Tweak previous fix to include removing unrenderable sources from config

In addition to the check added previously, when `SaltSourcesForm` attempts to populate, it will remove any source where the string is unrenderable by the graphics API.

SaltSources.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Drawing;
 
 namespace KeePassDiceware
 {
@@ -32,6 +33,22 @@ public class SaltSource : ICloneable
 				"\u00F0\u00F1\u00F2\u00F3\u00F4\u00F5\u00F6\u00F7" +
 				"\u00F8\u00F9\u00FA\u00FB\u00FC\u00FD\u00FE\u00FF";
 
+		private static bool? _runtimeCanHandleEmoji = null;
+		internal static bool RuntimeCanHandleEmoji
+		{
+			get
+			{
+				if (_runtimeCanHandleEmoji.HasValue)
+				{
+					return _runtimeCanHandleEmoji.Value;
+				}
+
+				_runtimeCanHandleEmoji = TestRuntimeRenderSupport(Emojis);
+
+				return _runtimeCanHandleEmoji.Value;
+			}
+		}
+
 		public string Name { get; set; }
 		[Browsable(false)]
 		public string Key => Name.Replace(" ", string.Empty);
@@ -60,6 +77,21 @@ public bool Enabled
 			}
 		}
 
+		internal bool? _canRender = null;
+		public bool CanRender
+		{
+			get
+			{
+				if (_canRender.HasValue)
+				{
+					return _canRender.Value;
+				}
+
+				_canRender = TestRuntimeRenderSupport(Pool);
+
+				return _canRender.Value;
+			}
+		}
 
 		public SaltSource(string name, string pool, bool enabled = true)
 		{
@@ -104,8 +136,30 @@ public static List<SaltSource> DefaultSources
 		}
 
 		/// <summary>
-		/// As <see cref="DefaultSources"/>, but without the "Emoji" source."/>
+		/// As <see cref="DefaultSources"/>, but without the "Emoji" source.
 		/// </summary>
 		public static List<SaltSource> DefaultSourcesWithoutEmoji => DefaultSources.FindAll(s => s.Name != "Emoji");
+
+		/// <summary>
+		/// Attempts to render the given string with the graphics API.
+		/// </summary>
+		/// <param name="testString">The string to attempt to render</param>
+		/// <returns>True if the render was successful, otherwise false</returns>
+		internal static bool TestRuntimeRenderSupport(string testString)
+		{
+			try
+			{
+				// attempt to render the given string to a temporary bitmap.
+				using Bitmap test = new(1, 1);
+				using var g = Graphics.FromImage(test);
+				g.DrawString(testString, SystemFonts.DefaultFont, Brushes.Black, 0, 0);
+				return true;
+			}
+			catch
+			{
+				// if drawing fails for any reason, assume this runtime can't handle characters in that string
+				return false;
+			}
+		}
 	}
 }

SaltSourcesForm.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
-using System.Drawing;
 using System.Linq;
 using System.Windows.Forms;
 
@@ -11,34 +10,6 @@ namespace KeePassDiceware
 {
 	public partial class SaltSourcesForm : Form
 	{
-		private static bool? _runtimeCanHandleEmoji = null;
-		private static bool RuntimeCanHandleEmoji
-		{
-			get
-			{
-				if (_runtimeCanHandleEmoji.HasValue)
-				{
-					return _runtimeCanHandleEmoji.Value;
-				}
-
-				try
-				{
-					// attempt to render an emoji string to a temporary bitmap.
-					using Bitmap test = new(1, 1);
-					using var g = Graphics.FromImage(test);
-					g.DrawString(SaltSource.Emojis, SystemFonts.DefaultFont, Brushes.Black, 0, 0);
-					_runtimeCanHandleEmoji = true;
-				}
-				catch
-				{
-					// if drawing an emoji fails for any reason, assume this runtime can't handle emoji.
-					_runtimeCanHandleEmoji = false;
-				}
-
-				return _runtimeCanHandleEmoji.Value;
-			}
-		}
-
 		public List<SaltSource> Result { get; private set; } = null;
 		private BindingList<SaltSource> DataSource { get; set; } = null;
 
@@ -100,6 +71,20 @@ internal void PopulateSaltSources(List<SaltSource> saltSources)
 		{
 			_pendingErrors.Clear();
 
+			int totalCount = saltSources.Count;
+
+			saltSources = saltSources.Where(ss => ss.CanRender).ToList();
+
+			int removed = totalCount - saltSources.Count;
+
+			if (removed > 0)
+			{
+				string removedS = removed == 1 ? string.Empty : "s";
+				string removedHelpingVerb = removed == 1 ? "was" : "were";
+				MessageBox.Show(this, $"{removed} salt source{removedS} {removedHelpingVerb} removed because they are not supported by the current runtime.",
+					$"Unsupported Source{removedS} Removed", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+			}
+
 			DataSource = new(saltSources.ConvertAll(ss => ss.Clone() as SaltSource))
 			{
 				AllowNew = true,
@@ -196,7 +181,7 @@ private int ValidateSourceNames()
 
 		private void RestoreDefaultsButton_Click(object sender, EventArgs e)
 		{
-			PopulateSaltSources(RuntimeCanHandleEmoji
+			PopulateSaltSources(SaltSource.RuntimeCanHandleEmoji
 				? SaltSource.DefaultSources
 				: SaltSource.DefaultSourcesWithoutEmoji
 			);