From 79998fdc62432c26f97707becd49511d05a87939 Mon Sep 17 00:00:00 2001
From: Enrico Forestieri <forenr@lyx.org>
Date: Fri, 24 Jul 2020 19:09:17 +0200
Subject: [PATCH] Fix placement of limits with integral signs

Since be836909c52 the positioning of super- and subscripts
for symbol fonts has been broken because the metrics of the
font of the environment (rather than those of the symbol itself)
were used.
---
 src/frontends/qt4/GuiFontMetrics.cpp | 11 +++++++----
 src/mathed/InsetMathChar.cpp         |  4 +---
 src/mathed/InsetMathSymbol.cpp       |  6 ++----
 src/mathed/MathSupport.cpp           |  5 +++--
 src/mathed/MathSupport.h             |  2 +-
 status.23x                           |  3 +++
 6 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/src/frontends/qt4/GuiFontMetrics.cpp b/src/frontends/qt4/GuiFontMetrics.cpp
index 67fcb2f0e4..02c5054094 100644
--- a/src/frontends/qt4/GuiFontMetrics.cpp
+++ b/src/frontends/qt4/GuiFontMetrics.cpp
@@ -212,16 +212,19 @@ int GuiFontMetrics::width(docstring const & s) const
 	/* For some reason QMetrics::width returns a wrong value with Qt5
 	 * with some arabic text. OTOH, QTextLayout is broken for single
 	 * characters with null width (like \not in mathed). Also, as a
-	 * safety measure, always use QMetrics::width with our math fonts.
+	 * safety measure, always use QMetrics::boundingRect().width()
+	 * with our math fonts.
 	*/
 	int w = 0;
 	if (s.length() == 1
 #if QT_VERSION >= 0x040800
 	    || font_.styleName() == "LyX"
 #endif
-	    )
-		w = metrics_.width(toqstr(s));
-	else {
+	    ) {
+		// keep value 0 for math chars with null width
+		if (metrics_.width(toqstr(s)) != 0)
+			w = metrics_.boundingRect(toqstr(s)).width();
+	} else {
 		QTextLayout tl;
 		tl.setText(toqstr(s));
 		tl.setFont(font_);
diff --git a/src/mathed/InsetMathChar.cpp b/src/mathed/InsetMathChar.cpp
index 1137c95e75..3a9d18c5c2 100644
--- a/src/mathed/InsetMathChar.cpp
+++ b/src/mathed/InsetMathChar.cpp
@@ -113,9 +113,7 @@ void InsetMathChar::metrics(MetricsInfo & mi, Dimension & dim) const
 	if (isMathFont(f) && subst_) {
 		// If the char has a substitute, draw the replacement symbol
 		// instead, but only in math mode.
-		mathedSymbolDim(mi.base, dim, subst_);
-		kerning_ = mathed_char_kerning(mi.base.font, *subst_->draw.rbegin());
-		return;
+		kerning_ = mathedSymbolDim(mi.base, dim, subst_);
 	} else if (!slanted(char_) && f == "mathnormal") {
 		Changer dummy = mi.base.font.changeShape(UP_SHAPE);
 		dim = theFontMetrics(mi.base.font).dimension(char_);
diff --git a/src/mathed/InsetMathSymbol.cpp b/src/mathed/InsetMathSymbol.cpp
index 92d2573560..106780e578 100644
--- a/src/mathed/InsetMathSymbol.cpp
+++ b/src/mathed/InsetMathSymbol.cpp
@@ -60,10 +60,8 @@ docstring InsetMathSymbol::name() const
 
 void InsetMathSymbol::metrics(MetricsInfo & mi, Dimension & dim) const
 {
-	// set dim
-	mathedSymbolDim(mi.base, dim, sym_);
-	// set kerning_
-	kerning_ = mathed_char_kerning(mi.base.font, *sym_->draw.rbegin());
+	// set dim and negative kerning_ to move a subscript leftward
+	kerning_ = -mathedSymbolDim(mi.base, dim, sym_);
 	// correct height for broken cmex and wasy font
 	if (sym_->inset == "cmex" || sym_->inset == "wasy") {
 		h_ = 4 * dim.des / 5;
diff --git a/src/mathed/MathSupport.cpp b/src/mathed/MathSupport.cpp
index b9ea145c67..26d508f12c 100644
--- a/src/mathed/MathSupport.cpp
+++ b/src/mathed/MathSupport.cpp
@@ -673,9 +673,9 @@ void mathed_draw_deco(PainterInfo & pi, int x, int y, int w, int h,
 }
 
 
-void mathedSymbolDim(MetricsBase & mb, Dimension & dim, latexkeys const * sym)
+int mathedSymbolDim(MetricsBase & mb, Dimension & dim, latexkeys const * sym)
 {
-	LASSERT((bool)sym, return);
+	LASSERT((bool)sym, return 0);
 	//lyxerr << "metrics: symbol: '" << sym->name
 	//	<< "' in font: '" << sym->inset
 	//	<< "' drawn as: '" << sym->draw
@@ -687,6 +687,7 @@ void mathedSymbolDim(MetricsBase & mb, Dimension & dim, latexkeys const * sym)
 	std::string const font = italic_upcase_greek ? "cmm" : sym->inset;
 	Changer dummy = mb.changeFontSet(font);
 	mathed_string_dim(mb.font, sym->draw, dim);
+	return mathed_char_kerning(mb.font, sym->draw.back());
 }
 
 
diff --git a/src/mathed/MathSupport.h b/src/mathed/MathSupport.h
index d9301453dd..7c40baa0b4 100644
--- a/src/mathed/MathSupport.h
+++ b/src/mathed/MathSupport.h
@@ -55,7 +55,7 @@ void mathed_string_dim(FontInfo const & font,
 
 int mathed_string_width(FontInfo const &, docstring const & s);
 
-void mathedSymbolDim(MetricsBase & mb, Dimension & dim, latexkeys const * sym);
+int mathedSymbolDim(MetricsBase & mb, Dimension & dim, latexkeys const * sym);
 
 void mathedSymbolDraw(PainterInfo & pi, int x, int y, latexkeys const * sym);
 
diff --git a/status.23x b/status.23x
index 1307003d96..080634f74e 100644
--- a/status.23x
+++ b/status.23x
@@ -78,6 +78,9 @@ What's new
 
 - Fix spacing of limits of sum-like operators in display style.
 
+- Fix positioning of super- and subscripts with integral signs.
+
+
 * INTERNALS