wpf - Progress bar with dynamic text & text color update

Question

I've a progressbar whose text changes dynamically. I want to update the appearance of it such that as soon as progress comes over text then text color should update. Something like this.

I need text color of text (black) appearing above blue background should automatically change to white. However text having white background should remain black.

Answer 1

Here is one way to do it using a modified version of the ProgressBars default Template. It contains two TextBlocks

• The first TextBlock is the black one
• The second TextBlock is the white one. This TextBlock has the Width of the full control and Clip set to the Width of the progress part

The text of the ProgressBar is binding to the Tag property. Usable like this.

<ProgressBar TextBlock.FontWeight="Bold"
             Tag="ProgressBar Text"
             Foreground="Blue"
             Style="{DynamicResource MyProgressBarStyle}"/>

MyProgressBarStyle

<LinearGradientBrush x:Key="ProgressBarBackground" EndPoint="1,0" StartPoint="0,0">
    <GradientStop Color="#BABABA" Offset="0"/>
    <GradientStop Color="#C7C7C7" Offset="0.5"/>
    <GradientStop Color="#BABABA" Offset="1"/>
</LinearGradientBrush>
<LinearGradientBrush x:Key="ProgressBarBorderBrush" EndPoint="0,1" StartPoint="0,0">
    <GradientStop Color="#B2B2B2" Offset="0"/>
    <GradientStop Color="#8C8C8C" Offset="1"/>
</LinearGradientBrush>
<LinearGradientBrush x:Key="ProgressBarGlassyHighlight" EndPoint="0,1" StartPoint="0,0">
    <GradientStop Color="#50FFFFFF" Offset="0.5385"/>
    <GradientStop Color="#00FFFFFF" Offset="0.5385"/>
</LinearGradientBrush>
<LinearGradientBrush x:Key="ProgressBarTopHighlight" EndPoint="0,1" StartPoint="0,0">
    <GradientStop Color="#80FFFFFF" Offset="0.05"/>
    <GradientStop Color="#00FFFFFF" Offset="0.25"/>
</LinearGradientBrush>
<LinearGradientBrush x:Key="ProgressBarIndicatorAnimatedFill" EndPoint="1,0" StartPoint="0,0">
    <GradientStop Color="#00FFFFFF" Offset="0"/>
    <GradientStop Color="#60FFFFFF" Offset="0.4"/>
    <GradientStop Color="#60FFFFFF" Offset="0.6"/>
    <GradientStop Color="#00FFFFFF" Offset="1"/>
</LinearGradientBrush>
<LinearGradientBrush x:Key="ProgressBarIndicatorDarkEdgeLeft" EndPoint="1,0" StartPoint="0,0">
    <GradientStop Color="#0C000000" Offset="0"/>
    <GradientStop Color="#20000000" Offset="0.3"/>
    <GradientStop Color="#00000000" Offset="1"/>
</LinearGradientBrush>
<LinearGradientBrush x:Key="ProgressBarIndicatorDarkEdgeRight" EndPoint="1,0" StartPoint="0,0">
    <GradientStop Color="#00000000" Offset="0"/>
    <GradientStop Color="#20000000" Offset="0.7"/>
    <GradientStop Color="#0C000000" Offset="1"/>
</LinearGradientBrush>
<RadialGradientBrush x:Key="ProgressBarIndicatorLightingEffectLeft" RadiusY="1" RadiusX="1" RelativeTransform="1,0,0,1,0.5,0.5">
    <GradientStop Color="#60FFFFC4" Offset="0"/>
    <GradientStop Color="#00FFFFC4" Offset="1"/>
</RadialGradientBrush>
<LinearGradientBrush x:Key="ProgressBarIndicatorLightingEffect" EndPoint="0,0" StartPoint="0,1">
    <GradientStop Color="#60FFFFC4" Offset="0"/>
    <GradientStop Color="#00FFFFC4" Offset="1"/>
</LinearGradientBrush>
<RadialGradientBrush x:Key="ProgressBarIndicatorLightingEffectRight" RadiusY="1" RadiusX="1" RelativeTransform="1,0,0,1,-0.5,0.5">
    <GradientStop Color="#60FFFFC4" Offset="0"/>
    <GradientStop Color="#00FFFFC4" Offset="1"/>
</RadialGradientBrush>
<LinearGradientBrush x:Key="ProgressBarIndicatorGlassyHighlight" EndPoint="0,1" StartPoint="0,0">
    <GradientStop Color="#90FFFFFF" Offset="0.5385"/>
    <GradientStop Color="#00FFFFFF" Offset="0.5385"/>
</LinearGradientBrush>
<Style x:Key="MyProgressBarStyle" TargetType="{x:Type ProgressBar}">
    <Setter Property="Foreground" Value="#01D328"/>
    <Setter Property="Background" Value="{StaticResource ProgressBarBackground}"/>
    <Setter Property="BorderBrush" Value="{StaticResource ProgressBarBorderBrush}"/>
    <Setter Property="BorderThickness" Value="1"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type ProgressBar}">
                <Grid x:Name="TemplateRoot" SnapsToDevicePixels="true">
                    <TextBlock Text="{TemplateBinding Tag}" Grid.ZIndex="2" Foreground="Black"
                                        HorizontalAlignment="Center"
                                        VerticalAlignment="Center"/>
                    <TextBlock Text="{TemplateBinding Tag}"
                                Grid.ZIndex="3" Foreground="White"
                                Width="{Binding ElementName=rectangle, Path=ActualWidth}"
                                TextAlignment="Center"
                                HorizontalAlignment="Stretch"
                                VerticalAlignment="Center">
                        <TextBlock.Clip>
                            <RectangleGeometry>
                                <RectangleGeometry.Rect>
                                    <MultiBinding Converter="{StaticResource RectConverter}">
                                        <Binding ElementName="Indicator" Path="ActualWidth"/>
                                        <Binding ElementName="Indicator" Path="ActualHeight"/>
                                    </MultiBinding>
                                </RectangleGeometry.Rect>
                            </RectangleGeometry>
                        </TextBlock.Clip>
                    </TextBlock>
                    <Rectangle x:Name="rectangle" Fill="{TemplateBinding Background}" RadiusY="2" RadiusX="2"/>
                    <Border Background="{StaticResource ProgressBarGlassyHighlight}" CornerRadius="2" Margin="1"/>
                    <Border BorderBrush="#80FFFFFF" BorderThickness="1,0,1,1" Background="{StaticResource ProgressBarTopHighlight}" Margin="1"/>
                    <Rectangle x:Name="PART_Track" Margin="1"/>
                    <Decorator x:Name="PART_Indicator" HorizontalAlignment="Left" Margin="1">
                        <Grid x:Name="Foreground">
                            <Rectangle x:Name="Indicator" Fill="{TemplateBinding Foreground}"/>
                            <Grid x:Name="Animation" ClipToBounds="true">
                                <Rectangle x:Name="PART_GlowRect" Fill="{StaticResource ProgressBarIndicatorAnimatedFill}" HorizontalAlignment="Left" Margin="-100,0,0,0" Width="100"/>
                            </Grid>
                            <Grid x:Name="Overlay">
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition MaxWidth="15"/>
                                    <ColumnDefinition Width="0.1*"/>
                                    <ColumnDefinition MaxWidth="15"/>
                                </Grid.ColumnDefinitions>
                                <Grid.RowDefinitions>
                                    <RowDefinition/>
                                    <RowDefinition/>
                                </Grid.RowDefinitions>
                                <Rectangle x:Name="LeftDark" Fill="{StaticResource ProgressBarIndicatorDarkEdgeLeft}" Margin="1,1,0,1" RadiusY="1" RadiusX="1" Grid.RowSpan="2"/>
                                <Rectangle x:Name="RightDark" Grid.Column="2" Fill="{StaticResource ProgressBarIndicatorDarkEdgeRight}" Margin="0,1,1,1" RadiusY="1" RadiusX="1" Grid.RowSpan="2"/>
                                <Rectangle x:Name="LeftLight" Grid.Column="0" Fill="{StaticResource ProgressBarIndicatorLightingEffectLeft}" Grid.Row="2"/>
                                <Rectangle x:Name="CenterLight" Grid.Column="1" Fill="{StaticResource ProgressBarIndicatorLightingEffect}" Grid.Row="2"/>
                                <Rectangle x:Name="RightLight" Grid.Column="2" Fill="{StaticResource ProgressBarIndicatorLightingEffectRight}" Grid.Row="2"/>
                                <Border x:Name="Highlight1" Background="{StaticResource ProgressBarIndicatorGlassyHighlight}" Grid.ColumnSpan="3" Grid.RowSpan="2"/>
                                <Border x:Name="Highlight2" Background="{StaticResource ProgressBarTopHighlight}" Grid.ColumnSpan="3" Grid.RowSpan="2"/>
                            </Grid>
                        </Grid>
                    </Decorator>
                    <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="2"/>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="Orientation" Value="Vertical">
                        <Setter Property="LayoutTransform" TargetName="TemplateRoot">
                            <Setter.Value>
                                <RotateTransform Angle="-90"/>
                            </Setter.Value>
                        </Setter>
                    </Trigger>
                    <Trigger Property="IsIndeterminate" Value="true">
                        <Setter Property="Visibility" TargetName="LeftDark" Value="Collapsed"/>
                        <Setter Property="Visibility" TargetName="RightDark" Value="Collapsed"/>
                        <Setter Property="Visibility" TargetName="LeftLight" Value="Collapsed"/>
                        <Setter Property="Visibility" TargetName="CenterLight" Value="Collapsed"/>
                        <Setter Property="Visibility" TargetName="RightLight" Value="Collapsed"/>
                        <Setter Property="Visibility" TargetName="Indicator" Value="Collapsed"/>
                    </Trigger>
                    <Trigger Property="IsIndeterminate" Value="false">
                        <Setter Property="Background" TargetName="Animation" Value="#80B5FFA9"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

RectConverter

public class RectConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        double width = (double)values[0];
        double height = (double)values[1];
        return new Rect(0, 0, width, height);
    }
    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}