Implement faded (configurable colour) zeroes in the Hex Editor

src/BizHawk.Client.EmuHawk/tools/HexEditor/HexColor.cs

@@ -20,6 +20,7 @@ private void HexColors_Form_Load(object sender, EventArgs e)
 			HexFreeze.BackColor = _hexEditor.Colors.Freeze;
 			HexFreezeHL.BackColor = _hexEditor.Colors.HighlightFreeze;
 			HexHighlight.BackColor = _hexEditor.Colors.Highlight;
+			Hex00.BackColor = _hexEditor.Colors.Foreground00;
 		}
 
 		private void HexBackground_Click(object sender, MouseEventArgs e)
@@ -33,6 +34,15 @@ private void HexBackground_Click(object sender, MouseEventArgs e)
 			}
 		}
 
+		private void Hex00_Click(object sender, MouseEventArgs e)
+		{
+			if (colorDialog1.ShowDialog().IsOk())
+			{
+				_hexEditor.Colors.Foreground00 = colorDialog1.Color;
+				Hex00.BackColor = colorDialog1.Color;
+			}
+		}
+
 		private void HexForeground_Click(object sender, MouseEventArgs e)
 		{
 			if (colorDialog1.ShowDialog().IsOk())

src/BizHawk.Client.EmuHawk/tools/HexEditor/HexEditor.cs

@@ -133,6 +133,7 @@ internal class ColorConfig
 			public Color Freeze { get; set;  }= Color.LightBlue;
 			public Color Highlight { get; set; } = Color.Pink;
 			public Color HighlightFreeze { get; set; } = Color.Violet;
+			public Color Foreground00 { get; set; } = Color.SlateGray;
 		}
 
 		[ConfigPersist]
@@ -219,11 +220,21 @@ private void HexEditor_Load(object sender, EventArgs e)
 
 		protected override void UpdateAfter()
 		{
+			if (AddressesLabel.ZeroColor != Colors.Foreground00)
+			{
+				AddressesLabel.ZeroColor = Colors.Foreground00;
+			}
+
 			AddressesLabel.Text = GenerateMemoryViewString(true);
 		}
 
 		protected override void GeneralUpdate()
 		{
+			if (AddressesLabel.ZeroColor != Colors.Foreground00)
+			{
+				AddressesLabel.ZeroColor = Colors.Foreground00;
+			}
+
 			AddressesLabel.Text = GenerateMemoryViewString(true);
 			AddressLabel.Text = GenerateAddressString();
 		}

src/BizHawk.WinForms.Controls/BizHawk.WinForms.Controls.csproj

@@ -10,4 +10,9 @@
 		<PackageReference Include="System.Drawing.Common" />
 		<ProjectReference Include="$(ProjectDir)../BizHawk.Common/BizHawk.Common.csproj" />
 	</ItemGroup>
+	<ItemGroup>
+	  <Compile Update="LabelEx\HexLabelEx.cs">
+	    <SubType>Component</SubType>
+	  </Compile>
+	</ItemGroup>
 </Project>

src/BizHawk.WinForms.Controls/LabelEx/HexLabelEx.cs

@@ -0,0 +1,128 @@
+using System.ComponentModel;
+using System.Drawing;
+using System.Windows.Forms;
+using BizHawk.Common;
+
+
+namespace BizHawk.WinForms.Controls
+{
+	/// <inheritdoc cref="Docs.LabelOrLinkLabel"/>
+	public class HexLabelEx : LabelExBase
+	{
+		[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
+		public new bool AutoSize => base.AutoSize;
+
+		[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
+		public new Size Size => base.Size;
+
+		public Color ZeroColor { get; set; } = Color.SlateGray;
+
+		private float spacingHexModifier;
+		private float spacingPreDivider;
+		private float spacingPostDividerModifier;
+		private float spacingAscii;
+		private float spacingLineModifier;
+
+		public HexLabelEx()
+		{
+			base.AutoSize = true;
+			this.BackColor = Color.Transparent;
+
+			spacingHexModifier = 0.7F;
+			spacingPreDivider = 3.0F;
+			spacingPostDividerModifier = 3.5F;
+			spacingAscii = 7.0F;
+			spacingLineModifier = 0.56F;
+
+			if (OSTailoredCode.IsUnixHost)
+			{
+				// TODO: spacing values will probably be different on linux
+			}
+		}
+
+		protected override void OnPaint(PaintEventArgs e)
+		{
+			string text = this.Text;
+			Font font = this.Font;
+			PointF point = new PointF(0, 0);
+			char gap = ' ';
+
+			string[] lines = text.Split(new[] { "\r\n", "\r", "\n" }, StringSplitOptions.None);
+
+			Color color = this.ForeColor;
+
+			foreach (string line in lines)
+			{
+				// split left and right panes
+				string[] panes = line.Split('|');
+
+				if (panes.Length < 2)
+				{
+					// skip - last line appears to be empty
+					continue;
+				}
+				else if (panes.Length > 2)
+				{
+					// pipe character present in the ascii pane?
+					for (int i = 2; i < panes.Length; i++)
+					{
+						panes[1] += "|" + panes[i];
+					}
+				}
+
+				// hex pane
+				string[] words = panes[0].Split(gap);
+				foreach (var word in words)
+				{
+					SizeF size = e.Graphics.MeasureString(word, font);
+
+					switch (word)
+					{
+						case "00":
+							color = ZeroColor;
+							break;
+
+						default:
+							color = this.ForeColor;
+							break;
+					}
+
+					DrawString(word, font, point, color);
+
+					point.X += size.Width + e.Graphics.MeasureString(gap.ToString(), font).Width + spacingHexModifier;
+				}
+
+				// divider
+				string div = "|";
+				point.X -= spacingPreDivider;
+				SizeF sizeDiv = e.Graphics.MeasureString(div, font);
+
+				DrawString(div, font, point, this.ForeColor);
+
+				point.X += e.Graphics.MeasureString(gap.ToString(), font).Width + spacingPostDividerModifier;
+
+				// ascii pane
+				char[] chars = panes[1].ToCharArray();
+				foreach (var c in chars)
+				{
+					string str = c.ToString();
+					DrawString(str, font, point, this.ForeColor);
+
+					// fixed size
+					point.X += spacingAscii;
+				}
+
+				point.X = 0;
+				point.Y += e.Graphics.MeasureString(line, font).Height + spacingLineModifier;
+			}
+
+			void DrawString(string s, Font f, PointF p, Color color)
+			{
+				using (Brush brush = new SolidBrush(color))
+				{
+					e.Graphics.DrawString(s, f, brush, p);
+				}
+			}
+		}
+	}
+}