1Tk_AllocFontFromObj(3) Tk Library Procedures Tk_AllocFontFromObj(3)
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6
8 Tk_AllocFontFromObj, Tk_GetFont, Tk_GetFontFromObj, Tk_NameOfFont,
9 Tk_FreeFontFromObj, Tk_FreeFont - maintain database of fonts
10
12 #include <tk.h>
13 Tk_Font │
15 Tk_AllocFontFromObj(interp, tkwin, objPtr) │
16 Tk_Font │
18 Tk_GetFont(interp, tkwin, string) │
19 Tk_Font │
21 Tk_GetFontFromObj(tkwin, objPtr) │
22 CONST char *
24 Tk_NameOfFont(tkfont)
25 Tk_Font │
27 Tk_FreeFontFromObj(tkwin, objPtr) │
28 void
30 Tk_FreeFont(tkfont)
31
34 Tcl_Interp *interp (in) Interpreter to use for error report‐
35 ing. If NULL, then no error messages
36 are left after errors.
37 Tk_Window tkwin (in) Token for window in which font will be
39 used.
40 Tcl_Obj *objPtr (in/out) │
42 Gives name or description of font. │
43 See documentation for the font command │
44 for details on acceptable formats. │
45 Internal rep will be modified to cache │
46 corresponding Tk_Font. │
47 const char *string (in) │
49 Same as objPtr except description of │
50 font is passed as a string and result‐ │
51 ing Tk_Font isn't cached.
52 Tk_Font tkfont (in) Opaque font token.
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55
57 Tk_AllocFontFromObj finds the font indicated by objPtr and returns a │
58 token that represents the font. The return value can be used in subse‐ │
59 quent calls to procedures such as Tk_GetFontMetrics, Tk_MeasureChars, │
60 and Tk_FreeFont. The Tk_Font token will remain valid until Tk_Free‐ │
61 FontFromObj or Tk_FreeFont is called to release it. ObjPtr can contain │
62 either a symbolic name or a font description; see the documentation for │
63 the font command for a description of the valid formats. If Tk_Alloc‐ │
64 FontFromObj is unsuccessful (because, for example, objPtr did not con‐ │
65 tain a valid font specification) then it returns NULL and leaves an │
66 error message in interp's result if interp isn't NULL. Tk_AllocFont‐ │
67 FromObj caches information about the return value in objPtr, which │
68 speeds up future calls to procedures such as Tk_AllocFontFromObj and │
69 Tk_GetFontFromObj. │
70 Tk_GetFont is identical to Tk_AllocFontFromObj except that the descrip‐ │
72 tion of the font is specified with a string instead of an object. This │
73 prevents Tk_GetFont from caching the matching Tk_Font, so Tk_GetFont is │
74 less efficient than Tk_AllocFontFromObj. │
75 Tk_GetFontFromObj returns the token for an existing font, given the │
77 window and description used to create the font. Tk_GetFontFromObj │
78 doesn't actually create the font; the font must already have been cre‐ │
79 ated with a previous call to Tk_AllocFontFromObj or Tk_GetFont. The │
80 return value is cached in objPtr, which speeds up future calls to │
81 Tk_GetFontFromObj with the same objPtr and tkwin.
82 Tk_AllocFontFromObj and Tk_GetFont maintain a database of all fonts
84 they have allocated. If the same font is requested multiple times
85 (e.g. by different windows or for different purposes), then a single
86 Tk_Font will be shared for all uses. The underlying resources will be
87 freed automatically when no-one is using the font anymore.
88 The procedure Tk_NameOfFont is roughly the inverse of Tk_GetFont.
90 Given a tkfont that was created by Tk_GetFont (or Tk_AllocFontFromObj),
91 the return value is the string argument that was passed to Tk_GetFont
92 to create the font. The string returned by Tk_NameOfFont is only guar‐
93 anteed to persist until the tkfont is deleted. The caller must not
94 modify this string.
95 When a font is no longer needed, Tk_FreeFontFromObj or Tk_FreeFont │
97 should be called to release it. For Tk_FreeFontFromObj the font to │
98 release is specified with the same information used to create it; for │
99 Tk_FreeFont the font to release is specified with its Tk_Font token. │
100 There should be exactly one call to Tk_FreeFontFromObj or Tk_FreeFont │
101 for each call to Tk_AllocFontFromObj or Tk_GetFont.
102
105 Tk_FontId(3)
106
109 font
110Tk 8.1 Tk_AllocFontFromObj(3)