Add attached property to allow slider tool tip formatting

MaterialDesignThemes.Wpf.Tests/Converters/SliderToolTipConverterTests.cs

@@ -0,0 +1,37 @@
+using System.Globalization;
+using Xunit;
+
+namespace MaterialDesignThemes.Wpf.Tests.Converters
+{
+    public class SliderToolTipConverterTests
+    {
+        [Theory]
+        [InlineData(1.4)]
+        [InlineData(-47.4)]
+        [InlineData(128.678)]
+        [InlineData(42)]
+        public void SliderConverterTest(object value)
+        {
+            Wpf.Converters.SliderToolTipConverter converter = new Wpf.Converters.SliderToolTipConverter();
+
+            //test a valid case
+            var result = converter.Convert(new object[] { value, "Test String Format {0}" }, typeof(string), null, CultureInfo.CurrentCulture);
+            Assert.Equal($"Test String Format {value}", result);
+
+            //test too many placeholders in format string
+            result = converter.Convert(new object[] { value, "{0} {1}" }, typeof(string), null, CultureInfo.CurrentCulture);
+            Assert.Equal(value.ToString(), result);
+
+            result = converter.Convert(new object[] { value, "{0} {1} {2}" }, typeof(string), null, CultureInfo.CurrentCulture);
+            Assert.Equal(value.ToString(), result);
+
+            //test empty format string
+            result = converter.Convert(new object[] { value, "" }, typeof(string), null, CultureInfo.CurrentCulture);
+            Assert.Equal(value.ToString(), result);
+
+            //test null format string
+            result = converter.Convert(new object[] { value, null }, typeof(string), null, CultureInfo.CurrentCulture);
+            Assert.Equal(value.ToString(), result);
+        }
+    }
+}

MaterialDesignThemes.Wpf/Converters/SliderToolTipConverter.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Globalization;
+using System.Text.RegularExpressions;
+using System.Windows.Data;
+
+namespace MaterialDesignThemes.Wpf.Converters
+{
+    public class SliderToolTipConverter : IMultiValueConverter
+    {
+        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (values.Length >= 2 && values[1] is string format && !string.IsNullOrEmpty(format))
+                try
+                {
+                    return string.Format(culture, format, values[0]);
+                }
+                catch (FormatException) { }
+            return System.Convert.ChangeType(values[0], targetType, culture);
+        }
+
+        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
+            => throw new NotImplementedException();
+    }
+}

MaterialDesignThemes.Wpf/SliderAssist.cs

@@ -17,5 +17,18 @@ public static void SetOnlyShowFocusVisualWhileDragging(RangeBase element, bool v
 
         public static bool GetOnlyShowFocusVisualWhileDragging(RangeBase element)
             => (bool)element.GetValue(OnlyShowFocusVisualWhileDraggingProperty);
+
+        public static readonly DependencyProperty ToolTipFormatProperty
+            = DependencyProperty.RegisterAttached(
+                "ToolTipFormat",
+                typeof(string),
+                typeof(SliderAssist),
+                new PropertyMetadata(null));
+
+        public static void SetToolTipFormat(RangeBase element, string value)
+            => element.SetValue(ToolTipFormatProperty, value);
+
+        public static string GetToolTipFormat(RangeBase element)
+            => (string)element.GetValue(ToolTipFormatProperty);
     }
 }

MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.Slider.xaml

@@ -10,6 +10,7 @@
     <converters:SliderValueLabelPositionConverter x:Key="SliderValueLabelPositionConverter" />
     <converters:BooleanAllConverter x:Key="BooleanAllConverter" />
     <converters:InvertBooleanConverter x:Key="InvertBooleanConverter" />
+    <converters:SliderToolTipConverter x:Key="SliderToolTipConverter" />
 
     <Style x:Key="MaterialDesignRepeatButton" TargetType="{x:Type RepeatButton}">
         <Setter Property="OverridesDefaultStyle" Value="True"/>
@@ -267,9 +268,15 @@
                     <TextBlock
                         Foreground="{DynamicResource MaterialDesignPaper}"
                         Margin="12,0,12,5"
-                        Text="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=RangeBase}, Path=Value}"
                         TextAlignment="Center"
-                        VerticalAlignment="Center" />
+                        VerticalAlignment="Center">
+                        <TextBlock.Text >
+                            <MultiBinding Converter="{StaticResource SliderToolTipConverter}" ValidatesOnDataErrors="True" NotifyOnValidationError="True" TargetNullValue="">
+                                <Binding RelativeSource="{RelativeSource FindAncestor, AncestorType=RangeBase}" Path="Value" TargetNullValue="" />
+                                <Binding Path="(wpf:SliderAssist.ToolTipFormat)" RelativeSource="{RelativeSource FindAncestor, AncestorType=RangeBase}" />
+                            </MultiBinding>
+                        </TextBlock.Text>
+                    </TextBlock>
                 </Grid>
             </Canvas>
             <AdornerDecorator>
@@ -451,9 +458,15 @@
                     <TextBlock
                         Foreground="{DynamicResource MaterialDesignPaper}"
                         Margin="12,0,17,0"
-                        Text="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=RangeBase}, Path=Value}"
                         TextAlignment="Center"
-                        VerticalAlignment="Center" />
+                        VerticalAlignment="Center">
+                        <TextBlock.Text >
+                            <MultiBinding Converter="{StaticResource SliderToolTipConverter}" ValidatesOnDataErrors="True" NotifyOnValidationError="True" TargetNullValue="">
+                                <Binding RelativeSource="{RelativeSource FindAncestor, AncestorType=RangeBase}" Path="Value" TargetNullValue="" />
+                                <Binding Path="(wpf:SliderAssist.ToolTipFormat)" RelativeSource="{RelativeSource FindAncestor, AncestorType=RangeBase}" />
+                            </MultiBinding>
+                        </TextBlock.Text>
+                    </TextBlock>
                 </Grid>
             </Canvas>
             <AdornerDecorator>