Add Background Brush to the control for more styling

#1898

Source/Engine/UI/GUI/Control.cs

@@ -81,6 +81,7 @@ namespace FlaxEngine.GUI
         // Style
 
         private Color _backgroundColor = Color.Transparent;
+        private IBrush _backgroundBrush = null;
 
         // Tooltip
 
@@ -174,6 +175,25 @@ namespace FlaxEngine.GUI
             set => _backgroundColor = value;
         }
 
+        /// <summary>
+        /// Gets or sets control background brush used to fill the contents. Uses Background Color property as tint color.
+        /// </summary>
+        [EditorDisplay("Background Style"), EditorOrder(2001)]
+        public IBrush BackgroundBrush
+        {
+            get => _backgroundBrush;
+            set
+            {
+                _backgroundBrush = value;
+
+#if FLAX_EDITOR
+                // Auto-reset background color so brush is visible as it uses it for tint
+                if (value != null && _backgroundColor == Color.Transparent && FlaxEditor.CustomEditors.CustomEditor.IsSettingValue)
+                    _backgroundColor = Color.White;
+#endif
+            }
+        }
+
         /// <summary>
         /// Gets or sets the anchor preset used by the control anchors (based on <see cref="AnchorMin"/> and <see cref="AnchorMax"/>).
         /// </summary>
@@ -416,9 +436,14 @@ namespace FlaxEngine.GUI
         public virtual void Draw()
         {
             // Paint Background
-            if (_backgroundColor.A > 0.0f)
+            var rect = new Rectangle(Float2.Zero, _bounds.Size);
+            if (BackgroundBrush != null)
             {
-                Render2D.FillRectangle(new Rectangle(Float2.Zero, Size), _backgroundColor);
+                BackgroundBrush.Draw(rect, _backgroundColor);
+            }
+            else if (_backgroundColor.A > 0.0f)
+            {
+                Render2D.FillRectangle(rect, _backgroundColor);
             }
         }