feat(ui): distinct Dark palette and recolor drawings on scheme switch

- Replace Dark part colors with high-contrast neon/electric palette
- Recolor existing drawings in open nests when scheme changes

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

OpenNest.Core/Drawing.cs

@@ -16,7 +16,7 @@ namespace OpenNest
         private static int nextColorIndex;
         private Program program;
 
-        public static readonly Color[] PartColors = new Color[]
+        public static Color[] PartColors = new Color[]
         {
             Color.FromArgb(205, 92, 92),    // Indian Red
             Color.FromArgb(148, 103, 189),  // Medium Purple

OpenNest/ColorScheme.cs

@@ -13,10 +13,13 @@ namespace OpenNest
         private Color edgeSpacingColor;
         private Color previewPartColor;
 
-        public static Color[] PartColors => Drawing.PartColors;
+        public string Name { get; set; } = "Unnamed";
+
+        public Color[] PartColors { get; set; } = Drawing.PartColors;
 
         public static readonly ColorScheme Default = new ColorScheme
         {
+            Name = "Classic",
             BackgroundColor = Color.DarkGray,
             LayoutOutlineColor = Color.Gray,
             LayoutFillColor = Color.WhiteSmoke,

OpenNest/ColorSchemeRegistry.cs

@@ -0,0 +1,203 @@
+using OpenNest.Forms;
+using OpenNest.Properties;
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.IO;
+using System.Linq;
+using System.Windows.Forms;
+
+namespace OpenNest
+{
+    public static class ColorSchemeRegistry
+    {
+        private static readonly Dictionary<string, ColorScheme> builtIns =
+            new(StringComparer.OrdinalIgnoreCase)
+            {
+                ["Classic"] = BuildClassic(),
+                ["Pastel"] = BuildPastel(),
+                ["Dark"] = BuildDark()
+            };
+
+        private static List<ColorScheme> diskCache;
+
+        public static IEnumerable<ColorScheme> AllSchemes
+        {
+            get
+            {
+                diskCache ??= LoadDiskSchemes().ToList();
+                return builtIns.Values.Concat(diskCache);
+            }
+        }
+
+        public static void Refresh() => diskCache = null;
+
+        public static ColorScheme Get(string name)
+        {
+            if (string.IsNullOrWhiteSpace(name))
+                return builtIns["Classic"];
+
+            var hit = AllSchemes.FirstOrDefault(
+                s => string.Equals(s.Name, name, StringComparison.OrdinalIgnoreCase));
+            return hit ?? builtIns["Classic"];
+        }
+
+        public static void ApplyActiveFromSettings()
+        {
+            var name = Settings.Default.ActiveColorScheme;
+            var scheme = Get(name);
+            Apply(scheme);
+        }
+
+        public static void Apply(ColorScheme scheme)
+        {
+            var d = ColorScheme.Default;
+            d.Name = scheme.Name;
+            d.BackgroundColor = scheme.BackgroundColor;
+            d.LayoutOutlineColor = scheme.LayoutOutlineColor;
+            d.LayoutFillColor = scheme.LayoutFillColor;
+            d.BoundingBoxColor = scheme.BoundingBoxColor;
+            d.RapidColor = scheme.RapidColor;
+            d.OriginColor = scheme.OriginColor;
+            d.EdgeSpacingColor = scheme.EdgeSpacingColor;
+            d.PreviewPartColor = scheme.PreviewPartColor;
+            d.PartColors = scheme.PartColors;
+
+            Drawing.PartColors = scheme.PartColors;
+
+            RecolorOpenNests(scheme.PartColors);
+        }
+
+        private static void RecolorOpenNests(Color[] palette)
+        {
+            foreach (Form f in Application.OpenForms)
+            {
+                if (f is not EditNestForm enf)
+                    continue;
+
+                var i = 0;
+                foreach (var drawing in enf.Nest.Drawings)
+                {
+                    if (drawing.IsCutOff)
+                        continue;
+                    drawing.Color = palette[i % palette.Length];
+                    i++;
+                }
+            }
+        }
+
+        private static IEnumerable<ColorScheme> LoadDiskSchemes()
+        {
+            var dir = Path.Combine(AppContext.BaseDirectory, "Schemes");
+            if (!Directory.Exists(dir))
+                yield break;
+
+            foreach (var path in Directory.GetFiles(dir, "*.json"))
+            {
+                ColorScheme scheme;
+                try
+                {
+                    scheme = ColorSchemeSerializer.Deserialize(File.ReadAllText(path));
+                }
+                catch
+                {
+                    continue;
+                }
+                if (!builtIns.ContainsKey(scheme.Name))
+                    yield return scheme;
+            }
+        }
+
+        private static ColorScheme BuildClassic() => new ColorScheme
+        {
+            Name = "Classic",
+            BackgroundColor = Color.DarkGray,
+            LayoutOutlineColor = Color.Gray,
+            LayoutFillColor = Color.WhiteSmoke,
+            BoundingBoxColor = Color.FromArgb(128, 128, 255),
+            RapidColor = Color.DodgerBlue,
+            OriginColor = Color.Gray,
+            EdgeSpacingColor = Color.FromArgb(180, 180, 180),
+            PreviewPartColor = Color.FromArgb(255, 140, 0),
+            PartColors = new[]
+            {
+                Color.FromArgb(205, 92, 92),
+                Color.FromArgb(148, 103, 189),
+                Color.FromArgb(75, 180, 175),
+                Color.FromArgb(210, 190, 75),
+                Color.FromArgb(190, 85, 175),
+                Color.FromArgb(185, 115, 85),
+                Color.FromArgb(120, 100, 190),
+                Color.FromArgb(200, 100, 140),
+                Color.FromArgb(80, 175, 155),
+                Color.FromArgb(195, 160, 85),
+                Color.FromArgb(175, 95, 160),
+                Color.FromArgb(215, 130, 130),
+            }
+        };
+
+        private static ColorScheme BuildPastel() => new ColorScheme
+        {
+            Name = "Pastel",
+            BackgroundColor = Color.FromArgb(70, 75, 85),
+            LayoutOutlineColor = Color.FromArgb(180, 180, 190),
+            LayoutFillColor = Color.FromArgb(245, 245, 248),
+            BoundingBoxColor = Color.FromArgb(128, 128, 255),
+            RapidColor = Color.DodgerBlue,
+            OriginColor = Color.FromArgb(160, 160, 160),
+            EdgeSpacingColor = Color.FromArgb(200, 200, 210),
+            PreviewPartColor = Color.FromArgb(255, 140, 0),
+            PartColors = new[]
+            {
+                Color.FromArgb(122, 179, 209), Color.FromArgb(254, 229, 174),
+                Color.FromArgb(143, 177, 229), Color.FromArgb(167, 172, 227),
+                Color.FromArgb(216, 249, 195), Color.FromArgb(209, 168, 216),
+                Color.FromArgb(222, 157, 190), Color.FromArgb(176, 255, 240),
+                Color.FromArgb(235, 205, 153), Color.FromArgb(177, 225, 180),
+                Color.FromArgb(125, 202, 241), Color.FromArgb(187, 206, 151),
+                Color.FromArgb(251, 175, 190), Color.FromArgb(129, 226, 227),
+                Color.FromArgb(255, 253, 207), Color.FromArgb(235, 205, 255),
+                Color.FromArgb(255, 197, 168), Color.FromArgb(116, 213, 234),
+                Color.FromArgb(190, 169, 122), Color.FromArgb(213, 159, 135),
+                Color.FromArgb(124, 184, 155), Color.FromArgb(255, 189, 214),
+                Color.FromArgb(146, 222, 255), Color.FromArgb(177, 173, 125),
+                Color.FromArgb(177, 166, 202), Color.FromArgb(197, 208, 255),
+                Color.FromArgb(255, 209, 243), Color.FromArgb(210, 255, 237),
+                Color.FromArgb(255, 237, 204), Color.FromArgb(167, 233, 255),
+                Color.FromArgb(182, 220, 255), Color.FromArgb(159, 177, 142),
+                Color.FromArgb(190, 248, 255), Color.FromArgb(187, 169, 136),
+                Color.FromArgb(199, 162, 168), Color.FromArgb(250, 255, 239),
+                Color.FromArgb(222, 233, 255), Color.FromArgb(255, 234, 225),
+                Color.FromArgb(240, 249, 255), Color.FromArgb(152, 176, 176),
+            }
+        };
+
+        private static ColorScheme BuildDark() => new ColorScheme
+        {
+            Name = "Dark",
+            BackgroundColor = Color.FromArgb(30, 30, 34),
+            LayoutOutlineColor = Color.FromArgb(90, 90, 95),
+            LayoutFillColor = Color.FromArgb(50, 50, 55),
+            BoundingBoxColor = Color.FromArgb(100, 160, 220),
+            RapidColor = Color.FromArgb(255, 200, 50),
+            OriginColor = Color.FromArgb(120, 120, 130),
+            EdgeSpacingColor = Color.FromArgb(90, 90, 100),
+            PreviewPartColor = Color.FromArgb(255, 170, 60),
+            PartColors = new[]
+            {
+                Color.FromArgb(255, 85, 85),   // Neon Red
+                Color.FromArgb(80, 220, 255),  // Electric Cyan
+                Color.FromArgb(255, 200, 50),  // Amber
+                Color.FromArgb(130, 255, 130), // Lime Green
+                Color.FromArgb(255, 130, 220), // Hot Pink
+                Color.FromArgb(255, 165, 70),  // Tangerine
+                Color.FromArgb(100, 180, 255), // Sky Blue
+                Color.FromArgb(200, 160, 255), // Lavender
+                Color.FromArgb(50, 230, 180),  // Mint
+                Color.FromArgb(255, 255, 100), // Lemon
+                Color.FromArgb(255, 120, 120), // Salmon
+                Color.FromArgb(140, 230, 255), // Ice Blue
+            }
+        };
+    }
+}

OpenNest/ColorSchemeSerializer.cs

@@ -0,0 +1,84 @@
+using System.Drawing;
+using System.Globalization;
+using System.Linq;
+using System.Text.Json;
+
+namespace OpenNest
+{
+    public static class ColorSchemeSerializer
+    {
+        private static readonly JsonSerializerOptions JsonOptions = new()
+        {
+            WriteIndented = true,
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+        };
+
+        public static string Serialize(ColorScheme scheme)
+        {
+            var dto = new ColorSchemeDto
+            {
+                Name = scheme.Name,
+                BackgroundColor = ToHex(scheme.BackgroundColor),
+                LayoutOutlineColor = ToHex(scheme.LayoutOutlineColor),
+                LayoutFillColor = ToHex(scheme.LayoutFillColor),
+                BoundingBoxColor = ToHex(scheme.BoundingBoxColor),
+                RapidColor = ToHex(scheme.RapidColor),
+                OriginColor = ToHex(scheme.OriginColor),
+                EdgeSpacingColor = ToHex(scheme.EdgeSpacingColor),
+                PreviewPartColor = ToHex(scheme.PreviewPartColor),
+                PartColors = scheme.PartColors.Select(ToHex).ToArray()
+            };
+            return JsonSerializer.Serialize(dto, JsonOptions);
+        }
+
+        public static ColorScheme Deserialize(string json)
+        {
+            var dto = JsonSerializer.Deserialize<ColorSchemeDto>(json, JsonOptions)
+                ?? throw new JsonException("ColorScheme JSON was null");
+
+            return new ColorScheme
+            {
+                Name = dto.Name ?? "Unnamed",
+                BackgroundColor = FromHex(dto.BackgroundColor),
+                LayoutOutlineColor = FromHex(dto.LayoutOutlineColor),
+                LayoutFillColor = FromHex(dto.LayoutFillColor),
+                BoundingBoxColor = FromHex(dto.BoundingBoxColor),
+                RapidColor = FromHex(dto.RapidColor),
+                OriginColor = FromHex(dto.OriginColor),
+                EdgeSpacingColor = FromHex(dto.EdgeSpacingColor),
+                PreviewPartColor = FromHex(dto.PreviewPartColor),
+                PartColors = (dto.PartColors ?? new string[0]).Select(FromHex).ToArray()
+            };
+        }
+
+        private static string ToHex(Color c) =>
+            "#" + c.R.ToString("X2") + c.G.ToString("X2") + c.B.ToString("X2");
+
+        private static Color FromHex(string hex)
+        {
+            if (string.IsNullOrWhiteSpace(hex))
+                return Color.Black;
+            var h = hex.TrimStart('#');
+            if (h.Length < 6)
+                return Color.Black;
+            var r = byte.Parse(h.Substring(0, 2), NumberStyles.HexNumber, CultureInfo.InvariantCulture);
+            var g = byte.Parse(h.Substring(2, 2), NumberStyles.HexNumber, CultureInfo.InvariantCulture);
+            var b = byte.Parse(h.Substring(4, 2), NumberStyles.HexNumber, CultureInfo.InvariantCulture);
+            return Color.FromArgb(r, g, b);
+        }
+
+        private class ColorSchemeDto
+        {
+            public string Name { get; set; }
+            public string BackgroundColor { get; set; }
+            public string LayoutOutlineColor { get; set; }
+            public string LayoutFillColor { get; set; }
+            public string BoundingBoxColor { get; set; }
+            public string RapidColor { get; set; }
+            public string OriginColor { get; set; }
+            public string EdgeSpacingColor { get; set; }
+            public string PreviewPartColor { get; set; }
+            public string[] PartColors { get; set; }
+        }
+    }
+}

OpenNest/Controls/PlateView.cs

@@ -464,6 +464,9 @@ namespace OpenNest.Controls
 
         protected override void OnPaint(PaintEventArgs e)
         {
+            if (BackColor != ColorScheme.BackgroundColor)
+                BackColor = ColorScheme.BackgroundColor;
+
             e.Graphics.SmoothingMode = SmoothingMode.HighSpeed;
 
             if (DrawOrigin)

OpenNest/Forms/MainForm.cs

@@ -71,6 +71,7 @@ namespace OpenNest.Forms
             NestEngineRegistry.LoadPlugins(enginesDir);
 
             OptionsForm.ApplyDisabledStrategies();
+            ColorSchemeRegistry.ApplyActiveFromSettings();
 
             foreach (var engine in NestEngineRegistry.AvailableEngines)
                 engineComboBox.Items.Add(engine.Name);

OpenNest/Forms/OptionsForm.Designer.cs

@@ -42,6 +42,8 @@
             this.bottomPanel1 = new OpenNest.Controls.BottomPanel();
             this.strategyGrid = new System.Windows.Forms.DataGridView();
             this.strategyGroupBox = new System.Windows.Forms.GroupBox();
+            this.colorSchemeLabel = new System.Windows.Forms.Label();
+            this.colorSchemeCombo = new System.Windows.Forms.ComboBox();
             ((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).BeginInit();
             this.tableLayoutPanel1.SuspendLayout();
             this.bottomPanel1.SuspendLayout();
@@ -95,15 +97,18 @@
             this.tableLayoutPanel1.Controls.Add(this.label1, 0, 1);
             this.tableLayoutPanel1.Controls.Add(this.textBox1, 1, 0);
             this.tableLayoutPanel1.Controls.Add(this.label3, 0, 0);
-            this.tableLayoutPanel1.Controls.Add(this.checkBox1, 0, 2);
+            this.tableLayoutPanel1.Controls.Add(this.colorSchemeLabel, 0, 2);
+            this.tableLayoutPanel1.Controls.Add(this.colorSchemeCombo, 1, 2);
+            this.tableLayoutPanel1.Controls.Add(this.checkBox1, 0, 3);
             this.tableLayoutPanel1.Controls.Add(this.numericUpDown1, 1, 1);
             this.tableLayoutPanel1.Controls.Add(this.button1, 3, 0);
             this.tableLayoutPanel1.Location = new System.Drawing.Point(12, 12);
             this.tableLayoutPanel1.Name = "tableLayoutPanel1";
-            this.tableLayoutPanel1.RowCount = 3;
+            this.tableLayoutPanel1.RowCount = 4;
-            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 33.33F));
+            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 25F));
-            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 33.33F));
+            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 25F));
-            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 33.34F));
+            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 25F));
+            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 25F));
             this.tableLayoutPanel1.Size = new System.Drawing.Size(684, 160);
             this.tableLayoutPanel1.TabIndex = 0;
             // 
@@ -198,6 +203,25 @@
             this.strategyGroupBox.TabStop = false;
             this.strategyGroupBox.Text = "Fill Strategies";
             //
+            // colorSchemeLabel
+            //
+            this.colorSchemeLabel.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right)));
+            this.colorSchemeLabel.AutoSize = true;
+            this.colorSchemeLabel.Location = new System.Drawing.Point(3, 92);
+            this.colorSchemeLabel.Name = "colorSchemeLabel";
+            this.colorSchemeLabel.Size = new System.Drawing.Size(145, 16);
+            this.colorSchemeLabel.TabIndex = 10;
+            this.colorSchemeLabel.Text = "Color scheme:";
+            //
+            // colorSchemeCombo
+            //
+            this.colorSchemeCombo.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right)));
+            this.colorSchemeCombo.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
+            this.colorSchemeCombo.Location = new System.Drawing.Point(154, 89);
+            this.colorSchemeCombo.Name = "colorSchemeCombo";
+            this.colorSchemeCombo.Size = new System.Drawing.Size(130, 24);
+            this.colorSchemeCombo.TabIndex = 11;
+            //
             // OptionsForm
             //
             this.AcceptButton = this.saveButton;
@@ -239,5 +263,7 @@
         private System.Windows.Forms.Button button1;
         private System.Windows.Forms.DataGridView strategyGrid;
         private System.Windows.Forms.GroupBox strategyGroupBox;
+        private System.Windows.Forms.Label colorSchemeLabel;
+        private System.Windows.Forms.ComboBox colorSchemeCombo;
     }
 }

OpenNest/Forms/OptionsForm.cs

@@ -68,6 +68,13 @@ namespace OpenNest.Forms
             checkBox1.Checked = Settings.Default.CreateNewNestOnOpen;
             numericUpDown1.Value = (decimal)Settings.Default.AutoSizePlateFactor;
 
+            colorSchemeCombo.Items.Clear();
+            foreach (var scheme in ColorSchemeRegistry.AllSchemes)
+                colorSchemeCombo.Items.Add(scheme.Name);
+            var active = Settings.Default.ActiveColorScheme;
+            var idx = colorSchemeCombo.Items.IndexOf(active);
+            colorSchemeCombo.SelectedIndex = idx >= 0 ? idx : 0;
+
             var disabledNames = ParseDisabledStrategies(Settings.Default.DisabledStrategies);
             foreach (DataGridViewRow row in strategyGrid.Rows)
                 row.Cells["Enabled"].Value = !disabledNames.Contains((string)row.Cells["Name"].Value);
@@ -78,6 +85,7 @@ namespace OpenNest.Forms
             Settings.Default.NestTemplatePath = textBox1.Text;
             Settings.Default.CreateNewNestOnOpen = checkBox1.Checked;
             Settings.Default.AutoSizePlateFactor = (double)numericUpDown1.Value;
+            Settings.Default.ActiveColorScheme = colorSchemeCombo.SelectedItem as string ?? "Classic";
 
             var disabledNames = new List<string>();
             foreach (DataGridViewRow row in strategyGrid.Rows)
@@ -89,6 +97,10 @@ namespace OpenNest.Forms
 
             Settings.Default.Save();
             ApplyDisabledStrategies();
+            ColorSchemeRegistry.ApplyActiveFromSettings();
+
+            foreach (Form f in Application.OpenForms)
+                f.Invalidate(invalidateChildren: true);
         }
 
         /// <summary>

OpenNest/OpenNest.csproj

@@ -15,6 +15,11 @@
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
   </ItemGroup>
+  <ItemGroup>
+    <None Update="Schemes\*.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\OpenNest.Api\OpenNest.Api.csproj" />
     <ProjectReference Include="..\OpenNest.Core\OpenNest.Core.csproj" />

OpenNest/Properties/Settings.Designer.cs

@@ -226,5 +226,17 @@ namespace OpenNest.Properties {
                 this["CuttingParametersJson"] = value;
             }
         }
+
+        [global::System.Configuration.UserScopedSettingAttribute()]
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+        [global::System.Configuration.DefaultSettingValueAttribute("Classic")]
+        public string ActiveColorScheme {
+            get {
+                return ((string)(this["ActiveColorScheme"]));
+            }
+            set {
+                this["ActiveColorScheme"] = value;
+            }
+        }
     }
 }

OpenNest/Properties/Settings.settings

@@ -53,5 +53,8 @@
     <Setting Name="CuttingParametersJson" Type="System.String" Scope="User">
       <Value Profile="(Default)" />
     </Setting>
+    <Setting Name="ActiveColorScheme" Type="System.String" Scope="User">
+      <Value Profile="(Default)">Classic</Value>
+    </Setting>
   </Settings>
 </SettingsFile>