[LyX/master] Implement variable size bigops

[Enrico Forestieri]

On Thu, Jul 23, 2020 at 03:24:13PM +0200, Jean-Marc Lasgouttes wrote:
> Le 23/07/2020 à 15:13, Enrico Forestieri a écrit :
> > On Thu, Jul 23, 2020 at 01:16:32PM +0200, Jean-Marc Lasgouttes wrote:
> > 
> > > Le 23/07/2020 à 12:22, Enrico Forestieri a écrit :
> > > > Here is an alternative patch. Please check whether the change in
> > > > InsetMathSymbol.cpp is compatible with the corresponding change
> > > > at e8ee0100.
> > > 
> > > I think it is OK. What about the users of mathedSymbolDim in InsetMathFrac?
> > > Is kerning irrelevant here?
> 
> This looks good for master and probably branch as far as I am concerned.

I am not really satisfied when navigating a formula with the cursor.
The caret will be placed in the middle of a symbol instead of after it.
Taking away the change to GuiFontMetrics.cpp makes navigation more
pleasant but both scripts are placed far away the symbol.

I propose the attached patch that leaves unchanged GuiFontMetrics::width()
and makes negative the kerning for a symbol, so that the subscript is
moved to the left instead of moving the superscript to the right.

-- 
Enrico
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diff --git a/src/mathed/InsetMathChar.cpp b/src/mathed/InsetMathChar.cpp
index 36bdeaa2ba..d5ef8dc1f5 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 276fab9ddc..ef2a3e94ec 100644
--- a/src/mathed/InsetMathSymbol.cpp
+++ b/src/mathed/InsetMathSymbol.cpp
@@ -68,14 +68,11 @@ Limits InsetMathSymbol::defaultLimits() const
 
 void InsetMathSymbol::metrics(MetricsInfo & mi, Dimension & dim) const
 {
-	mathedSymbolDim(mi.base, dim, sym_);
+	// set dim
+	// FIXME: this should depend on BufferView
+	// set kerning_
+	kerning_ = -mathedSymbolDim(mi.base, dim, sym_);
 	if (sym_->draw != sym_->name) {
-		// set dim
-		// FIXME: this should depend on BufferView
-		// set kerning_
-		kerning_ = mathed_char_kerning(mi.base.font,
-		                               mathedSymbol(mi.base, sym_).back());
-
 		// align character vertically
 		// FIXME: this should depend on BufferView
 		h_ = 0;
diff --git a/src/mathed/MathSupport.cpp b/src/mathed/MathSupport.cpp
index 12f8a842f6..45ca429681 100644
--- a/src/mathed/MathSupport.cpp
+++ b/src/mathed/MathSupport.cpp
@@ -680,9 +680,9 @@ docstring const &  mathedSymbol(MetricsBase & mb, latexkeys const * sym)
 }
 
 
-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
@@ -694,6 +694,7 @@ 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, mathedSymbol(mb, sym), dim);
+	return mathed_char_kerning(mb.font, mathedSymbol(mb, sym).back());
 }
 
 
diff --git a/src/mathed/MathSupport.h b/src/mathed/MathSupport.h
index fa7b2fe0ea..9fde420ce2 100644
--- a/src/mathed/MathSupport.h
+++ b/src/mathed/MathSupport.h
@@ -57,7 +57,7 @@ int mathed_string_width(FontInfo const &, docstring const & s);
 
 docstring const & mathedSymbol(MetricsBase & mb, latexkeys const * sym);
 
-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);