XAML WP8 and making a 'TextBlock' scroll down

Question

Alright, so I have a XAML page with a TextBlock in a Windows Phone 8 application. My dilemma is this:

I pragmatically add more content (formatted lines with Inlines.Add(new Run...) to the TextBlock. The text block is currently filled from bottom to up because of the ScrollViewer in the sense that a line appears in the bottom after another. I would also be fine with them starting to appear from the top as long as the TextBlock would continue to scroll down (actually this might look better) once it is full. My TextBlock is inside a ScrollViewer as below:

    <Popup x:Name="send_message_xaml" Grid.Row="1" VerticalOffset="0" Width="750" Height="auto">
        <StackPanel Orientation="Vertical" Margin="0,0" Width="auto" Height="auto">
            <ScrollViewer Height="345" HorizontalAlignment="Left" Margin="0,0,0,0" Name="scrollViewer1" VerticalAlignment="Bottom" Width="420" VerticalScrollBarVisibility="Auto">
                <TextBlock x:Name="message_log"  Margin="40,50,0,0" TextWrapping="Wrap" Width="420" VerticalAlignment="Top" FontSize="22"/>
            </ScrollViewer>
            <TextBox x:Name="message_to_send" InputScope="Chat" Width="480" KeyDown="message_to_send_KeyDown" Margin="15,0"/>
        </StackPanel>
    </Popup>

How can I get the textblock to scroll so that the newest appended message is always at the bottom? I found a bunch of these threads but none seem to solve my problem so far. Do I need to add some code somewhere with the appending?

Answer 1

You need to update the VerticalOffset based on the ScrollableHeight. When you add new inlines to the TextBlock, its height is going to change and that will notify the parent ScrollViewer. So, after you add new items to the inlines, run the Measure method and update the VerticalOffset.

Here is an example.