Страницы справочника OS X

Эта страница руководства является частью версии 5.0 Инструментов XCode

Читать страницы руководства

Tk_AllocFontFromObj(3)                      Tk Library Procedures                     Tk_AllocFontFromObj(3)



____________________________________________________________________________________________________________

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

SYNOPSIS
       #include <tk.h>

       Tk_Font
       Tk_AllocFontFromObj(interp, tkwin, objPtr)

       Tk_Font
       Tk_GetFont(interp, tkwin, string)

       Tk_Font
       Tk_GetFontFromObj(tkwin, objPtr)

       const char *
       Tk_NameOfFont(tkfont)

       Tk_Font
       Tk_FreeFontFromObj(tkwin, objPtr)

       void
       Tk_FreeFont(tkfont)


ARGUMENTS
       Tcl_Interp *interp (in)          Interpreter to use for error reporting.  If NULL, then no error mes-sages messages
                                        sages 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 Tk_Font.

       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.
____________________________________________________________________________________________________________

DESCRIPTION
       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_GetFontMetrics, Tk_Mea-sureChars, Tk_MeasureChars,
       sureChars, and Tk_FreeFont.  The Tk_Font token will remain valid until Tk_FreeFontFromObj or Tk_Free-Font Tk_FreeFont
       Font  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_AllocFontFro-mObj Tk_AllocFontFromObj
       mObj  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_AllocFont-FromObj Tk_AllocFontFromObj
       FromObj  caches  information about the return value in objPtr, which speeds up future calls to proce-dures procedures
       dures 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 noone
       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 string.

       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 information 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.


SEE ALSO
       Tk_FontId(3)

KEYWORDS
       font



Tk                                                   8.1                              Tk_AllocFontFromObj(3)