is TK_OPTION_INT then the internal form is an
integer. If the objOffset or internalOffset field is negative then the
value is not stored in that form. At least one of the offsets must be
greater than or equal to zero.
The flags field consists of one or more bits ORed together. The
following flags are supported:
TK_OPTION_NULL_OK
If this bit is set for an option then an empty string will be
accepted as the value for the option and the resulting internal
form will be a NULL pointer, a zero value, or None, depending on
the type of the option. If the flag is not set then empty
strings will result in errors. TK_OPTION_NULL_OK is typically
used to allow a feature to be turned off entirely, e.g. set a
cursor value to None so that a window simply inherits its
parent's cursor. Not all option types support the
TK_OPTION_NULL_OK flag; for those that do, there is an explicit
indication of that fact in the descriptions below.
TK_OPTION_DONT_SET_DEFAULT
If this bit is set for an option then no default value will be
set in Tk_InitOptions for this option. Neither the option
database, nor any system default value, nor optionTable are used
to give a default value to this option. Instead it is assumed
that the caller has already supplied a default value in the
widget code.
The type field of each Tk_OptionSpec structure determines how to
parse the value of that configuration option. The legal value
for type, and the corresponding actions, are described below.
If the type requires a tkwin value to be passed into procedures
like Tk_SetOptions, or if it uses the clientData field of the
Tk_OptionSpec, then it is indicated explicitly; if not
mentioned, the type requires neither tkwin nor clientData.
TK_OPTION_ANCHOR
The value must be a standard anchor position such as ne or
center. The internal form is a Tk_Anchor value like the ones
returned by Tk_GetAnchorFromObj.
TK_OPTION_BITMAP
The value must be a standard Tk bitmap name. The internal form
is a Pixmap token like the ones returned by
Tk_AllocBitmapFromObj. This option type requires tkwin to be
supplied to procedures such as Tk_SetOptions, and it supports
the TK_OPTION_NULL_OK flag.
TK_OPTION_BOOLEAN
The value must be a standard boolean value such as true or no.
The internal form is an integer with value 0 or 1. Note that if
the objOffset field is not used, information about the original
value of this option will be lost.
TK_OPTION_BORDER
The value must be a standard color name such as red or #ff8080.
The internal form is a Tk_3DBorder token like the ones returned
by Tk_Alloc3DBorderFromObj. This option type requires tkwin to
be supplied to procedures such as Tk_SetOptions, and it supports
the TK_OPTION_NULL_OK flag.
TK_OPTION_COLOR
The value must be a standard color name such as red or #ff8080.
The internal form is an (XColor *) token like the ones returned
by Tk_AllocColorFromObj. This option type requires tkwin to be
supplied to procedures such as Tk_SetOptions, and it supports
the TK_OPTION_NULL_OK flag.
TK_OPTION_CURSOR
The value must be a standard cursor name such as cross or @foo.
The internal form is a Tk_Cursor token like the ones returned by
Tk_AllocCursorFromObj. This option type requires tkwin to be
supplied to procedures such as Tk_SetOptions, and when the
option is set the cursor for the window is changed by calling
XDefineCursor. This option type also supports the
TK_OPTION_NULL_OK flag.
TK_OPTION_CUSTOM
This option allows applications to define new option types. The
clientData field of the entry points to a structure defining the
new option type. See the section CUSTOM OPTION TYPES below for
details.
TK_OPTION_DOUBLE
The string value must be a floating-point number in the format
accepted by strtol. The internal form is a C double value.
This option type supports the TK_OPTION_NULL_OK flag; if a NULL
value is set, the internal representation is set to zero.
TK_OPTION_END
Marks the end of the template. There must be a Tk_OptionSpec
structure with type TK_OPTION_END at the end of each template.
If the clientData field of this structure is not NULL, then it
points to an additional array of Tk_OptionSpec's, which is
itself terminated by another TK_OPTION_END entry. Templates may
be chained arbitrarily deeply. This feature allows common
options to be shared by several widget classes.
TK_OPTION_FONT
The value must be a standard font name such as Times 16. The
internal form is a Tk_Font handle like the ones returned by
Tk_AllocFontFromObj. This option type requires tkwin to be
supplied to procedures such as Tk_SetOptions, and it supports
the TK_OPTION_NULL_OK flag.
TK_OPTION_INT
The string value must be an integer in the format accepted by
strtol (e.g. 0 and 0x prefixes may be used to specify octal or
hexadecimal numbers, respectively). The internal form is a C
int value.
TK_OPTION_JUSTIFY
The value must be a standard justification value such as left.
The internal form is a Tk_Justify like the values returned by
Tk_GetJustifyFromObj.
TK_OPTION_PIXELS
The value must specify a screen distance such as 2i or 6.4. The
internal form is an integer value giving a distance in pixels,
like the values returned by Tk_GetPixelsFromObj. Note that if
the objOffset field is not used, information about the original
value of this option will be lost. See OBJOFFSET VS.
INTERNALOFFSET below for details. This option type supports the
TK_OPTION_NULL_OK flag; if a NULL value is set, the internal
representation is set to INT_MIN.
TK_OPTION_RELIEF
The value must be standard relief such as raised. The internal
form is an integer relief value such as TK_RELIEF_RAISED. This
option type supports the TK_OPTION_NULL_OK flag; if a NULL value
is set, the internal representation is set to TK_RELIEF_NULL.
TK_OPTION_STRING
The value may be any string. The internal form is a (char *)
pointer that points to a dynamically allocated copy of the
value. This option type supports the TK_OPTION_NULL_OK flag.
TK_OPTION_STRING_TABLE
For this type, clientData is a pointer to an array of strings
suitable for passing to Tcl_GetIndexFromObj. The value must be
one of the strings in the table, or a unique abbreviation of one
of the strings. The internal form is an integer giving the
index into the table of the matching string, like the return
value from Tcl_GetStringFromObj. This option type supports the
TK_OPTION_NULL_OK flag; if a NULL value is set, the internal
representation is set to -1.
TK_OPTION_SYNONYM
This type is used to provide alternative names for an option
(for example, -bg is often used as a synonym for -background).
The clientData field is a string that gives the name of another
option in the same table. Whenever the synonym option is used,
the information from the other option will be used instead.
TK_OPTION_WINDOW
The value must be a window path name. The internal form is a
Tk_Window token for the window. This option type requires tkwin
to be supplied to procedures such as Tk_SetOptions (in order to
identify the application), and it supports the TK_OPTION_NULL_OK
flag.
STORAGE MANAGEMENT ISSUES
If a field of a widget record has its offset stored in the objOffset or
internalOffset field of a Tk_OptionSpec structure then the procedures
described here will handle all of the storage allocation and resource
management issues associated with the field. When the value of an
option is changed, Tk_SetOptions (or Tk_FreeSavedOptions) will
automatically free any resources associated with the old value, such as
Tk_Fonts for TK_OPTION_FONT options or dynamically allocated memory for
TK_OPTION_STRING options. For an option stored as an object using the
objOffset field of a Tk_OptionSpec, the widget record shares the object
pointed to by the objv value from the call to Tk_SetOptions. The
reference count for this object is incremented when a pointer to it is
stored in the widget record and decremented when the option is
modified. When the widget is deleted Tk_FreeConfigOptions should be
invoked; it will free the resources associated with all options and
decrement reference counts for any objects.
However, the widget code is responsible for storing NULL or None in all
pointer and token fields before invoking Tk_InitOptions. This is
needed to allow proper cleanup in the rare case where an error occurs
in Tk_InitOptions.
OBJOFFSET VS. INTERNALOFFSET
In most cases it is simplest to use the internalOffset field of a
Tk_OptionSpec structure and not the objOffset field. This makes the
internal form of the value immediately available to the widget code so
the value does not have to be extracted from an object each time it is
used. However, there are two cases where the objOffset field is
useful. The first case is for TK_OPTION_PIXELS options. In this case,
the internal form is an integer pixel value that is valid only for a
particular screen. If the value of the option is retrieved, it will be
returned as a simple number. For example, after the command .b
configure -borderwidth 2m, the command .b configure -borderwidth might
return 7, which is the integer pixel value corresponding to 2m.
Unfortunately, this loses the original screen-independent value. Thus
for TK_OPTION_PIXELS options it is better to use the objOffset field.
In this case the original value of the option is retained in the object
and can be returned when the option is retrieved. In most cases it is
convenient to use the internalOffset field as well, so that the integer
value is immediately available for use in the widget code
(alternatively, Tk_GetPixelsFromObj can be used to extract the integer
value from the object whenever it is needed). Note that the problem of
losing information on retrievals exists only for TK_OPTION_PIXELS
options.
The second reason to use the objOffset field is in order to implement
new types of options not supported by these procedures. To implement a
new type of option, you can use TK_OPTION_STRING as the type in the
Tk_OptionSpec structure and set the objOffset field but not the
internalOffset field. Then, after calling Tk_SetOptions, convert the
object to internal form yourself.
Ttk widgets do not support the internalOffset machinery. Option values
of Ttk widgets are always stored as (Tcl_Obj *), meaning that the
objOffset field must be used.
CUSTOM OPTION TYPES
Applications can extend the built-in configuration types with
additional configuration types by writing procedures to parse, print,
free, and restore saved copies of the type and creating a structure
pointing to those procedures:
typedef struct Tk_ObjCustomOption {
const char *name;
Tk_CustomOptionSetProc *setProc;
Tk_CustomOptionGetProc *getProc;
Tk_CustomOptionRestoreProc *restoreProc;
Tk_CustomOptionFreeProc *freeProc;
ClientData clientData;
} Tk_ObjCustomOption;
typedef int Tk_CustomOptionSetProc(
ClientData clientData,
Tcl_Interp *interp,
Tk_Window tkwin,
Tcl_Obj **valuePtr,
char *recordPtr,
int internalOffset,
char *saveInternalPtr,
int flags);
typedef Tcl_Obj *Tk_CustomOptionGetProc(
ClientData clientData,
Tk_Window tkwin,
char *recordPtr,
int internalOffset);
typedef void Tk_CustomOptionRestoreProc(
ClientData clientData,
Tk_Window tkwin,
char *internalPtr,
char *saveInternalPtr);
typedef void Tk_CustomOptionFreeProc(
ClientData clientData,
Tk_Window tkwin,
char *internalPtr);
The Tk_ObjCustomOption structure contains six fields: a name for the
custom option type; pointers to the four procedures; and a clientData
value to be passed to those procedures when they are invoked. The
clientData value typically points to a structure containing information
that is needed by the procedures when they are parsing and printing
options. RestoreProc and freeProc may be NULL, indicating that no
function should be called for those operations.
The setProc procedure is invoked by Tk_SetOptions to convert a Tcl_Obj
into an internal representation and store the resulting value in the
widget record. The arguments are:
clientData
A copy of the clientData field in the Tk_ObjCustomOption
structure.
interp A pointer to a Tcl interpreter, used for error reporting.
Tkwin A copy of the tkwin argument to Tk_SetOptions
valuePtr
A pointer to a reference to a Tcl_Obj describing the new
value for the option; it could have been specified
explicitly in the call to Tk_SetOptions or it could come
from the option database or a default. If the objOffset
for the option is non-negative (the option value is
stored as a (Tcl_Obj *) in the widget record), the
Tcl_Obj pointer referenced by valuePtr is the pointer
that will be stored at the objOffset for the option.
SetProc may modify the value if necessary; for example,
setProc may change the value to NULL to support the
TK_OPTION_NULL_OK flag.
recordPtr
A pointer to the start of the widget record to modify.
internalOffset
Offset in bytes from the start of the widget record to
the location where the internal representation of the
option value is to be placed.
saveInternalPtr
A pointer to storage allocated in a Tk_SavedOptions
structure for the internal representation of the original
option value. Before setting the option to its new
value, setProc should set the value referenced by
saveInternalPtr to the original value of the option in
order to support Tk_RestoreSavedOptions.
flags A copy of the flags field in the Tk_OptionSpec structure
for the option
SetProc returns a standard Tcl result: TCL_OK to indicate successful
processing, or TCL_ERROR to indicate a failure of any kind. An error
message may be left in the Tcl interpreter given by interp in the case
of an error.
The getProc procedure is invoked by Tk_GetOptionValue and
Tk_GetOptionInfo to retrieve a Tcl_Obj representation of the internal
representation of an option. The clientData argument is a copy of the
clientData field in the Tk_ObjCustomOption structure. Tkwin is a copy
of the tkwin argument to Tk_GetOptionValue or Tk_GetOptionInfo.
RecordPtr is a pointer to the beginning of the widget record to query.
InternalOffset is the offset in bytes from the beginning of the widget
record to the location where the internal representation of the option
value is stored. GetProc must return a pointer to a Tcl_Obj
representing the value of the option.
The restoreProc procedure is invoked by Tk_RestoreSavedOptions to
restore a previously saved internal representation of a custom option
value. The clientData argument is a copy of the clientData field in
the Tk_ObjCustomOption structure. Tkwin is a copy of the tkwin
argument to Tk_GetOptionValue or Tk_GetOptionInfo. InternalPtr is a
pointer to the location where internal representation of the option
value is stored. SaveInternalPtr is a pointer to the saved value.
RestoreProc must copy the value from saveInternalPtr to internalPtr to
restore the value. RestoreProc need not free any memory associated
with either internalPtr or saveInternalPtr; freeProc will be invoked to
free that memory if necessary. RestoreProc has no return value.
The freeProc procedure is invoked by Tk_SetOptions and
Tk_FreeSavedOptions to free any storage allocated for the internal
representation of a custom option. The clientData argument is a copy
of the clientData field in the Tk_ObjCustomOption structure. Tkwin is
a copy of the tkwin argument to Tk_GetOptionValue or Tk_GetOptionInfo.
InternalPtr is a pointer to the location where the internal
representation of the option value is stored. The freeProc must free
any storage associated with the option. FreeProc has no return value.
KEYWORDS
anchor, bitmap, boolean, border, color, configuration option, cursor,
double, font, integer, justify, pixels, relief, screen distance,
synonym
Tk 8.1 Tk_SetOptions(3)
tk 8.6.15 - Generated Wed Dec 4 11:49:45 CST 2024