Blurry text in WPF even with ClearTypeHinting enabled?

Question

I have a grid with this template and styles in WPF/XAML:

<Setter Property="TextOptions.TextFormattingMode" Value="Display" />
<Setter Property="RenderOptions.ClearTypeHint" Value="Enabled" />
<Setter Property="Template">
    <Setter.Value>
        <ControlTemplate TargetType="{x:Type DataGridCell}">
            <Border Padding="{TemplateBinding Padding}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
                <ContentPresenter x:Name="CellContent" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" RenderOptions.ClearTypeHint="Enabled" />
            </Border>
            <ControlTemplate.Triggers>
                <Trigger Property="IsSelected" Value="True">
                    <Setter TargetName="CellContent" Property="TextOptions.TextFormattingMode" Value="Display" />
                    <Setter TargetName="CellContent" Property="RenderOptions.ClearTypeHint" Value="Enabled" />
                    <Setter TargetName="CellContent" Property="Effect">
                        <Setter.Value>
                            <DropShadowEffect ShadowDepth="2" BlurRadius="2" Color="Black" RenderingBias="Quality" />
                        </Setter.Value>
                    </Setter>
                </Trigger>
            </ControlTemplate.Triggers>
        </ControlTemplate>
    </Setter.Value>
</Setter>

The DropShadowEffect I have when you select a grid row, seems to make the text rendering blurry (gray anti-aliasing):

When I remove the drop shadow effect, it looks clear because it now uses ClearType and not gray sub-pixel anti-aliasing:

I have tried applying RenderOptions.ClearTypeHint="Enabled" to the ContentPresenter as seen above, but it does not help.

How do I force WPF to render the text that gets displayed with drop shadow effect to retain Cleartype anti-aliasing, instead of that ugly blurry gray sub-pixel anti-aliasing?

Some believe it's blurry because of the drop shadow -- this is not true. It's blurry only because ClearType is not used. This is how it looks like in Firefox when shadow AND ClearType:

ClearType enabled text is colorful -- but that blurry text is not, because it does not use ClearType -- it uses gray sub-pixel anti-aliasing and that's not how ClearType works: http://en.wikipedia.org/wiki/ClearType

The question is: how do I enable ClearType for this text?

Answer 1

How about setting TextOptions.TextFormattingMode to Display as well as RenderOptions.BitmapScalingMode to NearestNeighbor? The latter is new in WPF 3.5 SP1 and I normally use it to remove the blur. :)

<TextBlock Text="Hello world" TextOptions.TextFormattingMode="Display"
           RenderOptions.BitmapScalingMode="NearestNeighbor"
           HorizontalAlignment="Center" TextWrapping="Wrap"
           VerticalAlignment="Center" Foreground="White" FontFamily="Microsoft Sans Serif">
    <TextBlock.Effect>
        <DropShadowEffect ShadowDepth="2" BlurRadius="2" Color="Black"
                          RenderingBias="Quality"/>
    </TextBlock.Effect>
</TextBlock>

Below is how it looks like.

And this is how it looks like in FireFox.

Answer 2

The DropShadowEffect object cannot work with ClearType. This is stated on the MSDN page How to: Create Text with a Shadow:

These shadow effects do not go through the Windows Presentation Foundation (WPF) text rendering pipeline. As a result, ClearType is disabled when using these effects.

After all, DropShadowEffect is a bitmap effect, not a text effect.