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synced 2024-11-09 18:31:04 +00:00
Better algorithm for forcing bidi drawing
The use of RLO/LRO overrides to force text orientation was really hackish and the way it was done caused dropped letters in Mac OS X (for some unknown reasons). This new approach is much cleaner, except that it relies on features not advertised in documentation but present at least from Qt 4.5 to Qt 5.3: * TextFlag enum values TextForceLeftToRight and TextForceRightToLeft, which are strong versions of QPainter::setLayoutDirection; they are passed as a parameter of QPainter::drawText. * QTextLayout::setFlags method, which is required to pass the above flags to QTextLayout. The unicode override method is still used to draw strings Mac OS X because, for some reason, the direction was not really enforced in this case.
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@ -109,10 +109,10 @@ public:
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graphics::Image const & image) = 0;
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/** draw a string at position x, y (y is the baseline). The
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* text direction is deduced from \c str.
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* text direction is given by \c rtl.
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* \return the width of the drawn text.
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*/
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virtual int text(int x, int y, docstring const & str, FontInfo const & f) = 0;
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virtual int text(int x, int y, docstring const & str, FontInfo const & f, bool rtl = false) = 0;
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/** draw a string at position x, y (y is the baseline). The
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* text direction is enforced by the \c Font.
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@ -22,7 +22,6 @@
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#include "insets/Inset.h"
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#include "support/lassert.h"
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#include "support/lstrings.h"
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#include <QTextLayout>
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@ -148,9 +147,10 @@ namespace {
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void setTextLayout(QTextLayout & tl, docstring const & s, QFont const & font,
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bool const rtl)
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{
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QString const qs = toqstr(directedString(s, rtl));
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tl.setText(qs);
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tl.setText(toqstr(s));
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tl.setFont(font);
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// Note that both setFlags and the enums are undocumented
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tl.setFlags(rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight);
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tl.beginLayout();
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tl.createLine();
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tl.endLayout();
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@ -162,8 +162,7 @@ int GuiFontMetrics::pos2x(docstring const & s, int const pos, bool const rtl) co
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{
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QTextLayout tl;
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setTextLayout(tl, s, font_, rtl);
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// we take into account the unicode formatting characters
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return tl.lineForTextPosition(pos + 1).cursorToX(pos + 1);
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return tl.lineForTextPosition(pos).cursorToX(pos);
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}
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@ -172,13 +171,8 @@ int GuiFontMetrics::x2pos(docstring const & s, int & x, bool const rtl) const
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QTextLayout tl;
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setTextLayout(tl, s, font_, rtl);
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int pos = tl.lineForTextPosition(0).xToCursor(x);
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// take into account the unicode formatting characters
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if (pos > 0)
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--pos;
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if (pos > int(s.length()))
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pos = s.length();
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// correct x value to the actual cursor position.
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x = tl.lineForTextPosition(0).cursorToX(pos + 1);
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x = tl.lineForTextPosition(0).cursorToX(pos);
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return pos;
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}
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@ -9,6 +9,10 @@
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* Full author contact details are available in file CREDITS.
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*/
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#ifdef Q_WS_MAC
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#define USE_RTL_OVERRIDE 1
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#endif
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#include <config.h>
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#include "GuiPainter.h"
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@ -27,7 +31,6 @@
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#include "insets/Inset.h"
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#include "support/lassert.h"
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#include "support/lstrings.h"
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#include "support/debug.h"
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#include <QPixmapCache>
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@ -278,7 +281,7 @@ int GuiPainter::text(int x, int y, char_type c, FontInfo const & f)
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int GuiPainter::text(int x, int y, docstring const & s,
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FontInfo const & f)
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FontInfo const & f, bool const rtl)
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{
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//LYXERR0("text: x=" << x << ", s=" << s);
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if (s.empty())
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@ -304,8 +307,8 @@ int GuiPainter::text(int x, int y, docstring const & s,
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str = ' ' + str;
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#endif
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QFont const & ff = getFont(f);
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GuiFontMetrics const & fm = getFontMetrics(f);
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QFont const & ff = getFont(f);
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GuiFontMetrics const & fm = getFontMetrics(f);
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// Here we use the font width cache instead of
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// textwidth = fontMetrics().width(str);
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@ -390,7 +393,32 @@ int GuiPainter::text(int x, int y, docstring const & s,
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setQPainterPen(computeColor(f.realColor()));
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if (font() != ff)
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setFont(ff);
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/* In LyX, the character direction is forced by the language.
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* Therefore, we have to signal that fact to Qt.
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*/
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#ifdef USE_RTL_OVERRIDE
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/* Use unicode override characters to enforce drawing direction
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* Source: http://www.iamcal.com/understanding-bidirectional-text/
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*/
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if (rtl)
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// Right-to-left override: forces to draw text right-to-left
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str = QChar(0x202E) + str;
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else
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// Left-to-right override: forces to draw text left-to-right
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str = QChar(0x202D) + str;
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drawText(x, y, str);
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#else
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/* This is a cleanr solution, but it has two drawbacks
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* - it seems that it does not work under Mac OS X
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* - it is not really documented
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*/
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//This is much stronger than setLayoutDirection.
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int flag = rtl ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight;
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drawText(x + (rtl ? textwidth : 0), y - fm.maxAscent(), 0, 0,
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flag | Qt::TextDontClip,
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str);
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#endif
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//LYXERR(Debug::PAINTING, "draw " << string(str.toUtf8())
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// << " at " << x << "," << y);
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return textwidth;
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@ -399,8 +427,7 @@ int GuiPainter::text(int x, int y, docstring const & s,
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int GuiPainter::text(int x, int y, docstring const & str, Font const & f)
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{
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docstring const dstr = directedString(str, f.isVisibleRightToLeft());
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return text(x, y, dstr, f.fontInfo());
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return text(x, y, str, f.fontInfo(), f.isVisibleRightToLeft());
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}
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@ -410,7 +437,6 @@ int GuiPainter::text(int x, int y, docstring const & str, Font const & f,
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GuiFontMetrics const & fm = getFontMetrics(f.fontInfo());
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FontInfo fi = f.fontInfo();
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bool const rtl = f.isVisibleRightToLeft();
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docstring const dstr = directedString(str, rtl);
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// dimensions
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int const ascent = fm.maxAscent();
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@ -424,15 +450,15 @@ int GuiPainter::text(int x, int y, docstring const & str, Font const & f,
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Color const orig = fi.realColor();
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fi.setPaintColor(other);
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setClipRect(QRect(x + xmin, y - ascent, xmax - xmin, height));
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int const textwidth = text(x, y, dstr, fi);
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int const textwidth = text(x, y, str, fi, rtl);
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// Then the part in normal color
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// Note that in Qt5, it is not possible to use Qt::UniteClip
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fi.setPaintColor(orig);
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setClipRect(QRect(x, y - ascent, xmin, height));
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text(x, y, dstr, fi);
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text(x, y, str, fi, rtl);
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setClipRect(QRect(x + xmax, y - ascent, textwidth - xmax, height));
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text(x, y, dstr, fi);
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text(x, y, str, fi, rtl);
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setClipping(false);
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return textwidth;
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@ -87,10 +87,10 @@ public:
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lyx::graphics::Image const & image);
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/** draw a string at position x, y (y is the baseline). The
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* text direction is deduced from \c str.
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* text direction is given by \c rtl.
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* \return the width of the drawn text.
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*/
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virtual int text(int x, int y, docstring const & str, FontInfo const & f);
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virtual int text(int x, int y, docstring const & str, FontInfo const & f, bool rtl = false);
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/** draw a string at position x, y (y is the baseline). The
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* text direction is enforced by the \c Font.
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@ -1502,23 +1502,5 @@ docstring bformat(docstring const & fmt,
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return subst(str, from_ascii("%%"), from_ascii("%"));
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}
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docstring directedString(docstring const & s, bool const rtl)
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{
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/* In LyX, the character direction is forced by the language.
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* Therefore, we have to signal that fact to Qt.
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* Source: http://www.iamcal.com/understanding-bidirectional-text/
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*/
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// Left-to-right override: forces to draw text left-to-right
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char_type const LRO = 0x202D;
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// Right-to-left override: forces to draw text right-to-left
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char_type const RLO = 0x202E;
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// Pop directional formatting: return to previous state
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char_type const PDF = 0x202C;
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return (rtl ? RLO : LRO) + s + PDF;
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}
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} // namespace support
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} // namespace lyx
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@ -327,9 +327,6 @@ template<> docstring bformat(docstring const & fmt, int arg1, int arg2);
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template<> docstring bformat(docstring const & fmt, docstring arg1, docstring arg2, docstring arg3);
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template<> docstring bformat(docstring const & fmt, docstring arg1, docstring arg2, docstring arg3, docstring arg4);
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/// Return a string with Unicode overrides to enforce the writing direction
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docstring directedString(docstring const & s, bool rtl);
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} // namespace support
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} // namespace lyx
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