如何在不修改以前的文本的情况下更改WPF RichTextBox中的FontFamily

Question

当您使用RichTextBox的FontFamily属性时，它将更改FlowDocument中整个内容的FontFamily。 同样的方法，你可以执行一个像EditingCommands.ToggleBold这样的命令，它只改变插入符号下的单词或者只是写入新的文本，应该有一种方法可以对FontsFamilies和Color做同样的事情。

Answer 1

也许不是最巧妙的解决方案，但你可以从RichTextBox的继承并添加一些行为

声明自己的字体属性，因此您可以用字体

的列表

public class CustomControl1 : RichTextBox 
    { 

public static readonly DependencyProperty CurrentFontFamilyProperty = 
       DependencyProperty.Register("CurrentFontFamily", typeof(FontFamily), typeof (CustomControl1), new FrameworkPropertyMetadata(new FontFamily("Tahoma"), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,new PropertyChangedCallback(OnCurrentFontChanged))); 
    } 

覆盖后来将它们绑定OnTextInput。如果您CurrentFontProperty改变获得插入符的位置，你可以不同意在RichTextBox中还内置了用于处理KeyDown和KEYUP鼓泡和它们之间的的TextInput此事件产生

protected override void OnTextInput(TextCompositionEventArgs e) 
{ 
     if (fontchanged) 
     { 
      TextPointer tp = this.CaretPosition.GetInsertionPosition(LogicalDirection.Forward); 
      Run r = new Run(e.Text, tp); 
      r.FontFamily = CurrentFontFamily; 
      r.Foreground = CurrentForeground; 
      this.CaretPosition = r.ElementEnd; 
      fontchanged = false; 
     } 
     else 
      base.OnTextInput(e); 
    } 

，并创建一个新的运行新的文本输入并设置FontFamily = CurrentFontFamily。你也可以改变整个单词，如果卡尔特是一个字，这篇文章可能会发现有趣的单词Navigate Words in RichTextBox。

Answer 2

你会使用一个RUN RichTextBox的，像内：

<RichTextBox> 
    <Run FontFamily="Arial">My Arial Content</Run> 
    <Run FontFamily="Times" FontWeight="Bold">My bolded Times content</Run> 
    <Run>My Content that inherits Font From the RTB</Run> 
</RichTextBox> 

好吧，这得到了一些低级别的斗hickies玩。但是，我们去：

首先，将一些ToggleButtons和一个RichTextBox添加到XAML表单。在富文本框中，您会给它一些命令绑定，以便让系统知道一切正常。

这里的XAML：

<RichTextBox Height="119" Name="RichTextBox1" Width="254" > 
     <RichTextBox.CommandBindings> 
      <CommandBinding Command="EditingCommands.ToggleBold" CanExecute="CommandBinding_CanExecute" ></CommandBinding> 
      <CommandBinding Command="EditingCommands.ToggleItalic" CanExecute="CommandBinding_CanExecute" ></CommandBinding> 
     </RichTextBox.CommandBindings> 
</RichTextBox> 
<ToggleButton MinWidth="40" Command="EditingCommands.ToggleBold" Height="23" HorizontalAlignment="Left" Name="Button1" VerticalAlignment="Top" Width="75" CommandTarget="{Binding ElementName=RichTextBox1}" >Bold</ToggleButton> 
<ToggleButton MinWidth="40" Command="EditingCommands.ToggleBold" Height="23" HorizontalAlignment="Left" Name="Button2" VerticalAlignment="Top" Width="75" CommandTarget="{Binding ElementName=RichTextBox1}" >Italics</ToggleButton> 

现在，那里的东西是一个RichTextBox和两个切换按钮，和的ToggleButtons都跟化CommandBindings到ToggleBold/ToggleItalics独立。

在代码方面，我有两种方法：

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)  
End Sub 

Private Sub CommandBinding_CanExecute(ByVal sender As System.Object, ByVal e As System.Windows.Input.CanExecuteRoutedEventArgs) 
    e.CanExecute = True 
End Sub 

按钮单击事件处理程序是因为有一个按钮，需要事件处理程序可以使用。

CanExecute告诉按钮该值是否可用于加粗（例如，您可以检查长度，如果RTB为空时不尝试加粗）。

现在，对于真正低层次的事物控制，您将不得不在RichTextFormat中进行操作。按照此link了解更多。

Answer 3

这是我用来避免覆盖richtextbox。这允许您改变选择的样式（如果有），或者在插入符号后更改“要添加”文本的样式。希望能帮助到你。

public static void SetFontSize(RichTextBox target, double value) 
    { 
     // Make sure we have a richtextbox. 
     if (target == null) 
      return; 

     // Make sure we have a selection. Should have one even if there is no text selected. 
     if (target.Selection != null) 
     { 
      // Check whether there is text selected or just sitting at cursor 
      if (target.Selection.IsEmpty) 
      { 
       // Check to see if we are at the start of the textbox and nothing has been added yet 
       if (target.Selection.Start.Paragraph == null) 
       { 
        // Add a new paragraph object to the richtextbox with the fontsize 
        Paragraph p = new Paragraph(); 
        p.FontSize = value; 
        target.Document.Blocks.Add(p); 
       } 
       else 
       { 
        // Get current position of cursor 
        TextPointer curCaret = target.CaretPosition; 
        // Get the current block object that the cursor is in 
        Block curBlock = target.Document.Blocks.Where 
         (x => x.ContentStart.CompareTo(curCaret) == -1 && x.ContentEnd.CompareTo(curCaret) == 1).FirstOrDefault(); 
        if (curBlock != null) 
        { 
         Paragraph curParagraph = curBlock as Paragraph; 
         // Create a new run object with the fontsize, and add it to the current block 
         Run newRun = new Run(); 
         newRun.FontSize = value; 
         curParagraph.Inlines.Add(newRun); 
         // Reset the cursor into the new block. 
         // If we don't do this, the font size will default again when you start typing. 
         target.CaretPosition = newRun.ElementStart; 
        } 
       } 
      } 
      else // There is selected text, so change the fontsize of the selection 
      { 
       TextRange selectionTextRange = new TextRange(target.Selection.Start, target.Selection.End); 
       selectionTextRange.ApplyPropertyValue(TextElement.FontSizeProperty, value); 
      } 
     } 
     // Reset the focus onto the richtextbox after selecting the font in a toolbar etc 
     target.Focus(); 
    }