1Tk_FontId(3)                 Tk Library Procedures                Tk_FontId(3)
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NAME

8       Tk_FontId,  Tk_GetFontMetrics,  Tk_PostscriptFontName  - accessor func‐
9       tions for fonts
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SYNOPSIS

12       #include <tk.h>
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14       Font
15       Tk_FontId(tkfont)
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17       Tk_GetFontMetrics(tkfont, fmPtr)
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19       int
20       Tk_PostscriptFontName(tkfont, dsPtr)
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ARGUMENTS

23       Tk_Font tkfont (in)                 Opaque font  token  being  queried.
24                                           Must have been returned by a previ‐
25                                           ous call to Tk_GetFont.
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27       Tk_FontMetrics *fmPtr (out)         Pointer to structure in  which  the
28                                           font  metrics  for  tkfont  will be
29                                           stored. See DATA  STRUCTURES  below
30                                           for details.
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32       Tcl_DString *dsPtr (out)            Pointer     to    an    initialized
33                                           Tcl_DString to which  the  name  of
34                                           the  Postscript  font  that  corre‐
35                                           sponds to tkfont will be appended.
36______________________________________________________________________________
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DESCRIPTION

39       Given a tkfont, Tk_FontId returns the token  that  should  be  selected
40       into  an  XGCValues  structure in order to construct a graphics context
41       that can be used to draw text in the specified font.
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43       Tk_GetFontMetrics computes the ascent, descent, and  linespace  of  the
44       tkfont in pixels and stores those values in the structure pointer to by
45       fmPtr.  These values can be used in computations such as to space  mul‐
46       tiple lines of text, to align the baselines of text in different fonts,
47       and to vertically align text in a given region.  See the  documentation
48       for  the font command for definitions of the terms ascent, descent, and
49       linespace, used in font metrics.
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51       Tk_PostscriptFontName maps a tkfont  to  the  corresponding  Postscript
52       font  name  that should be used when printing.  The return value is the
53       size in points of the tkfont and the Postscript font name  is  appended
54       to  dsPtr.   DsPtr  must  refer to an initialized Tcl_DString.  Given a
55       “reasonable” Postscript printer, the  following  screen  font  families
56       should print correctly:
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58              Avant  Garde, Arial, Bookman, Courier, Courier New, Geneva, Hel‐
59              vetica, Monaco, New Century Schoolbook, New York, Palatino, Sym‐
60              bol, Times, Times New Roman, Zapf Chancery, and Zapf Dingbats.
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62       Any  other  font  families may not print correctly because the computed
63       Postscript font name may be incorrect or not exist on the printer.
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DATA STRUCTURES

66       The Tk_FontMetrics data  structure  is  used  by  Tk_GetFontMetrics  to
67       return information about a font and is defined as follows:
68              typedef struct Tk_FontMetrics {
69                  int ascent;
70                  int descent;
71                  int linespace;
72              } Tk_FontMetrics;
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74       The ascent field is the amount in pixels that the tallest letter sticks
75       up above the baseline, plus any extra blank space added by the designer
76       of the font.
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78       The  descent  is  the  largest  amount in pixels that any letter sticks
79       below the baseline, plus any extra blank space added by the designer of
80       the font.
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82       The  linespace is the sum of the ascent and descent.  How far apart two
83       lines of text in the same font should be placed so  that  none  of  the
84       characters in one line overlap any of the characters in the other line.
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SEE ALSO

87       font(n), MeasureChar(3)
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KEYWORDS

90       font, measurement, Postscript
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94Tk                                    8.0                         Tk_FontId(3)
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