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CentOS 7.0 - man page for tk_allocfontfromobj (centos section 3)

Tk_AllocFontFromObj(3)		      Tk Library Procedures		   Tk_AllocFontFromObj(3)


       Tk_AllocFontFromObj,  Tk_GetFont,  Tk_GetFontFromObj,  Tk_NameOfFont,  Tk_FreeFontFromObj,
       Tk_FreeFont - maintain database of fonts

       #include <tk.h>

       Tk_AllocFontFromObj(interp, tkwin, objPtr)

       Tk_GetFont(interp, tkwin, string)

       Tk_GetFontFromObj(tkwin, objPtr)

       const char *

       Tk_FreeFontFromObj(tkwin, objPtr)


       Tcl_Interp *interp (in)		Interpreter to use for error reporting.  If NULL, then no
					error messages are left after errors.

       Tk_Window tkwin (in)		Token for window in which font will be used.

       Tcl_Obj *objPtr (in/out) 	Gives name or description of font.  See documentation for
					the font  command  for	details  on  acceptable  formats.
					Internal  rep  will  be  modified  to cache corresponding

       const char *string (in)		Same as objPtr except description of font is passed as	a
					string and resulting Tk_Font is not cached.

       Tk_Font tkfont (in)		Opaque font token.

       Tk_AllocFontFromObj finds the font indicated by objPtr and returns a token that represents
       the font.  The return value can be used in subsequent calls to procedures such as  Tk_Get-
       FontMetrics,  Tk_MeasureChars, and Tk_FreeFont.	The Tk_Font token will remain valid until
       Tk_FreeFontFromObj or Tk_FreeFont is called to release it.  ObjPtr can  contain	either	a
       symbolic  name  or  a  font  description; see the documentation for the font command for a
       description of the valid formats.  If Tk_AllocFontFromObj is  unsuccessful  (because,  for
       example,  objPtr  did  not  contain  a  valid font specification) then it returns NULL and
       leaves an error message in interp's result if interp  is  not  NULL.   Tk_AllocFontFromObj
       caches  information about the return value in objPtr, which speeds up future calls to pro-
       cedures such as Tk_AllocFontFromObj and Tk_GetFontFromObj.

       Tk_GetFont is identical to Tk_AllocFontFromObj except that the description of the font  is
       specified  with	a string instead of an object.	This prevents Tk_GetFont from caching the
       matching Tk_Font, so Tk_GetFont is less efficient than Tk_AllocFontFromObj.

       Tk_GetFontFromObj returns the token for an existing font, given the window and description
       used  to  create  the font.  Tk_GetFontFromObj does not actually create the font; the font
       must already have been created with a previous call to Tk_AllocFontFromObj or  Tk_GetFont.
       The  return  value  is cached in objPtr, which speeds up future calls to Tk_GetFontFromObj
       with the same objPtr and tkwin.

       Tk_AllocFontFromObj and Tk_GetFont maintain a database of all fonts they  have  allocated.
       If  the	same font is requested multiple times (e.g. by different windows or for different
       purposes), then a single Tk_Font will be shared for all uses.   The  underlying	resources
       will be freed automatically when no-one is using the font anymore.

       The procedure Tk_NameOfFont is roughly the inverse of Tk_GetFont.  Given a tkfont that was
       created by Tk_GetFont (or Tk_AllocFontFromObj), the return value is  the  string  argument
       that was passed to Tk_GetFont to create the font.  The string returned by Tk_NameOfFont is
       only guaranteed to persist until the tkfont is deleted.	The caller must not  modify  this

       When  a	font  is  no longer needed, Tk_FreeFontFromObj or Tk_FreeFont should be called to
       release it.  For Tk_FreeFontFromObj the font to release is specified with the same  infor-
       mation  used  to  create  it;  for  Tk_FreeFont	the font to release is specified with its
       Tk_Font token.  There should be exactly one call to Tk_FreeFontFromObj or Tk_FreeFont  for
       each call to Tk_AllocFontFromObj or Tk_GetFont.



Tk					       8.1			   Tk_AllocFontFromObj(3)

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