Extend the GUIColorAttribute functionality

Editor.Extras/Drawers/GUIColorDrawer.cs

@@ -1,5 +1,6 @@
 using TriInspector;
 using TriInspector.Drawers;
+using TriInspector.Resolvers;
 using UnityEngine;
 
 [assembly: RegisterTriAttributeDrawer(typeof(GUIColorDrawer), TriDrawerOrder.Decorator)]
@@ -11,13 +12,24 @@ public class GUIColorDrawer : TriAttributeDrawer<GUIColorAttribute>
         public override void OnGUI(Rect position, TriProperty property, TriElement next)
         {
             var oldColor = GUI.color;
-            var newColor = new Color(Attribute.R, Attribute.G, Attribute.B, Attribute.A);
-
+            var newColor = Color.white;
+
+            if (string.IsNullOrEmpty(Attribute.GetColor))
+            {
+                newColor = Attribute.Color;
+            }
+            else
+            {
+                var colorResolver = ValueResolver.Resolve<Color>(property.Definition, Attribute.GetColor ?? "");
+
+                newColor = colorResolver.GetValue(property, Color.white);
+            }
+
             GUI.color = newColor;
             GUI.contentColor = newColor;
-
+            
             next.OnGUI(position);
-
+            
             GUI.color = oldColor;
             GUI.contentColor = oldColor;
         }

Editor.Samples/Styling/Styling_GUIColorSample.cs

@@ -6,15 +6,46 @@ public class Styling_GUIColorSample : ScriptableObject
     [GUIColor(0.8f, 1.0f, 0.6f)]
     public Vector3 vec;
 
-    [GUIColor(0.6f, 0.9f, 1.0f)]
+    [GUIColor("0000FF")]
     [Button]
     public void BlueButton()
     {
     }
 
-    [GUIColor(1.0f, 0.6f, 0.6f)]
+    [GUIColor("cyan")]
+    [Button]
+    public void CyanButton()
+    {
+    }
+
+    [GUIColor("$GetGreenColor")]
+    [Button]
+    public void GreenButton()
+    {
+    }
+
+    [GUIColor(255, 75, 75)]
     [Button]
     public void RedButton()
     {
     }
+
+    [GUIColor("$GetColor")]
+    [Button(ButtonSizes.Large)]
+    public void ColoredButton()
+    {
+    }
+
+    private Color GetGreenColor => Color.green;
+
+    private Color GetColor
+    {
+        get
+        {
+            var time = (float) UnityEditor.EditorApplication.timeSinceStartup;
+            var hue = time * 0.225f % 1f;
+            var color = Color.HSVToRGB(hue, 1f, 1f);
+            return color;
+        }
+    }
 }

Runtime/Attributes/GUIColorAttribute.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics;
+using UnityEngine;
 
 namespace TriInspector
 {
@@ -8,17 +9,40 @@ namespace TriInspector
     [Conditional("UNITY_EDITOR")]
     public class GUIColorAttribute : Attribute
     {
-        public float R { get; }
-        public float G { get; }
-        public float B { get; }
-        public float A { get; }
-
+        public Color Color { get; }
+        public string GetColor { get; }
+
         public GUIColorAttribute(float r, float g, float b, float a = 1f)
         {
-            R = r;
-            G = g;
-            B = b;
-            A = a;
+            Color = new Color(r, g, b, a);
+        }
+
+        public GUIColorAttribute(byte r, byte g, byte b, byte a = byte.MaxValue)
+        {
+            Color = new Color32(r, g, b, a);
+        }
+
+        public GUIColorAttribute(string value)
+        {
+            if (value.StartsWith("$"))
+            {
+                GetColor = value;
+
+                return;
+            }
+
+            if (ColorUtility.TryParseHtmlString(value, out var color))
+            {
+            }
+            else if (ColorUtility.TryParseHtmlString($"#{value}", out color))
+            {
+            }
+            else
+            {
+                color = Color.white;
+            }
+
+            Color = color;
         }
     }
 }