From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Tue, 6 Dec 2016 15:06:03 +0000 (+0100)
Subject: Handle negative values gracefully.
X-Git-Tag: 2.3.0alpha1~655
X-Git-Url: https://git.lyx.org/gitweb/?a=commitdiff_plain;h=c8a829d273020d10ae5a22eb8a9fabafe7b81e6e;p=features.git

Handle negative values gracefully.

It may happen (for example with on the fly spell checking) that
GuiFontMetrics::pos2x is called with a negative pos value. Add a
special case for this situation.

Fixes bug #10506
---

diff --git a/src/frontends/qt4/GuiFontMetrics.cpp b/src/frontends/qt4/GuiFontMetrics.cpp
index 77cda80434..d3c89f1a59 100644
--- a/src/frontends/qt4/GuiFontMetrics.cpp
+++ b/src/frontends/qt4/GuiFontMetrics.cpp
@@ -205,6 +205,8 @@ GuiFontMetrics::getTextLayout(docstring const & s, QFont font,
 int GuiFontMetrics::pos2x(docstring const & s, int const pos, bool const rtl,
                           double const wordspacing) const
 {
+	if (pos <= 0)
+		return rtl ? width(s) : 0;
 	QTextLayout const & tl = getTextLayout(s, font_, rtl, wordspacing);
 	/* Since QString is UTF-16 and docstring is UCS-4, the offsets may
 	 * not be the same when there are high-plan unicode characters