fixed non-printables

UICatalog/Scenarios/CharacterMap.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using Terminal.Gui;
+using Rune = System.Rune;
 
 namespace UICatalog {
 	/// <summary>
@@ -57,7 +58,7 @@ namespace UICatalog {
 			jumpList.Y = Pos.Bottom (label);
 			jumpList.Width = Dim.Fill ();
 			jumpList.SelectedItemChanged = (args) => {
-				charMap.Start = radioItems[args.SelectedItem].start;
+				charMap.Start = radioItems [args.SelectedItem].start;
 			};
 
 			Win.Add (jumpList);
@@ -105,6 +106,15 @@ namespace UICatalog {
 #if true
 		private void CharMap_DrawContent (Rect viewport)
 		{
+			Rune ReplaceNonPrintables (Rune c)
+			{
+				if (c < 0x20) {
+					return new Rune (c + 0x2400);         // U+25A1 □ WHITE SQUARE
+				} else {
+					return c;
+				}
+			}
+
 			for (int header = 0; header < 16; header++) {
 				Move (viewport.X + RowHeaderWidth + (header * 2), 0);
 				Driver.AddStr ($" {header:x} ");
@@ -117,7 +127,8 @@ namespace UICatalog {
 					Driver.AddStr (rowLabel);
 					for (int col = 0; col < 16; col++) {
 						Move (viewport.X + RowHeaderWidth + (col * 2), 0 + y + 1);
-						Driver.AddStr ($" {(char)((-viewport.Y + row) * 16 + col)}");
+						Driver.AddRune (' ');
+						Driver.AddRune (ReplaceNonPrintables (new Rune (((uint)((uint)(-viewport.Y + row) * 16 + col)))));
 					}
 				}
 			}