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"
59 * Argument-dependent lookup implies that this function shall be
60 * declared in the namespace of its argument. But this is std
61 * namespace, since lyx::docstring is just std::basic_string<wchar_t>.
63 uint qHash(lyx::docstring const & s)
65 return qHash(QByteArray(reinterpret_cast<char const *>(s.data()),
66 s.size() * sizeof(lyx::docstring::value_type)));
76 // Maximal size/cost for various caches. See QCache documentation to
77 // see what cost means.
79 // Limit strwidth_cache_ total cost to 1MB of string data.
80 int const strwidth_cache_max_cost = 1024 * 1024;
81 // Limit breakstr_cache_ total cost to 10MB of string data.
82 // This is useful for documents with very large insets.
83 int const breakstr_cache_max_cost = 10 * 1024 * 1024;
84 // Qt 5.x already has its own caching of QTextLayout objects
85 // but it does not seem to work well on MacOS X.
87 //FIXME KILLQT4: check wether setting the cache to 0 hurts on macOS
88 // Limit qtextlayout_cache_ size to 500 elements (we do not know the
89 // size of the QTextLayout objects anyway).
90 int const qtextlayout_cache_max_size = 500;
93 int const qtextlayout_cache_max_size = 0;
98 * Convert a UCS4 character into a QChar.
99 * This is a hack (it does only make sense for the common part of the UCS4
100 * and UTF16 encodings) and should not be used.
101 * This does only exist because of performance reasons (a real conversion
102 * using iconv is too slow on windows).
104 * This is no real conversion but a simple cast in reality. This is the reason
105 * why this works well for symbol fonts used in mathed too, even though
106 * these are not real ucs4 characters. These are codepoints in the
107 * computer modern fonts used, nothing unicode related.
108 * See comment in GuiPainter::text() for more explanation.
110 inline QChar const ucs4_to_qchar(char_type const ucs4)
112 LATTEST(is_utf16(ucs4));
113 return QChar(static_cast<unsigned short>(ucs4));
118 GuiFontMetrics::GuiFontMetrics(QFont const & font)
119 : font_(font), metrics_(font, 0),
120 strwidth_cache_(strwidth_cache_max_cost),
121 breakstr_cache_(breakstr_cache_max_cost),
122 qtextlayout_cache_(qtextlayout_cache_max_size)
124 // Determine italic slope
125 double const defaultSlope = tan(qDegreesToRadians(19.0));
126 QRawFont raw = QRawFont::fromFont(font);
127 QByteArray post(raw.fontTable("post"));
128 if (post.length() == 0) {
129 slope_ = defaultSlope;
130 LYXERR(Debug::FONT, "Screen font doesn't have 'post' table.");
132 // post table description:
133 // https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6post.html
134 int32_t italicAngle = qFromBigEndian(*reinterpret_cast<int32_t *>(post.data() + 4));
135 double angle = italicAngle / 65536.0; // Fixed-point 16.16 to floating-point
136 slope_ = -tan(qDegreesToRadians(angle));
137 // Correct italic fonts with zero slope
138 if (slope_ == 0.0 && font.italic())
139 slope_ = defaultSlope;
140 LYXERR(Debug::FONT, "Italic slope: " << slope_);
142 // If those characters have a non-zero width, we need to avoid them.
143 // This happens with Qt4 with monospace fonts
144 needs_naked_ = width(QString() + QChar(0x2060) + QChar(0x202d) + QChar(0x202e)) > 0;
146 // LYXERR0("Font " << font.family() << " needs naked text layouts!");
150 int GuiFontMetrics::maxAscent() const
152 return metrics_.ascent();
156 int GuiFontMetrics::maxDescent() const
158 // We add 1 as the value returned by QT is different than X
159 // See http://doc.trolltech.com/2.3/qfontmetrics.html#200b74
161 return metrics_.descent() + 1;
165 int GuiFontMetrics::em() const
167 return QFontInfo(font_).pixelSize();
171 int GuiFontMetrics::xHeight() const
173 // LATTEST(metrics_.xHeight() == ascent('x'));
174 return metrics_.xHeight();
178 int GuiFontMetrics::lineWidth() const
180 return metrics_.lineWidth();
184 int GuiFontMetrics::underlinePos() const
186 return metrics_.underlinePos();
190 int GuiFontMetrics::strikeoutPos() const
192 return metrics_.strikeOutPos();
196 bool GuiFontMetrics::italic() const
198 return font_.italic();
202 double GuiFontMetrics::italicSlope() const
209 int const outOfLimitMetric = -10000;
213 int GuiFontMetrics::lbearing(char_type c) const
215 int value = lbearing_cache_.value(c, outOfLimitMetric);
216 if (value != outOfLimitMetric)
220 value = metrics_.leftBearing(ucs4_to_qchar(c));
222 // FIXME: QFontMetrics::leftBearing does not support the
223 // full unicode range. Once it does, we could use:
224 // metrics_.leftBearing(toqstr(docstring(1, c)));
228 lbearing_cache_.insert(c, value);
234 int GuiFontMetrics::rbearing(char_type c) const
236 int value = rbearing_cache_.value(c, outOfLimitMetric);
237 if (value != outOfLimitMetric)
240 // Qt rbearing is from the right edge of the char's width().
242 QChar sc = ucs4_to_qchar(c);
243 value = width(c) - metrics_.rightBearing(sc);
245 // FIXME: QFontMetrics::leftBearing does not support the
246 // full unicode range. Once it does, we could use:
247 // metrics_.rightBearing(toqstr(docstring(1, c)));
251 rbearing_cache_.insert(c, value);
257 int GuiFontMetrics::width(docstring const & s) const
259 PROFILE_THIS_BLOCK(width);
260 if (int * wid_p = strwidth_cache_.object_ptr(s))
262 PROFILE_CACHE_MISS(width);
263 /* Several problems have to be taken into account:
264 * * QFontMetrics::width does not returns a wrong value with Qt5 with
265 * some arabic text, since the glyph-shaping operations are not
266 * done (documented in Qt5).
267 * * QTextLayout is broken for single characters with null width
268 * (like \not in mathed).
269 * * While QTextLine::horizontalAdvance is the right thing to use
270 * for text strings, it does not give a good result with some
271 * characters like the \int (gyph 4) of esint.
273 * The metrics of some of our math fonts (eg. esint) are such that
274 * QTextLine::horizontalAdvance leads, more or less, in the middle
275 * of a symbol. This is the horizontal position where a subscript
276 * should be drawn, so that the superscript has to be moved rightward.
277 * This is done when the kerning() method of the math insets returns
278 * a positive value. The problem with this choice is that navigating
279 * a formula becomes weird. For example, a selection extends only over
280 * about half of the symbol. In order to avoid this, with our math
281 * fonts we use QTextLine::naturalTextWidth, so that a superscript can
282 * be drawn right after the symbol, and move the subscript leftward by
283 * recording a negative value for the kerning.
286 // is the string a single character from a math font ?
287 bool const math_char = s.length() == 1 && font_.styleName() == "LyX";
289 QString const qs = toqstr(s);
290 int br_width = metrics_.boundingRect(qs).width();
291 #if QT_VERSION >= 0x050b00
292 int s_width = metrics_.horizontalAdvance(qs);
294 int s_width = metrics_.width(qs);
296 // keep value 0 for math chars with width 0
298 w = max(br_width, s_width);
301 tl.setText(toqstr(s));
304 QTextLine line = tl.createLine();
306 w = iround(line.horizontalAdvance());
308 strwidth_cache_.insert(s, w, s.size() * sizeof(char_type));
313 int GuiFontMetrics::width(QString const & ucs2) const
315 return width(qstring_to_ucs4(ucs2));
319 int GuiFontMetrics::signedWidth(docstring const & s) const
325 return -width(s.substr(1, s.size() - 1));
331 uint qHash(TextLayoutKey const & key)
333 double params = (2 * key.rtl - 1) * key.ws;
334 return std::qHash(key.s) ^ ::qHash(params);
338 // This holds a translation table between the original string and the
339 // QString that we can use with QTextLayout.
340 struct TextLayoutHelper
342 /// Create the helper
343 /// \c s is the original string
344 /// \c isrtl is true if the string is right-to-left
345 /// \c naked is true to disable the insertion of zero width annotations
346 /// FIXME KILLQT4: remove \c naked argument when Qt4 support goes away.
347 TextLayoutHelper(docstring const & s, bool isrtl, bool naked = false);
349 /// translate QString index to docstring index
350 docstring::size_type qpos2pos(int qpos) const
352 return lower_bound(pos2qpos_.begin(), pos2qpos_.end(), qpos) - pos2qpos_.begin();
355 /// Translate docstring index to QString index
356 int pos2qpos(docstring::size_type pos) const { return pos2qpos_[pos]; }
358 // The original string
362 // is string right-to-left?
366 // This vector contains the QString pos for each string position
367 vector<int> pos2qpos_;
371 TextLayoutHelper::TextLayoutHelper(docstring const & s, bool isrtl, bool naked)
372 : docstr(s), rtl(isrtl)
374 // Reserve memory for performance purpose
375 pos2qpos_.reserve(s.size());
376 qstr.reserve(2 * s.size());
378 /* Qt will not break at a leading or trailing space, and we need
379 * that sometimes, see http://www.lyx.org/trac/ticket/9921.
381 * To work around the problem, we enclose the string between
382 * word joiner characters so that the QTextLayout algorithm will
383 * agree to break the text at these extremal spaces.
385 // Unicode character WORD JOINER
386 QChar const word_joiner(0x2060);
390 #ifdef BIDI_USE_OVERRIDE
391 /* Unicode override characters enforce drawing direction
392 * Source: http://www.iamcal.com/understanding-bidirectional-text/
393 * Left-to-right override is 0x202d and right-to-left override is 0x202e.
396 qstr += QChar(rtl ? 0x202e : 0x202d);
399 // Now translate the string character-by-character.
400 bool was_space = false;
401 for (char_type const c : s) {
402 // insert a word joiner character between consecutive spaces
403 bool const is_space = isSpace(c);
404 if (!naked && is_space && was_space)
406 was_space = is_space;
407 // Remember the QString index at this point
408 pos2qpos_.push_back(qstr.size());
409 // Performance: UTF-16 characters are easier
411 qstr += ucs4_to_qchar(c);
416 // Final word joiner (see above)
420 // Add virtual position at the end of the string
421 pos2qpos_.push_back(qstr.size());
423 //QString dump = qstr;
424 //LYXERR0("TLH: " << dump.replace(word_joiner, "|").toStdString());
430 shared_ptr<QTextLayout>
431 getTextLayout_helper(TextLayoutHelper const & tlh, double const wordspacing,
434 auto const ptl = make_shared<QTextLayout>();
435 ptl->setCacheEnabled(true);
436 font.setWordSpacing(wordspacing);
439 /* Use undocumented flag to enforce drawing direction
440 * FIXME: This does not work with Qt 5.11 (ticket #11284).
442 ptl->setFlags(tlh.rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
444 ptl->setText(tlh.qstr);
455 shared_ptr<QTextLayout const>
456 GuiFontMetrics::getTextLayout(TextLayoutHelper const & tlh,
457 double const wordspacing) const
459 PROFILE_THIS_BLOCK(getTextLayout_TLH);
460 TextLayoutKey key{tlh.docstr, tlh.rtl, wordspacing};
461 if (auto ptl = qtextlayout_cache_[key])
463 PROFILE_CACHE_MISS(getTextLayout_TLH);
464 auto const ptl = getTextLayout_helper(tlh, wordspacing, font_);
465 qtextlayout_cache_.insert(key, ptl);
470 shared_ptr<QTextLayout const>
471 GuiFontMetrics::getTextLayout(docstring const & s, bool const rtl,
472 double const wordspacing) const
474 PROFILE_THIS_BLOCK(getTextLayout);
475 TextLayoutKey key{s, rtl, wordspacing};
476 if (auto ptl = qtextlayout_cache_[key])
478 PROFILE_CACHE_MISS(getTextLayout);
479 TextLayoutHelper tlh(s, rtl, needs_naked_);
480 auto const ptl = getTextLayout_helper(tlh, wordspacing, font_);
481 qtextlayout_cache_.insert(key, ptl);
486 int GuiFontMetrics::pos2x(docstring const & s, int pos, bool const rtl,
487 double const wordspacing) const
489 TextLayoutHelper tlh(s, rtl, needs_naked_);
490 auto ptl = getTextLayout(tlh, wordspacing);
491 // pos can be negative, see #10506.
492 int const qpos = tlh.pos2qpos(max(pos, 0));
493 return static_cast<int>(ptl->lineForTextPosition(qpos).cursorToX(qpos));
497 int GuiFontMetrics::x2pos(docstring const & s, int & x, bool const rtl,
498 double const wordspacing) const
500 TextLayoutHelper tlh(s, rtl, needs_naked_);
501 auto ptl = getTextLayout(tlh, wordspacing);
502 QTextLine const & tline = ptl->lineForTextPosition(0);
503 int qpos = tline.xToCursor(x);
504 int newx = static_cast<int>(tline.cursorToX(qpos));
505 // The value of qpos may be wrong in rtl text (see ticket #10569).
506 // To work around this, let's have a look at adjacent positions to
507 // see whether we find closer matches.
508 if (rtl && newx < x) {
510 int const xm = static_cast<int>(tline.cursorToX(qpos - 1));
511 if (abs(xm - x) < abs(newx - x)) {
517 } else if (rtl && newx > x) {
518 while (qpos < tline.textLength()) {
519 int const xp = static_cast<int>(tline.cursorToX(qpos + 1));
520 if (abs(xp - x) < abs(newx - x)) {
527 // correct x value to the actual cursor position.
530 return tlh.qpos2pos(qpos);
535 GuiFontMetrics::breakString_helper(docstring const & s, int first_wid, int wid,
536 bool rtl, bool force) const
538 TextLayoutHelper const tlh(s, rtl, needs_naked_);
542 /* Use undocumented flag to enforce drawing direction
543 * FIXME: This does not work with Qt 5.11 (ticket #11284).
545 tl.setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
547 tl.setText(tlh.qstr);
551 * Some Asian languages split lines anywhere (no notion of
552 * word). It seems that QTextLayout is not aware of this fact.
554 * https://en.wikipedia.org/wiki/Line_breaking_rules_in_East_Asian_languages
556 * FIXME: Something shall be done about characters which are
557 * not allowed at the beginning or end of line.
559 to.setWrapMode(force ? QTextOption::WrapAtWordBoundaryOrAnywhere
560 : QTextOption::WordWrap);
561 tl.setTextOption(to);
566 QTextLine line = tl.createLine();
569 line.setLineWidth(first ? first_wid : wid);
576 for (int i = 0 ; i < tl.lineCount() ; ++i) {
577 QTextLine const & line = tl.lineAt(i);
578 int const line_epos = line.textStart() + line.textLength();
579 int const epos = tlh.qpos2pos(line_epos);
580 // This does not take trailing spaces into account, except for the last line.
581 int const wid = iround(line.naturalTextWidth());
582 // If the line is not the last one, trailing space is always omitted.
584 // For the last line, compute the width without trailing space
585 if (i + 1 == tl.lineCount() && !s.empty() && isSpace(s.back())
586 && line.textStart() <= tlh.pos2qpos(s.size() - 1))
587 nspc_wid = iround(line.cursorToX(tlh.pos2qpos(s.size() - 1)));
588 breaks.emplace_back(epos - pos, wid, nspc_wid);
596 uint qHash(BreakStringKey const & key)
598 // assume widths are less than 10000. This fits in 32 bits.
599 uint params = key.force + 2 * key.rtl + 4 * key.first_wid + 10000 * key.wid;
600 return std::qHash(key.s) ^ ::qHash(params);
604 FontMetrics::Breaks GuiFontMetrics::breakString(docstring const & s, int first_wid, int wid,
605 bool rtl, bool force) const
607 PROFILE_THIS_BLOCK(breakString);
611 BreakStringKey key{s, first_wid, wid, rtl, force};
613 if (auto * brks_ptr = breakstr_cache_.object_ptr(key))
616 PROFILE_CACHE_MISS(breakString);
617 brks = breakString_helper(s, first_wid, wid, rtl, force);
618 breakstr_cache_.insert(key, brks, sizeof(key) + s.size() * sizeof(char_type));
624 void GuiFontMetrics::rectText(docstring const & str,
625 int & w, int & ascent, int & descent) const
627 // FIXME: let offset depend on font (this is Inset::TEXT_TO_OFFSET)
628 int const offset = 4;
630 w = width(str) + offset;
631 ascent = metrics_.ascent() + offset / 2;
632 descent = metrics_.descent() + offset / 2;
636 void GuiFontMetrics::buttonText(docstring const & str, const int offset,
637 int & w, int & ascent, int & descent) const
639 rectText(str, w, ascent, descent);
644 Dimension const GuiFontMetrics::defaultDimension() const
646 return Dimension(0, maxAscent(), maxDescent());
650 Dimension const GuiFontMetrics::dimension(char_type c) const
652 return Dimension(width(c), ascent(c), descent(c));
656 GuiFontMetrics::AscendDescend const GuiFontMetrics::fillMetricsCache(
661 r = metrics_.boundingRect(ucs4_to_qchar(c));
663 r = metrics_.boundingRect(toqstr(docstring(1, c)));
665 AscendDescend ad = { -r.top(), r.bottom() + 1};
666 // We could as well compute the width but this is not really
667 // needed for now as it is done directly in width() below.
668 metrics_cache_.insert(c, ad);
674 int GuiFontMetrics::width(char_type c) const
676 int value = width_cache_.value(c, outOfLimitMetric);
677 if (value != outOfLimitMetric)
680 #if QT_VERSION >= 0x050b00
682 value = metrics_.horizontalAdvance(ucs4_to_qchar(c));
684 value = metrics_.horizontalAdvance(toqstr(docstring(1, c)));
687 value = metrics_.width(ucs4_to_qchar(c));
689 value = metrics_.width(toqstr(docstring(1, c)));
692 width_cache_.insert(c, value);
698 int GuiFontMetrics::ascent(char_type c) const
700 static AscendDescend const outOfLimitAD =
701 {outOfLimitMetric, outOfLimitMetric};
702 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
703 if (value.ascent != outOfLimitMetric)
706 value = fillMetricsCache(c);
711 int GuiFontMetrics::descent(char_type c) const
713 static AscendDescend const outOfLimitAD =
714 {outOfLimitMetric, outOfLimitMetric};
715 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
716 if (value.descent != outOfLimitMetric)
717 return value.descent;
719 value = fillMetricsCache(c);
720 return value.descent;
723 } // namespace frontend