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 /* For some reason QMetrics::width returns a wrong value with Qt5
185 * with some arabic text. OTOH, QTextLayout is broken for single
186 * characters with null width (like \not in mathed). Also, as a
187 * safety measure, always use QMetrics::width with our math fonts.
191 #if QT_VERSION >= 0x040800
192 || font_.styleName() == "LyX"
195 w = metrics_.width(toqstr(s));
198 tl.setText(toqstr(s));
201 QTextLine line = tl.createLine();
203 w = iround(line.horizontalAdvance());
205 strwidth_cache_.insert(s, w, s.size() * sizeof(char_type));
210 int GuiFontMetrics::width(QString const & ucs2) const
212 return width(qstring_to_ucs4(ucs2));
216 int GuiFontMetrics::signedWidth(docstring const & s) const
222 return -width(s.substr(1, s.size() - 1));
228 shared_ptr<QTextLayout const>
229 GuiFontMetrics::getTextLayout(docstring const & s, bool const rtl,
230 double const wordspacing) const
232 PROFILE_THIS_BLOCK(getTextLayout);
233 docstring const s_cache =
234 s + (rtl ? "r" : "l") + convert<docstring>(wordspacing);
235 if (auto ptl = qtextlayout_cache_[s_cache])
237 PROFILE_CACHE_MISS(getTextLayout);
238 auto const ptl = make_shared<QTextLayout>();
239 ptl->setCacheEnabled(true);
240 ptl->setText(toqstr(s));
242 copy.setWordSpacing(wordspacing);
244 // Note that both setFlags and the enums are undocumented
245 ptl->setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
249 qtextlayout_cache_.insert(s_cache, ptl);
254 int GuiFontMetrics::pos2x(docstring const & s, int pos, bool const rtl,
255 double const wordspacing) const
259 shared_ptr<QTextLayout const> tl = getTextLayout(s, rtl, wordspacing);
260 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
261 * not be the same when there are high-plan unicode characters
264 int const qpos = toqstr(s.substr(0, pos)).length();
265 return static_cast<int>(tl->lineForTextPosition(qpos).cursorToX(qpos));
269 int GuiFontMetrics::x2pos(docstring const & s, int & x, bool const rtl,
270 double const wordspacing) const
272 shared_ptr<QTextLayout const> tl = getTextLayout(s, rtl, wordspacing);
273 QTextLine const & tline = tl->lineForTextPosition(0);
274 int qpos = tline.xToCursor(x);
275 int newx = static_cast<int>(tline.cursorToX(qpos));
276 // The value of qpos may be wrong in rtl text (see ticket #10569).
277 // To work around this, let's have a look at adjacent positions to
278 // see whether we find closer matches.
279 if (rtl && newx < x) {
281 int const xm = static_cast<int>(tline.cursorToX(qpos - 1));
282 if (abs(xm - x) < abs(newx - x)) {
288 } else if (rtl && newx > x) {
289 while (qpos < tline.textLength()) {
290 int const xp = static_cast<int>(tline.cursorToX(qpos + 1));
291 if (abs(xp - x) < abs(newx - x)) {
298 // correct x value to the actual cursor position.
301 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
302 * not be the same when there are high-plan unicode characters
305 #if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
306 return qstring_to_ucs4(tl->text().left(qpos)).length();
308 /* Due to QTBUG-25536 in 4.8.1 <= Qt < 5.1.0, the string returned
309 * by QString::toUcs4 (used by qstring_to_ucs4) may have wrong
310 * length. We work around the problem by trying all docstring
311 * positions until the right one is found. This is slow only if
312 * there are many high-plane Unicode characters. It might be
313 * worthwhile to implement a dichotomy search if this shows up
316 int pos = min(qpos, static_cast<int>(s.length()));
317 while (pos >= 0 && toqstr(s.substr(0, pos)).length() != qpos)
319 LASSERT(pos > 0 || qpos == 0, /**/);
325 int GuiFontMetrics::countExpanders(docstring const & str) const
327 // Numbers of characters that are expanded by inter-word spacing. These
328 // characters are spaces, except for characters 09-0D which are treated
329 // specially. (From a combination of testing with the notepad found in qt's
330 // examples, and reading the source code.) In addition, consecutive spaces
331 // only count as one expander.
332 bool wasspace = false;
334 for (char_type c : str)
335 if (c > 0x0d && QChar(c).isSpace()) {
347 GuiFontMetrics::breakAt_helper(docstring const & s, int const x,
348 bool const rtl, bool const force) const
351 /* Qt will not break at a leading or trailing space, and we need
352 * that sometimes, see http://www.lyx.org/trac/ticket/9921.
354 * To work around the problem, we enclose the string between
355 * zero-width characters so that the QTextLayout algorithm will
356 * agree to break the text at these extremal spaces.
358 // Unicode character ZERO WIDTH NO-BREAK SPACE
359 QChar const zerow_nbsp(0xfeff);
360 QString qs = zerow_nbsp + toqstr(s) + zerow_nbsp;
362 /* Use unicode override characters to enforce drawing direction
363 * Source: http://www.iamcal.com/understanding-bidirectional-text/
366 // Right-to-left override: forces to draw text right-to-left
367 qs = QChar(0x202E) + qs;
369 // Left-to-right override: forces to draw text left-to-right
370 qs = QChar(0x202D) + qs;
371 int const offset = 2;
373 // Alternative version that breaks with Qt5 and arabic text (#10436)
374 // Note that both setFlags and the enums are undocumented
375 tl.setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
376 int const offset = 1;
382 to.setWrapMode(force ? QTextOption::WrapAtWordBoundaryOrAnywhere
383 : QTextOption::WordWrap);
384 tl.setTextOption(to);
386 QTextLine line = tl.createLine();
387 line.setLineWidth(x);
390 int const line_wid = iround(line.horizontalAdvance());
391 if ((force && line.textLength() == offset) || line_wid > x)
393 /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
394 * not be the same when there are high-plan unicode characters
397 // The variable `offset' is here to account for the extra leading characters.
398 // The ending character zerow_nbsp has to be ignored if the line is complete.
399 int const qlen = line.textLength() - offset - (line.textLength() == qs.length());
400 #if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
401 int len = qstring_to_ucs4(qs.mid(offset, qlen)).length();
403 /* Due to QTBUG-25536 in 4.8.1 <= Qt < 5.1.0, the string returned
404 * by QString::toUcs4 (used by qstring_to_ucs4) may have wrong
405 * length. We work around the problem by trying all docstring
406 * positions until the right one is found. This is slow only if
407 * there are many high-plane Unicode characters. It might be
408 * worthwhile to implement a dichotomy search if this shows up
411 int len = min(qlen, static_cast<int>(s.length()));
412 while (len >= 0 && toqstr(s.substr(0, len)).length() != qlen)
414 LASSERT(len > 0 || qlen == 0, /**/);
416 return {len, line_wid};
420 bool GuiFontMetrics::breakAt(docstring & s, int & x, bool const rtl, bool const force) const
422 PROFILE_THIS_BLOCK(breakAt);
426 docstring const s_cache =
427 s + convert<docstring>(x) + (rtl ? "r" : "l") + (force ? "f" : "w");
430 if (breakat_cache_.contains(s_cache))
431 pp = breakat_cache_[s_cache];
433 PROFILE_CACHE_MISS(breakAt);
434 pp = breakAt_helper(s, x, rtl, force);
435 breakat_cache_.insert(s_cache, pp, s_cache.size() * sizeof(char_type));
439 s = s.substr(0, pp.first);
445 void GuiFontMetrics::rectText(docstring const & str,
446 int & w, int & ascent, int & descent) const
448 // FIXME: let offset depend on font (this is Inset::TEXT_TO_OFFSET)
449 int const offset = 4;
451 w = width(str) + offset;
452 ascent = metrics_.ascent() + offset / 2;
453 descent = metrics_.descent() + offset / 2;
457 void GuiFontMetrics::buttonText(docstring const & str, const int offset,
458 int & w, int & ascent, int & descent) const
460 rectText(str, w, ascent, descent);
465 Dimension const GuiFontMetrics::defaultDimension() const
467 return Dimension(0, maxAscent(), maxDescent());
471 Dimension const GuiFontMetrics::dimension(char_type c) const
473 return Dimension(width(c), ascent(c), descent(c));
477 GuiFontMetrics::AscendDescend const GuiFontMetrics::fillMetricsCache(
482 r = metrics_.boundingRect(ucs4_to_qchar(c));
484 r = metrics_.boundingRect(toqstr(docstring(1, c)));
486 AscendDescend ad = { -r.top(), r.bottom() + 1};
487 // We could as well compute the width but this is not really
488 // needed for now as it is done directly in width() below.
489 metrics_cache_.insert(c, ad);
495 int GuiFontMetrics::width(char_type c) const
497 int value = width_cache_.value(c, outOfLimitMetric);
498 if (value != outOfLimitMetric)
502 value = metrics_.width(ucs4_to_qchar(c));
504 value = metrics_.width(toqstr(docstring(1, c)));
506 width_cache_.insert(c, value);
512 int GuiFontMetrics::ascent(char_type c) const
514 static AscendDescend const outOfLimitAD =
515 {outOfLimitMetric, outOfLimitMetric};
516 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
517 if (value.ascent != outOfLimitMetric)
520 value = fillMetricsCache(c);
525 int GuiFontMetrics::descent(char_type c) const
527 static AscendDescend const outOfLimitAD =
528 {outOfLimitMetric, outOfLimitMetric};
529 AscendDescend value = metrics_cache_.value(c, outOfLimitAD);
530 if (value.descent != outOfLimitMetric)
531 return value.descent;
533 value = fillMetricsCache(c);
534 return value.descent;
537 } // namespace frontend