WPF how to see last added text line in TexBox - wpf-controls

Question

I would like simmulate Console text output in my WPF app
but when I add new lines in TextBox I should use scroll bar to see last added text but I want to see last added text but for firsts lines use scroll bar
<TextBox TextWrapping="Wrap" AcceptsReturn="True" VerticalScrollBarVisibility="Auto"
Text="{Binding Path=Data, Mode=TwoWay}" />`

Answer 1

Use the ScrollToLine method of TextBox (and the LineCount property to know how many lines there are) after adding text in order to make sure that the just-added line is visible.

Answer 2

Please consider scrolling the textbox directly from code behind like this (e.g. when text changes):
private void SampleTextBox_TextChanged(object sender, TextChangedEventArgs e)
{
if (SampleTextBox.LineCount != -1)
{
SampleTextBox.ScrollToLine(SampleTextBox.LineCount - 1);
}
}
Please tell me if this helps.

Answer 3

thanks for answers: I expected to do it from XAML but as I undestood it's only possible from code behind
so here is my implimentation now with checkbox for stop ScrollToEnd function:
public partial class MainWindow : Window
{
private bool isScrollToEnd;
Timer timer;
public double WaitTime
{
get { return waitTime / 1000; }
set { waitTime = value * 1000; }
}
private double waitTime;
public MainWindow()
{
InitializeComponent();
isScrollToEnd = true;
waitTime = 5000;
tbWaitTime.DataContext = this;
timer = new Timer(waitTime);
timer.Elapsed += new ElapsedEventHandler(timer_Elapsed);
}
// событие изменения текста в контроле tbConsole
private void tbConsole_TextChanged(object sender, TextChangedEventArgs e)
{
if (tbConsole.LineCount != -1 && isScrollToEnd)
{
tbConsole.ScrollToLine(tbConsole.LineCount - 1);
cbIsScrolling.IsChecked = false;
}
}
private void cbIsScrolling_Click(object sender, RoutedEventArgs e)
{
if ((bool)cbIsScrolling.IsChecked)
{
isScrollToEnd = !(bool)cbIsScrolling.IsChecked;
isScrollToEnd = false;
timer.Interval = waitTime;
timer.Start();
return;
}
isScrollToEnd = true;
timer.Stop();
cbIsScrolling.IsChecked = false;
}
void timer_Elapsed(object sender, ElapsedEventArgs e)
{
timer.Stop();
isScrollToEnd = true;
}
}
and here is XAML code:
<StackPanel Grid.Column="1" Grid.Row="2" Grid.ColumnSpan="2" Grid.RowSpan="2">
<StackPanel Orientation="Horizontal" HorizontalAlignment="Right" Margin="0,3,10,2" VerticalAlignment="Top">
<Label Content="Stop autoscrolling for:" />
<TextBox Name="tbWaitTime" Text="{Binding Path=WaitTime}"
MinWidth="25" MaxWidth="50" Margin="5,0,0,0" />
<Label Content="sec."/>
<CheckBox Name="cbIsScrolling"
HorizontalAlignment="Right" VerticalAlignment="Center"
Click="cbIsScrolling_Click" />
</StackPanel>
<TextBox Name="tbConsole"
Background="LightGoldenrodYellow" Padding="5" Height="100"
VerticalScrollBarVisibility="Auto"
TextWrapping="Wrap"
AcceptsReturn="True"
Text="{Binding Path=Data, Mode=TwoWay}" TextChanged="tbConsole_TextChanged" />
</StackPanel>