Tcl 8.7/Tk8.7a5 Documentation > Tk C API > GetFont

Tcl/Tk Applications | Tcl Commands | Tk Commands | Tcl C API | Tk C API

NAME

Tk_AllocFontFromObj, Tk_GetFont, Tk_GetFontFromObj, Tk_NameOfFont, Tk_FontGetDescription, Tk_FreeFontFromObj, Tk_FreeFont — 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)

Tcl_Obj *

Tk_FontGetDescription(tkfont)

const char *

Tk_NameOfFont(tkfont)

Tk_Font

Tk_FreeFontFromObj(tkwin, objPtr)

void

Tk_FreeFont(tkfont)

ARGUMENTS

DESCRIPTION

SEE ALSO

KEYWORDS

NAME

SYNOPSIS

ARGUMENTS

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.

DESCRIPTION

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_FontGetDescription returns information about the font description as a Tcl list. One possible result is "{{DejaVu Sans} -16 bold underline}".

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

KEYWORDS