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::lineWidth() const
122 return metrics_.lineWidth();
126 int GuiFontMetrics::underlinePos() const
128 return metrics_.underlinePos();
132 int GuiFontMetrics::strikeoutPos() const
134 return metrics_.strikeOutPos();
138 int GuiFontMetrics::lbearing(char_type c) const
141 // FIXME: QFontMetrics::leftBearing does not support the
142 // full unicode range. Once it does, we could use:
143 //return metrics_.leftBearing(toqstr(docstring(1, c)));
146 return metrics_.leftBearing(ucs4_to_qchar(c));
151 int const outOfLimitMetric = -10000;
155 int GuiFontMetrics::rbearing(char_type c) const
157 int value = rbearing_cache_.value(c, outOfLimitMetric);
158 if (value != outOfLimitMetric)
161 // Qt rbearing is from the right edge of the char's width().
163 QChar sc = ucs4_to_qchar(c);
164 value = width(c) - metrics_.rightBearing(sc);
166 // FIXME: QFontMetrics::leftBearing does not support the
167 // full unicode range. Once it does, we could use:
168 // metrics_.rightBearing(toqstr(docstring(1, c)));
172 rbearing_cache_.insert(c, value);
178 int GuiFontMetrics::width(docstring const & s) const
180 PROFILE_THIS_BLOCK(width);
181 if (strwidth_cache_.contains(s))
182 return strwidth_cache_[s];
183 PROFILE_CACHE_MISS(width);
184 /* Several problems have to be taken into account:
185 * * QFontMetrics::width does not returns a wrong value with Qt5 with
186 * some arabic text, since the glyph-shaping operations are not
187 * done (documented in Qt5).
188 * * QTextLayout is broken for single characters with null width
189 * (like \not in mathed).
190 * * While QTextLine::horizontalAdvance is the right thing to use
191 * for text strings, it does not give a good result with some
192 * characters like the \int (gyph 4) of esint.
194 * Also, as a safety measure, always use QFontMetrics::width with
198 // is the string a single character from a math font ?
199 #if QT_VERSION >= 0x040800
200 bool const math_char = s.length() == 1 || font_.styleName() == "LyX";
202 bool const math_char = s.length() == 1;
204 // keep value 0 for math chars with width 0
205 if (!math_char || metrics_.width(toqstr(s)) != 0) {
207 tl.setText(toqstr(s));
210 QTextLine line = tl.createLine();
213 w = iround(line.naturalTextWidth());
215 w = iround(line.horizontalAdvance());
217 strwidth_cache_.insert(s, w, s.size() * sizeof(char_type));
222 int GuiFontMetrics::width(QString const & ucs2) const
224 return width(qstring_to_ucs4(ucs2));
228 int GuiFontMetrics::signedWidth(docstring const & s) const
234 return -width(s.substr(1, s.size() - 1));
240 shared_ptr<QTextLayout const>
241 GuiFontMetrics::getTextLayout(docstring const & s, bool const rtl,
242 double const wordspacing) const
244 PROFILE_THIS_BLOCK(getTextLayout);
245 docstring const s_cache =
246 s + (rtl ? "r" : "l") + convert<docstring>(wordspacing);
247 if (auto ptl = qtextlayout_cache_[s_cache])
249 PROFILE_CACHE_MISS(getTextLayout);
250 auto const ptl = make_shared<QTextLayout>();
251 ptl->setCacheEnabled(true);
252 ptl->setText(toqstr(s));
254 copy.setWordSpacing(wordspacing);
256 // Note that both setFlags and the enums are undocumented
257 ptl->setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
261 qtextlayout_cache_.insert(s_cache, ptl);
266 int GuiFontMetrics::pos2x(docstring const & s, int pos, bool const rtl,
267 double const wordspacing) const
271 shared_ptr<QTextLayout const> tl = getTextLayout(s, rtl, wordspacing);
272 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
273 * not be the same when there are high-plan unicode characters
276 int const qpos = toqstr(s.substr(0, pos)).length();
277 return static_cast<int>(tl->lineForTextPosition(qpos).cursorToX(qpos));
281 int GuiFontMetrics::x2pos(docstring const & s, int & x, bool const rtl,
282 double const wordspacing) const
284 shared_ptr<QTextLayout const> tl = getTextLayout(s, rtl, wordspacing);
285 QTextLine const & tline = tl->lineForTextPosition(0);
286 int qpos = tline.xToCursor(x);
287 int newx = static_cast<int>(tline.cursorToX(qpos));
288 // The value of qpos may be wrong in rtl text (see ticket #10569).
289 // To work around this, let's have a look at adjacent positions to
290 // see whether we find closer matches.
291 if (rtl && newx < x) {
293 int const xm = static_cast<int>(tline.cursorToX(qpos - 1));
294 if (abs(xm - x) < abs(newx - x)) {
300 } else if (rtl && newx > x) {
301 while (qpos < tline.textLength()) {
302 int const xp = static_cast<int>(tline.cursorToX(qpos + 1));
303 if (abs(xp - x) < abs(newx - x)) {
310 // correct x value to the actual cursor position.
313 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
314 * not be the same when there are high-plan unicode characters
317 #if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
318 return qstring_to_ucs4(tl->text().left(qpos)).length();
320 /* Due to QTBUG-25536 in 4.8.1 <= Qt < 5.1.0, the string returned
321 * by QString::toUcs4 (used by qstring_to_ucs4) may have wrong
322 * length. We work around the problem by trying all docstring
323 * positions until the right one is found. This is slow only if
324 * there are many high-plane Unicode characters. It might be
325 * worthwhile to implement a dichotomy search if this shows up
328 int pos = min(qpos, static_cast<int>(s.length()));
329 while (pos >= 0 && toqstr(s.substr(0, pos)).length() != qpos)
331 LASSERT(pos > 0 || qpos == 0, /**/);
337 int GuiFontMetrics::countExpanders(docstring const & str) const
339 // Numbers of characters that are expanded by inter-word spacing. These
340 // characters are spaces, except for characters 09-0D which are treated
341 // specially. (From a combination of testing with the notepad found in qt's
342 // examples, and reading the source code.) In addition, consecutive spaces
343 // only count as one expander.
344 bool wasspace = false;
346 for (char_type c : str)
347 if (c > 0x0d && QChar(c).isSpace()) {
359 GuiFontMetrics::breakAt_helper(docstring const & s, int const x,
360 bool const rtl, bool const force) const
363 /* Qt will not break at a leading or trailing space, and we need
364 * that sometimes, see http://www.lyx.org/trac/ticket/9921.
366 * To work around the problem, we enclose the string between
367 * zero-width characters so that the QTextLayout algorithm will
368 * agree to break the text at these extremal spaces.
370 // Unicode character ZERO WIDTH NO-BREAK SPACE
371 QChar const zerow_nbsp(0xfeff);
372 QString qs = zerow_nbsp + toqstr(s) + zerow_nbsp;
374 /* Use unicode override characters to enforce drawing direction
375 * Source: http://www.iamcal.com/understanding-bidirectional-text/
378 // Right-to-left override: forces to draw text right-to-left
379 qs = QChar(0x202E) + qs;
381 // Left-to-right override: forces to draw text left-to-right
382 qs = QChar(0x202D) + qs;
383 int const offset = 2;
385 // Alternative version that breaks with Qt5 and arabic text (#10436)
386 // Note that both setFlags and the enums are undocumented
387 tl.setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
388 int const offset = 1;
394 to.setWrapMode(force ? QTextOption::WrapAtWordBoundaryOrAnywhere
395 : QTextOption::WordWrap);
396 tl.setTextOption(to);
398 QTextLine line = tl.createLine();
399 line.setLineWidth(x);
402 int const line_wid = iround(line.horizontalAdvance());
403 if ((force && line.textLength() == offset) || line_wid > x)
405 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
406 * not be the same when there are high-plan unicode characters
409 // The variable `offset' is here to account for the extra leading characters.
410 // The ending character zerow_nbsp has to be ignored if the line is complete.
411 int const qlen = line.textLength() - offset - (line.textLength() == qs.length());
412 #if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
413 int len = qstring_to_ucs4(qs.mid(offset, qlen)).length();
415 /* Due to QTBUG-25536 in 4.8.1 <= Qt < 5.1.0, the string returned
416 * by QString::toUcs4 (used by qstring_to_ucs4) may have wrong
417 * length. We work around the problem by trying all docstring
418 * positions until the right one is found. This is slow only if
419 * there are many high-plane Unicode characters. It might be
420 * worthwhile to implement a dichotomy search if this shows up
423 int len = min(qlen, static_cast<int>(s.length()));
424 while (len >= 0 && toqstr(s.substr(0, len)).length() != qlen)
426 LASSERT(len > 0 || qlen == 0, /**/);
428 return {len, line_wid};
432 bool GuiFontMetrics::breakAt(docstring & s, int & x, bool const rtl, bool const force) const
434 PROFILE_THIS_BLOCK(breakAt);
438 docstring const s_cache =
439 s + convert<docstring>(x) + (rtl ? "r" : "l") + (force ? "f" : "w");
442 if (breakat_cache_.contains(s_cache))
443 pp = breakat_cache_[s_cache];
445 PROFILE_CACHE_MISS(breakAt);
446 pp = breakAt_helper(s, x, rtl, force);
447 breakat_cache_.insert(s_cache, pp, s_cache.size() * sizeof(char_type));
451 s = s.substr(0, pp.first);
457 void GuiFontMetrics::rectText(docstring const & str,
458 int & w, int & ascent, int & descent) const
460 // FIXME: let offset depend on font (this is Inset::TEXT_TO_OFFSET)
461 int const offset = 4;
463 w = width(str) + offset;
464 ascent = metrics_.ascent() + offset / 2;
465 descent = metrics_.descent() + offset / 2;
469 void GuiFontMetrics::buttonText(docstring const & str, const int offset,
470 int & w, int & ascent, int & descent) const
472 rectText(str, w, ascent, descent);
477 Dimension const GuiFontMetrics::defaultDimension() const
479 return Dimension(0, maxAscent(), maxDescent());
483 Dimension const GuiFontMetrics::dimension(char_type c) const
485 return Dimension(width(c), ascent(c), descent(c));
489 GuiFontMetrics::AscendDescend const GuiFontMetrics::fillMetricsCache(
494 r = metrics_.boundingRect(ucs4_to_qchar(c));
496 r = metrics_.boundingRect(toqstr(docstring(1, c)));
498 AscendDescend ad = { -r.top(), r.bottom() + 1};
499 // We could as well compute the width but this is not really
500 // needed for now as it is done directly in width() below.
501 metrics_cache_.insert(c, ad);
507 int GuiFontMetrics::width(char_type c) const
509 int value = width_cache_.value(c, outOfLimitMetric);
510 if (value != outOfLimitMetric)
514 value = metrics_.width(ucs4_to_qchar(c));
516 value = metrics_.width(toqstr(docstring(1, c)));
518 width_cache_.insert(c, value);
524 int GuiFontMetrics::ascent(char_type c) const
526 static AscendDescend const outOfLimitAD =
527 {outOfLimitMetric, outOfLimitMetric};
528 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
529 if (value.ascent != outOfLimitMetric)
532 value = fillMetricsCache(c);
537 int GuiFontMetrics::descent(char_type c) const
539 static AscendDescend const outOfLimitAD =
540 {outOfLimitMetric, outOfLimitMetric};
541 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
542 if (value.descent != outOfLimitMetric)
543 return value.descent;
545 value = fillMetricsCache(c);
546 return value.descent;
549 } // namespace frontend