[LyX/master] Centralize the code that removes trailing spaces from end row element.

[Jean-Marc Lasgouttes]

commit ef6dfe18c2149c6b96a806badde9548d7fd9f912
Author: Jean-Marc Lasgouttes <lasgouttes at lyx.org>
Date:   Tue Aug 31 19:23:55 2021 +0200

    Centralize the code that removes trailing spaces from end row element.
    
    Move to Row::Element::rtrim the code in Row::shortenIfNeeded that
    removes trailing spaces from last element in row, so that it can be
    called when actually breaking a row.
    
    Fixes bug found by Kornel.
---
 src/Row.cpp         |   28 +++++++++++++++-------------
 src/Row.h           |    2 ++
 src/TextMetrics.cpp |    4 ++++
 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/src/Row.cpp b/src/Row.cpp
index 38dbb85..d3529a3 100644
--- a/src/Row.cpp
+++ b/src/Row.cpp
@@ -35,7 +35,6 @@ using namespace std;
 
 namespace lyx {
 
-using support::rtrim;
 using frontend::FontMetrics;
 
 
@@ -162,6 +161,20 @@ Row::Element Row::Element::splitAt(int w, bool force)
 }
 
 
+void Row::Element::rtrim()
+{
+	if (type != STRING)
+		return;
+	/* This is intended for strings that have been created by splitAt.
+	 * They may have trailing spaces, but they are not counted in the
+	 * string length (QTextLayout feature, actually). We remove them,
+	 * and decrease endpos, since spaces at row break are invisible.
+	 */
+	str = support::rtrim(str);
+	endpos = pos + str.length();
+}
+
+
 bool Row::isMarginSelected(bool left, DocIterator const & beg,
 		DocIterator const & end) const
 {
@@ -539,14 +552,6 @@ Row::Elements Row::shortenIfNeeded(int const w, int const next_width)
 				break;
 			}
 			end_ = brk.endpos;
-			/* after breakAt, there may be spaces at the end of the
-			 * string, but they are not counted in the string length
-			 * (QTextLayout feature, actually). We remove them, but do
-			 * not change the end of the row, since spaces at row
-			 * break are invisible.
-			 */
-			brk.str = rtrim(brk.str);
-			brk.endpos = brk.pos + brk.str.length();
 			*cit_brk = brk;
 			dim_.wid = wid_brk + brk.dim.wid;
 			// If there are other elements, they should be removed.
@@ -578,11 +583,8 @@ Row::Elements Row::shortenIfNeeded(int const w, int const next_width)
 	 * boundary this time.
 	 */
 	Element remainder = cit->splitAt(w - wid, true);
-	if (remainder.isValid()) {
+	if (cit->row_flags & BreakAfter) {
 		end_ = cit->endpos;
-		// See comment above.
-		cit->str = rtrim(cit->str);
-		cit->endpos = cit->pos + cit->str.length();
 		dim_.wid = wid + cit->dim.wid;
 		// If there are other elements, they should be removed.
 		return splitFrom(elements_, next(cit, 1), remainder);
diff --git a/src/Row.h b/src/Row.h
index b0b1755..7466797 100644
--- a/src/Row.h
+++ b/src/Row.h
@@ -101,6 +101,8 @@ public:
 		 *   respects the row breaking rules of characters.
 		 */
 		Element splitAt(int w, bool force);
+		// remove trailing spaces (useful for end of row)
+		void rtrim();
 
 		//
 		bool isRTL() const { return font.isVisibleRightToLeft(); }
diff --git a/src/TextMetrics.cpp b/src/TextMetrics.cpp
index 37894f6..a7dd300 100644
--- a/src/TextMetrics.cpp
+++ b/src/TextMetrics.cpp
@@ -1061,6 +1061,10 @@ Row newRow(TextMetrics const & tm, pit_type pit, pos_type pos, bool is_rtl)
 void cleanupRow(Row & row, pos_type pos, pos_type real_endpos, bool is_rtl)
 {
 	row.endpos(pos);
+	// remove trailing spaces on row break
+	if (pos < real_endpos && !row.empty())
+		row.back().rtrim();
+	// boundary exists when there was no space at the end of row
 	row.right_boundary(!row.empty() && pos < real_endpos
 	                   && row.back().endpos == pos);
 	// make sure that the RTL elements are in reverse ordering