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/debug.h"
22 #include "support/lassert.h"
23 #include "support/lyxlib.h"
24 #include "support/textutils.h"
26 #define DISABLE_PMPROF
27 #include "support/pmprof.h"
33 #if QT_VERSION >= 0x050100
36 #define qDegreesToRadians(degree) (degree * (M_PI / 180))
40 using namespace lyx::support;
42 /* Define what mechanisms are used to enforce text direction. There
43 * are two methods that work with different Qt versions. Here we try
44 * to use both methods together.
46 // Define to use unicode override characters to force direction
47 #define BIDI_USE_OVERRIDE
48 // Define to use QTextLayout flag to force direction
51 #if !defined(BIDI_USE_OVERRIDE) && !defined(BIDI_USE_FLAG)
52 # error "Define at least one of BIDI_USE_OVERRIDE or BIDI_USE_FLAG"
56 #if QT_VERSION < 0x050000
57 inline uint qHash(double key)
59 return qHash(QByteArray(reinterpret_cast<char const *>(&key), sizeof(key)));
67 * Argument-dependent lookup implies that this function shall be
68 * declared in the namespace of its argument. But this is std
69 * namespace, since lyx::docstring is just std::basic_string<wchar_t>.
71 uint qHash(lyx::docstring const & s)
73 return qHash(QByteArray(reinterpret_cast<char const *>(s.data()),
74 s.size() * sizeof(lyx::docstring::value_type)));
84 // Maximal size/cost for various caches. See QCache documentation to
85 // see what cost means.
87 // Limit strwidth_cache_ total cost to 1MB of string data.
88 int const strwidth_cache_max_cost = 1024 * 1024;
89 // Limit breakstr_cache_ total cost to 10MB of string data.
90 // This is useful for documents with very large insets.
91 int const breakstr_cache_max_cost = 10 * 1024 * 1024;
92 // Qt 5.x already has its own caching of QTextLayout objects
93 // but it does not seem to work well on MacOS X.
94 #if (QT_VERSION < 0x050000) || defined(Q_OS_MAC)
95 // Limit qtextlayout_cache_ size to 500 elements (we do not know the
96 // size of the QTextLayout objects anyway).
97 int const qtextlayout_cache_max_size = 500;
100 int const qtextlayout_cache_max_size = 0;
105 * Convert a UCS4 character into a QChar.
106 * This is a hack (it does only make sense for the common part of the UCS4
107 * and UTF16 encodings) and should not be used.
108 * This does only exist because of performance reasons (a real conversion
109 * using iconv is too slow on windows).
111 * This is no real conversion but a simple cast in reality. This is the reason
112 * why this works well for symbol fonts used in mathed too, even though
113 * these are not real ucs4 characters. These are codepoints in the
114 * computer modern fonts used, nothing unicode related.
115 * See comment in GuiPainter::text() for more explanation.
117 inline QChar const ucs4_to_qchar(char_type const ucs4)
119 LATTEST(is_utf16(ucs4));
120 return QChar(static_cast<unsigned short>(ucs4));
125 GuiFontMetrics::GuiFontMetrics(QFont const & font)
126 : font_(font), metrics_(font, 0),
127 strwidth_cache_(strwidth_cache_max_cost),
128 breakstr_cache_(breakstr_cache_max_cost),
129 qtextlayout_cache_(qtextlayout_cache_max_size)
131 // Determine italic slope
132 double const defaultSlope = tan(qDegreesToRadians(19.0));
133 QRawFont raw = QRawFont::fromFont(font);
134 QByteArray post(raw.fontTable("post"));
135 if (post.length() == 0) {
136 slope_ = defaultSlope;
137 LYXERR(Debug::FONT, "Screen font doesn't have 'post' table.");
139 // post table description:
140 // https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6post.html
141 int32_t italicAngle = qFromBigEndian(*reinterpret_cast<int32_t *>(post.data() + 4));
142 double angle = italicAngle / 65536.0; // Fixed-point 16.16 to floating-point
143 slope_ = -tan(qDegreesToRadians(angle));
144 // Correct italic fonts with zero slope
145 if (slope_ == 0.0 && font.italic())
146 slope_ = defaultSlope;
147 LYXERR(Debug::FONT, "Italic slope: " << slope_);
152 int GuiFontMetrics::maxAscent() const
154 return metrics_.ascent();
158 int GuiFontMetrics::maxDescent() const
160 // We add 1 as the value returned by QT is different than X
161 // See http://doc.trolltech.com/2.3/qfontmetrics.html#200b74
163 return metrics_.descent() + 1;
167 int GuiFontMetrics::em() const
169 return QFontInfo(font_).pixelSize();
173 int GuiFontMetrics::xHeight() const
175 // LATTEST(metrics_.xHeight() == ascent('x'));
176 return metrics_.xHeight();
180 int GuiFontMetrics::lineWidth() const
182 return metrics_.lineWidth();
186 int GuiFontMetrics::underlinePos() const
188 return metrics_.underlinePos();
192 int GuiFontMetrics::strikeoutPos() const
194 return metrics_.strikeOutPos();
198 bool GuiFontMetrics::italic() const
200 return font_.italic();
204 double GuiFontMetrics::italicSlope() const
211 int const outOfLimitMetric = -10000;
215 int GuiFontMetrics::lbearing(char_type c) const
217 int value = lbearing_cache_.value(c, outOfLimitMetric);
218 if (value != outOfLimitMetric)
222 value = metrics_.leftBearing(ucs4_to_qchar(c));
224 // FIXME: QFontMetrics::leftBearing does not support the
225 // full unicode range. Once it does, we could use:
226 // metrics_.leftBearing(toqstr(docstring(1, c)));
230 lbearing_cache_.insert(c, value);
236 int GuiFontMetrics::rbearing(char_type c) const
238 int value = rbearing_cache_.value(c, outOfLimitMetric);
239 if (value != outOfLimitMetric)
242 // Qt rbearing is from the right edge of the char's width().
244 QChar sc = ucs4_to_qchar(c);
245 value = width(c) - metrics_.rightBearing(sc);
247 // FIXME: QFontMetrics::leftBearing does not support the
248 // full unicode range. Once it does, we could use:
249 // metrics_.rightBearing(toqstr(docstring(1, c)));
253 rbearing_cache_.insert(c, value);
259 int GuiFontMetrics::width(docstring const & s) const
261 PROFILE_THIS_BLOCK(width);
262 if (int * wid_p = strwidth_cache_.object_ptr(s))
264 PROFILE_CACHE_MISS(width);
265 /* Several problems have to be taken into account:
266 * * QFontMetrics::width does not returns a wrong value with Qt5 with
267 * some arabic text, since the glyph-shaping operations are not
268 * done (documented in Qt5).
269 * * QTextLayout is broken for single characters with null width
270 * (like \not in mathed).
271 * * While QTextLine::horizontalAdvance is the right thing to use
272 * for text strings, it does not give a good result with some
273 * characters like the \int (gyph 4) of esint.
275 * The metrics of some of our math fonts (eg. esint) are such that
276 * QTextLine::horizontalAdvance leads, more or less, in the middle
277 * of a symbol. This is the horizontal position where a subscript
278 * should be drawn, so that the superscript has to be moved rightward.
279 * This is done when the kerning() method of the math insets returns
280 * a positive value. The problem with this choice is that navigating
281 * a formula becomes weird. For example, a selection extends only over
282 * about half of the symbol. In order to avoid this, with our math
283 * fonts we use QTextLine::naturalTextWidth, so that a superscript can
284 * be drawn right after the symbol, and move the subscript leftward by
285 * recording a negative value for the kerning.
288 // is the string a single character from a math font ?
289 #if QT_VERSION >= 0x040800
290 bool const math_char = s.length() == 1 && font_.styleName() == "LyX";
292 bool const math_char = s.length() == 1;
295 QString const qs = toqstr(s);
296 int br_width = metrics_.boundingRect(qs).width();
297 #if QT_VERSION >= 0x050b00
298 int s_width = metrics_.horizontalAdvance(qs);
300 int s_width = metrics_.width(qs);
302 // keep value 0 for math chars with width 0
304 w = max(br_width, s_width);
307 tl.setText(toqstr(s));
310 QTextLine line = tl.createLine();
312 w = iround(line.horizontalAdvance());
314 strwidth_cache_.insert(s, w, s.size() * sizeof(char_type));
319 int GuiFontMetrics::width(QString const & ucs2) const
321 return width(qstring_to_ucs4(ucs2));
325 int GuiFontMetrics::signedWidth(docstring const & s) const
331 return -width(s.substr(1, s.size() - 1));
337 uint qHash(TextLayoutKey const & key)
339 double params = (2 * key.rtl - 1) * key.ws;
340 return std::qHash(key.s) ^ ::qHash(params);
344 // This holds a translation table between the original string and the
345 // QString that we can use with QTextLayout.
346 struct TextLayoutHelper
348 /// Create the helper
349 /// \c s is the original string
350 /// \c isrtl is true if the string is right-to-left
351 /// \c naked is true to disable the insertion of zero width annotations
352 TextLayoutHelper(docstring const & s, bool isrtl, bool naked = false);
354 /// translate QString index to docstring index
355 docstring::size_type qpos2pos(int qpos) const
357 return lower_bound(pos2qpos_.begin(), pos2qpos_.end(), qpos) - pos2qpos_.begin();
360 /// Translate docstring index to QString index
361 int pos2qpos(docstring::size_type pos) const { return pos2qpos_[pos]; }
363 // The original string
367 // is string right-to-left?
371 // This vector contains the QString pos for each string position
372 vector<int> pos2qpos_;
376 TextLayoutHelper::TextLayoutHelper(docstring const & s, bool isrtl, bool naked)
377 : docstr(s), rtl(isrtl)
379 // Reserve memory for performance purpose
380 pos2qpos_.reserve(s.size());
381 qstr.reserve(2 * s.size());
383 /* Qt will not break at a leading or trailing space, and we need
384 * that sometimes, see http://www.lyx.org/trac/ticket/9921.
386 * To work around the problem, we enclose the string between
387 * word joiner characters so that the QTextLayout algorithm will
388 * agree to break the text at these extremal spaces.
390 // Unicode character WORD JOINER
391 QChar const word_joiner(0x2060);
395 #ifdef BIDI_USE_OVERRIDE
396 /* Unicode override characters enforce drawing direction
397 * Source: http://www.iamcal.com/understanding-bidirectional-text/
398 * Left-to-right override is 0x202d and right-to-left override is 0x202e.
401 qstr += QChar(rtl ? 0x202e : 0x202d);
404 // Now translate the string character-by-character.
405 bool was_space = false;
406 for (char_type const c : s) {
407 // insert a word joiner character between consecutive spaces
408 bool const is_space = isSpace(c);
409 if (!naked && is_space && was_space)
411 was_space = is_space;
412 // Remember the QString index at this point
413 pos2qpos_.push_back(qstr.size());
414 // Performance: UTF-16 characters are easier
416 qstr += ucs4_to_qchar(c);
421 // Final word joiner (see above)
425 // Add virtual position at the end of the string
426 pos2qpos_.push_back(qstr.size());
428 //QString dump = qstr;
429 //LYXERR0("TLH: " << dump.replace(word_joiner, "|").toStdString());
435 shared_ptr<QTextLayout>
436 getTextLayout_helper(TextLayoutHelper const & tlh, double const wordspacing,
439 auto const ptl = make_shared<QTextLayout>();
440 ptl->setCacheEnabled(true);
441 font.setWordSpacing(wordspacing);
444 /* Use undocumented flag to enforce drawing direction
445 * FIXME: This does not work with Qt 5.11 (ticket #11284).
447 ptl->setFlags(tlh.rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
449 ptl->setText(tlh.qstr);
460 shared_ptr<QTextLayout const>
461 GuiFontMetrics::getTextLayout(TextLayoutHelper const & tlh,
462 double const wordspacing) const
464 PROFILE_THIS_BLOCK(getTextLayout_TLH);
465 TextLayoutKey key{tlh.docstr, tlh.rtl, wordspacing};
466 if (auto ptl = qtextlayout_cache_[key])
468 PROFILE_CACHE_MISS(getTextLayout_TLH);
469 auto const ptl = getTextLayout_helper(tlh, wordspacing, font_);
470 qtextlayout_cache_.insert(key, ptl);
475 shared_ptr<QTextLayout const>
476 GuiFontMetrics::getTextLayout(docstring const & s, bool const rtl,
477 double const wordspacing) const
479 PROFILE_THIS_BLOCK(getTextLayout);
480 TextLayoutKey key{s, rtl, wordspacing};
481 if (auto ptl = qtextlayout_cache_[key])
483 PROFILE_CACHE_MISS(getTextLayout);
484 TextLayoutHelper tlh(s, rtl);
485 auto const ptl = getTextLayout_helper(tlh, wordspacing, font_);
486 qtextlayout_cache_.insert(key, ptl);
491 int GuiFontMetrics::pos2x(docstring const & s, int pos, bool const rtl,
492 double const wordspacing) const
494 TextLayoutHelper tlh(s, rtl);
495 auto ptl = getTextLayout(tlh, wordspacing);
496 // pos can be negative, see #10506.
497 int const qpos = tlh.pos2qpos(max(pos, 0));
498 return static_cast<int>(ptl->lineForTextPosition(qpos).cursorToX(qpos));
502 int GuiFontMetrics::x2pos(docstring const & s, int & x, bool const rtl,
503 double const wordspacing) const
505 TextLayoutHelper tlh(s, rtl);
506 auto ptl = getTextLayout(tlh, wordspacing);
507 QTextLine const & tline = ptl->lineForTextPosition(0);
508 int qpos = tline.xToCursor(x);
509 int newx = static_cast<int>(tline.cursorToX(qpos));
510 // The value of qpos may be wrong in rtl text (see ticket #10569).
511 // To work around this, let's have a look at adjacent positions to
512 // see whether we find closer matches.
513 if (rtl && newx < x) {
515 int const xm = static_cast<int>(tline.cursorToX(qpos - 1));
516 if (abs(xm - x) < abs(newx - x)) {
522 } else if (rtl && newx > x) {
523 while (qpos < tline.textLength()) {
524 int const xp = static_cast<int>(tline.cursorToX(qpos + 1));
525 if (abs(xp - x) < abs(newx - x)) {
532 // correct x value to the actual cursor position.
535 return tlh.qpos2pos(qpos);
540 GuiFontMetrics::breakString_helper(docstring const & s, int first_wid, int wid,
541 bool rtl, bool force) const
543 TextLayoutHelper const tlh(s, rtl);
547 /* Use undocumented flag to enforce drawing direction
548 * FIXME: This does not work with Qt 5.11 (ticket #11284).
550 tl.setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
552 tl.setText(tlh.qstr);
556 * Some Asian languages split lines anywhere (no notion of
557 * word). It seems that QTextLayout is not aware of this fact.
559 * https://en.wikipedia.org/wiki/Line_breaking_rules_in_East_Asian_languages
561 * FIXME: Something shall be done about characters which are
562 * not allowed at the beginning or end of line.
564 to.setWrapMode(force ? QTextOption::WrapAtWordBoundaryOrAnywhere
565 : QTextOption::WordWrap);
566 tl.setTextOption(to);
571 QTextLine line = tl.createLine();
574 line.setLineWidth(first ? first_wid : wid);
581 for (int i = 0 ; i < tl.lineCount() ; ++i) {
582 QTextLine const & line = tl.lineAt(i);
583 int const line_epos = line.textStart() + line.textLength();
584 int const epos = tlh.qpos2pos(line_epos);
585 #if QT_VERSION >= 0x050000
586 // This does not take trailing spaces into account, except for the last line.
587 int const wid = iround(line.naturalTextWidth());
588 // If the line is not the last one, trailing space is always omitted.
590 // For the last line, compute the width without trailing space
591 if (i + 1 == tl.lineCount() && !s.empty() && isSpace(s.back())
592 && line.textStart() <= tlh.pos2qpos(s.size() - 1))
593 nspc_wid = iround(line.cursorToX(tlh.pos2qpos(s.size() - 1)));
595 // With some monospace fonts, the value of horizontalAdvance()
596 // can be wrong with Qt4. One hypothesis is that the invisible
597 // characters that we use are given a non-null width.
598 // FIXME: this is slower than it could be but we'll get rid of Qt4 anyway
599 docstring ss = s.substr(pos, epos - pos);
600 int const wid = width(ss);
601 if (!ss.empty() && isSpace(ss.back()))
603 int const nspc_wid = i + 1 < tl.lineCount() ? width(ss) : wid;
605 breaks.emplace_back(epos - pos, wid, nspc_wid);
608 // FIXME: should it be kept in some form?
609 if ((force && line.textLength() == brkStrOffset) || line_wid > x)
610 return {-1, line_wid};
618 uint qHash(BreakStringKey const & key)
620 // assume widths are less than 10000. This fits in 32 bits.
621 uint params = key.force + 2 * key.rtl + 4 * key.first_wid + 10000 * key.wid;
622 return std::qHash(key.s) ^ ::qHash(params);
626 FontMetrics::Breaks GuiFontMetrics::breakString(docstring const & s, int first_wid, int wid,
627 bool rtl, bool force) const
629 PROFILE_THIS_BLOCK(breakString);
633 BreakStringKey key{s, first_wid, wid, rtl, force};
635 if (auto * brks_ptr = breakstr_cache_.object_ptr(key))
638 PROFILE_CACHE_MISS(breakString);
639 brks = breakString_helper(s, first_wid, wid, rtl, force);
640 breakstr_cache_.insert(key, brks, sizeof(key) + s.size() * sizeof(char_type));
646 void GuiFontMetrics::rectText(docstring const & str,
647 int & w, int & ascent, int & descent) const
649 // FIXME: let offset depend on font (this is Inset::TEXT_TO_OFFSET)
650 int const offset = 4;
652 w = width(str) + offset;
653 ascent = metrics_.ascent() + offset / 2;
654 descent = metrics_.descent() + offset / 2;
658 void GuiFontMetrics::buttonText(docstring const & str, const int offset,
659 int & w, int & ascent, int & descent) const
661 rectText(str, w, ascent, descent);
666 Dimension const GuiFontMetrics::defaultDimension() const
668 return Dimension(0, maxAscent(), maxDescent());
672 Dimension const GuiFontMetrics::dimension(char_type c) const
674 return Dimension(width(c), ascent(c), descent(c));
678 GuiFontMetrics::AscendDescend const GuiFontMetrics::fillMetricsCache(
683 r = metrics_.boundingRect(ucs4_to_qchar(c));
685 r = metrics_.boundingRect(toqstr(docstring(1, c)));
687 AscendDescend ad = { -r.top(), r.bottom() + 1};
688 // We could as well compute the width but this is not really
689 // needed for now as it is done directly in width() below.
690 metrics_cache_.insert(c, ad);
696 int GuiFontMetrics::width(char_type c) const
698 int value = width_cache_.value(c, outOfLimitMetric);
699 if (value != outOfLimitMetric)
702 #if QT_VERSION >= 0x050b00
704 value = metrics_.horizontalAdvance(ucs4_to_qchar(c));
706 value = metrics_.horizontalAdvance(toqstr(docstring(1, c)));
709 value = metrics_.width(ucs4_to_qchar(c));
711 value = metrics_.width(toqstr(docstring(1, c)));
714 width_cache_.insert(c, value);
720 int GuiFontMetrics::ascent(char_type c) const
722 static AscendDescend const outOfLimitAD =
723 {outOfLimitMetric, outOfLimitMetric};
724 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
725 if (value.ascent != outOfLimitMetric)
728 value = fillMetricsCache(c);
733 int GuiFontMetrics::descent(char_type c) const
735 static AscendDescend const outOfLimitAD =
736 {outOfLimitMetric, outOfLimitMetric};
737 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
738 if (value.descent != outOfLimitMetric)
739 return value.descent;
741 value = fillMetricsCache(c);
742 return value.descent;
745 } // namespace frontend