DOKK / manpages / debian 11 / tk8.6-doc / Tk_GetFont.3tk.en
Tk_AllocFontFromObj(3tk) Tk Library Procedures Tk_AllocFontFromObj(3tk) 







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








#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)









  
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 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.
    
    

    

  










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_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 procedures 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
    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.








Tk_FontId(3tk)








font







  

    8.1
    Tk