HPUX ConfigWidg[3]
ConfigWidg in anderen Kapiteln des hpux Handbuch:
Tk_ConfigureWidget(3) Tk Tk_ConfigureWidget(3)
Tk Library Procedures Tk Library Procedures
3.3
___________________________________________________________________________
NAME
Tk_ConfigureWidget, Tk_Offset, Tk_ConfigureInfo, Tk_FreeOptions -
process configuration options for widgets
SYNOPSIS
#include <tk.h>
int
Tk_ConfigureWidget(interp, tkwin, specs, argc, argv, widgRec, flags)
int
Tk_Offset(type, field)
int
Tk_ConfigureInfo(interp, tkwin, specs, widgRec, argvName, flags)
Tk_FreeOptions(specs, widgRec, display, flags) |
ARGUMENTS
Tcl_Interp *interp (in) Interpreter to use for returning
error messages.
Tk_Window tkwin (in) Window used to represent widget
(needed to set up X resources).
Tk_ConfigSpec *specs (in) Pointer to table specifying legal
configuration options for this
widget.
int argc (in) Number of arguments in argv.
char **argv (in) Command-line options for
configuring widget.
char *widgRec (in/out) Points to widget record
structure. Fields in this
structure get modified by
Tk_ConfigureWidget to hold
configuration information.
int flags (in) If non-zero, then it specifies an
OR-ed combination of flags that
control the processing of
configuration information.
TK_CONFIG_ARGV_ONLY causes the
option database and defaults to
be ignored, and flag bits
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TK_CONFIG_USER_BIT and higher are
used to selectively disable
entries in specs.
type name type (in) The name of the type of a widget
record.
field name field (in) The name of a field in records of
type type.
char *argvName (in) The name used on Tcl command
lines to refer to a particular
option (e.g. when creating a
widget or invoking the configure
widget command). If non-NULL,
then information is returned only
for this option. If NULL, then
information is returned for all
available options.
Display *display (in) Display containing widget whose
record is being freed; needed in
order to free up resources.
___________________________________________________________________________
DESCRIPTION
Tk_ConfigureWidget is called to configure various aspects of a widget,
such as colors, fonts, border width, etc. It is intended as a
convenience procedure to reduce the amount of code that must be
written in individual widget managers to handle configuration
information. It is typically invoked when widgets are created, and
again when the configure command is invoked for a widget. Although
intended primarily for widgets, Tk_ConfigureWidget can be used in
other situations where argc-argv information is to be used to fill in
a record structure, such as configuring graphical elements for a
canvas widget or entries of a menu.
Tk_ConfigureWidget processes a table specifying the configuration
options that are supported (specs) and a collection of command-line
arguments (argc and argv) to fill in fields of a record (widgRec). It
uses the option database and defaults specified in specs to fill in
fields of widgRec that are not specified in argv. Tk_ConfigureWidget
normally returns the value TCL_OK; in this case it does not modify
interp. If an error occurs then TCL_ERROR is returned and
Tk_ConfigureWidget will leave an error message in interp->result in
the standard Tcl fashion. In the event of an error return, some of
the fields of widgRec could already have been set, if configuration
information for them was successfully processed before the error
occurred. The other fields will be set to reasonable initial values |
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so that Tk_FreeOptions can be called for cleanup. |
The specs array specifies the kinds of configuration options expected
by the widget. Each of its entries specifies one configuration option
and has the following structure:
typedef struct {
int type;
char *argvName;
char *dbName;
char *dbClass;
char *defValue;
int offset;
int specFlags;
Tk_CustomOption *customPtr; |
} Tk_ConfigSpec;
The type field indicates what type of configuration option this is
(e.g. TK_CONFIG_COLOR for a color value, or TK_CONFIG_INT for an
integer value). The type field indicates how to use the value of the
option (more on this below). The argvName field is a string such as
``-font'' or ``-bg'', which is compared with the values in argv (if
argvName is NULL it means this is a grouped entry; see GROUPED
ENTRIES below). The dbName and dbClass fields are used to look up a
value for this option in the option database. The defValue field
specifies a default value for this configuration option if no value is
specified in either argv or the option database. Offset indicates
where in widgRec to store information about this option, and specFlags
contains additional information to control the processing of this
configuration option (see FLAGS below). The last field, customPtr, is
only used if type is TK_CONFIG_CUSTOM; see CUSTOM OPTION TYPES below.
Tk_ConfigureWidget first processes argv to see which (if any)
configuration options are specified there. Argv must contain an even
number of fields; the first of each pair of fields must match the
argvName of some entry in specs (unique abbreviations are acceptable),
and the second field of the pair contains the value for that
configuration option. If there are entries in spec for which there
were no matching entries in argv, Tk_ConfigureWidget uses the dbName
and dbClass fields of the specs entry to probe the option database;
if a value is found, then it is used as the value for the option.
Finally, if no entry is found in the option database, the defValue
field of the specs entry is used as the value for the configuration
option. If the defValue is NULL, or if the TK_CONFIG_DONT_SET_DEFAULT
bit is set in flags, then there is no default value and this specs
entry will be ignored if no value is specified in argv or the option
database.
Once a string value has been determined for a configuration option,
Tk_ConfigureWidget translates the string value into a more useful
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form, such as a color if type is TK_CONFIG_COLOR or an integer if type
is TK_CONFIG_INT. This value is then stored in the record pointed to
by widgRec. This record is assumed to contain information relevant to
the manager of the widget; its exact type is unknown to
Tk_ConfigureWidget. The offset field of each specs entry indicates
where in widgRec to store the information about this configuration
option. You should use the Tk_Offset macro to generate offset values
(see below for a description of Tk_Offset). The location indicated by
widgRec and offset will be referred to as the ``target'' in the
descriptions below.
The type field of each entry in specs determines what to do with the
string value of that configuration option. The legal values for type,
and the corresponding actions, are:
TK_CONFIG_ACTIVE_CURSOR
The value must be an ASCII string identifying a cursor in a form |
suitable for passing to Tk_GetCursor. The value is converted to a |
Cursor by calling Tk_GetCursor and the result is stored in the |
target. In addition, the resulting cursor is made the active |
cursor for tkwin by calling XDefineCursor. If TK_CONFIG_NULL_OK |
is specified in specFlags then the value may be an empty string, |
in which case the target and tkwin's active cursor will be set to |
None. If the previous value of the target wasn't None, then it |
is freed by passing it to Tk_FreeCursor. |
TK_CONFIG_ANCHOR |
The value must be an ASCII string identifying an anchor point in |
one of the ways accepted by Tk_GetAnchor. The string is |
converted to a Tk_Anchor by calling Tk_GetAnchor and the result |
is stored in the target. |
TK_CONFIG_BITMAP
The value must be an ASCII string identifying a bitmap in a form
suitable for passing to Tk_GetBitmap. The value is converted to
a Pixmap by calling Tk_GetBitmap and the result is stored in the
target. If TK_CONFIG_NULL_OK is specified in specFlags then the |
value may be an empty string, in which case the target is set to |
None. If the previous value of the target wasn't None, then it |
is freed by passing it to Tk_FreeBitmap.
TK_CONFIG_BOOLEAN
The value must be an ASCII string specifying a boolean value.
Any of the values ``true'', ``yes'', ``on'', or ``1'', or an
abbreviation of one of these values, means true; any of the
values ``false'', ``no'', ``off'', or ``0'', or an abbreviation
of one of these values, means false. The target is expected to
be an integer; for true values it will be set to 1 and for false
values it will be set to 0.
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TK_CONFIG_BORDER
The value must be an ASCII string identifying a border color in a
form suitable for passing to Tk_Get3DBorder. The value is
converted to a (Tk_3DBorder *) by calling Tk_Get3DBorder and the
result is stored in the target. If TK_CONFIG_NULL_OK is |
specified in specFlags then the value may be an empty string, in |
which case the target will be set to NULL. If the previous value |
of the target wasn't NULL, then it is freed by passing it to
Tk_Free3DBorder.
TK_CONFIG_CAP_STYLE
The value must be an ASCII string identifying a cap style in one |
of the ways accepted by Tk_GetCapStyle. The string is converted |
to an integer value corresponding to the cap style by calling |
Tk_GetCapStyle and the result is stored in the target. |
TK_CONFIG_COLOR
The value must be an ASCII string identifying a color in a form
suitable for passing to Tk_GetColor. The value is converted to
an (XColor *) by calling Tk_GetColor and the result is stored in
the target. If TK_CONFIG_NULL_OK is specified in specFlags then |
the value may be an empty string, in which case the target will |
be set to None. If the previous value of the target wasn't NULL, |
then it is freed by passing it to Tk_FreeColor.
TK_CONFIG_CURSOR
This option is identical to TK_CONFIG_ACTIVE_CURSOR except that
the new cursor is not made the active one for tkwin.
TK_CONFIG_CUSTOM
This option allows applications to define new option types. The |
customPtr field of the entry points to a structure defining the |
new option type. See the section CUSTOM OPTION TYPES below for |
details. |
TK_CONFIG_DOUBLE
The value must be an ASCII floating-point number in the format
accepted by strtol. The string is converted to a double value,
and the value is stored in the target.
TK_CONFIG_END
Marks the end of the table. The last entry in specs must have
this type; all of its other fields are ignored and it will never
match any arguments.
TK_CONFIG_FONT
The value must be an ASCII string identifying a font in a form
suitable for passing to Tk_GetFontStruct. The value is converted
to an (XFontStruct *) by calling Tk_GetFontStruct and the result
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is stored in the target. If TK_CONFIG_NULL_OK is specified in |
specFlags then the value may be an empty string, in which case |
the target will be set to NULL. If the previous value of the |
target wasn't NULL, then it is freed by passing it to
Tk_FreeFontStruct.
TK_CONFIG_INT
The value must be an ASCII integer string in the format accepted
by strtol (e.g. ``0'' and ``0x'' prefixes may be used to specify
octal or hexadecimal numbers, respectively). The string is
converted to an integer value and the integer is stored in the
target.
TK_CONFIG_JOIN_STYLE
The value must be an ASCII string identifying a join style in one |
of the ways accepted by Tk_GetJoinStyle. The string is converted |
to an integer value corresponding to the join style by calling |
Tk_GetJoinStyle and the result is stored in the target. |
TK_CONFIG_JUSTIFY |
The value must be an ASCII string identifying a justification |
method in one of the ways accepted by Tk_GetJustify. The string |
is converted to a Tk_Justify by calling Tk_GetJustify and the |
result is stored in the target. |
TK_CONFIG_MM |
The value must specify a screen distance in one of the forms |
acceptable to Tk_GetScreenMM. The string is converted to |
double-precision floating-point distance in millimeters and the |
value is stored in the target. |
TK_CONFIG_PIXELS |
The value must specify screen units in one of the forms |
acceptable to Tk_GetPixels. The string is converted to an |
integer distance in pixels and the value is stored in the target. |
TK_CONFIG_RELIEF
The value must be an ASCII string identifying a relief in a form
suitable for passing to Tk_GetRelief. The value is converted to
an integer relief value by calling Tk_GetRelief and the result is
stored in the target.
TK_CONFIG_STRING
A copy of the value is made by allocating memory space with |
malloc and copying the value into the dynamically-allocated |
space. A pointer to the new string is stored in the target. If |
TK_CONFIG_NULL_OK is specified in specFlags then the value may be |
an empty string, in which case the target will be set to NULL. |
If the previous value of the target wasn't NULL, then it is freed |
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by passing it to free. |
TK_CONFIG_SYNONYM
This type value identifies special entries in specs that are
synonyms for other entries. If an argv value matches the
argvName of a TK_CONFIG_SYNONYM entry, the entry isn't used
directly. Instead, Tk_ConfigureWidget searches specs for another
entry whose argvName is the same as the dbName field in the
TK_CONFIG_SYNONYM entry; this new entry is used just as if its
argvName had matched the argv value. The synonym mechanism
allows multiple argv values to be used for a single configuration
option, such as ``-background'' and ``-bg''.
TK_CONFIG_UID
The value is translated to a Tk_Uid (by passing it to Tk_GetUid).
The resulting value is stored in the target. If |
TK_CONFIG_NULL_OK is specified in specFlags and the value is an |
empty string then the target will be set to NULL. |
TK_CONFIG_WINDOW |
The value must be a window path name. It is translated to a |
Tk_Window token and the token is stored in the target. |
GROUPED ENTRIES
In some cases it is useful to generate multiple resources from a
single configuration value. For example, a color name might be used
both to generate the background color for a widget (using
TK_CONFIG_COLOR) and to generate a 3-D border to draw around the
widget (using TK_CONFIG_BORDER). In cases like this it is possible to
specify that several consecutive entries in specs are to be treated as
a group. The first entry is used to determine a value (using its
argvName, dbName, dbClass, and defValue fields). The value will be
processed several times (one for each entry in the group), generating
multiple different resources and modifying multiple targets within
widgRec. Each of the entries after the first must have a NULL value
in its argvName field; this indicates that the entry is to be grouped
with the entry that precedes it. Only the type and offset fields are
used from these follow-on entries.
FLAGS
The flags argument passed to Tk_ConfigureWidget is used in conjunction
with the specFlags fields in the entries of specs to provide
additional control over the processing of configuration options.
These values are used in three different ways as described below.
First, if the flags argument to Tk_ConfigureWidget has the
TK_CONFIG_ARGV_ONLY bit set (i.e., flags | TK_CONFIG_ARGV_ONLY != 0),
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then the option database and defValue fields are not used. In this
case, if an entry in specs doesn't match a field in argv then nothing
happens: the corresponding target isn't modified. This feature is
useful when the goal is to modify certain configuration options while
leaving others in their current state, such as when a configure widget
command is being processed.
Second, the specFlags field of an entry in specs may be used to |
control the processing of that entry. Each specFlags field may |
consists of an OR-ed combination of the following values: |
TK_CONFIG_COLOR_ONLY |
If this bit is set then the entry will only be considered if the |
display for tkwin has more than one bit plane. If the display is |
monochromatic then this specs entry will be ignored. |
TK_CONFIG_MONO_ONLY |
If this bit is set then the entry will only be considered if the |
display for tkwin has exactly one bit plane. If the display is |
not monochromatic then this specs entry will be ignored. |
TK_CONFIG_NULL_OK |
This bit is only relevant for some types of entries (see the |
descriptions of the various entry types above). If this bit is |
set, it indicates that an empty string value for the field is |
acceptable and if it occurs then the target should be set to NULL |
or None, depending on the type of the target. This flag 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. If this bit isn't set then empty strings are |
processed as strings, which generally results in an error. |
TK_CONFIG_DONT_SET_DEFAULT |
If this bit is one, it means that the defValue field of the entry |
should only be used for returning the default value in |
Tk_ConfigureInfo. In calls to Tk_ConfigureWidget no default will |
be supplied for entries with this flag set; it is assumed that |
the caller has already supplied a default value in the target |
location. This flag provides a performance optimization where it |
is expensive to process the default string: the client can |
compute the default once, save the value, and provide it before |
calling Tk_ConfigureWidget. |
TK_CONFIG_OPTION_SPECIFIED |
This bit is set and cleared by Tk_ConfigureWidget. Whenever |
Tk_ConfigureWidget returns, this bit will be set in all the |
entries where a value was specified in argv. It will be zero in |
all other entries. This bit provides a way for clients to |
determine which values actually changed in a call to |
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Tk_ConfigureWidget. |
The TK_CONFIG_MONO_ONLY and TK_CONFIG_COLOR_ONLY flags are typically
used to specify different default values for monochrome and color
displays. This is done by creating two entries in specs that are
identical except for their defValue and specFlags fields. One entry
should have the value TK_CONFIG_MONO_ONLY in its specFlags and the
default value for monochrome displays in its defValue; the other
entry entry should have the value TK_CONFIG_COLOR_ONLY in its
specFlags and the appropriate defValue for color displays.
Third, it is possible to use flags and specFlags together to
selectively disable some entries. This feature is not needed very
often. It is useful in cases where several similar kinds of widgets
are implemented in one place. It allows a single specs table to be
created with all the configuration options for all the widget types.
When processing a particular widget type, only entries relevant to
that type will be used. This effect is achieved by setting the high-
order bits (those in positions equal to or greater than
TK_CONFIG_USER_BIT) in specFlags values or in flags. In order for a
particular entry in specs to be used, its high-order bits must match
exactly the high-order bits of the flags value passed to
Tk_ConfigureWidget. If a specs table is being used for N different
widget types, then N of the high-order bits will be used. Each specs
entry will have one of more of those bits set in its specFlags field
to indicate the widget types for which this entry is valid. When
calling Tk_ConfigureWidget, flags will have a single one of these bits
set to select the entries for the desired widget type. For a working
example of this feature, see the code in tkButton.c.
TK_OFFSET
The Tk_Offset macro is provided as a safe way of generating the offset
values for entries in Tk_ConfigSpec 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.
TK_CONFIGUREINFO
The Tk_ConfigureInfo procedure may be used to obtain information about
one or all of the options for a given widget. Given a token for a
window (tkwin), a table describing the configuration options for a
class of widgets (specs), a pointer to a widget record containing the
current information for a widget (widgRec), and a NULL argvName
argument, Tk_ConfigureInfo generates a string describing all of the
configuration options for the window. The string is placed in
interp->result. Under normal circumstances it returns TCL_OK; if an
error occurs then it returns TCL_ERROR and interp->result contains an
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error message.
If argvName is NULL, then the value left in interp->result by
Tk_ConfigureInfo consists of a list of one or more entries, each of
which describes one configuration option (i.e. one entry in specs).
Each entry in the list will contain either two or five values. If the
corresponding entry in specs has type TK_CONFIG_SYNONYM, then the list
will contain two values: the argvName for the entry and the dbName
(synonym name). Otherwise the list will contain five values:
argvName, dbName, dbClass, defValue, and current value. The current
value is computed from the appropriate field of widgRec by calling
procedures like Tk_NameOfColor.
If the argvName argument to Tk_ConfigureInfo is non-NULL, then it
indicates a single option, and information is returned only for that
option. The string placed in interp->result will be a list containing
two or five values as described above; this will be identical to the
corresponding sublist that would have been returned if argvName had
been NULL.
The flags argument to Tk_ConfigureInfo is used to restrict the specs
entries to consider, just as for Tk_ConfigureWidget.
TK_FREEOPTIONS
The Tk_FreeOptions procedure may be invoked during widget cleanup to |
release all of the resources associated with configuration options. |
It scans through specs and for each entry corresponding to a resource |
that must be explicitly freed (e.g. those with type TK_CONFIG_COLOR), |
it frees the resource in the widget record. If the field in the |
widget record doesn't refer to a resource (e.g. it contains a null |
pointer) then no resource is freed for that entry. After freeing a |
resource, Tk_FreeOptions sets the corresponding field of the widget |
record to null. |
CUSTOM OPTION TYPES
Applications can extend the built-in configuration types with |
additional configuration types by writing procedures to parse and |
print options of the a type and creating a structure pointing to those |
procedures: |
typedef struct Tk_CustomOption { |
Tk_OptionParseProc *parseProc; |
Tk_OptionPrintProc *printProc; |
ClientData clientData; |
} Tk_CustomOption; |
typedef int Tk_OptionParseProc( |
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ClientData clientData, |
Tcl_Interp *interp, |
Tk_Window tkwin, |
char *value, |
char *widgRec, |
int offset); |
typedef char *Tk_OptionPrintProc( |
ClientData clientData, |
Tk_Window tkwin, |
char *widgRec, |
int offset, |
Tcl_FreeProc **freeProcPtr); |
The Tk_CustomOption structure contains three fields, which are |
pointers to the two 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. The |
parseProc procedure is invoked by Tk_ConfigureWidget to parse a string |
and store the resulting value in the widget record. The clientData |
argument is a copy of the clientData field in the Tk_CustomOption |
structure. The interp argument points to a Tcl interpreter used for |
error reporting. Tkwin is a copy of the tkwin argument to |
Tk_ConfigureWidget. The value argument is a string describing the |
value for the option; it could have been specified explicitly in the |
call to Tk_ConfigureWidget or it could come from the option database |
or a default. Value will never be a null pointer but it may point to |
an empty string. RecordPtr is the same as the widgRec argument to |
Tk_ConfigureWidget; it points to the start of the widget record to |
modify. The last argument, offset, gives the offset in bytes from the |
start of the widget record to the location where the option value is |
to be placed. The procedure should translate the string to whatever |
form is appropriate for the option and store the value in the widget |
record. It should normally return TCL_OK, but if an error occurs in |
translating the string to a value then it should return TCL_ERROR and |
store an error message in interp->result. The printProc procedure is |
called by Tk_ConfigureInfo to produce a string value describing an |
existing option. Its clientData, tkwin, widgRec, and offset arguments |
all have the same meaning as for Tk_OptionParseProc procedures. The |
printProc procedure should examine the option whose value is stored at |
offset in widgRec, produce a string describing that option, and return |
a pointer to the string. If the string is stored in dynamically- |
allocated memory, then the procedure must set *freeProcPtr to the |
address of a procedure to call to free the string's memory; |
Tk_ConfigureInfo will call this procedure when it is finished with the |
string. If the result string is stored in static memory then |
printProc need not do anything with the freeProcPtr argument. Once |
parseProc and printProc have been defined and a Tk_CustomOption |
structure has been created for them, options of this new type may be |
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manipulated with Tk_ConfigSpec entries whose type fields are |
TK_CONFIG_CUSTOM and whose customPtr fields point to the |
Tk_CustomOption structure. |
EXAMPLES
Although the explanation of Tk_ConfigureWidget is fairly complicated,
its actual use is pretty straightforward. The easiest way to get
started is to copy the code from an existing widget. The library
implementation of frames (tkFrame.c) has a simple configuration table,
and the library implementation of buttons (tkButton.c) has a much more
complex table that uses many of the fancy specFlags mechanisms.
KEYWORDS
anchor, bitmap, boolean, border, cap style, color, configuration
options, cursor, custom, double, font, integer, join style, justify,
millimeters, pixels, relief, synonym, uid
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