- NAME
- Tk_CreateOptionTable, Tk_DeleteOptionTable, Tk_InitOptions, Tk_SetOptions, Tk_FreeSavedOptions, Tk_RestoreSavedOptions, Tk_GetOptionValue, Tk_GetOptionInfo, Tk_FreeConfigOptions — 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)
- ARGUMENTS
- DESCRIPTION
- TEMPLATES
- TK_OPTION_NULL_OK
- TK_OPTION_DONT_SET_DEFAULT
- TK_OPTION_ANCHOR
- TK_OPTION_BITMAP
- TK_OPTION_BOOLEAN
- TK_OPTION_BORDER
- TK_OPTION_COLOR
- TK_OPTION_CURSOR
- TK_OPTION_CUSTOM
- TK_OPTION_DOUBLE
- TK_OPTION_END
- TK_OPTION_FONT
- TK_OPTION_INT
- TK_OPTION_JUSTIFY
- TK_OPTION_PIXELS
- TK_OPTION_RELIEF
- TK_OPTION_STRING
- TK_OPTION_STRING_TABLE
- TK_OPTION_SYNONYM
- TK_OPTION_WINDOW
- STORAGE MANAGEMENT ISSUES
- OBJOFFSET VS. INTERNALOFFSET
- CUSTOM OPTION TYPES
- clientData
- interp
- Tkwin
- valuePtr
- recordPtr
- internalOffset
- saveInternalPtr
- flags
- KEYWORDS
Tk_CreateOptionTable, Tk_DeleteOptionTable, Tk_InitOptions, Tk_SetOptions, Tk_FreeSavedOptions, Tk_RestoreSavedOptions, Tk_GetOptionValue, Tk_GetOptionInfo, Tk_FreeConfigOptions — process configuration options
#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)
- 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.
- void *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.
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: 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 for all of the widget's configuration options that do not
have TK_OPTION_DONT_SET_DEFAULT set in their flags field.
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, except those having
TK_OPTION_DONT_SET_DEFAULT set, 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.
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 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;
size_t objOffset;
size_t 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
offsetof 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.
- 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: if the objOffset field is not
used then 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 zero.
- 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 the empty string is specified as the value for the option,
the integer relief value 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.
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.
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: 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.
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 {
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.
anchor, bitmap, boolean, border, color, configuration option, cursor, double, font, integer, justify, pixels, relief, screen distance, synonym
Copyright © 1998 Sun Microsystems, Inc.