Added GradientColorBlockWidget

OpenRA.Game/Graphics/RgbaColorRenderer.cs

@@ -238,6 +238,29 @@ namespace OpenRA.Graphics
 			parent.DrawRGBAVertices(vertices);
 		}
 
+		public void FillRect(float3 a, float3 b, float3 c, float3 d, Color topLeftColor, Color topRightColor, Color bottomRightColor, Color bottomLeftColor)
+		{
+			vertices[0] = VertexWithColor(a + Offset, topLeftColor);
+			vertices[1] = VertexWithColor(b + Offset, topRightColor);
+			vertices[2] = VertexWithColor(c + Offset, bottomRightColor);
+			vertices[3] = VertexWithColor(c + Offset, bottomRightColor);
+			vertices[4] = VertexWithColor(d + Offset, bottomLeftColor);
+			vertices[5] = VertexWithColor(a + Offset, topLeftColor);
+
+			parent.DrawRGBAVertices(vertices);
+		}
+
+		static Vertex VertexWithColor(float3 xyz, Color color)
+		{
+			color = Util.PremultiplyAlpha(color);
+			var cr = color.R / 255.0f;
+			var cg = color.G / 255.0f;
+			var cb = color.B / 255.0f;
+			var ca = color.A / 255.0f;
+
+			return new Vertex(xyz, cr, cg, cb, ca, 0, 0);
+		}
+
 		public void FillEllipse(float3 tl, float3 br, Color color, int vertices = 32)
 		{
 			// TODO: Create an ellipse polygon instead

OpenRA.Game/Widgets/WidgetUtils.cs

@@ -71,6 +71,17 @@ namespace OpenRA.Widgets
 			Game.Renderer.RgbaColorRenderer.FillRect(tl, br, c);
 		}
 
+		public static void FillRectWithColor(Rectangle r, Color topLeftColor, Color topRightColor, Color bottomRightColor, Color bottomLeftColor)
+		{
+			var tl = new float2(r.Left - 0.5f, r.Top - 0.5f);
+			var br = new float2(r.Right - 0.5f, r.Bottom - 0.5f);
+
+			var tr = new float3(br.X, tl.Y, 0);
+			var bl = new float3(tl.X, br.Y, 0);
+
+			Game.Renderer.RgbaColorRenderer.FillRect(tl, tr, br, bl, topLeftColor, topRightColor, bottomRightColor, bottomLeftColor);
+		}
+
 		public static void FillEllipseWithColor(Rectangle r, Color c)
 		{
 			var tl = new float2(r.Left, r.Top);

OpenRA.Mods.Common/Widgets/GradientColorBlockWidget.cs

@@ -0,0 +1,57 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2019 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 OpenRA.Primitives;
+using OpenRA.Widgets;
+
+namespace OpenRA.Mods.Common.Widgets
+{
+	public class GradientColorBlockWidget : Widget
+	{
+		public Color TopLeftColor { get; set; }
+		public Color TopRightColor { get; set; }
+		public Color BottomRightColor { get; set; }
+		public Color BottomLeftColor { get; set; }
+
+		public Func<Color> GetTopLeftColor;
+		public Func<Color> GetTopRightColor;
+		public Func<Color> GetBottomRightColor;
+		public Func<Color> GetBottomLeftColor;
+
+		public GradientColorBlockWidget()
+		{
+			GetTopLeftColor = () => TopLeftColor;
+			GetTopRightColor = () => TopRightColor;
+			GetBottomRightColor = () => BottomRightColor;
+			GetBottomLeftColor = () => BottomLeftColor;
+		}
+
+		protected GradientColorBlockWidget(GradientColorBlockWidget widget)
+			: base(widget)
+		{
+			GetTopLeftColor = widget.GetTopLeftColor;
+			GetTopRightColor = widget.GetTopRightColor;
+			GetBottomRightColor = widget.GetBottomRightColor;
+			GetBottomLeftColor = widget.GetBottomLeftColor;
+		}
+
+		public override Widget Clone()
+		{
+			return new GradientColorBlockWidget(this);
+		}
+
+		public override void Draw()
+		{
+			WidgetUtils.FillRectWithColor(RenderBounds, GetTopLeftColor(), GetTopRightColor(), GetBottomRightColor(), GetBottomLeftColor());
+		}
+	}
+}