commit ea3cdb15529d013bcac231c5b1f25628f5067b42
Author: Jean-Marc Lasgouttes <[email protected]>
Date: Wed Nov 2 17:42:56 2016 +0100
QString only uses UTF-16, not UCS-4
This means that, when a string contains high-plane Unicode characters,
the length of a docstring and the corresponding QString will be
different: Qt will encode these characters using several 16bit
characters.
We have additionally to take into account QTBUG-25536, which implies
that sometimes qstring_to_ucs4(toqstr(s)) !=s. It is not clear whether
this bug can be a problem in other places.
Fixes bug #10443.
(cherry picked from commit 5d85a42bf0a182585b800a80817a6e1208ef7ec3)
---
src/frontends/qt4/GuiFontMetrics.cpp | 65 +++++++++++++++++++++++++++++-----
status.22x | 3 ++
2 files changed, 59 insertions(+), 9 deletions(-)
diff --git a/src/frontends/qt4/GuiFontMetrics.cpp
b/src/frontends/qt4/GuiFontMetrics.cpp
index 74ed392..1d472b5 100644
--- a/src/frontends/qt4/GuiFontMetrics.cpp
+++ b/src/frontends/qt4/GuiFontMetrics.cpp
@@ -206,7 +206,12 @@ int GuiFontMetrics::pos2x(docstring const & s, int const
pos, bool const rtl,
double const wordspacing) const
{
QTextLayout const & tl = getTextLayout(s, font_, rtl, wordspacing);
- return static_cast<int>(tl.lineForTextPosition(pos).cursorToX(pos));
+ /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
+ * not be the same when there are high-plan unicode characters
+ * (bug #10443).
+ */
+ int const qpos = toqstr(s.substr(0, pos)).length();
+ return static_cast<int>(tl.lineForTextPosition(qpos).cursorToX(qpos));
}
@@ -214,10 +219,30 @@ int GuiFontMetrics::x2pos(docstring const & s, int & x,
bool const rtl,
double const wordspacing) const
{
QTextLayout const & tl = getTextLayout(s, font_, rtl, wordspacing);
- int pos = tl.lineForTextPosition(0).xToCursor(x);
+ int const qpos = tl.lineForTextPosition(0).xToCursor(x);
// correct x value to the actual cursor position.
- x = static_cast<int>(tl.lineForTextPosition(0).cursorToX(pos));
+ x = static_cast<int>(tl.lineForTextPosition(0).cursorToX(qpos));
+ /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
+ * not be the same when there are high-plan unicode characters
+ * (bug #10443).
+ */
+#if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
+ return qstring_to_ucs4(tl.text().left(qpos)).length();
+#else
+ /* Due to QTBUG-25536 in 4.8.1 <= Qt < 5.1.0, the string returned
+ * by QString::toUcs4 (used by qstring_to_ucs4)may have wrong
+ * length. We work around the problem by trying all docstring
+ * positions until the right one is found. This is slow only if
+ * there are many high-plane Unicode characters. It might be
+ * worthwhile to implement a dichotomy search if this shows up
+ * under a profiler.
+ */
+ int pos = min(qpos, static_cast<int>(s.length()));
+ while (pos >= 0 && toqstr(s.substr(0, pos)).length() != qpos)
+ --pos;
+ LASSERT(pos > 0 || qpos == 0, /**/);
return pos;
+#endif
}
@@ -235,17 +260,17 @@ bool GuiFontMetrics::breakAt(docstring & s, int & x, bool
const rtl, bool const
*/
// Unicode character ZERO WIDTH NO-BREAK SPACE
QChar const zerow_nbsp(0xfeff);
- QString str = zerow_nbsp + toqstr(s) + zerow_nbsp;
+ QString qs = zerow_nbsp + toqstr(s) + zerow_nbsp;
#if 1
/* Use unicode override characters to enforce drawing direction
* Source: http://www.iamcal.com/understanding-bidirectional-text/
*/
if (rtl)
// Right-to-left override: forces to draw text right-to-left
- str = QChar(0x202E) + str;
+ qs = QChar(0x202E) + qs;
else
// Left-to-right override: forces to draw text left-to-right
- str = QChar(0x202D) + str;
+ qs = QChar(0x202D) + qs;
int const offset = 2;
#else
// Alternative version that breaks with Qt5 and arabic text (#10436)
@@ -254,7 +279,7 @@ bool GuiFontMetrics::breakAt(docstring & s, int & x, bool
const rtl, bool const
int const offset = 1;
#endif
- tl.setText(str);
+ tl.setText(qs);
tl.setFont(font_);
QTextOption to;
to.setWrapMode(force ? QTextOption::WrapAnywhere :
QTextOption::WordWrap);
@@ -267,8 +292,30 @@ bool GuiFontMetrics::breakAt(docstring & s, int & x, bool
const rtl, bool const
if ((force && line.textLength() == offset) ||
int(line.naturalTextWidth()) > x)
return false;
x = int(line.naturalTextWidth());
- // The offset is here to account for the extra leading characters.
- s = s.substr(0, line.textLength() - offset);
+ /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
+ * not be the same when there are high-plan unicode characters
+ * (bug #10443).
+ */
+ // The variable `offset' is here to account for the extra leading
characters.
+ // The ending character zerow_nbsp has to be ignored if the line is
complete.
+ int const qlen = line.textLength() - offset - (line.textLength() ==
qs.length());
+#if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
+ s = qstring_to_ucs4(qs.mid(offset, qlen));
+#else
+ /* Due to QTBUG-25536 in 4.8.1 <= Qt < 5.1.0, the string returned
+ * by QString::toUcs4 (used by qstring_to_ucs4)may have wrong
+ * length. We work around the problem by trying all docstring
+ * positions until the right one is found. This is slow only if
+ * there are many high-plane Unicode characters. It might be
+ * worthwhile to implement a dichotomy search if this shows up
+ * under a profiler.
+ */
+ int len = min(qlen, static_cast<int>(s.length()));
+ while (len >= 0 && toqstr(s.substr(0, len)).length() != qlen)
+ --len;
+ LASSERT(len > 0 || qlen == 0, /**/);
+ s = s.substr(0, len);
+#endif
return true;
}
diff --git a/status.22x b/status.22x
index 49b351d..2719c6a 100644
--- a/status.22x
+++ b/status.22x
@@ -118,6 +118,9 @@ What's new
- Fix selection painting in right-to-left texts (bug 10424).
+- Fix cursor movement when the document contains high-plane Unicode
+ characters (bug 10443).
+
- Allow using colors supported by xcolor inside mathed (bug 10417).
- Change description of "frame of button" color to "button frame" (bug 10135).
