Why is only half of my label displayed? [WPF]

Answer 1

Do a LayoutTransform instead of a RenderTransform.

In WPF, RenderTransforms are performed on controls after they have been laid out.

In your case, the Label is being cut short by the width of the column, first; then, the RenderTransform is applied (the rotate is the only one that does anything), resulting it the odd-looking Label.

A LayoutTransform is done before a control is laid out.

Like this:

<Grid ShowGridLines="True">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="146.334" />
        <ColumnDefinition Width="94.666" />
    </Grid.ColumnDefinitions>
    <Label 
        Name="label1" 
        Content="Prashant"
        Margin="0"  
        Width="Auto" 
        VerticalAlignment="Center"
        RenderTransformOrigin="0.5,0.5">
        <Label.LayoutTransform>
            <TransformGroup>
                <ScaleTransform ScaleX="1" ScaleY="1"/>
                <SkewTransform AngleX="0" AngleY="0"/>
                <RotateTransform Angle="-90"/>
                <TranslateTransform X="0" Y="0"/>
            </TransformGroup>
        </Label.LayoutTransform>
    </Label>
</Grid>