From 7f23ca912c5e92bf30bdc05b6d801082f6643e8e Mon Sep 17 00:00:00 2001
From: Enrico Forestieri <forenr@lyx.org>
Date: Sun, 22 Oct 2017 13:12:33 +0200
Subject: [PATCH] Fix issue with change-tracked deleted display math

- If a display math not starting a new paragraph is deleted, the
  current \lyxdeleted macro (if any) must be closed and a new one
  started, otherwise the display math will be shifted up.

- Use \linewidth instead of \columnwidth because the former will adapt
  to the reduced horizontal width in list environments, avoiding shifting
  to the right the diplay math.
---
 src/Changes.cpp              | 13 ++++++++-----
 src/Paragraph.cpp            | 27 +++++++++++++++++++++++----
 src/mathed/InsetMathHull.cpp |  8 ++++----
 3 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/src/Changes.cpp b/src/Changes.cpp
index 8d4933c55f..b4226582f4 100644
--- a/src/Changes.cpp
+++ b/src/Changes.cpp
@@ -394,11 +394,16 @@ int Changes::latexMarkChange(otexstream & os, BufferParams const & bparams,
 
 	int column = 0;
 
+	bool const dvipost = LaTeXFeatures::isAvailable("dvipost") &&
+			(runparams.flavor == OutputParams::LATEX
+			 || runparams.flavor == OutputParams::DVILUATEX);
+
 	if (oldChange.type != Change::UNCHANGED) {
 		// close \lyxadded or \lyxdeleted
 		os << '}';
 		column++;
-		if (oldChange.type == Change::DELETED && !runparams.wasDisplayMath)
+		if (oldChange.type == Change::DELETED
+		    && !runparams.wasDisplayMath && !dvipost)
 			--runparams.inulemcmd;
 	}
 
@@ -410,7 +415,7 @@ int Changes::latexMarkChange(otexstream & os, BufferParams const & bparams,
 	docstring macro_beg;
 	if (change.type == Change::DELETED) {
 		macro_beg = from_ascii("\\lyxdeleted{");
-		if (!runparams.inDisplayMath)
+		if (!runparams.inDisplayMath && !dvipost)
 			++runparams.inulemcmd;
 	}
 	else if (change.type == Change::INSERTED)
@@ -422,9 +427,7 @@ int Changes::latexMarkChange(otexstream & os, BufferParams const & bparams,
 
 	// signature needed by \lyxsout to correctly strike out display math
 	if (change.type == Change::DELETED && runparams.inDisplayMath
-	    && (!LaTeXFeatures::isAvailable("dvipost")
-		|| (runparams.flavor != OutputParams::LATEX
-		    && runparams.flavor != OutputParams::DVILUATEX))) {
+	    && !dvipost) {
 		if (os.afterParbreak())
 			str += from_ascii("\\\\\\noindent\n");
 		else
diff --git a/src/Paragraph.cpp b/src/Paragraph.cpp
index 76202516a8..f130fa08c8 100644
--- a/src/Paragraph.cpp
+++ b/src/Paragraph.cpp
@@ -2454,6 +2454,8 @@ void Paragraph::latex(BufferParams const & bparams,
 		runparams.wasDisplayMath = runparams.inDisplayMath;
 		runparams.inDisplayMath = false;
 		bool deleted_display_math = false;
+		Change const & change = runparams.inDeletedInset
+			? runparams.changeOfDeletedInset : lookupChange(i);
 
 		// Check whether a display math inset follows
 		if (d->text_[i] == META_INSET
@@ -2468,11 +2470,28 @@ void Paragraph::latex(BufferParams const & bparams,
 				// cannot set it here because it is a counter.
 				deleted_display_math = isDeleted(i);
 			}
+			if (bparams.output_changes && deleted_display_math
+			    && runningChange == change
+			    && change.type == Change::DELETED
+			    && !os.afterParbreak()) {
+				// A display math in the same paragraph follows.
+				// We have to close and then reopen \lyxdeleted,
+				// otherwise the math will be shifted up.
+				OutputParams rp = runparams;
+				if (open_font) {
+					bool needPar = false;
+					column += running_font.latexWriteEndChanges(
+						os, bparams, rp, basefont,
+						basefont, needPar);
+					open_font = false;
+				}
+				basefont = getLayoutFont(bparams, outerfont);
+				running_font = basefont;
+				column += Changes::latexMarkChange(os, bparams,
+					Change(Change::INSERTED), change, rp);
+			}
 		}
 
-		Change const & change = runparams.inDeletedInset
-			? runparams.changeOfDeletedInset : lookupChange(i);
-
 		if (bparams.output_changes && runningChange != change) {
 			if (open_font) {
 				bool needPar = false;
@@ -2549,7 +2568,7 @@ void Paragraph::latex(BufferParams const & bparams,
 		char_type const c = d->text_[i];
 
 		// A display math inset inside an ulem command will be output
-		// as a box of width \columnwidth, so we have to either disable
+		// as a box of width \linewidth, so we have to either disable
 		// indentation if the inset starts a paragraph, or start a new
 		// line to accommodate such box. This has to be done before
 		// writing any font changing commands.
diff --git a/src/mathed/InsetMathHull.cpp b/src/mathed/InsetMathHull.cpp
index e07d5984b2..78175f3f70 100644
--- a/src/mathed/InsetMathHull.cpp
+++ b/src/mathed/InsetMathHull.cpp
@@ -126,14 +126,14 @@ namespace {
 		if (os.strikeoutMath()) {
 			if (os.ulemCmd() == WriteStream::UNDERLINE)
 				os << "\\raisebox{-\\belowdisplayshortskip}{"
-				      "\\lyxmathsout{\\parbox[b]{\\columnwidth}{";
+				      "\\lyxmathsout{\\parbox[b]{\\linewidth}{";
 			else
-				os << "\\lyxmathsout{\\parbox{\\columnwidth}{";
+				os << "\\lyxmathsout{\\parbox{\\linewidth}{";
 		} else if (os.ulemCmd() == WriteStream::UNDERLINE)
 			os << "\\raisebox{-\\belowdisplayshortskip}{"
-			      "\\parbox[b]{\\columnwidth}{";
+			      "\\parbox[b]{\\linewidth}{";
 		else if (os.ulemCmd() == WriteStream::STRIKEOUT)
-			os << "\\parbox{\\columnwidth}{";
+			os << "\\parbox{\\linewidth}{";
 	}