Added RatingBar.InvertDirection to support inverting "fill" direction (#3116)

Adds RatingBar.InvertDirection which is then used in all calculations regarding value, fractional value, preview offsets (X and Y), and rating bar button gradient.

Author: nicolaihenriksen

MainDemo.Wpf/RatingBar.xaml

@@ -197,6 +197,55 @@
                  VerticalAlignment="Top"
                  Text="{Binding ElementName=CustomRatingBarFractionalPreview, Path=Value, StringFormat=Rating: {0}}" />
     </StackPanel>
+
+    <TextBlock Style="{StaticResource MaterialDesignHeadline5TextBlock}" Text="Rating bar with preview, fractional values, and InvertDirection=true" />
+
+    <StackPanel Margin="0,16,0,0" Orientation="Horizontal">
+      <smtx:XamlDisplay Margin="5,0,0,5"
+                        VerticalContentAlignment="Top"
+                        UniqueKey="fractionalPreviewRatingBar_3">
+        <materialDesign:RatingBar x:Name="BasicRatingBarFractionalPreview2"
+                                  IsPreviewValueEnabled="True"
+                                  Max="5"
+                                  Min="0"
+                                  InvertDirection="True"
+                                  ValueIncrements="0.25"
+                                  Value="0" />
+      </smtx:XamlDisplay>
+
+      <TextBlock Margin="10,2,0,0"
+                 VerticalAlignment="Top"
+                 Text="{Binding ElementName=BasicRatingBarFractionalPreview2, Path=Value, StringFormat=Rating: {0}}" />
+
+      <smtx:XamlDisplay Margin="24,0,0,5" UniqueKey="fractionalPreviewRatingBar_4">
+        <materialDesign:RatingBar x:Name="CustomRatingBarFractionalPreview2"
+                                  IsPreviewValueEnabled="True"
+                                  Max="3"
+                                  Min="0"
+                                  Orientation="Vertical"
+                                  InvertDirection="True"
+                                  ValueIncrements="0.25"
+                                  Value="2">
+          <materialDesign:RatingBar.ValueItemTemplate>
+            <DataTemplate DataType="system:Int32">
+              <Grid>
+                <materialDesign:PackIcon Width="24"
+                                         Height="24"
+                                         Kind="Heart" />
+                <TextBlock HorizontalAlignment="Center"
+                           VerticalAlignment="Center"
+                           FontSize="8"
+                           Foreground="{DynamicResource PrimaryHueMidForegroundBrush}"
+                           Text="{Binding}" />
+              </Grid>
+            </DataTemplate>
+          </materialDesign:RatingBar.ValueItemTemplate>
+        </materialDesign:RatingBar>
+      </smtx:XamlDisplay>
+      <TextBlock Margin="10,2,0,0"
+                 VerticalAlignment="Top"
+                 Text="{Binding ElementName=CustomRatingBarFractionalPreview2, Path=Value, StringFormat=Rating: {0}}" />
+    </StackPanel>
   </StackPanel>
 </UserControl>
 

MaterialDesignThemes.Wpf.Tests/RatingBarTests.cs

@@ -231,6 +231,29 @@ public void TextBlockForegroundConverter_ShouldReturnFractionalGradientStops_Whe
         Assert.Equal(brush.Color.WithAlphaChannel(RatingBar.TextBlockForegroundConverter.SemiTransparent), stop2.Color);
     }
 
+    [Fact]
+    public void TextBlockForegroundConverter_ShouldReturnFractionalGradientStops_WhenValueCovers10PercentOfButtonValueAndDirectionIsInverted()
+    {
+        // Arrange
+        SolidColorBrush brush = Brushes.Red;
+        IMultiValueConverter converter = RatingBar.TextBlockForegroundConverter.Instance;
+        object[] values = Arrange_TextBlockForegroundConverterValues(brush, value: 1.1, buttonValue: 2, invertDirection: true);
+
+        // Act
+        var result = converter.Convert(values, typeof(Brush), null, CultureInfo.CurrentCulture) as Brush;
+
+        // Assert
+        Assert.IsAssignableFrom<LinearGradientBrush>(result);
+        LinearGradientBrush resultBrush = (LinearGradientBrush)result!;
+        Assert.Equal(2, resultBrush.GradientStops.Count);
+        GradientStop stop1 = resultBrush.GradientStops[0];
+        GradientStop stop2 = resultBrush.GradientStops[1];
+        Assert.Equal(0.9, stop1.Offset, 10);
+        Assert.Equal(brush.Color.WithAlphaChannel(RatingBar.TextBlockForegroundConverter.SemiTransparent), stop1.Color);
+        Assert.Equal(0.9, stop2.Offset, 10);
+        Assert.Equal(brush.Color, stop2.Color);
+    }
+
     [Fact]
     public void TextBlockForegroundConverter_ShouldReturnFractionalGradientStops_WhenValueCovers42PercentOfButtonValue()
     {
@@ -277,15 +300,15 @@ public void TextBlockForegroundConverter_ShouldReturnFractionalGradientStops_Whe
         Assert.Equal(brush.Color.WithAlphaChannel(RatingBar.TextBlockForegroundConverter.SemiTransparent), stop2.Color);
     }
 
-    private static object[] Arrange_TextBlockForegroundConverterValues(SolidColorBrush brush, double value, int buttonValue, Orientation orientation = Orientation.Horizontal) =>
-        new object[] { brush, orientation, value, buttonValue };
+    private static object[] Arrange_TextBlockForegroundConverterValues(SolidColorBrush brush, double value, int buttonValue, Orientation orientation = Orientation.Horizontal, bool invertDirection = false) =>
+        new object[] { brush, orientation, invertDirection, value, buttonValue };
 
     [Fact]
     public void PreviewIndicatorTransformXConverter_ShouldCenterPreviewIndicator_WhenFractionalValuesAreDisabledAndOrientationIsHorizontal()
     {
         // Arrange
         IMultiValueConverter converter = RatingBar.PreviewIndicatorTransformXConverter.Instance;
-        object[] values = Arrange_PreviewIndicatorTransformXConverterValues(100, 20, Orientation.Horizontal, false, 1, 1);
+        object[] values = Arrange_PreviewIndicatorTransformXConverterValues(100, 20, Orientation.Horizontal, false, false, 1, 1);
 
         // Act
         double? result = converter.Convert(values, typeof(double), null, CultureInfo.CurrentCulture) as double?;
@@ -295,27 +318,29 @@ public void PreviewIndicatorTransformXConverter_ShouldCenterPreviewIndicator_Whe
         Assert.Equal(40.0, result); // 50% of 100 minus 20/2
     }
 
-    [Fact]
-    public void PreviewIndicatorTransformXConverter_ShouldOffsetPreviewIndicatorByPercentage_WhenFractionalValuesAreEnabledAndOrientationIsHorizontal()
+    [Theory]
+    [InlineData(false, 15.0)] // 25% of 100 minus 20/2
+    [InlineData(true, 65.0)]  // 75% of 100 minus 20/2
+    public void PreviewIndicatorTransformXConverter_ShouldOffsetPreviewIndicatorByPercentage_WhenFractionalValuesAreEnabledAndOrientationIsHorizontal(bool invertDirection, double expectedValue)
     {
         // Arrange
         IMultiValueConverter converter = RatingBar.PreviewIndicatorTransformXConverter.Instance;
-        object[] values = Arrange_PreviewIndicatorTransformXConverterValues(100, 20, Orientation.Horizontal, true, 1.25, 1);
+        object[] values = Arrange_PreviewIndicatorTransformXConverterValues(100, 20, Orientation.Horizontal, invertDirection, true, 1.25, 1);
 
         // Act
         double? result = converter.Convert(values, typeof(double), null, CultureInfo.CurrentCulture) as double?;
 
         // Assert
         Assert.NotNull(result);
-        Assert.Equal(15.0, result); // 25% of 100 minus 20/2
+        Assert.Equal(expectedValue, result); 
     }
 
     [Fact]
     public void PreviewIndicatorTransformXConverter_ShouldPlacePreviewIndicatorWithSmallMargin_WhenFractionalValuesAreDisabledAndOrientationIsVertical()
     {
         // Arrange
         IMultiValueConverter converter = RatingBar.PreviewIndicatorTransformXConverter.Instance;
-        object[] values = Arrange_PreviewIndicatorTransformXConverterValues(100, 20, Orientation.Vertical, false, 1, 1);
+        object[] values = Arrange_PreviewIndicatorTransformXConverterValues(100, 20, Orientation.Vertical, false, false, 1, 1);
         double expectedValue = -20 - RatingBar.PreviewIndicatorTransformXConverter.Margin;
 
         // Act
@@ -331,7 +356,7 @@ public void PreviewIndicatorTransformXConverter_ShouldPlacePreviewIndicatorWithS
     {
         // Arrange
         IMultiValueConverter converter = RatingBar.PreviewIndicatorTransformXConverter.Instance;
-        object[] values = Arrange_PreviewIndicatorTransformXConverterValues(100, 20, Orientation.Vertical, true, 1.25, 1);
+        object[] values = Arrange_PreviewIndicatorTransformXConverterValues(100, 20, Orientation.Vertical, false, true, 1.25, 1);
         double expectedValue = -20 - RatingBar.PreviewIndicatorTransformXConverter.Margin;
 
         // Act
@@ -344,15 +369,15 @@ public void PreviewIndicatorTransformXConverter_ShouldPlacePreviewIndicatorWithS
 
 
 
-    private static object[] Arrange_PreviewIndicatorTransformXConverterValues(double ratingBarButtonActualWidth, double previewValueActualWidth, Orientation orientation, bool isFractionalValueEnabled, double previewValue, int buttonValue) =>
-        new object[] { ratingBarButtonActualWidth, previewValueActualWidth, orientation, isFractionalValueEnabled, previewValue, buttonValue };
+    private static object[] Arrange_PreviewIndicatorTransformXConverterValues(double ratingBarButtonActualWidth, double previewValueActualWidth, Orientation orientation, bool invertDirection, bool isFractionalValueEnabled, double previewValue, int buttonValue) =>
+        new object[] { ratingBarButtonActualWidth, previewValueActualWidth, orientation, invertDirection, isFractionalValueEnabled, previewValue, buttonValue };
 
     [Fact]
     public void PreviewIndicatorTransformYConverter_ShouldPlacePreviewIndicatorWithSmallMargin_WhenFractionalValuesAreDisabledAndOrientationIsHorizontal()
     {
         // Arrange
         IMultiValueConverter converter = RatingBar.PreviewIndicatorTransformYConverter.Instance;
-        object[] values = Arrange_PreviewIndicatorTransformYConverterValues(100, 20, Orientation.Horizontal, false, 1, 1);
+        object[] values = Arrange_PreviewIndicatorTransformYConverterValues(100, 20, Orientation.Horizontal, false, false, 1, 1);
         double expectedValue = -20 - RatingBar.PreviewIndicatorTransformYConverter.Margin;
 
         // Act
@@ -368,7 +393,7 @@ public void PreviewIndicatorTransformYConverter_ShouldPlacePreviewIndicatorWithS
     {
         // Arrange
         IMultiValueConverter converter = RatingBar.PreviewIndicatorTransformYConverter.Instance;
-        object[] values = Arrange_PreviewIndicatorTransformYConverterValues(100, 20, Orientation.Horizontal, true, 1.25, 1);
+        object[] values = Arrange_PreviewIndicatorTransformYConverterValues(100, 20, Orientation.Horizontal, false, true, 1.25, 1);
         double expectedValue = -20 - RatingBar.PreviewIndicatorTransformYConverter.Margin;
 
         // Act
@@ -384,7 +409,7 @@ public void PreviewIndicatorTransformYConverter_ShouldCenterPreviewIndicator_Whe
     {
         // Arrange
         IMultiValueConverter converter = RatingBar.PreviewIndicatorTransformYConverter.Instance;
-        object[] values = Arrange_PreviewIndicatorTransformYConverterValues(100, 20, Orientation.Vertical, false, 1, 1);
+        object[] values = Arrange_PreviewIndicatorTransformYConverterValues(100, 20, Orientation.Vertical, false, false, 1, 1);
 
         // Act
         double? result = converter.Convert(values, typeof(double), null, CultureInfo.CurrentCulture) as double?;
@@ -394,23 +419,25 @@ public void PreviewIndicatorTransformYConverter_ShouldCenterPreviewIndicator_Whe
         Assert.Equal(40.0, result); // 50% of 100 minus 20/2
     }
 
-    [Fact]
-    public void PreviewIndicatorTransformYConverter_ShouldPreviewIndicatorByPercentage_WhenFractionalValuesAreEnabledAndOrientationIsVertical()
+    [Theory]
+    [InlineData(false, 15.0)] // 25% of 100 minus 20/2
+    [InlineData(true, 65.0)]  // 75% of 100 minus 20/2
+    public void PreviewIndicatorTransformYConverter_ShouldPreviewIndicatorByPercentage_WhenFractionalValuesAreEnabledAndOrientationIsVertical(bool invertDirection, double expectedValue)
     {
         // Arrange
         IMultiValueConverter converter = RatingBar.PreviewIndicatorTransformYConverter.Instance;
-        object[] values = Arrange_PreviewIndicatorTransformYConverterValues(100, 20, Orientation.Vertical, true, 1.25, 1);
+        object[] values = Arrange_PreviewIndicatorTransformYConverterValues(100, 20, Orientation.Vertical, invertDirection, true, 1.25, 1);
 
         // Act
         double? result = converter.Convert(values, typeof(double), null, CultureInfo.CurrentCulture) as double?;
 
         // Assert
         Assert.NotNull(result);
-        Assert.Equal(15.0, result); // 25% of 100 minus 20/2
+        Assert.Equal(expectedValue, result);
     }
 
-    private static object[] Arrange_PreviewIndicatorTransformYConverterValues(double ratingBarButtonActualHeight, double previewValueActualHeight, Orientation orientation, bool isFractionalValueEnabled, double previewValue, int buttonValue) =>
-        new object[] { ratingBarButtonActualHeight, previewValueActualHeight, orientation, isFractionalValueEnabled, previewValue, buttonValue };
+    private static object[] Arrange_PreviewIndicatorTransformYConverterValues(double ratingBarButtonActualHeight, double previewValueActualHeight, Orientation orientation, bool invertDirection, bool isFractionalValueEnabled, double previewValue, int buttonValue) =>
+        new object[] { ratingBarButtonActualHeight, previewValueActualHeight, orientation, invertDirection, isFractionalValueEnabled, previewValue, buttonValue };
 }
 
 internal static class ColorExtensions