Store change bar information in row element

It is wrong to compute this at paint time. In general, painting a row
should not require any access to a paragraph object, but we are far
from there now.

(cherry picked from commit 4858bb3bb6)

src/Row.cpp

@@ -164,7 +164,8 @@ Row::Row()
 	  begin_margin_sel(false), end_margin_sel(false),
 	  changed_(false), crc_(0),
 	  pit_(0), pos_(0), end_(0),
-	  right_boundary_(false), flushed_(false), rtl_(false)
+	  right_boundary_(false), flushed_(false), rtl_(false),
+	  changebar_(false)
 {}
 
 
@@ -371,6 +372,8 @@ void Row::finalizeLast()
 	if (elt.final)
 		return;
 	elt.final = true;
+	if (elt.change.changed())
+		changebar_ = true;
 
 	if (elt.type == STRING) {
 		dim_.wid -= elt.dim.wid;

src/Row.h

@@ -266,6 +266,11 @@ public:
 	void reverseRTL(bool rtl_par);
 	///
 	bool isRTL() const { return rtl_; }
+	///
+	bool needsChangeBar() const { return changebar_; }
+	///
+	void needsChangeBar(bool ncb) { changebar_ = ncb; }
+
 	/// Find row element that contains \c pos, and compute x offset.
 	const_iterator const findElement(pos_type pos, bool boundary, double & x) const;
 
@@ -326,6 +331,8 @@ private:
 	Dimension dim_;
 	/// true when this row lives in a right-to-left paragraph
 	bool rtl_;
+	/// true when a changebar should be drawn in the margin
+	bool changebar_;
 };
 
 

src/RowPainter.cpp

@@ -247,18 +247,6 @@ void RowPainter::paintChange(Row::Element const & e) const
 
 void RowPainter::paintChangeBar() const
 {
-	pos_type const start = row_.pos();
-	pos_type end = row_.endpos();
-
-	if (par_.size() == end) {
-		// this is the last row of the paragraph;
-		// thus, we must also consider the imaginary end-of-par character
-		end++;
-	}
-
-	if (start == end || !par_.isChanged(start, end))
-		return;
-
 	int const height = tm_.isLastRow(row_)
 		? row_.ascent()
 		: row_.height();

src/TextMetrics.cpp

@@ -964,6 +964,10 @@ bool TextMetrics::breakRow(Row & row, int const right_margin) const
 		row.addVirtual(end, docstring(1, char_type(0x00B6)), f, Change());
 	}
 
+	// Is there a end-of-paragaph change?
+	if (i == end && par.lookupChange(end).changed() && !need_new_row)
+		row.needsChangeBar(true);
+
 	// if the row is too large, try to cut at last separator. In case
 	// of success, reset indication that the row was broken abruptly.
 	int const next_width = max_width_ - leftMargin(row.pit(), row.endpos())
@@ -1937,7 +1941,8 @@ void TextMetrics::drawParagraph(PainterInfo & pi, pit_type const pit, int const
 		rp.paintSelection();
 		rp.paintAppendix();
 		rp.paintDepthBar();
-		rp.paintChangeBar();
+		if (row.needsChangeBar())
+			rp.paintChangeBar();
 		if (i == 0 && !row.isRTL())
 			rp.paintFirst();
 		if (i == nrows - 1 && row.isRTL())