How to stretch a text field relative to data width in Jasper Reports

You can set HorizontalAlignment to Left, set your MaxWidth and then bind Width to the ActualWidth of the parent element:

<Page
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <StackPanel Name="Container">   
    <TextBox Background="Azure" 
    Width="{Binding ElementName=Container,Path=ActualWidth}"
    Text="Hello" HorizontalAlignment="Left" MaxWidth="200" />
  </StackPanel>
</Page>

I have found the answer. The key to the solution is grouping the elements inside a row together.

1. Remove all the static text labels. Use text fields instead, with the text in quotes. They can be grouped with other text fields and data fields.
2. Put all the data fields after the quoted text field in the same group as the quoted text field.
3. Now, do the same with all the rows that you want to display. Separate group for individual row.

Select all the elements in a group, or, all the elements in all the gorups and do this:

• Set "Position" to "Float"
• Set "Stretch Type" to "Relative to the tallest object"
• Check "Print when detail overflows" checkbox.
• Check the "Stretch with overflow" checkbox.

That's all we can do to make things "stretch" together.

Now, the band would have to stretch dynamically with these stretched details. Just go to the band properties, set Split type to "Default" and split allowed to true. This did the trick for me.