Stop TextBox in ScrollViewer from growing with content - wpf

Question

I have a ScrollViewer with HorizontalScrollBarVisibility set to "Auto" that contains a TextBox. The problem is that when a user enters text, the TextBox keeps growing in order to show the entire content. What do I need to change, so that the TextBox only grabs the available width (but is not smaller than a given minimal width)?
The horizontal scroll-bar should only appear if the available horizontal space is not sufficient for the given minimal width.
The TextBox should only grow if there is more horizontal space available.
<ScrollViewer HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="50"/>
<ColumnDefinition Width="*" MinWidth="50"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<TextBlock Grid.Column="0" Text="test:"/>
<TextBox Grid.Column="1"/>
</Grid>
</ScrollViewer>
The horizontal scrollbar appears even though the MinWidth constrain is fulfilled:

Answer 1

This seems to be a common problem but I haven't found a satisfying solution on the net.
Here is my solution:
<ScrollViewer HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="50"/>
<ColumnDefinition Width="*" MinWidth="100"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<TextBlock Grid.Column="0" Text="test:"/>
<local:TextBoxDecorator Grid.Column="1">
<TextBox Text="content content content content content content"/>
</local:TextBoxDecorator>
</Grid>
</ScrollViewer>
c#
public class TextBoxDecorator : Decorator {
// properties
public override UIElement Child {
get {
return base.Child;
}
set {
var oldValue = base.Child;
if (oldValue != null) {
var binding = BindingOperations.GetBinding(oldValue, FrameworkElement.WidthProperty);
if ((binding != null) && (binding.Source == this))
BindingOperations.ClearBinding(oldValue, FrameworkElement.WidthProperty);
}
base.Child = value;
if ((value != null) &&
BindingOperations.GetBinding(value, FrameworkElement.WidthProperty) == null)
BindingOperations.SetBinding(
value,
FrameworkElement.WidthProperty,
new Binding() {
Source = this,
Path = new PropertyPath(FrameworkElement.ActualWidthProperty),
Mode = BindingMode.OneWay
});
}
}
// methods
protected override Size MeasureOverride(Size constraint) {
Size result = base.MeasureOverride(constraint);
if (double.IsInfinity(constraint.Width))
result.Width = (Child as FrameworkElement)?.MinWidth ?? 0.0;
return result;
}
}
Let me know if this was helpful or if you have any feedback.