Merge pull request #68 from AvaloniaUtils/reworkColorsPicking

Replace MultiDynamicResourceExtension with ResourceProvider for Background lookup

DialogHost.Avalonia/DialogHost.axaml

@@ -25,11 +25,8 @@
     <Setter Property="HorizontalAlignment" Value="Stretch" />
     <Setter Property="VerticalAlignment" Value="Stretch" />
     <Setter Property="DialogMargin" Value="8" />
-    <Setter Property="OverlayBackground"
-            Value="{utilities:MultiDynamicResource DefaultBrush=Black, ResourceKeys=SystemControlBackgroundBaseHighBrush}" />
-    <Setter Property="Background"
-            Value="{utilities:MultiDynamicResource DefaultBrush=Black, ResourceKeys=SystemControlBackgroundAltHighBrush;MaterialDesignPaper;MaterialPaperBrush}">
-    </Setter>
+    <Setter Property="OverlayBackground" Value="{DynamicResource DialogHostOverlayBackgroundMixinBrush}" />
+    <Setter Property="Background" Value="{DynamicResource DialogHostBackgroundMixinBrush}" />
     <Setter Property="dialogHostAvalonia:DialogHostStyle.ClipToBounds" Value="False" />
     <Setter Property="dialogHostAvalonia:DialogHostStyle.CornerRadius" Value="2" />
     <Setter Property="Template">

DialogHost.Avalonia/DialogHostStyles.axaml.cs

@@ -1,5 +1,8 @@
-using Avalonia.Controls;
+using System.Collections.Generic;
+using Avalonia;
+using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
+using Avalonia.Media;
 using Avalonia.Styling;
 
 namespace DialogHostAvalonia {
@@ -19,7 +22,7 @@ namespace DialogHostAvalonia {
     /// </Application>
     /// </code>
     /// </remarks>
-    public class DialogHostStyles : Styles {
+    public class DialogHostStyles : Styles, IResourceNode {
         /// <inheritdoc />
         public DialogHostStyles() {
             AvaloniaXamlLoader.Load(this);
@@ -29,5 +32,56 @@ public DialogHostStyles() {
         public DialogHostStyles(IResourceHost owner) : base(owner) {
             AvaloniaXamlLoader.Load(this);
         }
+
+        /// <summary>
+        /// Lists of resource keys which will be used as defaults for DialogHost.Background property
+        /// </summary>
+        public static IReadOnlyList<string> BackgroundColorKeys { get; } = ["SystemControlPageBackgroundChromeLowBrush"];
+
+        /// <summary>
+        /// Lists of resource keys which will be used as defaults for DialogHost.OverlayBackground property
+        /// </summary>
+        public static IReadOnlyList<string> OverlayBackgroundColorKeys { get; } =
+            ["SystemControlBackgroundAltHighBrush", "MaterialDesignPaper", "MaterialPaperBrush"];
+
+        bool IResourceNode.HasResources => true;
+
+        /// <summary>
+        /// Tries to find a resource within the object.
+        /// </summary>
+        /// <param name="key">The resource key.</param>
+        /// <param name="theme">Theme used to select theme dictionary.</param>
+        /// <param name="value">
+        /// When this method returns, contains the value associated with the specified key,
+        /// if the key is found; otherwise, null.
+        /// </param>
+        /// <returns>
+        /// True if the resource if found, otherwise false.
+        /// </returns>
+        bool IResourceNode.TryGetResource(object key, ThemeVariant? theme, out object? value) {
+            if (key is "DialogHostBackgroundMixinBrush") {
+                foreach (var colorKey in BackgroundColorKeys) {
+                    if (Application.Current!.TryGetResource(colorKey, theme, out value)) {
+                        return true;
+                    }
+                }
+
+                value = Brushes.Black;
+                return true;
+            }
+
+            if (key is "DialogHostOverlayBackgroundMixinBrush") {
+                foreach (var colorKey in OverlayBackgroundColorKeys) {
+                    if (Application.Current!.TryGetResource(colorKey, theme, out value)) {
+                        return true;
+                    }
+                }
+
+                value = Brushes.Black;
+                return true;
+            }
+
+            return base.TryGetResource(key, theme, out value);
+        }
     }
 }