Automatic vertical scroll bar in WPF TextBlock

Question

I have a TextBlock in WPF  I write many lines to it  far exceeding its vertical height  I expected a vertical scroll bar to appear automatically when that happens  but it didn t  I tried to look for a scroll bar property in the Properties pane  but could not find one   How can I make vertical scroll bar created automatically for my TextBlock once its contents exceed its height   Clarification  I would rather do it from the designer and not by directly writing to the XAML

User · Answer

lt ScrollViewer MaxHeight  50                  Width  Auto                 HorizontalScrollBarVisibility  Disabled                VerticalScrollBarVisibility  Auto  gt        lt TextBlock Text   Binding Path                     Style   StaticResource TextStyle Data                    TextWrapping  Wrap    gt   lt  ScrollViewer gt    I am doing this in another way by putting MaxHeight in ScrollViewer   Just Adjust the MaxHeight to show more or fewer lines of text  Easy

User · Answer

This answer describes a solution using MVVM   This solution is great if you want to add a logging box to a window  that automatically scrolls to the bottom each time a new logging message is added   Once these attached properties are added  they can be reused anywhere  so it makes for very modular and reusable software   Add this XAML    lt TextBox IsReadOnly  True              Foreground  Gainsboro                                      FontSize  13            ScrollViewer HorizontalScrollBarVisibility  Auto           ScrollViewer VerticalScrollBarVisibility  Auto           ScrollViewer CanContentScroll  True           attachedBehaviors TextBoxApppendBehaviors AppendText   Binding LogBoxViewModel AttachedPropertyAppend                                                   attachedBehaviors TextBoxClearBehavior TextBoxClear   Binding LogBoxViewModel AttachedPropertyClear                                                TextWrapping  Wrap  gt    Add this attached property   public static class TextBoxApppendBehaviors        region AppendText Attached Property     public static readonly DependencyProperty AppendTextProperty           DependencyProperty RegisterAttached               AppendText               typeof  string               typeof  TextBoxApppendBehaviors               new UIPropertyMetadata null  OnAppendTextChanged         public static string GetAppendText TextBox textBox                return  string textBox GetValue AppendTextProperty              public static void SetAppendText          TextBox textBox          string value                textBox SetValue AppendTextProperty  value              private static void OnAppendTextChanged          DependencyObject d          DependencyPropertyChangedEventArgs args                if  args NewValue    null                        return                     string toAppend   args NewValue ToString             if  toAppend                              return                     TextBox textBox   d as TextBox          textBox  AppendText toAppend           textBox  ScrollToEnd               endregion     And this attached property  to clear the box    public static class TextBoxClearBehavior       public static readonly DependencyProperty TextBoxClearProperty           DependencyProperty RegisterAttached               TextBoxClear               typeof bool               typeof TextBoxClearBehavior               new UIPropertyMetadata false  OnTextBoxClearPropertyChanged         public static bool GetTextBoxClear DependencyObject obj                return  bool obj GetValue TextBoxClearProperty              public static void SetTextBoxClear DependencyObject obj  bool value                obj SetValue TextBoxClearProperty  value              private static void OnTextBoxClearPropertyChanged          DependencyObject d          DependencyPropertyChangedEventArgs args                if   bool args NewValue    false                        return                     var textBox    TextBox d          textBox  Clear                 Then  if you re using a dependency injection framework such as MEF  you can place all of the logging-specific code into it s own ViewModel   public interface ILogBoxViewModel       void CmdAppend string toAppend       void CmdClear         bool AttachedPropertyClear   get  set         string AttachedPropertyAppend   get  set        Export typeof ILogBoxViewModel    public class LogBoxViewModel   ILogBoxViewModel  INotifyPropertyChanged       private readonly ILog  log   LogManager GetLogger lt LogBoxViewModel gt          private bool  attachedPropertyClear      private string  attachedPropertyAppend       public void CmdAppend string toAppend                string toLog      DateTime Now HH mm ss  -  toAppend  n               Attached properties only fire on a change  This means it will still work if we publish the same message twice          AttachedPropertyAppend               AttachedPropertyAppend   toLog            log Info   Appended to log box   toAppend                 public void CmdClear                 AttachedPropertyClear   false          AttachedPropertyClear   true            log Info   Cleared the GUI log box                public bool AttachedPropertyClear               get   return  attachedPropertyClear            set    attachedPropertyClear   value  OnPropertyChanged                 public string AttachedPropertyAppend               get   return  attachedPropertyAppend            set    attachedPropertyAppend   value  OnPropertyChanged                  region INotifyPropertyChanged     public event PropertyChangedEventHandler PropertyChanged        NotifyPropertyChangedInvocator      protected virtual void OnPropertyChanged  CallerMemberName  string propertyName   null                PropertyChanged  Invoke this  new PropertyChangedEventArgs propertyName               endregion     Here s how it works    The ViewModel toggles the Attached Properties to control the TextBox  As it s using  Append   it s lightning fast  Any other ViewModel can generate logging messages by calling methods on the logging ViewModel  As we use the ScrollViewer built into the TextBox  we can make it automatically scroll to the bottom of the textbox each time a new message is added

User · Answer

I tried to to get these suggestions to work for a textblock  but couldn t get it to work  I even tried to get it to work from the designer   Look in Layout and expand the list by clicking the down-arrow  V  at the bottom  I tried setting the scrollviewer to Visible and then Auto  but it still wouldn t work    I eventually gave up and changed the TextBlock to a TextBox with the Readonly attribute set  and it worked like a charm

User · Answer

This is a simple solution to that question  The vertical scroll will be activated only when the text overflows    lt TextBox  Text  Try typing some text here   ScrollViewer VerticalScrollBarVisibility  Auto  TextWrapping  WrapWithOverflow    gt

User · Answer

Dont know if someone else has this problem but wrapping my TextBlock into a ScrollViewer somewhow messed up my UI - as a simple workaround I figured out that replacing the TextBlock by a TextBox like this one   lt TextBox  Name  textBlock  SelectionBrush  Transparent  Cursor  Arrow  IsReadOnly  True  Text  My Text  VerticalScrollBarVisibility  Auto  gt    creates a TextBox that looks and behaves like a TextBlock with a scrollbar  and you can do it all in the designer

User · Answer

can use the following now    lt TextBox Name  myTextBox            ScrollViewer HorizontalScrollBarVisibility  Auto           ScrollViewer VerticalScrollBarVisibility  Auto           ScrollViewer CanContentScroll  True  gt SOME TEXT  lt  TextBox gt

User · Answer

Wrap it in a scroll viewer    lt ScrollViewer gt       lt TextBlock   gt   lt  ScrollViewer gt    NOTE this answer applies to a TextBlock  a read-only text element  as asked for in the original question   If you want to show scroll bars in a TextBox  an editable text element  then use the ScrollViewer attached properties    lt TextBox ScrollViewer HorizontalScrollBarVisibility  Disabled           ScrollViewer VerticalScrollBarVisibility  Auto    gt    Valid values for these two properties are Disabled  Auto  Hidden and Visible

User · Answer

You can use  ScrollViewer HorizontalScrollBarVisibility  Visible  ScrollViewer VerticalScrollBarVisibility  Visible    These are attached property of wpf  For more information  http   wpfbugs blogspot in 2014 02 wpf-layout-controls-scrollviewer html

User · Answer

lt ScrollViewer Height  239  VerticalScrollBarVisibility  Auto  gt       lt TextBox AcceptsReturn  True  TextWrapping  Wrap  LineHeight  10    gt   lt  ScrollViewer gt    This is way to use the scrolling TextBox in XAML and use it as a text area

User · Answer

Something better would be    lt Grid Width  Your-specified-value   gt       lt ScrollViewer gt            lt TextBlock Width  Auto  TextWrapping  Wrap    gt       lt  ScrollViewer gt   lt  Grid gt    This makes sure that the text in your textblock does not overflow and overlap the elements below the textblock as may be the case if you do not use the grid  That happened to me when I tried other solutions even though the textblock was already in a grid with other elements  Keep in mind that the width of the textblock should be Auto and you should specify the desired with in the Grid element  I did this in my code and it works beautifully   HTH

[c#] Automatic vertical scroll bar in WPF TextBlock?

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