[LyX/master] Amend 08b4a01fd33f

[Udi Fogiel]

commit db168dc6bba9c33603eec5045aeec7569f3d21dc
Author: Udi Fogiel <ufogiel at lyx.org>
Date:   Sat Aug 15 03:23:19 2026 +0300

    Amend 08b4a01fd33f
    
    That commit forced LtR direction on mathed glyph draws to fix #12928,
    but this also routed them through Qt's text shaping (QTextLayout),
    which corrupts raw glyph-index symbols such as \int that are
    not real Unicode text. Decouple direction enforcement from shaping in
    GuiPainter::text() so mathed keeps forced LtR ordering without
    triggering the shaper.
---
 src/frontends/qt/GuiPainter.cpp | 12 +++++++++---
 src/frontends/qt/GuiPainter.h   |  3 ++-
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/frontends/qt/GuiPainter.cpp b/src/frontends/qt/GuiPainter.cpp
index 0121fe5dfc..600bcfa20f 100644
--- a/src/frontends/qt/GuiPainter.cpp
+++ b/src/frontends/qt/GuiPainter.cpp
@@ -290,14 +290,14 @@ void GuiPainter::text(int x, int y, char_type c, FontInfo const & f, Direction c
 
 void GuiPainter::text(int x, int y, docstring const & s, FontInfo const & f, Direction const dir)
 {
-	text(x, y, s, f, dir, 0.0, 0.0);
+	text(x, y, s, f, dir, 0.0, 0.0, false, false);
 }
 
 
 void GuiPainter::text(int x, int y, docstring const & s,
                       FontInfo const & f, Direction const dir,
                       double const wordspacing, double const tw,
-                      bool const invert)
+                      bool const invert, bool const shape)
 {
 	//LYXERR0("text: x=" << x << ", s=" << s);
 	if (s.empty())
@@ -336,11 +336,17 @@ void GuiPainter::text(int x, int y, docstring const & s,
 		// Brighten that for workarea display (#13218)
 		rc.mergeColor = Color_foreground;
 	setQPainterPen(computeColor(rc));
-	if (dir != Auto) {
+	if (dir != Auto && shape) {
 		auto ptl = fm.getTextLayout(s, dir == RtL, wordspacing);
 		QTextLine const & tline = ptl->lineForTextPosition(0);
 		ptl->draw(this, QPointF(x, y - tline.ascent()));
 	} else {
+		if (dir == Auto)
+			setLayoutDirection(Qt::LayoutDirectionAuto);
+		else if (dir == RtL)
+			setLayoutDirection(Qt::RightToLeft);
+		else
+			setLayoutDirection(Qt::LeftToRight);
 		if (font() != ff)
 			setFont(ff);
 		drawText(x, y, str);
diff --git a/src/frontends/qt/GuiPainter.h b/src/frontends/qt/GuiPainter.h
index abc4df9065..9b193b3cfd 100644
--- a/src/frontends/qt/GuiPainter.h
+++ b/src/frontends/qt/GuiPainter.h
@@ -202,10 +202,11 @@ private:
 		Qt::PenJoinStyle js = Qt::BevelJoin);
 
 	// Real text() method
+	// shape = false skips Qt's text shaper for raw math glyph draws.
 	void text(int x, int y, docstring const & s,
 		  FontInfo const & f, Direction const dir,
 		  double const wordspacing, double tw,
-		  bool const invert = false);
+		  bool const invert = false, bool const shape = true);
 
 	QColor current_color_;
 	Painter::line_style current_ls_;