How can limit the height of a grid row in wpf

Question

I'm developing an Outlook Add-in in WPF. Outlook Add-in is an UserControl. My simplified XAML code look's :

<UserControl>
        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition Height="150"/>
                <RowDefinition Height="*"/>
                <RowDefinition Height="20"/>
            </Grid.RowDefinitions>
            <TextBlock Grid.Row="0">Header</TextBlock>
            <ListBox Grid.Row="1"></ListBox>
            <Button Grid.Row="2"></Button>
        </Grid>
    </UserControl>

The list box items are loaded dynamically. With the help of this class that I founded here http://www.codeproject.com/KB/WPF/GridLengthAnimation.aspx the height of the 3rd row is set to 0.4* when the button is pressed.

The problem is that when I have more items in the list box the second row expands and the 3rd row disappears.The solution could be if I set the MaxHeight of the second row to 100% height-170, but I don't know the available height for the UserControl.

Any ideas?

Answer 1

Instead of specifying Height try specifying MinHeight for the 3rd row, that way it won't shrink beyond a certain size.

Answer 2

The problem was here ( on the library that I've used )

 public override object GetCurrentValue(object defaultOriginValue,
        object defaultDestinationValue, AnimationClock animationClock)
    {
        double fromVal = ((GridLength)GetValue(GridLengthAnimation.FromProperty)).Value;
        double toVal = ((GridLength)GetValue(GridLengthAnimation.ToProperty)).Value;

        if (fromVal > toVal)
        {
            return new GridLength((1 - animationClock.CurrentProgress.Value) * (fromVal - toVal) + toVal, GridUnitType.Pixel);
        }
        else
            return new GridLength(animationClock.CurrentProgress.Value * (toVal - fromVal) + fromVal, GridUnitType.Pixel);
    }

I've replaced GridUnitType.Star with GridUnitType.Pixel. And now it work's perfectly