Add support for GIMP and JASC palettes (with per-color alpha)

OpenRA.Mods.Common/OpenRA.Mods.Common.csproj

@@ -530,6 +530,7 @@
     <Compile Include="Traits\World\MPStartUnits.cs" />
     <Compile Include="Traits\World\PaletteFromCurrentTileset.cs" />
     <Compile Include="Traits\World\PaletteFromFile.cs" />
+    <Compile Include="Traits\World\PaletteFromGimpOrJascFile.cs" />
     <Compile Include="Traits\World\PaletteFromRGBA.cs" />
     <Compile Include="Traits\World\ValidateOrder.cs" />
     <Compile Include="Pathfinder\CellInfoLayerPool.cs" />

OpenRA.Mods.Common/Traits/World/PaletteFromFile.cs

@@ -15,6 +15,7 @@
 
 namespace OpenRA.Mods.Common.Traits
 {
+	[Desc("Load VGA palette (.pal) registers.")]
 	class PaletteFromFileInfo : ITraitInfo
 	{
 		[FieldLoader.Require, PaletteDefinition]

OpenRA.Mods.Common/Traits/World/PaletteFromGimpOrJascFile.cs

@@ -0,0 +1,127 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2018 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.IO;
+using OpenRA.Graphics;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[Desc("Load a GIMP .gpl or JASC .pal palette file. Supports per-color alpha. Index 0 is hardcoded to be fully transparent/invisible.")]
+	class PaletteFromGimpOrJascFileInfo : ITraitInfo
+	{
+		[FieldLoader.Require, PaletteDefinition]
+		[Desc("Palette name used internally.")]
+		public readonly string Name = null;
+
+		[Desc("Defines for which tileset IDs this palette should be loaded.",
+			"If none specified, it applies to all tileset IDs not explicitly excluded.")]
+		public readonly HashSet<string> Tilesets = new HashSet<string>();
+
+		[Desc("Don't load palette for these tileset IDs.")]
+		public readonly HashSet<string> ExcludeTilesets = new HashSet<string>();
+
+		[FieldLoader.Require]
+		[Desc("Name of the file to load.")]
+		public readonly string Filename = null;
+
+		[Desc("Premultiply colors with their alpha values.")]
+		public readonly bool Premultiply = true;
+
+		public readonly bool AllowModifiers = true;
+
+		public object Create(ActorInitializer init) { return new PaletteFromGimpOrJascFile(init.World, this); }
+	}
+
+	class PaletteFromGimpOrJascFile : ILoadsPalettes, IProvidesAssetBrowserPalettes
+	{
+		readonly World world;
+		readonly PaletteFromGimpOrJascFileInfo info;
+
+		public PaletteFromGimpOrJascFile(World world, PaletteFromGimpOrJascFileInfo info)
+		{
+			this.world = world;
+			this.info = info;
+		}
+
+		public void LoadPalettes(WorldRenderer wr)
+		{
+			var colors = new uint[Palette.Size];
+			using (var s = world.Map.Open(info.Filename))
+			{
+				using (var lines = s.ReadAllLines().GetEnumerator())
+				{
+					if (lines == null)
+						return;
+
+					if (!lines.MoveNext() || (lines.Current != "GIMP Palette" && lines.Current != "JASC-PAL"))
+						throw new InvalidDataException("File `{0}` is not a valid GIMP or JASC palette.".F(info.Filename));
+
+					byte r, g, b, a;
+					a = 255;
+					var i = 0;
+
+					while (lines.MoveNext() && i < Palette.Size)
+					{
+						// Skip until first color. Ignore # comments, Name/Columns and blank lines as well as JASC header values.
+						if (string.IsNullOrEmpty(lines.Current) || !char.IsDigit(lines.Current.Trim()[0]) || lines.Current == "0100" || lines.Current == "256")
+							continue;
+
+						var rgba = lines.Current.Split((char[])null, StringSplitOptions.RemoveEmptyEntries);
+						if (rgba.Length < 3)
+							throw new InvalidDataException("Invalid RGB(A) triplet/quartet: ({0})".F(string.Join(" ", rgba)));
+
+						if (!byte.TryParse(rgba[0], out r))
+							throw new InvalidDataException("Invalid R value: {0}".F(rgba[0]));
+
+						if (!byte.TryParse(rgba[1], out g))
+							throw new InvalidDataException("Invalid G value: {0}".F(rgba[1]));
+
+						if (!byte.TryParse(rgba[2], out b))
+							throw new InvalidDataException("Invalid B value: {0}".F(rgba[2]));
+
+						// Check if color has a (valid) alpha value.
+						// Note: We can't throw on "rgba.Length > 3 but parse failed", because in GIMP palettes the 'invalid' value is probably a color name string.
+						var noAlpha = rgba.Length > 3 ? !byte.TryParse(rgba[3], out a) : true;
+
+						// Index 0 should always be completely transparent/background color
+						if (i == 0)
+							colors[i] = 0;
+						else if (noAlpha)
+							colors[i] = (uint)Color.FromArgb(r, g, b).ToArgb();
+						else if (info.Premultiply)
+							colors[i] = (uint)Color.FromArgb(a, r * a / 255, g * a / 255, b * a / 255).ToArgb();
+						else
+							colors[i] = (uint)Color.FromArgb(a, r, g, b).ToArgb();
+
+						i++;
+					}
+				}
+			}
+
+			wr.AddPalette(info.Name, new ImmutablePalette(colors), info.AllowModifiers);
+		}
+
+		public IEnumerable<string> PaletteNames
+		{
+			get
+			{
+				// Only expose the palette if it is available for the shellmap's tileset (which is a requirement for its use).
+				if ((info.Tilesets.Count == 0 || info.Tilesets.Contains(world.Map.Rules.TileSet.Id))
+					&& !info.ExcludeTilesets.Contains(world.Map.Rules.TileSet.Id))
+					yield return info.Name;
+			}
+		}
+	}
+}