Force my grid to scale with 4:3 resolution - wpf

Question

I designed my page to be 4:3 scalable and I'd like to have my grid to scale to 4:3 on any screen.
For example, on a 1900x1200, my grid will scale to 1600x1200 and we'll have 150px on each side of my grid. How can i manage to have this behavior ?
I've started with the following lines :
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="1024*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="768*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid Grid.Row="1" Grid.Column="1" Name="my_grid" />
</Grid>
But I don't see how to manage the 4:3 thing. I'd like to force my grid to stretch until it has the highest 4:3 resolution possible and then let the free space on the sides.
Do you think I can manage to do this only in WPF ?
Thanks

Answer 1

You could use the ViewBox control. Design your XAML as you have done and place it inside it. The ViewBox will scale to fit the content to the available size. It will not resize the content so everything (ratios, width, etc.) will be left intact.
See http://msdn.microsoft.com/en-us/library/system.windows.controls.viewbox.aspx

Answer 2

Thanks to Sascha i did :
<Viewbox Name="grid_jeu" Stretch="Uniform" HorizontalAlignment="Center" VerticalAlignment="Center" Grid.Column="1" Grid.Row="1" >
<MyControl Name="my_grid" />
</Viewbox>
My Control is designed this way :
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="32" MaxHeight="32"/>
<RowDefinition Height="72" MaxHeight="72"/>
<RowDefinition Height="10" MaxHeight="10"/>
<RowDefinition Height="*"/>
<RowDefinition Height="20" MaxHeight="20"/>
<RowDefinition Height="90" MaxHeight="90"/>
<RowDefinition Height="32" MaxHeight="32"/>
</Grid.RowDefinitions>
</Grid>
I'd like to have only one row and one column which scale. As you can see I tried to put "MaxHeight" and "MaxWidth" to avoid my rows to scale but it doesn't work. When I launch my application I have my 309px column which scales to 420.