From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Wed, 22 Jul 2015 22:39:27 +0000 (+0200)
Subject: Another go at improving row shortening
X-Git-Tag: 2.2.0alpha1~399
X-Git-Url: https://git.lyx.org/gitweb/?a=commitdiff_plain;h=d893400f93ab44837e60ec61a362a45c316bf072;p=features.git

Another go at improving row shortening

Instead of remembering the last breakable element in the row, search
backward in the row and consider all string elements one by one until
a correct place to break is found.

This fixes the case where the row ends with a string, but there is no
space soon enough in the string to break it here. In this case, we
need to consider the previous row.
---

diff --git a/src/Row.cpp b/src/Row.cpp
index a619874b93..a61e19f9f1 100644
--- a/src/Row.cpp
+++ b/src/Row.cpp
@@ -224,7 +224,8 @@ ostream & operator<<(ostream & os, Row::Element const & e)
 
 	switch (e.type) {
 	case Row::STRING:
-		os << "STRING: `" << to_utf8(e.str) << "', ";
+		os << "STRING: `" << to_utf8(e.str) << "' ("
+		   << e.countSeparators() << " sep.), ";
 		break;
 	case Row::VIRTUAL:
 		os << "VIRTUAL: `" << to_utf8(e.str) << "', ";
@@ -378,54 +379,58 @@ void Row::shortenIfNeeded(pos_type const keep, int const w)
 {
 	if (empty() || width() <= w)
 		return;
+
 	Elements::iterator const beg = elements_.begin();
 	Elements::iterator const end = elements_.end();
 	int wid = left_margin;
 
-	// The last breakable element that has been found and its x position.
-	Elements::iterator last_brk = elements_.end();
-	int last_wid = 0;
-
+	// Search for the first element that goes beyond right margin
 	Elements::iterator cit = beg;
 	for ( ; cit != end ; ++cit) {
-		if (cit->countSeparators() && cit->pos >= keep) {
-			last_brk = cit;
-			last_wid = wid;
-		}
 		if (wid + cit->dim.wid > w)
 			break;
 		wid += cit->dim.wid;
 	}
 
-	/* We have found a suitable separable element. This is the common case.
-	 * Try to break it cleanly (at word boundary) at a length that is both
-	 * - less than the available space on the row
-	 * - shorter than the natural width of the element, in order to enforce
-	 *   break-up.
-	 */
-	if (last_brk != end
-		&& last_brk->breakAt(min(w - last_wid, last_brk->dim.wid - 2), false)) {
-		end_ = last_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 endo of the row, since the spaces at row break
-		 * are invisible.
-		 */
-		last_brk->str = rtrim(last_brk->str);
-		last_brk->endpos = last_brk->pos + last_brk->str.length();
-		dim_.wid = last_wid + last_brk->dim.wid;
-		// If there are other elements, they should be removed.
-		elements_.erase(next(last_brk, 1), end);
-		return;
-	}
-
 	if (cit == end) {
 		// This should not happen since the row is too long.
 		LYXERR0("Something is wrong cannot shorten row: " << *this);
 		return;
 	}
 
+	// Iterate backwards over breakable elements and try to break them
+	Elements::iterator cit_brk = cit;
+	int wid_brk = wid + cit_brk->dim.wid;
+	++cit_brk;
+	while (cit_brk != beg) {
+		--cit_brk;
+		Element & brk = *cit_brk;
+		wid_brk -= brk.dim.wid;
+		if (brk.countSeparators() == 0 || brk.pos < keep)
+			continue;
+		/* We have found a suitable separable element. This is the common case.
+		 * Try to break it cleanly (at word boundary) at a length that is both
+		 * - less than the available space on the row
+		 * - shorter than the natural width of the element, in order to enforce
+		 *   break-up.
+		 */
+		if (brk.breakAt(min(w - wid_brk, brk.dim.wid - 2), false)) {
+			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 endo of the row, since the spaces at row
+			 * break are invisible.
+			 */
+			brk.str = rtrim(brk.str);
+			brk.endpos = brk.pos + brk.str.length();
+			dim_.wid = wid_brk + brk.dim.wid;
+			// If there are other elements, they should be removed.
+			elements_.erase(cit_brk + 1, end);
+			return;
+		}
+	}
+
 	if (cit != beg && cit->type == VIRTUAL) {
 		// It is not possible to separate a virtual element from the
 		// previous one.
@@ -434,8 +439,8 @@ void Row::shortenIfNeeded(pos_type const keep, int const w)
 	}
 
 	if (cit != beg) {
-		// There is no separator, but several elements have been
-		// added. We can cut right here.
+		// There is no usable separator, but several elements have
+		// been added. We can cut right here.
 		end_ = cit->pos;
 		dim_.wid = wid;
 		elements_.erase(cit, end);