Tk_GetFontStruct(3Tk)Tk_GetFontStruct(3Tk)NAME
Tk_GetFontStruct, Tk_NameOfFontStruct, Tk_FreeFontStruct - maintain
database of fonts
SYNOPSIS
#include <tk.h>
XFontStruct *
Tk_GetFontStruct(interp, tkwin, nameId)
char *
Tk_NameOfFontStruct(fontStructPtr)Tk_FreeFontStruct(fontStructPtr)ARGUMENTS
Tcl_Interp *interp (in) Interpreter to use for error
reporting.
Tk_Window tkwin (in) Token for window in which font
will be used.
Tk_Uid nameId (in) Name of desired font.
XFontStruct *fontStructPtr (in) Font structure to return name
for or delete.
DESCRIPTION
Tk_GetFont loads the font indicated by nameId and returns a pointer to
information about the font. The pointer returned by Tk_GetFont will
remain valid until Tk_FreeFont is called to release it. NameId can be
either a font name or pattern; any value that could be passed to
XLoadQueryFont may be passed to Tk_GetFont. If Tk_GetFont is
unsuccessful (because, for example, there is no font corresponding to
nameId) then it returns NULL and stores an error message in interp-
>result.
Tk_GetFont maintains a database of all fonts it has allocated. If the
same nameId is requested multiple times (e.g. by different windows or for
different purposes), then additional calls for the same nameId will be
handled very quickly, without involving the X server. For this reason,
it is generally better to use Tk_GetFont in place of X library procedures
like XLoadQueryFont.
The procedure Tk_NameOfFontStruct is roughly the inverse of
Tk_GetFontStruct. If its fontStructPtr argument was created by
Tk_GetFontStruct, then the return value is the nameId argument that was
passed to Tk_GetFontStruct to create the font. If fontStructPtr was not
created by a call to Tk_GetFontStruct, then the return value is a
hexadecimal string giving the X identifier for the associated font.
Note: the string returned by Tk_NameOfFontStruct is only guaranteed to
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Tk_GetFontStruct(3Tk)Tk_GetFontStruct(3Tk)
persist until the next call to Tk_NameOfFontStruct.
When a font returned by Tk_GetFont is no longer needed, Tk_FreeFont
should be called to release it. There should be exactly one call to
Tk_FreeFont for each call to Tk_GetFont. When a font is no longer in use
anywhere (i.e. it has been freed as many times as it has been gotten)
Tk_FreeFont will release it to the X server and delete it from the
database.
KEYWORDS
font
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