4 * This file is part of LyX, the document processor.
5 * Licence details can be found in the file COPYING.
9 * \author Abdelrazak Younes
11 * Full author contact details are available in file CREDITS.
14 #ifndef FONT_METRICS_H
15 #define FONT_METRICS_H
17 #include "support/strfwd.h"
20 * A class holding helper functions for determining
21 * the screen dimensions of fonts.
23 * The geometry is the standard typographical geometry,
26 * --------------+------------------<maxAscent
28 * <-------> (right bearing)
32 * origin>____ | oo oo | oo oo
34 * --------------+---ooooo--|--oooo-<baseline
37 * descent>______| oooo |
39 * --------------+----------+-------<maxDescent
41 * Caution: All char_type and docstring arguments of any method of this class
42 * are no UCS4 chars or strings if the font is a symbol font. They simply
43 * denote the code points of the font instead. You have to keep this in mind
44 * when you implement the methods in a frontend. You must not pass these
45 * parameters to a unicode conversion function in particular.
57 virtual ~FontMetrics() {}
59 /// return the maximum ascent of the font
60 virtual int maxAscent() const = 0;
61 /// return the maximum descent of the font
62 virtual int maxDescent() const = 0;
63 /// return default dimension of the font.
64 /// \warning \c width is set to zero.
65 virtual Dimension const defaultDimension() const = 0;
66 /// return the width of the char in the font
67 virtual int width(char_type c) const = 0;
68 /// return the ascent of the char in the font
69 virtual int ascent(char_type c) const = 0;
70 /// return the descent of the char in the font
71 virtual int descent(char_type c) const = 0;
72 /// return the left bearing of the char in the font
73 virtual int lbearing(char_type c) const = 0;
74 /// return the right bearing of the char in the font
75 virtual int rbearing(char_type c) const = 0;
76 /// return the width of the string in the font
77 virtual int width(docstring const & s) const = 0;
79 virtual int signedWidth(docstring const & s) const = 0;
80 /// return char dimension for the font.
81 virtual Dimension const dimension(char_type c) const = 0;
83 * fill in width,ascent,descent with the values for the
84 * given string in the font.
86 virtual void rectText(docstring const & str,
89 int & descent) const = 0;
91 * fill in width,ascent,descent with the values for the
92 * given string in the font for a button.
94 virtual void buttonText(docstring const & str,
97 int & descent) const = 0;
99 /// return the maximum descent of the font
100 inline int maxHeight() const { return maxAscent() + maxDescent(); }
102 /// return the descent of the char in the font
103 inline int height(char_type c) const { return ascent(c) + descent(c); }
105 /// return the inner width of the char in the font
106 inline int center(char_type c) const {
107 return (rbearing(c) - lbearing(c)) / 2;
112 } // namespace frontend
117 /// Implementation is in Application.cpp
118 frontend::FontMetrics const & theFontMetrics(Font const & f);
119 frontend::FontMetrics const & theFontMetrics(FontInfo const & fi);
123 #endif // FONT_METRICS_H