Fixed Font Scaling issue when FontSize is not set explicitly (#9719)

* Fixed Font Scaling issue for Fluent styles when Font Size is not explicity set

* Updated TextElement.FontSize metadata overrides to use ThemeMessageFontSize

* Added a condition that is used to calculate the default font size before ThemMode and Resources are synced for Application

* Fixed spelling

* Enable scaling in all the Fluent styles

* Made ThemeMessageFontSize scaling factor const

Author: dipeshmsft

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Controls/Control.cs

@@ -192,7 +192,7 @@ public FontFamily FontFamily
         public static readonly DependencyProperty FontSizeProperty =
                 TextElement.FontSizeProperty.AddOwner(
                         typeof(Control),
-                        new FrameworkPropertyMetadata(SystemFonts.MessageFontSize,
+                        new FrameworkPropertyMetadata(SystemFonts.ThemeMessageFontSize,
                             FrameworkPropertyMetadataOptions.Inherits));
 
         /// <summary>

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Controls/DataGridTextColumn.cs

@@ -320,7 +320,7 @@ public FontFamily FontFamily
         public static readonly DependencyProperty FontSizeProperty =
                 TextElement.FontSizeProperty.AddOwner(
                         typeof(DataGridTextColumn),
-                        new FrameworkPropertyMetadata(SystemFonts.MessageFontSize, FrameworkPropertyMetadataOptions.Inherits, DataGridColumn.NotifyPropertyChangeForRefreshContent));
+                        new FrameworkPropertyMetadata(SystemFonts.ThemeMessageFontSize, FrameworkPropertyMetadataOptions.Inherits, DataGridColumn.NotifyPropertyChangeForRefreshContent));
 
         /// <summary>
         ///     The size of the desired font.

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Controls/MenuItem.cs

@@ -174,7 +174,7 @@ static MenuItem()
 
             ForegroundProperty.OverrideMetadata(typeof(MenuItem), new FrameworkPropertyMetadata(SystemColors.MenuTextBrush));
             FontFamilyProperty.OverrideMetadata(typeof(MenuItem), new FrameworkPropertyMetadata(SystemFonts.MessageFontFamily));
-            FontSizeProperty.OverrideMetadata(typeof(MenuItem), new FrameworkPropertyMetadata(SystemFonts.MessageFontSize));
+            FontSizeProperty.OverrideMetadata(typeof(MenuItem), new FrameworkPropertyMetadata(SystemFonts.ThemeMessageFontSize));
             FontStyleProperty.OverrideMetadata(typeof(MenuItem), new FrameworkPropertyMetadata(SystemFonts.MessageFontStyle));
             FontWeightProperty.OverrideMetadata(typeof(MenuItem), new FrameworkPropertyMetadata(SystemFonts.MessageFontWeight));
 

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Documents/TextElement.cs

@@ -647,7 +647,7 @@ public static FontStretch GetFontStretch(DependencyObject element)
                         typeof(double),
                         typeof(TextElement),
                         new FrameworkPropertyMetadata(
-                                SystemFonts.MessageFontSize,
+                                SystemFonts.ThemeMessageFontSize,
                                 FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.Inherits),
                         new ValidateValueCallback(IsValidFontSize));
 

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/FrameworkElement.cs

@@ -2411,7 +2411,7 @@ static FrameworkElement()
 
             // Coerce Callback for font properties for responding to system themes
             TextElement.FontFamilyProperty.OverrideMetadata(_typeofThis, new FrameworkPropertyMetadata(SystemFonts.MessageFontFamily, FrameworkPropertyMetadataOptions.Inherits, null, new CoerceValueCallback(CoerceFontFamily)));
-            TextElement.FontSizeProperty.OverrideMetadata(_typeofThis, new FrameworkPropertyMetadata(SystemFonts.MessageFontSize, FrameworkPropertyMetadataOptions.Inherits, null, new CoerceValueCallback(CoerceFontSize)));
+            TextElement.FontSizeProperty.OverrideMetadata(_typeofThis, new FrameworkPropertyMetadata(SystemFonts.ThemeMessageFontSize, FrameworkPropertyMetadataOptions.Inherits, null, new CoerceValueCallback(CoerceFontSize)));
             TextElement.FontStyleProperty.OverrideMetadata(_typeofThis, new FrameworkPropertyMetadata(SystemFonts.MessageFontStyle, FrameworkPropertyMetadataOptions.Inherits, null, new CoerceValueCallback(CoerceFontStyle)));
             TextElement.FontWeightProperty.OverrideMetadata(_typeofThis, new FrameworkPropertyMetadata(SystemFonts.MessageFontWeight, FrameworkPropertyMetadataOptions.Inherits, null, new CoerceValueCallback(CoerceFontWeight)));
 
@@ -5564,7 +5564,7 @@ private static object CoerceFontSize(DependencyObject o, object value)
             // For root elements with default values, return current system metric if local value has not been set
             if (ShouldUseSystemFont((FrameworkElement)o, TextElement.FontSizeProperty))
             {
-                return SystemFonts.MessageFontSize;
+                return SystemFonts.ThemeMessageFontSize;
             }
 
             return value;

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/SystemFonts.cs

@@ -422,15 +422,25 @@ public static TextDecorationCollection StatusFontTextDecorations
         ///     Maps to SPI_NONCLIENTMETRICS
         /// </summary>
         public static double MessageFontSize
+        {
+            get
+            {
+                return ConvertFontHeight(SystemParameters.NonClientMetrics.lfMessageFont.lfHeight);
+            }
+        }
+
+        internal static double ThemeMessageFontSize
         {
             get
             {
                 // TODO : Find a better solution to this. Difference in default size of font in Fluent and other themes.
-                if(ThemeManager.IsFluentThemeEnabled)
+                if(ThemeManager.IsFluentThemeEnabled 
+                    || ThemeManager.IsFluentThemeDictionaryIncluded())
                 {
-                    return ThemeManager.DefaultFluentThemeFontSize;
+                    return MessageFontSize * ThemeManager.DefaultFluentFontSizeFactor ;
                 }
-                return ConvertFontHeight(SystemParameters.NonClientMetrics.lfMessageFont.lfHeight);
+
+                return MessageFontSize;
             }
         }
 

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/ThemeManager.cs

@@ -204,6 +204,11 @@ internal static ResourceDictionary GetThemeDictionary(ThemeMode themeMode)
         return rd;
     }
 
+    internal static bool IsFluentThemeDictionaryIncluded()
+    {
+        return Application.Current != null && LastIndexOfFluentThemeDictionary(Application.Current.Resources) != -1;
+    }
+
     #endregion
 
 
@@ -323,7 +328,7 @@ internal static bool IsFluentThemeEnabled
 
     internal static bool IgnoreWindowResourcesChange { get; set; } = false;
 
-    internal static double DefaultFluentThemeFontSize => 14;
+    internal const double DefaultFluentFontSizeFactor = 14.0 / 12.0 ;
 
     internal static WindowCollection FluentEnabledWindows { get; set; } = new WindowCollection();
 

src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/Button.xaml

@@ -26,7 +26,6 @@
         <Setter Property="VerticalAlignment" Value="Center" />
         <Setter Property="HorizontalContentAlignment" Value="Center" />
         <Setter Property="VerticalContentAlignment" Value="Center" />
-        <Setter Property="FontSize" Value="{DynamicResource ControlContentThemeFontSize}" />
         <Setter Property="FontWeight" Value="Normal" />
         <Setter Property="Border.CornerRadius" Value="{DynamicResource ControlCornerRadius}" />
         <Setter Property="SnapsToDevicePixels" Value="True" />
@@ -86,7 +85,6 @@
         <Setter Property="VerticalAlignment" Value="Center" />
         <Setter Property="HorizontalContentAlignment" Value="Center" />
         <Setter Property="VerticalContentAlignment" Value="Center" />
-        <Setter Property="FontSize" Value="{DynamicResource ControlContentThemeFontSize}" />
         <Setter Property="FontWeight" Value="Normal" />
         <Setter Property="Border.CornerRadius" Value="{DynamicResource ControlCornerRadius}" />
         <Setter Property="SnapsToDevicePixels" Value="True" />

src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/CheckBox.xaml

@@ -39,7 +39,6 @@
         <Setter Property="HorizontalContentAlignment" Value="Left" />
         <Setter Property="VerticalContentAlignment" Value="Top" />
         <Setter Property="Cursor" Value="Hand" />
-        <Setter Property="FontSize" Value="{DynamicResource ControlContentThemeFontSize}" />
         <Setter Property="FontWeight" Value="Normal" />
         <Setter Property="KeyboardNavigation.IsTabStop" Value="True" />
         <Setter Property="Focusable" Value="True" />

src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/ComboBox.xaml

@@ -152,7 +152,6 @@
         <Setter Property="Background" Value="{DynamicResource ComboBoxBackground}" />
         <Setter Property="BorderBrush" Value="{DynamicResource ControlElevationBorderBrush}" />
         <Setter Property="BorderThickness" Value="{StaticResource ComboBoxBorderThemeThickness}" />
-        <Setter Property="FontSize" Value="{DynamicResource ControlContentThemeFontSize}" />
         <Setter Property="ScrollViewer.CanContentScroll" Value="False" />
         <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Hidden" />
         <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Hidden" />