From 8af3077753381238e1fb3e21d65017b94778a47c Mon Sep 17 00:00:00 2001
From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Wed, 29 Nov 2017 11:16:09 +0100
Subject: [PATCH] Make sure that rows are repainted when they get (un)selected

The bug is the following: when selecting several paragraphs quickly
enough, some rows do not get selected.This is a consequence of the
removal of row crc, which lead to not taking into account the
selection status of the row in the decision to repaint.

The solution chosen here is to add a Row::change() helper function to
modify row members. This will set the Row changed status whenever the
value of the member changes.

(cherry picked from commit ae60749f89fb4ee0fca05ac75979d434f6b0401d)
---
 src/Row.cpp         | 16 ++++++++--------
 src/Row.h           | 23 +++++++++++++++++++++++
 src/TextMetrics.cpp |  4 ++--
 3 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/src/Row.cpp b/src/Row.cpp
index ad492c1a7a..3fb87bd7e1 100644
--- a/src/Row.cpp
+++ b/src/Row.cpp
@@ -203,8 +203,8 @@ void Row::setSelectionAndMargins(DocIterator const & beg,
 	setSelection(beg.pos(), end.pos());
 
 	if (selection()) {
-		end_margin_sel = isMarginSelected(false, beg, end);
-		begin_margin_sel = isMarginSelected(true, beg, end);
+		change(end_margin_sel, isMarginSelected(false, beg, end));
+		change(begin_margin_sel, isMarginSelected(true, beg, end));
 	}
 }
 
@@ -212,18 +212,18 @@ void Row::setSelectionAndMargins(DocIterator const & beg,
 void Row::setSelection(pos_type beg, pos_type end) const
 {
 	if (pos_ >= beg && pos_ <= end)
-		sel_beg = pos_;
+		change(sel_beg, pos_);
 	else if (beg > pos_ && beg <= end_)
-		sel_beg = beg;
+		change(sel_beg, beg);
 	else
-		sel_beg = -1;
+		change(sel_beg, -1);
 
 	if (end_ >= beg && end_ <= end)
-		sel_end = end_;
+		change(sel_end,end_);
 	else if (end < end_ && end >= pos_)
-		sel_end = end;
+		change(sel_end, end);
 	else
-		sel_end = -1;
+		change(sel_end, -1);
 }
 
 
diff --git a/src/Row.h b/src/Row.h
index a1fedd7e5d..49513d32b9 100644
--- a/src/Row.h
+++ b/src/Row.h
@@ -136,6 +136,29 @@ public:
 
 	///
 	Row();
+	/**
+	 * Helper function: set variable \c var to value \c val, and mark
+	 * row as changed is the values were different. This is intended
+	 * for use when changing members of the row object.
+	 */
+	template<class T1, class T2>
+	void change(T1 & var, T2 const val) {
+		if (var != val)
+			changed(true);
+		var = val;
+	}
+	/**
+	 * Helper function: set variable \c var to value \c val, and mark
+	 * row as changed is the values were different. This is intended
+	 * for use when changing members of the row object.
+	 * This is the const version, useful for mutable members.
+	 */
+	template<class T1, class T2>
+	void change(T1 & var, T2 const val) const {
+		if (var != val)
+			changed(true);
+		var = val;
+	}
 	///
 	bool changed() const { return changed_; }
 	///
diff --git a/src/TextMetrics.cpp b/src/TextMetrics.cpp
index 42637d7899..e7bd6190e2 100644
--- a/src/TextMetrics.cpp
+++ b/src/TextMetrics.cpp
@@ -1884,9 +1884,9 @@ void TextMetrics::drawParagraph(PainterInfo & pi, pit_type const pit, int const
 		// whether this row is the first or last and update the margins.
 		if (row.selection()) {
 			if (row.sel_beg == 0)
-				row.begin_margin_sel = sel_beg.pit() < pit;
+				row.change(row.begin_margin_sel, sel_beg.pit() < pit);
 			if (row.sel_end == sel_end_par.lastpos())
-				row.end_margin_sel = sel_end.pit() > pit;
+				row.change(row.end_margin_sel, sel_end.pit() > pit);
 		}
 
 		// has row changed since last paint?