2 * \file GuiFontMetrics.cpp
3 * This file is part of LyX, the document processor.
4 * Licence details can be found in the file COPYING.
9 * Full author contact details are available in file CREDITS.
14 #include "GuiFontMetrics.h"
16 #include "qt_helpers.h"
18 #include "Dimension.h"
22 #include "insets/Inset.h"
24 #include "support/lassert.h"
26 #include <QTextLayout>
29 using namespace lyx::support;
36 * Convert a UCS4 character into a QChar.
37 * This is a hack (it does only make sense for the common part of the UCS4
38 * and UTF16 encodings) and should not be used.
39 * This does only exist because of performance reasons (a real conversion
40 * using iconv is too slow on windows).
42 * This is no real conversion but a simple cast in reality. This is the reason
43 * why this works well for symbol fonts used in mathed too, even though
44 * these are not real ucs4 characters. These are codepoints in the
45 * computer modern fonts used, nothing unicode related.
46 * See comment in GuiPainter::text() for more explanation.
48 inline QChar const ucs4_to_qchar(char_type const ucs4)
50 LATTEST(is_utf16(ucs4));
51 return QChar(static_cast<unsigned short>(ucs4));
56 GuiFontMetrics::GuiFontMetrics(QFont const & font) : font_(font), metrics_(font, 0)
61 int GuiFontMetrics::maxAscent() const
63 return metrics_.ascent();
67 int GuiFontMetrics::maxDescent() const
69 // We add 1 as the value returned by QT is different than X
70 // See http://doc.trolltech.com/2.3/qfontmetrics.html#200b74
71 return metrics_.descent() + 1;
75 int GuiFontMetrics::lbearing(char_type c) const
78 // FIXME: QFontMetrics::leftBearingdoes not support the
79 // full unicode range. Once it does, we could use:
80 //return metrics_.leftBearing(toqstr(docstring(1, c)));
83 return metrics_.leftBearing(ucs4_to_qchar(c));
88 int const outOfLimitMetric = -10000;
92 int GuiFontMetrics::rbearing(char_type c) const
94 int value = rbearing_cache_.value(c, outOfLimitMetric);
95 if (value != outOfLimitMetric)
98 // Qt rbearing is from the right edge of the char's width().
100 QChar sc = ucs4_to_qchar(c);
101 value = width(c) - metrics_.rightBearing(sc);
103 // FIXME: QFontMetrics::leftBearing does not support the
104 // full unicode range. Once it does, we could use:
105 // metrics_.rightBearing(toqstr(docstring(1, c)));
109 rbearing_cache_.insert(c, value);
115 int GuiFontMetrics::width(docstring const & s) const
118 map<docstring, int>::const_iterator it = strwidth_cache_.find(s);
119 if (it != strwidth_cache_.end()) {
122 w = metrics_.width(toqstr(s));
123 strwidth_cache_[s] = w;
129 int GuiFontMetrics::width(QString const & ucs2) const
131 return width(qstring_to_ucs4(ucs2));
135 int GuiFontMetrics::signedWidth(docstring const & s) const
141 return -width(s.substr(1, s.size() - 1));
147 void setTextLayout(QTextLayout & tl, docstring const & s, QFont const & font,
150 tl.setText(toqstr(s));
152 // Note that both setFlags and the enums are undocumented
153 tl.setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
161 int GuiFontMetrics::pos2x(docstring const & s, int const pos, bool const rtl) const
164 setTextLayout(tl, s, font_, rtl);
165 return static_cast<int>(tl.lineForTextPosition(pos).cursorToX(pos));
169 int GuiFontMetrics::x2pos(docstring const & s, int & x, bool const rtl) const
172 setTextLayout(tl, s, font_, rtl);
173 int pos = tl.lineForTextPosition(0).xToCursor(x);
174 // correct x value to the actual cursor position.
175 x = static_cast<int>(tl.lineForTextPosition(0).cursorToX(pos));
180 void GuiFontMetrics::rectText(docstring const & str,
181 int & w, int & ascent, int & descent) const
183 static int const d = Inset::TEXT_TO_INSET_OFFSET / 2;
185 w = width(str) + Inset::TEXT_TO_INSET_OFFSET;
186 ascent = metrics_.ascent() + d;
187 descent = metrics_.descent() + d;
192 void GuiFontMetrics::buttonText(docstring const & str,
193 int & w, int & ascent, int & descent) const
195 rectText(str, w, ascent, descent);
196 w += Inset::TEXT_TO_INSET_OFFSET;
200 Dimension const GuiFontMetrics::defaultDimension() const
202 return Dimension(0, maxAscent(), maxDescent());
206 Dimension const GuiFontMetrics::dimension(char_type c) const
208 return Dimension(width(c), ascent(c), descent(c));
212 GuiFontMetrics::AscendDescend const GuiFontMetrics::fillMetricsCache(
217 r = metrics_.boundingRect(ucs4_to_qchar(c));
219 r = metrics_.boundingRect(toqstr(docstring(1, c)));
221 AscendDescend ad = { -r.top(), r.bottom() + 1};
222 // We could as well compute the width but this is not really
223 // needed for now as it is done directly in width() below.
224 metrics_cache_.insert(c, ad);
230 int GuiFontMetrics::width(char_type c) const
232 int value = width_cache_.value(c, outOfLimitMetric);
233 if (value != outOfLimitMetric)
237 value = metrics_.width(ucs4_to_qchar(c));
239 value = metrics_.width(toqstr(docstring(1, c)));
241 width_cache_.insert(c, value);
247 int GuiFontMetrics::ascent(char_type c) const
249 static AscendDescend const outOfLimitAD =
250 {outOfLimitMetric, outOfLimitMetric};
251 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
252 if (value.ascent != outOfLimitMetric)
255 value = fillMetricsCache(c);
260 int GuiFontMetrics::descent(char_type c) const
262 static AscendDescend const outOfLimitAD =
263 {outOfLimitMetric, outOfLimitMetric};
264 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
265 if (value.descent != outOfLimitMetric)
266 return value.descent;
268 value = fillMetricsCache(c);
269 return value.descent;
272 } // namespace frontend