Try to recover from broken pango-markup.

Espreon noticed an ampersand in a campaign description breaks the
description markup. Now try to recover from unescaped ampersands. The
rest of the broken markup remains broken (pango seems to handle
unescaped single quotes and double quotes properly).

changelog

@@ -11,6 +11,7 @@ Version 1.9.10+svn:
    * Fixed disappearing theme UI buttons after changing fullscreen/windowed mode
      or resolution in Preferences during a game
    * Fixed define handling of wmlxgettext (bug #18622)
+   * Changed: Try to recover from broken pango-markup.
 
 Version 1.9.10:
  * AI:

src/text.cpp

@@ -301,17 +301,9 @@ bool ttext::set_text(const std::string& text, const bool markedup)
 					<< "' contains invalid utf-8, trimmed the invalid parts.\n";
 		}
 		if(markedup) {
-			if(!pango_parse_markup(narrow.c_str(), narrow.size()
-						, 0, NULL, NULL, NULL, NULL)) {
-
-				ERR_GUI_L << "ttext::" << __func__
-						<< " text '" << narrow
-						<< "' has broken markup, set to normal text.\n";
-
-				set_text(_("The text contains invalid markup: ") + narrow, false);
+			if(!set_markup(narrow)) {
 				return false;
 			}
-			pango_layout_set_markup(layout_, narrow.c_str(), narrow.size());
 		} else {
 			/*
 			 * pango_layout_set_text after pango_layout_set_markup might
@@ -684,5 +676,58 @@ void ttext::create_surface_buffer(const size_t size) const
 	memset(surface_buffer_, 0, size);
 }
 
+bool ttext::set_markup(const std::string& text)
+{
+	if(pango_parse_markup(text.c_str(), text.size()
+			, 0, NULL, NULL, NULL, NULL)) {
+
+		/* Markup is valid so set it. */
+		pango_layout_set_markup(layout_, text.c_str(), text.size());
+		return true;
+	}
+
+	/*
+	 * The markup is invalid. Try to recover.
+	 *
+	 * The pango engine tested seems to accept stray single quotes »'« and
+	 * double quotes »"«. Stray ampersands »&« seem to give troubles.
+	 * So only try to recover from broken ampersands, by simply replacing them
+	 * with the escaped version.
+	 */
+	std::string semi_escaped;
+	BOOST_FOREACH(const char c, text) {
+		if(c == '&') {
+			semi_escaped += "&amp;";
+		} else {
+			semi_escaped += c;
+		}
+	}
+
+	/*
+	 * If at least one ampersand is replaced the semi-escaped string
+	 * is longer than the original.
+	 */
+	if(text.size() != semi_escaped.size()
+			&& !pango_parse_markup(semi_escaped.c_str(), semi_escaped.size()
+				, 0, NULL, NULL, NULL, NULL)) {
+
+		/* Fixing the ampersands didn't work. */
+		ERR_GUI_L << "ttext::" << __func__
+				<< " text '" << text
+				<< "' has broken markup, set to normal text.\n";
+
+		set_text(_("The text contains invalid markup: ") + text, false);
+		return false;
+	}
+
+	/* Replacement worked, still warn the user about the error. */
+	ERR_GUI_L << "ttext::" << __func__
+			<< " text '" << text
+			<< "' has unescaped ampersands '&', escaped them.\n";
+
+	pango_layout_set_markup(layout_, semi_escaped.c_str(), semi_escaped.size());
+	return true;
+}
+
 } // namespace font
 

src/text.hpp

@@ -301,6 +301,21 @@ private:
 	 * @param size                The required size of the buffer.
 	 */
 	void create_surface_buffer(const size_t size) const;
+
+	/**
+	 * Sets the markup'ed text.
+	 *
+	 * It tries to set the text as markup. If the markup is invalid it will try
+	 * a bit harder to recover from the errors and still set the markup.
+	 *
+	 * @param text                The text to set as markup.
+	 *
+	 * @returns                   Whether the markup was set or an
+	 *                            unrecoverable error occurred and the text is
+	 *                            set as plain text with an error message.
+	 */
+	bool set_markup(const std::string& text);
+
 };
 
 } // namespace font