1Tk_FontId(3) Tk Library Procedures Tk_FontId(3)
2______________________________________________________________________________
6
8 Tk_FontId, Tk_GetFontMetrics, Tk_PostscriptFontName - accessor func‐
9 tions for fonts
10
12 #include <tk.h>
13 Font
15 Tk_FontId(tkfont)
16 void
18 Tk_GetFontMetrics(tkfont, fmPtr)
19 int
21 Tk_PostscriptFontName(tkfont, dsPtr)
22
25 Tk_Font tkfont (in) Opaque font token being queried.
26 Must have been returned by a previ‐
27 ous call to Tk_GetFont.
28 Tk_FontMetrics *fmPtr (out) Pointer to structure in which the
30 font metrics for tkfont will be
31 stored.
32 Tcl_DString *dsPtr (out) Pointer to an initialized
34 Tcl_DString to which the name of
35 the Postscript font that corre‐
36 sponds to tkfont will be appended.
37_________________________________________________________________
38
41 Given a tkfont, Tk_FontId returns the token that should be selected
42 into an XGCValues structure in order to construct a graphics context
43 that can be used to draw text in the specified font.
44 Tk_GetFontMetrics computes the ascent, descent, and linespace of the
46 tkfont in pixels and stores those values in the structure pointer to by
47 fmPtr. These values can be used in computations such as to space mul‐
48 tiple lines of text, to align the baselines of text in different fonts,
49 and to vertically align text in a given region. See the documentation
50 for the font command for definitions of the terms ascent, descent, and
51 linespace, used in font metrics.
52 Tk_PostscriptFontName maps a tkfont to the corresponding Postcript font
54 name that should be used when printing. The return value is the size
55 in points of the tkfont and the Postscript font name is appended to
56 dsPtr. DsPtr must refer to an initialized Tcl_DString. Given a ``rea‐
57 sonable'' Postscript printer, the following screen font families should
58 print correctly:
59 Avant Garde, Arial, Bookman, Courier, Courier New, Geneva, Hel‐
61 vetica, Monaco, New Century Schoolbook, New York, Palatino, Sym‐
62 bol, Times, Times New Roman, Zapf Chancery, and Zapf Dingbats.
63 Any other font families may not print correctly because the computed
65 Postscript font name may be incorrect or not exist on the printer.
66
68 The Tk_FontMetrics data structure is used by Tk_GetFontMetrics to │
69 return information about a font and is defined as follows: │
70 typedef struct Tk_FontMetrics { │
71 int ascent; │
72 int descent; │
73 int linespace; │
74 } Tk_FontMetrics; │
75 The linespace field is the amount in pixels that the tallest letter │
76 sticks up above the baseline, plus any extra blank space added by the │
77 designer of the font. │
78 The descent is the largest amount in pixels that any letter sticks │
80 below the baseline, plus any extra blank space added by the designer of │
81 the font. │
82 The linespace is the sum of the ascent and descent. How far apart two │
84 lines of text in the same font should be placed so that none of the │
85 characters in one line overlap any of the characters in the other line.
86
88 font
89Tk 8.0 Tk_FontId(3)