多行文本框：在狀態欄中顯示當前行/字符索引

Question

我有一個多行文本框，用戶可以在其中編輯文本。 在狀態欄中，我想顯示當前行/字符索引。 我知道我可以得到CaretIndex，並使用GetLineIndexFromCharacterIndex來獲取行索引。

但是，我會如何將綁定到狀態欄？

Answer 1

RichTextBox rtb = new RichTextBox(); 
int offset = 0; 
rtb.CaretPosition.GetOffsetToPosition(rtb.Document.ContentStart); 
rtb.CaretPosition.GetPositionAtOffset(offset).GetCharacterRect(LogicalDirection.Forward); 

Answer 2

IMHO，最簡單的和可靠的方法是採樣兩者CarteIndex並使用DispatcherTimer的GetLineIndexFromCharacterIndex成員。然後在狀態欄綁定上暴露幾個DP的值。

Answer 3

我會使用附加的行爲。該行爲可以通過SelectionChanged偵聽更改，並相應地更新兩個附加屬性CaretIndex和LineIndex。

<TextBox Name="textBox" 
     AcceptsReturn="True" 
     local:CaretBehavior.ObserveCaret="True"/> 

<TextBlock Text="{Binding ElementName=textBox, 
          Path=(local:CaretBehavior.LineIndex)}"/> 
<TextBlock Text="{Binding ElementName=textBox, 
          Path=(local:CaretBehavior.CaretIndex)}"/> 

CaretBehavior

public static class CaretBehavior 
{ 
    public static readonly DependencyProperty ObserveCaretProperty = 
     DependencyProperty.RegisterAttached 
     (
      "ObserveCaret", 
      typeof(bool), 
      typeof(CaretBehavior), 
      new UIPropertyMetadata(false, OnObserveCaretPropertyChanged) 
     ); 
    public static bool GetObserveCaret(DependencyObject obj) 
    { 
     return (bool)obj.GetValue(ObserveCaretProperty); 
    } 
    public static void SetObserveCaret(DependencyObject obj, bool value) 
    { 
     obj.SetValue(ObserveCaretProperty, value); 
    } 
    private static void OnObserveCaretPropertyChanged(DependencyObject dpo, 
                DependencyPropertyChangedEventArgs e) 
    { 
     TextBox textBox = dpo as TextBox; 
     if (textBox != null) 
     { 
      if ((bool)e.NewValue == true) 
      { 
       textBox.SelectionChanged += textBox_SelectionChanged; 
      } 
      else 
      { 
       textBox.SelectionChanged -= textBox_SelectionChanged; 
      } 
     } 
    } 

    static void textBox_SelectionChanged(object sender, RoutedEventArgs e) 
    { 
     TextBox textBox = sender as TextBox; 
     int caretIndex = textBox.CaretIndex; 
     SetCaretIndex(textBox, caretIndex); 
     SetLineIndex(textBox, textBox.GetLineIndexFromCharacterIndex(caretIndex)); 
    } 

    private static readonly DependencyProperty CaretIndexProperty = 
     DependencyProperty.RegisterAttached("CaretIndex", typeof(int), typeof(CaretBehavior)); 
    public static void SetCaretIndex(DependencyObject element, int value) 
    { 
     element.SetValue(CaretIndexProperty, value); 
    } 
    public static int GetCaretIndex(DependencyObject element) 
    { 
     return (int)element.GetValue(CaretIndexProperty); 
    } 

    private static readonly DependencyProperty LineIndexProperty = 
     DependencyProperty.RegisterAttached("LineIndex", typeof(int), typeof(CaretBehavior)); 
    public static void SetLineIndex(DependencyObject element, int value) 
    { 
     element.SetValue(LineIndexProperty, value); 
    } 
    public static int GetLineIndex(DependencyObject element) 
    { 
     return (int)element.GetValue(LineIndexProperty); 
    } 
}