feat(UI): Moved code for writing route error message to 'map' interfa…

…ce (endless-sky#10168)

data/_ui/interfaces.txt

@@ -11,6 +11,7 @@
 # You should have received a copy of the GNU General Public License along with
 # this program. If not, see <https://www.gnu.org/licenses/>.
 
+
 # Colors used to reflect the active or hovered interface button.
 color "hover" 1. 1. 1. 0.
 color "active" .75 .75 .75 0.
@@ -194,6 +195,11 @@ color "map wormhole" .5 .2 .9 1.
 color "map orbits fleet destination" 1. 1. 1. 1.
 color "map danger none" .1 .6 0. .4
 
+# Colors used for the routing issue text in the map panel when
+# a route to the selected system cannot be determined.
+color "map route error text" 1. 0. 0. 1.
+color "map route error shadow" 0. 0. 0. 1.
+
 # Miscellaneous colors
 color "wormholes: Ember Waste" .7 .1 .3
 
@@ -1431,6 +1437,16 @@ interface "map"
 	value "max zoom" 2
 	value "min zoom" -2
 
+	anchor top
+	string "route error"
+		center 1 59
+		size 18
+		color "map route error shadow"
+	string "route error"
+		center 0 58
+		size 18
+		color "map route error text"
+
 
 
 interface "info panel"

source/MapPanel.cpp

@@ -131,7 +131,6 @@ namespace {
 	}
 
 	const Color black(0.f, 1.f);
-	const Color red(1.f, 0.f, 0.f, 1.f);
 
 	// Hovering an escort pip for this many frames activates the tooltip.
 	const int HOVER_TIME = 60;
@@ -411,13 +410,11 @@ void MapPanel::FinishDrawing(const string &buttonCondition)
 	{
 		static const string UNAVAILABLE = "You have no available route to this system.";
 		static const string UNKNOWN = "You have not yet mapped a route to this system.";
-		const Font &font = FontSet::Get(18);
-
 		const string &message = player.CanView(*selectedSystem) ? UNAVAILABLE : UNKNOWN;
-		Point point(-font.Width(message) / 2, Screen::Top() + 40);
-		font.Draw(message, point + Point(1, 1), black);
-		font.Draw(message, point, red);
+		info.SetString("route error", message);
 	}
+
+	mapInterface->Draw(info, this);
 }