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"
20 #include "support/convert.h"
21 #include "support/lassert.h"
22 #include "support/lyxlib.h"
24 #define DISABLE_PMPROF
25 #include "support/pmprof.h"
30 using namespace lyx::support;
35 * Argument-dependent lookup implies that this function shall be
36 * declared in the namespace of its argument. But this is std
37 * namespace, since lyx::docstring is just std::basic_string<wchar_t>.
39 uint qHash(lyx::docstring const & s)
41 return qHash(QByteArray(reinterpret_cast<char const *>(s.data()),
42 s.size() * sizeof(lyx::docstring::value_type)));
52 * Limit (strwidth|breakat)_cache_ size to 512kB of string data.
53 * Limit qtextlayout_cache_ size to 500 elements (we do not know the
54 * size of the QTextLayout objects anyway).
55 * Note that all these numbers are arbitrary.
56 * Also, setting size to 0 is tantamount to disabling the cache.
58 int cache_metrics_width_size = 1 << 19;
59 int cache_metrics_breakat_size = 1 << 19;
60 // Qt 5.x already has its own caching of QTextLayout objects
61 // but it does not seem to work well on MacOS X.
62 #if (QT_VERSION < 0x050000) || defined(Q_OS_MAC)
63 int cache_metrics_qtextlayout_size = 500;
65 int cache_metrics_qtextlayout_size = 0;
71 * Convert a UCS4 character into a QChar.
72 * This is a hack (it does only make sense for the common part of the UCS4
73 * and UTF16 encodings) and should not be used.
74 * This does only exist because of performance reasons (a real conversion
75 * using iconv is too slow on windows).
77 * This is no real conversion but a simple cast in reality. This is the reason
78 * why this works well for symbol fonts used in mathed too, even though
79 * these are not real ucs4 characters. These are codepoints in the
80 * computer modern fonts used, nothing unicode related.
81 * See comment in GuiPainter::text() for more explanation.
83 inline QChar const ucs4_to_qchar(char_type const ucs4)
85 LATTEST(is_utf16(ucs4));
86 return QChar(static_cast<unsigned short>(ucs4));
91 GuiFontMetrics::GuiFontMetrics(QFont const & font)
92 : font_(font), metrics_(font, 0),
93 strwidth_cache_(cache_metrics_width_size),
94 breakat_cache_(cache_metrics_breakat_size),
95 qtextlayout_cache_(cache_metrics_qtextlayout_size)
100 int GuiFontMetrics::maxAscent() const
102 return metrics_.ascent();
106 int GuiFontMetrics::maxDescent() const
108 // We add 1 as the value returned by QT is different than X
109 // See http://doc.trolltech.com/2.3/qfontmetrics.html#200b74
110 return metrics_.descent() + 1;
114 int GuiFontMetrics::em() const
116 return QFontInfo(font_).pixelSize();
120 int GuiFontMetrics::xHeight() const
122 // LATTEST(metrics_.xHeight() == ascent('x'));
123 return metrics_.xHeight();
127 int GuiFontMetrics::lineWidth() const
129 return metrics_.lineWidth();
133 int GuiFontMetrics::underlinePos() const
135 return metrics_.underlinePos();
139 int GuiFontMetrics::strikeoutPos() const
141 return metrics_.strikeOutPos();
145 int GuiFontMetrics::lbearing(char_type c) const
148 // FIXME: QFontMetrics::leftBearing does not support the
149 // full unicode range. Once it does, we could use:
150 //return metrics_.leftBearing(toqstr(docstring(1, c)));
153 return metrics_.leftBearing(ucs4_to_qchar(c));
158 int const outOfLimitMetric = -10000;
162 int GuiFontMetrics::rbearing(char_type c) const
164 int value = rbearing_cache_.value(c, outOfLimitMetric);
165 if (value != outOfLimitMetric)
168 // Qt rbearing is from the right edge of the char's width().
170 QChar sc = ucs4_to_qchar(c);
171 value = width(c) - metrics_.rightBearing(sc);
173 // FIXME: QFontMetrics::leftBearing does not support the
174 // full unicode range. Once it does, we could use:
175 // metrics_.rightBearing(toqstr(docstring(1, c)));
179 rbearing_cache_.insert(c, value);
185 int GuiFontMetrics::width(docstring const & s) const
187 PROFILE_THIS_BLOCK(width);
188 if (strwidth_cache_.contains(s))
189 return strwidth_cache_[s];
190 PROFILE_CACHE_MISS(width);
191 /* Several problems have to be taken into account:
192 * * QFontMetrics::width does not returns a wrong value with Qt5 with
193 * some arabic text, since the glyph-shaping operations are not
194 * done (documented in Qt5).
195 * * QTextLayout is broken for single characters with null width
196 * (like \not in mathed).
197 * * While QTextLine::horizontalAdvance is the right thing to use
198 * for text strings, it does not give a good result with some
199 * characters like the \int (gyph 4) of esint.
201 * Also, as a safety measure, always use QFontMetrics::width with
205 // is the string a single character from a math font ?
206 #if QT_VERSION >= 0x040800
207 bool const math_char = s.length() == 1 || font_.styleName() == "LyX";
209 bool const math_char = s.length() == 1;
211 // keep value 0 for math chars with width 0
212 if (!math_char || metrics_.width(toqstr(s)) != 0) {
214 tl.setText(toqstr(s));
217 QTextLine line = tl.createLine();
220 w = iround(line.naturalTextWidth());
222 w = iround(line.horizontalAdvance());
224 strwidth_cache_.insert(s, w, s.size() * sizeof(char_type));
229 int GuiFontMetrics::width(QString const & ucs2) const
231 return width(qstring_to_ucs4(ucs2));
235 int GuiFontMetrics::signedWidth(docstring const & s) const
241 return -width(s.substr(1, s.size() - 1));
247 shared_ptr<QTextLayout const>
248 GuiFontMetrics::getTextLayout(docstring const & s, bool const rtl,
249 double const wordspacing) const
251 PROFILE_THIS_BLOCK(getTextLayout);
252 docstring const s_cache =
253 s + (rtl ? "r" : "l") + convert<docstring>(wordspacing);
254 if (auto ptl = qtextlayout_cache_[s_cache])
256 PROFILE_CACHE_MISS(getTextLayout);
257 auto const ptl = make_shared<QTextLayout>();
258 ptl->setCacheEnabled(true);
259 ptl->setText(toqstr(s));
261 copy.setWordSpacing(wordspacing);
263 // Note that both setFlags and the enums are undocumented
264 ptl->setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
268 qtextlayout_cache_.insert(s_cache, ptl);
273 int GuiFontMetrics::pos2x(docstring const & s, int pos, bool const rtl,
274 double const wordspacing) const
278 shared_ptr<QTextLayout const> tl = getTextLayout(s, rtl, wordspacing);
279 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
280 * not be the same when there are high-plan unicode characters
283 int const qpos = toqstr(s.substr(0, pos)).length();
284 return static_cast<int>(tl->lineForTextPosition(qpos).cursorToX(qpos));
288 int GuiFontMetrics::x2pos(docstring const & s, int & x, bool const rtl,
289 double const wordspacing) const
291 shared_ptr<QTextLayout const> tl = getTextLayout(s, rtl, wordspacing);
292 QTextLine const & tline = tl->lineForTextPosition(0);
293 int qpos = tline.xToCursor(x);
294 int newx = static_cast<int>(tline.cursorToX(qpos));
295 // The value of qpos may be wrong in rtl text (see ticket #10569).
296 // To work around this, let's have a look at adjacent positions to
297 // see whether we find closer matches.
298 if (rtl && newx < x) {
300 int const xm = static_cast<int>(tline.cursorToX(qpos - 1));
301 if (abs(xm - x) < abs(newx - x)) {
307 } else if (rtl && newx > x) {
308 while (qpos < tline.textLength()) {
309 int const xp = static_cast<int>(tline.cursorToX(qpos + 1));
310 if (abs(xp - x) < abs(newx - x)) {
317 // correct x value to the actual cursor position.
320 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
321 * not be the same when there are high-plan unicode characters
324 #if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
325 return qstring_to_ucs4(tl->text().left(qpos)).length();
327 /* Due to QTBUG-25536 in 4.8.1 <= Qt < 5.1.0, the string returned
328 * by QString::toUcs4 (used by qstring_to_ucs4) may have wrong
329 * length. We work around the problem by trying all docstring
330 * positions until the right one is found. This is slow only if
331 * there are many high-plane Unicode characters. It might be
332 * worthwhile to implement a dichotomy search if this shows up
335 int pos = min(qpos, static_cast<int>(s.length()));
336 while (pos >= 0 && toqstr(s.substr(0, pos)).length() != qpos)
338 LASSERT(pos > 0 || qpos == 0, /**/);
344 int GuiFontMetrics::countExpanders(docstring const & str) const
346 // Numbers of characters that are expanded by inter-word spacing. These
347 // characters are spaces, except for characters 09-0D which are treated
348 // specially. (From a combination of testing with the notepad found in qt's
349 // examples, and reading the source code.) In addition, consecutive spaces
350 // only count as one expander.
351 bool wasspace = false;
353 for (char_type c : str)
354 if (c > 0x0d && QChar(c).isSpace()) {
366 GuiFontMetrics::breakAt_helper(docstring const & s, int const x,
367 bool const rtl, bool const force) const
370 /* Qt will not break at a leading or trailing space, and we need
371 * that sometimes, see http://www.lyx.org/trac/ticket/9921.
373 * To work around the problem, we enclose the string between
374 * zero-width characters so that the QTextLayout algorithm will
375 * agree to break the text at these extremal spaces.
377 // Unicode character ZERO WIDTH NO-BREAK SPACE
378 QChar const zerow_nbsp(0xfeff);
379 QString qs = zerow_nbsp + toqstr(s) + zerow_nbsp;
381 /* Use unicode override characters to enforce drawing direction
382 * Source: http://www.iamcal.com/understanding-bidirectional-text/
385 // Right-to-left override: forces to draw text right-to-left
386 qs = QChar(0x202E) + qs;
388 // Left-to-right override: forces to draw text left-to-right
389 qs = QChar(0x202D) + qs;
390 int const offset = 2;
392 // Alternative version that breaks with Qt5 and arabic text (#10436)
393 // Note that both setFlags and the enums are undocumented
394 tl.setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
395 int const offset = 1;
401 to.setWrapMode(force ? QTextOption::WrapAtWordBoundaryOrAnywhere
402 : QTextOption::WordWrap);
403 tl.setTextOption(to);
405 QTextLine line = tl.createLine();
406 line.setLineWidth(x);
409 int const line_wid = iround(line.horizontalAdvance());
410 if ((force && line.textLength() == offset) || line_wid > x)
412 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
413 * not be the same when there are high-plan unicode characters
416 // The variable `offset' is here to account for the extra leading characters.
417 // The ending character zerow_nbsp has to be ignored if the line is complete.
418 int const qlen = line.textLength() - offset - (line.textLength() == qs.length());
419 #if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
420 int len = qstring_to_ucs4(qs.mid(offset, qlen)).length();
422 /* Due to QTBUG-25536 in 4.8.1 <= Qt < 5.1.0, the string returned
423 * by QString::toUcs4 (used by qstring_to_ucs4) may have wrong
424 * length. We work around the problem by trying all docstring
425 * positions until the right one is found. This is slow only if
426 * there are many high-plane Unicode characters. It might be
427 * worthwhile to implement a dichotomy search if this shows up
430 int len = min(qlen, static_cast<int>(s.length()));
431 while (len >= 0 && toqstr(s.substr(0, len)).length() != qlen)
433 LASSERT(len > 0 || qlen == 0, /**/);
435 return {len, line_wid};
439 bool GuiFontMetrics::breakAt(docstring & s, int & x, bool const rtl, bool const force) const
441 PROFILE_THIS_BLOCK(breakAt);
445 docstring const s_cache =
446 s + convert<docstring>(x) + (rtl ? "r" : "l") + (force ? "f" : "w");
449 if (breakat_cache_.contains(s_cache))
450 pp = breakat_cache_[s_cache];
452 PROFILE_CACHE_MISS(breakAt);
453 pp = breakAt_helper(s, x, rtl, force);
454 breakat_cache_.insert(s_cache, pp, s_cache.size() * sizeof(char_type));
458 s = s.substr(0, pp.first);
464 void GuiFontMetrics::rectText(docstring const & str,
465 int & w, int & ascent, int & descent) const
467 // FIXME: let offset depend on font (this is Inset::TEXT_TO_OFFSET)
468 int const offset = 4;
470 w = width(str) + offset;
471 ascent = metrics_.ascent() + offset / 2;
472 descent = metrics_.descent() + offset / 2;
476 void GuiFontMetrics::buttonText(docstring const & str, const int offset,
477 int & w, int & ascent, int & descent) const
479 rectText(str, w, ascent, descent);
484 Dimension const GuiFontMetrics::defaultDimension() const
486 return Dimension(0, maxAscent(), maxDescent());
490 Dimension const GuiFontMetrics::dimension(char_type c) const
492 return Dimension(width(c), ascent(c), descent(c));
496 GuiFontMetrics::AscendDescend const GuiFontMetrics::fillMetricsCache(
501 r = metrics_.boundingRect(ucs4_to_qchar(c));
503 r = metrics_.boundingRect(toqstr(docstring(1, c)));
505 AscendDescend ad = { -r.top(), r.bottom() + 1};
506 // We could as well compute the width but this is not really
507 // needed for now as it is done directly in width() below.
508 metrics_cache_.insert(c, ad);
514 int GuiFontMetrics::width(char_type c) const
516 int value = width_cache_.value(c, outOfLimitMetric);
517 if (value != outOfLimitMetric)
521 value = metrics_.width(ucs4_to_qchar(c));
523 value = metrics_.width(toqstr(docstring(1, c)));
525 width_cache_.insert(c, value);
531 int GuiFontMetrics::ascent(char_type c) const
533 static AscendDescend const outOfLimitAD =
534 {outOfLimitMetric, outOfLimitMetric};
535 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
536 if (value.ascent != outOfLimitMetric)
539 value = fillMetricsCache(c);
544 int GuiFontMetrics::descent(char_type c) const
546 static AscendDescend const outOfLimitAD =
547 {outOfLimitMetric, outOfLimitMetric};
548 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
549 if (value.descent != outOfLimitMetric)
550 return value.descent;
552 value = fillMetricsCache(c);
553 return value.descent;
556 } // namespace frontend