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_);
149 // If those characters have a non-zero width, we need to avoid them.
150 // This happens with Qt4 with monospace fonts
151 needs_naked_ = width(QString() + QChar(0x2060) + QChar(0x202d) + QChar(0x202e)) > 0;
153 // LYXERR0("Font " << font.family() << " needs naked text layouts!");
157 int GuiFontMetrics::maxAscent() const
159 return metrics_.ascent();
163 int GuiFontMetrics::maxDescent() const
165 // We add 1 as the value returned by QT is different than X
166 // See http://doc.trolltech.com/2.3/qfontmetrics.html#200b74
168 return metrics_.descent() + 1;
172 int GuiFontMetrics::em() const
174 return QFontInfo(font_).pixelSize();
178 int GuiFontMetrics::xHeight() const
180 // LATTEST(metrics_.xHeight() == ascent('x'));
181 return metrics_.xHeight();
185 int GuiFontMetrics::lineWidth() const
187 return metrics_.lineWidth();
191 int GuiFontMetrics::underlinePos() const
193 return metrics_.underlinePos();
197 int GuiFontMetrics::strikeoutPos() const
199 return metrics_.strikeOutPos();
203 bool GuiFontMetrics::italic() const
205 return font_.italic();
209 double GuiFontMetrics::italicSlope() const
216 int const outOfLimitMetric = -10000;
220 int GuiFontMetrics::lbearing(char_type c) const
222 int value = lbearing_cache_.value(c, outOfLimitMetric);
223 if (value != outOfLimitMetric)
227 value = metrics_.leftBearing(ucs4_to_qchar(c));
229 // FIXME: QFontMetrics::leftBearing does not support the
230 // full unicode range. Once it does, we could use:
231 // metrics_.leftBearing(toqstr(docstring(1, c)));
235 lbearing_cache_.insert(c, value);
241 int GuiFontMetrics::rbearing(char_type c) const
243 int value = rbearing_cache_.value(c, outOfLimitMetric);
244 if (value != outOfLimitMetric)
247 // Qt rbearing is from the right edge of the char's width().
249 QChar sc = ucs4_to_qchar(c);
250 value = width(c) - metrics_.rightBearing(sc);
252 // FIXME: QFontMetrics::leftBearing does not support the
253 // full unicode range. Once it does, we could use:
254 // metrics_.rightBearing(toqstr(docstring(1, c)));
258 rbearing_cache_.insert(c, value);
264 int GuiFontMetrics::width(docstring const & s) const
266 PROFILE_THIS_BLOCK(width);
267 if (int * wid_p = strwidth_cache_.object_ptr(s))
269 PROFILE_CACHE_MISS(width);
270 /* Several problems have to be taken into account:
271 * * QFontMetrics::width does not returns a wrong value with Qt5 with
272 * some arabic text, since the glyph-shaping operations are not
273 * done (documented in Qt5).
274 * * QTextLayout is broken for single characters with null width
275 * (like \not in mathed).
276 * * While QTextLine::horizontalAdvance is the right thing to use
277 * for text strings, it does not give a good result with some
278 * characters like the \int (gyph 4) of esint.
280 * The metrics of some of our math fonts (eg. esint) are such that
281 * QTextLine::horizontalAdvance leads, more or less, in the middle
282 * of a symbol. This is the horizontal position where a subscript
283 * should be drawn, so that the superscript has to be moved rightward.
284 * This is done when the kerning() method of the math insets returns
285 * a positive value. The problem with this choice is that navigating
286 * a formula becomes weird. For example, a selection extends only over
287 * about half of the symbol. In order to avoid this, with our math
288 * fonts we use QTextLine::naturalTextWidth, so that a superscript can
289 * be drawn right after the symbol, and move the subscript leftward by
290 * recording a negative value for the kerning.
293 // is the string a single character from a math font ?
294 #if QT_VERSION >= 0x040800
295 bool const math_char = s.length() == 1 && font_.styleName() == "LyX";
297 bool const math_char = s.length() == 1;
300 QString const qs = toqstr(s);
301 int br_width = metrics_.boundingRect(qs).width();
302 #if QT_VERSION >= 0x050b00
303 int s_width = metrics_.horizontalAdvance(qs);
305 int s_width = metrics_.width(qs);
307 // keep value 0 for math chars with width 0
309 w = max(br_width, s_width);
312 tl.setText(toqstr(s));
315 QTextLine line = tl.createLine();
317 w = iround(line.horizontalAdvance());
319 strwidth_cache_.insert(s, w, s.size() * sizeof(char_type));
324 int GuiFontMetrics::width(QString const & ucs2) const
326 return width(qstring_to_ucs4(ucs2));
330 int GuiFontMetrics::signedWidth(docstring const & s) const
336 return -width(s.substr(1, s.size() - 1));
342 uint qHash(TextLayoutKey const & key)
344 double params = (2 * key.rtl - 1) * key.ws;
345 return std::qHash(key.s) ^ ::qHash(params);
349 // This holds a translation table between the original string and the
350 // QString that we can use with QTextLayout.
351 struct TextLayoutHelper
353 /// Create the helper
354 /// \c s is the original string
355 /// \c isrtl is true if the string is right-to-left
356 /// \c naked is true to disable the insertion of zero width annotations
357 /// FIXME: remove \c naked argument when Qt4 support goes away.
358 TextLayoutHelper(docstring const & s, bool isrtl, bool naked = false);
360 /// translate QString index to docstring index
361 docstring::size_type qpos2pos(int qpos) const
363 return lower_bound(pos2qpos_.begin(), pos2qpos_.end(), qpos) - pos2qpos_.begin();
366 /// Translate docstring index to QString index
367 int pos2qpos(docstring::size_type pos) const { return pos2qpos_[pos]; }
369 // The original string
373 // is string right-to-left?
377 // This vector contains the QString pos for each string position
378 vector<int> pos2qpos_;
382 TextLayoutHelper::TextLayoutHelper(docstring const & s, bool isrtl, bool naked)
383 : docstr(s), rtl(isrtl)
385 // Reserve memory for performance purpose
386 pos2qpos_.reserve(s.size());
387 qstr.reserve(2 * s.size());
389 /* Qt will not break at a leading or trailing space, and we need
390 * that sometimes, see http://www.lyx.org/trac/ticket/9921.
392 * To work around the problem, we enclose the string between
393 * word joiner characters so that the QTextLayout algorithm will
394 * agree to break the text at these extremal spaces.
396 // Unicode character WORD JOINER
397 QChar const word_joiner(0x2060);
401 #ifdef BIDI_USE_OVERRIDE
402 /* Unicode override characters enforce drawing direction
403 * Source: http://www.iamcal.com/understanding-bidirectional-text/
404 * Left-to-right override is 0x202d and right-to-left override is 0x202e.
407 qstr += QChar(rtl ? 0x202e : 0x202d);
410 // Now translate the string character-by-character.
411 bool was_space = false;
412 for (char_type const c : s) {
413 // insert a word joiner character between consecutive spaces
414 bool const is_space = isSpace(c);
415 if (!naked && is_space && was_space)
417 was_space = is_space;
418 // Remember the QString index at this point
419 pos2qpos_.push_back(qstr.size());
420 // Performance: UTF-16 characters are easier
422 qstr += ucs4_to_qchar(c);
427 // Final word joiner (see above)
431 // Add virtual position at the end of the string
432 pos2qpos_.push_back(qstr.size());
434 //QString dump = qstr;
435 //LYXERR0("TLH: " << dump.replace(word_joiner, "|").toStdString());
441 shared_ptr<QTextLayout>
442 getTextLayout_helper(TextLayoutHelper const & tlh, double const wordspacing,
445 auto const ptl = make_shared<QTextLayout>();
446 ptl->setCacheEnabled(true);
447 font.setWordSpacing(wordspacing);
450 /* Use undocumented flag to enforce drawing direction
451 * FIXME: This does not work with Qt 5.11 (ticket #11284).
453 ptl->setFlags(tlh.rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
455 ptl->setText(tlh.qstr);
466 shared_ptr<QTextLayout const>
467 GuiFontMetrics::getTextLayout(TextLayoutHelper const & tlh,
468 double const wordspacing) const
470 PROFILE_THIS_BLOCK(getTextLayout_TLH);
471 TextLayoutKey key{tlh.docstr, tlh.rtl, wordspacing};
472 if (auto ptl = qtextlayout_cache_[key])
474 PROFILE_CACHE_MISS(getTextLayout_TLH);
475 auto const ptl = getTextLayout_helper(tlh, wordspacing, font_);
476 qtextlayout_cache_.insert(key, ptl);
481 shared_ptr<QTextLayout const>
482 GuiFontMetrics::getTextLayout(docstring const & s, bool const rtl,
483 double const wordspacing) const
485 PROFILE_THIS_BLOCK(getTextLayout);
486 TextLayoutKey key{s, rtl, wordspacing};
487 if (auto ptl = qtextlayout_cache_[key])
489 PROFILE_CACHE_MISS(getTextLayout);
490 TextLayoutHelper tlh(s, rtl, needs_naked_);
491 auto const ptl = getTextLayout_helper(tlh, wordspacing, font_);
492 qtextlayout_cache_.insert(key, ptl);
497 int GuiFontMetrics::pos2x(docstring const & s, int pos, bool const rtl,
498 double const wordspacing) const
500 TextLayoutHelper tlh(s, rtl, needs_naked_);
501 auto ptl = getTextLayout(tlh, wordspacing);
502 // pos can be negative, see #10506.
503 int const qpos = tlh.pos2qpos(max(pos, 0));
504 return static_cast<int>(ptl->lineForTextPosition(qpos).cursorToX(qpos));
508 int GuiFontMetrics::x2pos(docstring const & s, int & x, bool const rtl,
509 double const wordspacing) const
511 TextLayoutHelper tlh(s, rtl, needs_naked_);
512 auto ptl = getTextLayout(tlh, wordspacing);
513 QTextLine const & tline = ptl->lineForTextPosition(0);
514 int qpos = tline.xToCursor(x);
515 int newx = static_cast<int>(tline.cursorToX(qpos));
516 // The value of qpos may be wrong in rtl text (see ticket #10569).
517 // To work around this, let's have a look at adjacent positions to
518 // see whether we find closer matches.
519 if (rtl && newx < x) {
521 int const xm = static_cast<int>(tline.cursorToX(qpos - 1));
522 if (abs(xm - x) < abs(newx - x)) {
528 } else if (rtl && newx > x) {
529 while (qpos < tline.textLength()) {
530 int const xp = static_cast<int>(tline.cursorToX(qpos + 1));
531 if (abs(xp - x) < abs(newx - x)) {
538 // correct x value to the actual cursor position.
541 return tlh.qpos2pos(qpos);
546 GuiFontMetrics::breakString_helper(docstring const & s, int first_wid, int wid,
547 bool rtl, bool force) const
549 TextLayoutHelper const tlh(s, rtl, needs_naked_);
553 /* Use undocumented flag to enforce drawing direction
554 * FIXME: This does not work with Qt 5.11 (ticket #11284).
556 tl.setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
558 tl.setText(tlh.qstr);
562 * Some Asian languages split lines anywhere (no notion of
563 * word). It seems that QTextLayout is not aware of this fact.
565 * https://en.wikipedia.org/wiki/Line_breaking_rules_in_East_Asian_languages
567 * FIXME: Something shall be done about characters which are
568 * not allowed at the beginning or end of line.
570 to.setWrapMode(force ? QTextOption::WrapAtWordBoundaryOrAnywhere
571 : QTextOption::WordWrap);
572 tl.setTextOption(to);
577 QTextLine line = tl.createLine();
580 line.setLineWidth(first ? first_wid : wid);
587 for (int i = 0 ; i < tl.lineCount() ; ++i) {
588 QTextLine const & line = tl.lineAt(i);
589 int const line_epos = line.textStart() + line.textLength();
590 int const epos = tlh.qpos2pos(line_epos);
591 // This does not take trailing spaces into account, except for the last line.
592 int const wid = iround(line.naturalTextWidth());
593 // If the line is not the last one, trailing space is always omitted.
595 // For the last line, compute the width without trailing space
596 if (i + 1 == tl.lineCount() && !s.empty() && isSpace(s.back())
597 && line.textStart() <= tlh.pos2qpos(s.size() - 1))
598 nspc_wid = iround(line.cursorToX(tlh.pos2qpos(s.size() - 1)));
599 breaks.emplace_back(epos - pos, wid, nspc_wid);
607 uint qHash(BreakStringKey const & key)
609 // assume widths are less than 10000. This fits in 32 bits.
610 uint params = key.force + 2 * key.rtl + 4 * key.first_wid + 10000 * key.wid;
611 return std::qHash(key.s) ^ ::qHash(params);
615 FontMetrics::Breaks GuiFontMetrics::breakString(docstring const & s, int first_wid, int wid,
616 bool rtl, bool force) const
618 PROFILE_THIS_BLOCK(breakString);
622 BreakStringKey key{s, first_wid, wid, rtl, force};
624 if (auto * brks_ptr = breakstr_cache_.object_ptr(key))
627 PROFILE_CACHE_MISS(breakString);
628 brks = breakString_helper(s, first_wid, wid, rtl, force);
629 breakstr_cache_.insert(key, brks, sizeof(key) + s.size() * sizeof(char_type));
635 void GuiFontMetrics::rectText(docstring const & str,
636 int & w, int & ascent, int & descent) const
638 // FIXME: let offset depend on font (this is Inset::TEXT_TO_OFFSET)
639 int const offset = 4;
641 w = width(str) + offset;
642 ascent = metrics_.ascent() + offset / 2;
643 descent = metrics_.descent() + offset / 2;
647 void GuiFontMetrics::buttonText(docstring const & str, const int offset,
648 int & w, int & ascent, int & descent) const
650 rectText(str, w, ascent, descent);
655 Dimension const GuiFontMetrics::defaultDimension() const
657 return Dimension(0, maxAscent(), maxDescent());
661 Dimension const GuiFontMetrics::dimension(char_type c) const
663 return Dimension(width(c), ascent(c), descent(c));
667 GuiFontMetrics::AscendDescend const GuiFontMetrics::fillMetricsCache(
672 r = metrics_.boundingRect(ucs4_to_qchar(c));
674 r = metrics_.boundingRect(toqstr(docstring(1, c)));
676 AscendDescend ad = { -r.top(), r.bottom() + 1};
677 // We could as well compute the width but this is not really
678 // needed for now as it is done directly in width() below.
679 metrics_cache_.insert(c, ad);
685 int GuiFontMetrics::width(char_type c) const
687 int value = width_cache_.value(c, outOfLimitMetric);
688 if (value != outOfLimitMetric)
691 #if QT_VERSION >= 0x050b00
693 value = metrics_.horizontalAdvance(ucs4_to_qchar(c));
695 value = metrics_.horizontalAdvance(toqstr(docstring(1, c)));
698 value = metrics_.width(ucs4_to_qchar(c));
700 value = metrics_.width(toqstr(docstring(1, c)));
703 width_cache_.insert(c, value);
709 int GuiFontMetrics::ascent(char_type c) const
711 static AscendDescend const outOfLimitAD =
712 {outOfLimitMetric, outOfLimitMetric};
713 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
714 if (value.ascent != outOfLimitMetric)
717 value = fillMetricsCache(c);
722 int GuiFontMetrics::descent(char_type c) const
724 static AscendDescend const outOfLimitAD =
725 {outOfLimitMetric, outOfLimitMetric};
726 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
727 if (value.descent != outOfLimitMetric)
728 return value.descent;
730 value = fillMetricsCache(c);
731 return value.descent;
734 } // namespace frontend