From d52e04a9b308c0cb72c93e416a4bd59d9e8f9b39 Mon Sep 17 00:00:00 2001
From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Fri, 22 Mar 2019 16:13:30 +0100
Subject: [PATCH] Fix fonts used by sub/superscript in text

Several changes are needed to get things right:
* nested supersripts only work with inheritFonts=true.

* to get caret position right, it is necessary to remember the outside
  font of the inset before computing metrics.

* to get the size right at insertion time, it is necessary to trigger
  a metrics computation just after inset insertion.
---
 src/Text3.cpp              | 10 ++++++++++
 src/insets/InsetScript.cpp |  5 +++--
 src/insets/InsetScript.h   |  4 +++-
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/Text3.cpp b/src/Text3.cpp
index 6db9c2b8d5..e8c3dee124 100644
--- a/src/Text3.cpp
+++ b/src/Text3.cpp
@@ -2030,6 +2030,16 @@ void Text::dispatch(Cursor & cur, FuncRequest & cmd)
 		// inside it.
 		doInsertInset(cur, this, cmd, true, true);
 		cur.posForward();
+		if (act == LFUN_SCRIPT_INSERT) {
+			/* Script insets change the font style in metrics(), and
+			 * this is used to compute the height of the caret
+			 * (because the font is stored in TextMetrics::font_).
+			 * When we insert, we have to make sure that metrics are
+			 * computed so that the caret height is wrong. Arguably,
+			 * this is hackish.*/
+			bv->processUpdateFlags(Update::SinglePar);
+		}
+		cur.setCurrentFont();
 		// Some insets are numbered, others are shown in the outline pane so
 		// let's update the labels and the toc backend.
 		cur.forceBufferUpdate();
diff --git a/src/insets/InsetScript.cpp b/src/insets/InsetScript.cpp
index 918492fb55..c7bdd4279d 100644
--- a/src/insets/InsetScript.cpp
+++ b/src/insets/InsetScript.cpp
@@ -160,6 +160,8 @@ Inset::DisplayType InsetScript::display() const
 void InsetScript::metrics(MetricsInfo & mi, Dimension & dim) const
 {
 	int const shift = params_.shift(mi.base.font);
+	// Remember the value of the outser font, so that it can be used in cursorPos.
+	outer_font_ = mi.base.font;
 	Changer dummy = mi.base.changeScript();
 	InsetText::metrics(mi, dim);
 	dim.asc -= shift;
@@ -178,8 +180,7 @@ void InsetScript::draw(PainterInfo & pi, int x, int y) const
 void InsetScript::cursorPos(BufferView const & bv,
 		CursorSlice const & sl, bool boundary, int & x, int & y) const
 {
-	Font const font = bv.textMetrics(&text()).displayFont(sl.pit(), sl.pos());
-	int const shift = params_.shift(font.fontInfo());
+	int const shift = params_.shift(outer_font_);
 	InsetText::cursorPos(bv, sl, boundary, x, y);
 	y += shift;
 }
diff --git a/src/insets/InsetScript.h b/src/insets/InsetScript.h
index 3107b6255d..1aee8e8dd0 100644
--- a/src/insets/InsetScript.h
+++ b/src/insets/InsetScript.h
@@ -86,7 +86,7 @@ public:
 	///
 	bool neverIndent() const { return true; }
 	///
-	bool inheritFont() const { return false; }
+	bool inheritFont() const { return true; }
 	///
 	int plaintext(odocstringstream & ods, OutputParams const & op,
 	              size_t max_length = INT_MAX) const;
@@ -129,6 +129,8 @@ private:
 	friend class InsetScriptParams;
 	///
 	InsetScriptParams params_;
+	/// The font of containing inset; this is necessary to compute shift
+	mutable FontInfo outer_font_;
 };