New reverseRTL implementation

The old version was a bit complicated and wrong for RtL paragraphs
containing LtR text. THe new one is clearer.

src/Row.cpp

@@ -382,24 +382,25 @@ void Row::shorten_if_needed(pos_type const keep, int const w)
 }
 
 
-void Row::reverseRTL()
+void Row::reverseRTL(bool const rtl_par)
 {
 	pos_type i = 0;
 	pos_type const end = elements_.size();
 	while (i < end) {
-		// skip LtR elements
+		// gather a sequence of elements with the same direction
-		while (i < end && !elements_[i].font.isRightToLeft())
+		bool const rtl = elements_[i].font.isVisibleRightToLeft();
-			++i;
-		if (i >= end)
-			break;
-
-		// look for a RTL sequence
 		pos_type j = i;
-		while (j < end && elements_[j].font.isRightToLeft())
+		while (j < end && elements_[j].font.isVisibleRightToLeft() == rtl)
 			++j;
-		reverse(elements_.begin() + i, elements_.begin() + j);
+		// if the direction is not the same as the paragraph
+		// direction, the sequence has to be reverted.
+		if (rtl != rtl_par)
+			reverse(elements_.begin() + i, elements_.begin() + j);
 		i = j;
 	}
+	// If the paragraph itself is RTL, reverse everything
+	if (rtl_par)
+		reverse(elements_.begin(), elements_.end());
 }
 
 } // namespace lyx

src/Row.h

@@ -212,7 +212,7 @@ public:
 	 * Find sequences of right-to-left elements and reverse them.
 	 * This should be called once the row is completely built.
 	 */
-	void reverseRTL();
+	void reverseRTL(bool rtl_par);
 
 	friend std::ostream & operator<<(std::ostream & os, Row const & row);
 

src/TextMetrics.cpp

@@ -929,7 +929,7 @@ void TextMetrics::breakRow(Row & row, int const right_margin, pit_type const pit
 		row.pop_back();
 
 	// make sure that the RTL elements are in reverse ordering
-	row.reverseRTL();
+	row.reverseRTL(text_->isRTL(par));
 
 	row.dimension().wid += right_margin;
 }