Implement xdg-desktop-portal accent-color spec (#12674)

* Use Tmds.DBus.SourceGenerator 0.0.11

* Use xdg-desktop-portal settings to retrieve accent color

---------

Co-authored-by: Jumar Macato <16554748+jmacato@users.noreply.github.com>

src/Avalonia.FreeDesktop/DBusPlatformSettings.cs

@@ -40,8 +40,15 @@ namespace Avalonia.FreeDesktop
         {
             try
             {
-                var value = await _settings!.ReadAsync("org.freedesktop.appearance", "color-scheme");
-                return ToColorScheme(((value.Value as DBusVariantItem)!.Value as DBusUInt32Item)!.Value);
+                var version = await _settings!.GetVersionPropertyAsync();
+                DBusVariantItem value;
+                if (version >= 2)
+                    value = await _settings!.ReadOneAsync("org.freedesktop.appearance", "color-scheme");
+                else
+                    value = (DBusVariantItem)(await _settings!.ReadAsync("org.freedesktop.appearance", "color-scheme")).Value;
+                if (value.Value is DBusUInt32Item dBusUInt32Item)
+                    return ToColorScheme(dBusUInt32Item.Value);
+                return null;
             }
             catch (DBusException)
             {
@@ -53,8 +60,15 @@ namespace Avalonia.FreeDesktop
         {
             try
             {
-                var value = await _settings!.ReadAsync("org.kde.kdeglobals.General", "AccentColor");
-                return ToAccentColor(((value.Value as DBusVariantItem)!.Value as DBusStringItem)!.Value);
+                var version = await _settings!.GetVersionPropertyAsync();
+                DBusVariantItem value;
+                if (version >= 2)
+                    value = await _settings!.ReadOneAsync("org.freedesktop.appearance", "accent-color");
+                else
+                    value = (DBusVariantItem)(await _settings!.ReadAsync("org.freedesktop.appearance", "accent-color")).Value;
+                if (value.Value is DBusStructItem dBusStructItem)
+                    return ToAccentColor(dBusStructItem);
+                return null;
             }
             catch (DBusException)
             {
@@ -62,7 +76,7 @@ namespace Avalonia.FreeDesktop
             }
         }
 
-        private async void SettingsChangedHandler(Exception? exception, (string @namespace, string key, DBusVariantItem value) valueTuple)
+        private void SettingsChangedHandler(Exception? exception, (string @namespace, string key, DBusVariantItem value) valueTuple)
         {
             if (exception is not null)
                 return;
@@ -71,7 +85,11 @@ namespace Avalonia.FreeDesktop
             {
                 case ("org.freedesktop.appearance", "color-scheme", { } colorScheme):
                     _themeVariant = ToColorScheme((colorScheme.Value as DBusUInt32Item)!.Value);
-                    _accentColor = await TryGetAccentColorAsync();
+                    _lastColorValues = BuildPlatformColorValues();
+                    OnColorValuesChanged(_lastColorValues!);
+                    break;
+                case ("org.freedesktop.appearance", "accent-color", { } accentColor):
+                    _accentColor = ToAccentColor((accentColor.Value as DBusStructItem)!);
                     _lastColorValues = BuildPlatformColorValues();
                     OnColorValuesChanged(_lastColorValues!);
                     break;
@@ -92,18 +110,27 @@ namespace Avalonia.FreeDesktop
         private static PlatformThemeVariant ToColorScheme(uint value)
         {
             /*
-            <member>0: No preference</member>
-            <member>1: Prefer dark appearance</member>
-            <member>2: Prefer light appearance</member>
+            0: No preference
+            1: Prefer dark appearance
+            2: Prefer light appearance
             */
             var isDark = value == 1;
             return isDark ? PlatformThemeVariant.Dark : PlatformThemeVariant.Light;
         }
 
-        private static Color ToAccentColor(string value)
+        private static Color? ToAccentColor(DBusStructItem value)
         {
-            var rgb = value.Split(',');
-            return new Color(255, byte.Parse(rgb[0]), byte.Parse(rgb[1]), byte.Parse(rgb[2]));
+            /*
+            Indicates the system's preferred accent color as a tuple of RGB values
+            in the sRGB color space, in the range [0,1].
+            Out-of-range RGB values should be treated as an unset accent color.
+             */
+            var r = (value[0] as DBusDoubleItem)!.Value;
+            var g = (value[1] as DBusDoubleItem)!.Value;
+            var b = (value[2] as DBusDoubleItem)!.Value;
+            if (r is < 0 or > 1 || g is < 0 or > 1 || b is < 0 or > 1)
+                return null;
+            return Color.FromRgb((byte)(r * 255), (byte)(g * 255), (byte)(b * 255));
         }
     }
 }

src/Avalonia.FreeDesktop/DBusXml/org.freedesktop.portal.Settings.xml

@@ -43,13 +43,21 @@
           Unknown values should be treated as 0 (no preference).
         </para></listitem>
       </varlistentry>
+      <varlistentry>
+        <term>org.freedesktop.appearance accent-color (ddd)</term>
+        <listitem><para>
+          Indicates the system's preferred accent color as a tuple of RGB values
+          in the sRGB color space, in the range [0,1].
+          Out-of-range RGB values should be treated as an unset accent color.
+        </para></listitem>
+      </varlistentry>
     </variablelist>
 
     Implementations can provide other keys; they are entirely
     implementation details that are undocumented. If you are a
     toolkit and want to use this please open an issue.
 
-    This documentation describes version 1 of this interface.
+    This documentation describes version 2 of this interface.
   -->
   <interface name="org.freedesktop.portal.Settings">
 
@@ -73,8 +81,31 @@
       @value: The value @key is set to.
 
       Reads a single value. Returns an error on any unknown namespace or key.
+
+      Deprecated, use ReadOne instead. The value argument was intended to have
+      the value inside one layer of variant as it is in ReadOne, for example
+      `&lt;string "hello"&gt;` in GVariant text notation; but it is actually
+      returned inside two layers of variant, for example
+      `&lt;&lt;string "hello"&gt;&gt;`.
     -->
     <method name='Read'>
+      <annotation name="org.freedesktop.DBus.Deprecated" value="true"/>
+      <arg name='namespace' type='s'/>
+      <arg name='key' type='s'/>
+      <arg name='value' direction='out' type='v'/>
+    </method>
+
+    <!--
+      ReadOne:
+      @namespace: Namespace to look up @key in.
+      @key: The key to get.
+      @value: The value @key is set to.
+
+      Reads a single value which may be any valid DBus type. Returns an error on any unknown namespace or key.
+
+      This method was added in version 2.
+    -->
+    <method name='ReadOne'>
       <arg name='namespace' type='s'/>
       <arg name='key' type='s'/>
       <arg name='value' direction='out' type='v'/>