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/convert.h"
25 #include "support/lassert.h"
27 #define DISABLE_PMPROF
28 #include "support/pmprof.h"
33 using namespace lyx::support;
38 * Argument-dependent lookup implies that this function shall be
39 * declared in the namespace of its argument. But this is std
40 * namespace, since lyx::docstring is just std::basic_string<wchar_t>.
42 uint qHash(lyx::docstring const & s)
44 return qHash(QByteArray(reinterpret_cast<char const *>(s.data()),
45 s.size() * sizeof(lyx::docstring::value_type)));
55 * Limit (strwidth|breakat)_cache_ size to 512kB of string data.
56 * Limit qtextlayout_cache_ size to 500 elements (we do not know the
57 * size of the QTextLayout objects anyway).
58 * Note that all these numbers are arbitrary.
59 * Also, setting size to 0 is tantamount to disabling the cache.
61 int cache_metrics_width_size = 1 << 19;
62 int cache_metrics_breakat_size = 1 << 19;
63 // Qt 5.x already has its own caching of QTextLayout objects
64 #if (QT_VERSION < 0x050000)
65 int cache_metrics_qtextlayout_size = 500;
67 int cache_metrics_qtextlayout_size = 0;
73 * Convert a UCS4 character into a QChar.
74 * This is a hack (it does only make sense for the common part of the UCS4
75 * and UTF16 encodings) and should not be used.
76 * This does only exist because of performance reasons (a real conversion
77 * using iconv is too slow on windows).
79 * This is no real conversion but a simple cast in reality. This is the reason
80 * why this works well for symbol fonts used in mathed too, even though
81 * these are not real ucs4 characters. These are codepoints in the
82 * computer modern fonts used, nothing unicode related.
83 * See comment in GuiPainter::text() for more explanation.
85 inline QChar const ucs4_to_qchar(char_type const ucs4)
87 LATTEST(is_utf16(ucs4));
88 return QChar(static_cast<unsigned short>(ucs4));
93 GuiFontMetrics::GuiFontMetrics(QFont const & font)
94 : font_(font), metrics_(font, 0),
95 strwidth_cache_(cache_metrics_width_size),
96 breakat_cache_(cache_metrics_breakat_size),
97 qtextlayout_cache_(cache_metrics_qtextlayout_size)
102 int GuiFontMetrics::maxAscent() const
104 return metrics_.ascent();
108 int GuiFontMetrics::maxDescent() const
110 // We add 1 as the value returned by QT is different than X
111 // See http://doc.trolltech.com/2.3/qfontmetrics.html#200b74
112 return metrics_.descent() + 1;
116 int GuiFontMetrics::em() const
118 return QFontInfo(font_).pixelSize();
122 int GuiFontMetrics::lineWidth() const
124 return metrics_.lineWidth();
128 int GuiFontMetrics::underlinePos() const
130 return metrics_.underlinePos();
134 int GuiFontMetrics::strikeoutPos() const
136 return metrics_.strikeOutPos();
140 int GuiFontMetrics::lbearing(char_type c) const
143 // FIXME: QFontMetrics::leftBearing does not support the
144 // full unicode range. Once it does, we could use:
145 //return metrics_.leftBearing(toqstr(docstring(1, c)));
148 return metrics_.leftBearing(ucs4_to_qchar(c));
153 int const outOfLimitMetric = -10000;
157 int GuiFontMetrics::rbearing(char_type c) const
159 int value = rbearing_cache_.value(c, outOfLimitMetric);
160 if (value != outOfLimitMetric)
163 // Qt rbearing is from the right edge of the char's width().
165 QChar sc = ucs4_to_qchar(c);
166 value = width(c) - metrics_.rightBearing(sc);
168 // FIXME: QFontMetrics::leftBearing does not support the
169 // full unicode range. Once it does, we could use:
170 // metrics_.rightBearing(toqstr(docstring(1, c)));
174 rbearing_cache_.insert(c, value);
180 int GuiFontMetrics::width(docstring const & s) const
182 PROFILE_THIS_BLOCK(width);
183 if (strwidth_cache_.contains(s))
184 return strwidth_cache_[s];
185 PROFILE_CACHE_MISS(width);
186 /* For some reason QMetrics::width returns a wrong value with Qt5
187 * with some arabic text. OTOH, QTextLayout is broken for single
188 * characters with null width (like \not in mathed). Also, as a
189 * safety measure, always use QMetrics::width with our math fonts.
193 #if QT_VERSION >= 0x040800
194 || font_.styleName() == "LyX"
197 w = metrics_.width(toqstr(s));
200 tl.setText(toqstr(s));
203 QTextLine line = tl.createLine();
205 w = int(line.naturalTextWidth());
207 strwidth_cache_.insert(s, w, s.size() * sizeof(char_type));
212 int GuiFontMetrics::width(QString const & ucs2) const
214 return width(qstring_to_ucs4(ucs2));
218 int GuiFontMetrics::signedWidth(docstring const & s) const
224 return -width(s.substr(1, s.size() - 1));
230 shared_ptr<QTextLayout const>
231 GuiFontMetrics::getTextLayout(docstring const & s, bool const rtl,
232 double const wordspacing) const
234 PROFILE_THIS_BLOCK(getTextLayout);
235 docstring const s_cache =
236 s + (rtl ? "r" : "l") + convert<docstring>(wordspacing);
237 if (auto ptl = qtextlayout_cache_[s_cache])
239 PROFILE_CACHE_MISS(getTextLayout);
240 auto const ptl = make_shared<QTextLayout>();
241 ptl->setCacheEnabled(true);
242 ptl->setText(toqstr(s));
244 copy.setWordSpacing(wordspacing);
246 // Note that both setFlags and the enums are undocumented
247 ptl->setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
251 qtextlayout_cache_.insert(s_cache, ptl);
256 int GuiFontMetrics::pos2x(docstring const & s, int pos, bool const rtl,
257 double const wordspacing) const
261 shared_ptr<QTextLayout const> tl = getTextLayout(s, rtl, wordspacing);
262 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
263 * not be the same when there are high-plan unicode characters
266 int const qpos = toqstr(s.substr(0, pos)).length();
267 return static_cast<int>(tl->lineForTextPosition(qpos).cursorToX(qpos));
271 int GuiFontMetrics::x2pos(docstring const & s, int & x, bool const rtl,
272 double const wordspacing) const
274 shared_ptr<QTextLayout const> tl = getTextLayout(s, rtl, wordspacing);
275 int const qpos = tl->lineForTextPosition(0).xToCursor(x);
276 // correct x value to the actual cursor position.
277 x = static_cast<int>(tl->lineForTextPosition(0).cursorToX(qpos));
278 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
279 * not be the same when there are high-plan unicode characters
282 #if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
283 return qstring_to_ucs4(tl->text().left(qpos)).length();
285 /* Due to QTBUG-25536 in 4.8.1 <= Qt < 5.1.0, the string returned
286 * by QString::toUcs4 (used by qstring_to_ucs4) may have wrong
287 * length. We work around the problem by trying all docstring
288 * positions until the right one is found. This is slow only if
289 * there are many high-plane Unicode characters. It might be
290 * worthwhile to implement a dichotomy search if this shows up
293 int pos = min(qpos, static_cast<int>(s.length()));
294 while (pos >= 0 && toqstr(s.substr(0, pos)).length() != qpos)
296 LASSERT(pos > 0 || qpos == 0, /**/);
302 int GuiFontMetrics::countExpanders(docstring const & str) const
304 // Numbers of characters that are expanded by inter-word spacing. These
305 // characters are spaces, except for characters 09-0D which are treated
306 // specially. (From a combination of testing with the notepad found in qt's
307 // examples, and reading the source code.) In addition, consecutive spaces
308 // only count as one expander.
309 bool wasspace = false;
311 for (char_type c : str)
312 if (c > 0x0d && QChar(c).isSpace()) {
324 GuiFontMetrics::breakAt_helper(docstring const & s, int const x,
325 bool const rtl, bool const force) const
328 /* Qt will not break at a leading or trailing space, and we need
329 * that sometimes, see http://www.lyx.org/trac/ticket/9921.
331 * To work around the problem, we enclose the string between
332 * zero-width characters so that the QTextLayout algorithm will
333 * agree to break the text at these extremal spaces.
335 // Unicode character ZERO WIDTH NO-BREAK SPACE
336 QChar const zerow_nbsp(0xfeff);
337 QString qs = zerow_nbsp + toqstr(s) + zerow_nbsp;
339 /* Use unicode override characters to enforce drawing direction
340 * Source: http://www.iamcal.com/understanding-bidirectional-text/
343 // Right-to-left override: forces to draw text right-to-left
344 qs = QChar(0x202E) + qs;
346 // Left-to-right override: forces to draw text left-to-right
347 qs = QChar(0x202D) + qs;
348 int const offset = 2;
350 // Alternative version that breaks with Qt5 and arabic text (#10436)
351 // Note that both setFlags and the enums are undocumented
352 tl.setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
353 int const offset = 1;
359 to.setWrapMode(force ? QTextOption::WrapAtWordBoundaryOrAnywhere
360 : QTextOption::WordWrap);
361 tl.setTextOption(to);
363 QTextLine line = tl.createLine();
364 line.setLineWidth(x);
367 if ((force && line.textLength() == offset) || int(line.naturalTextWidth()) > x)
369 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
370 * not be the same when there are high-plan unicode characters
373 // The variable `offset' is here to account for the extra leading characters.
374 // The ending character zerow_nbsp has to be ignored if the line is complete.
375 int const qlen = line.textLength() - offset - (line.textLength() == qs.length());
376 #if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
377 int len = qstring_to_ucs4(qs.mid(offset, qlen)).length();
379 /* Due to QTBUG-25536 in 4.8.1 <= Qt < 5.1.0, the string returned
380 * by QString::toUcs4 (used by qstring_to_ucs4) may have wrong
381 * length. We work around the problem by trying all docstring
382 * positions until the right one is found. This is slow only if
383 * there are many high-plane Unicode characters. It might be
384 * worthwhile to implement a dichotomy search if this shows up
387 int len = min(qlen, static_cast<int>(s.length()));
388 while (len >= 0 && toqstr(s.substr(0, len)).length() != qlen)
390 LASSERT(len > 0 || qlen == 0, /**/);
392 // The -1 is here to account for the leading zerow_nbsp.
393 return {len, int(line.naturalTextWidth())};
397 bool GuiFontMetrics::breakAt(docstring & s, int & x, bool const rtl, bool const force) const
399 PROFILE_THIS_BLOCK(breakAt);
403 docstring const s_cache =
404 s + convert<docstring>(x) + (rtl ? "r" : "l") + (force ? "f" : "w");
407 if (breakat_cache_.contains(s_cache))
408 pp = breakat_cache_[s_cache];
410 PROFILE_CACHE_MISS(breakAt);
411 pp = breakAt_helper(s, x, rtl, force);
412 breakat_cache_.insert(s_cache, pp, s_cache.size() * sizeof(char_type));
416 s = s.substr(0, pp.first);
422 void GuiFontMetrics::rectText(docstring const & str,
423 int & w, int & ascent, int & descent) const
425 static int const d = Inset::TEXT_TO_INSET_OFFSET / 2;
427 w = width(str) + Inset::TEXT_TO_INSET_OFFSET;
428 ascent = metrics_.ascent() + d;
429 descent = metrics_.descent() + d;
433 void GuiFontMetrics::buttonText(docstring const & str,
434 int & w, int & ascent, int & descent) const
436 rectText(str, w, ascent, descent);
437 w += Inset::TEXT_TO_INSET_OFFSET;
441 Dimension const GuiFontMetrics::defaultDimension() const
443 return Dimension(0, maxAscent(), maxDescent());
447 Dimension const GuiFontMetrics::dimension(char_type c) const
449 return Dimension(width(c), ascent(c), descent(c));
453 GuiFontMetrics::AscendDescend const GuiFontMetrics::fillMetricsCache(
458 r = metrics_.boundingRect(ucs4_to_qchar(c));
460 r = metrics_.boundingRect(toqstr(docstring(1, c)));
462 AscendDescend ad = { -r.top(), r.bottom() + 1};
463 // We could as well compute the width but this is not really
464 // needed for now as it is done directly in width() below.
465 metrics_cache_.insert(c, ad);
471 int GuiFontMetrics::width(char_type c) const
473 int value = width_cache_.value(c, outOfLimitMetric);
474 if (value != outOfLimitMetric)
478 value = metrics_.width(ucs4_to_qchar(c));
480 value = metrics_.width(toqstr(docstring(1, c)));
482 width_cache_.insert(c, value);
488 int GuiFontMetrics::ascent(char_type c) const
490 static AscendDescend const outOfLimitAD =
491 {outOfLimitMetric, outOfLimitMetric};
492 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
493 if (value.ascent != outOfLimitMetric)
496 value = fillMetricsCache(c);
501 int GuiFontMetrics::descent(char_type c) const
503 static AscendDescend const outOfLimitAD =
504 {outOfLimitMetric, outOfLimitMetric};
505 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
506 if (value.descent != outOfLimitMetric)
507 return value.descent;
509 value = fillMetricsCache(c);
510 return value.descent;
513 } // namespace frontend