Binding different properties to different sources - wpf

Question

I have a Window with a ListBox which has a DataTemplate, bound to an ObservableCollection of LogItems. The ItemsSource of the ListBox is set in code to the collection; the bindings on the TextBox and TextBlock which make up the DataTemplate are set in XAML. So far, so conventional. However, I need to set the font size/family for the TextBlock at runtime. Currently this information is held in a static cGlobals class. So I need to be able to bind the TextBlock.Text to the LogItems collection, but the TextBlock.FontSize property to the cGlobals.LogFontSize property. How can I do this, either via binding as sketched out in the XAML below, or in code?
<ListBox . . . . >
<ListBox.ItemTemplate>
<DataTemplate>
<Grid HorizontalAlignment="Stretch" . . . . >
<Grid.RowDefinitions>
<RowDefinition Height="20" />
<RowDefinition Height="*" MinHeight="40" />
</Grid.RowDefinitions>
<TextBox Grid.Row="0" Background="Honeydew" Text="{Binding Mode=OneWay, Path=Header, . . . . />
<TextBlock FontSize="{Binding ??????}" Grid.Row="1" Text="{Binding Path=BodyText}" />
</Grid>
</DataTemplate >
</ListBox.ItemTemplate >
</ListBox>

Answer 1

xaml
<Window x:Class="WpfApplication6.StaticBinding"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication6"
Title="StaticBinding" Height="300" Width="300">
<Grid>
<TextBlock FontSize="{Binding Source={x:Static local:Global.FontSize}}" Text="abc"/>
</Grid>
Global
public class Global
{
public static double FontSize
{
get { return 20.0; }
}
}

Answer 2

You will need to declare a public property of Type cGlobals but the class cannot be static because you will need to use it as a return type. It does not look like you are following the Model-View-ViewModel pattern, since you are assigning the ItemsSource in the code-behind instead of XAML, so you will need to declare the property in the code-behind. In your Code-Behind(your .xaml.cs file)
private CGlobals _cGlobals;
public CGlobals CGlobals{get{return _cGlobals;}}
public CodeBehindConstructor(){
_cGlobals = new CGlobal{FontSize = 12, FontFamily="Times New Roman"};
}
xaml:
<Window Name="TheWindow">
<TextBlock FontSize="{Binding CGlobals.FontSize, ElementName=TheWindow}" Grid.Row="1" Text="{Binding Path=BodyText}" />
</Window>