Specifying RowDefinition.Height in code

Question

When you're creating a Grid in xaml you can define the RowDefinitions as such

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="*"/>
        <RowDefinition Height="Auto"/>
    </Grid.RowDefinitions>
</Grid>

I have a need to do the same thing in code. I know I can write

RowDefinition row = new RowDefinition();
row.Height = new GridLength(1.0, GridUnitType.Star);

but that doesn't help me much since I've got a string coming in. I could probably create my own "string to GridLength" converter but this doesn't feel right since it works ever so smooth from xaml. Of course, I've tried the following but it doesn't work

row.Height = new GridLength("*");

What am I missing here?

Answer 1

The GridLength struct has a TypeConverter defined which is being used when instantiated from Xaml. You can use it in code as well. It's called GridLengthConverter

If you look at GridLength.cs with Reflector it looks like this. Notice the TypeConverter

[StructLayout(LayoutKind.Sequential), TypeConverter(typeof(GridLengthConverter))]
public struct GridLength : IEquatable<GridLength>
{
    //...
}

You can use it like

GridLengthConverter gridLengthConverter = new GridLengthConverter();
row.Height = (GridLength)gridLengthConverter.ConvertFrom("*");

Answer 2

you are missing to include your RowDefinition to RowDefinitions

RowDefinition row = new RowDefinition();
row.Height = new GridLength(1.0, GridUnitType.Star);
YourGrid.RowDefinitions.Add(row);

See you! Rutx

Answer 3

No need to create a converter, there already is one, which is being used by the XAML-parser as well:

var converter = new GridLengthConverter();
row.Height = (GridLength)converter.ConvertFromString("*");

On a sidenote, you will find converters like this for a lot of types, as many get parsed from strings in XAML, e.g. BrushConverter & ImageSourceConverter