如何为下一个要写入的文本设置RichTextBox字体？

Question

我需要为要在RichTextBox中编写的下一个文本设置字体系列.我尝试用...设置

<RichTextBox x:Name="RichTextEditor" MaxWidth="1000" SpellCheck.IsEnabled="True"
             FontFamily="{Binding ElementName=TextFontComboBox, Path=SelectedItem}"
             FontSize="{Binding ElementName=TextSizeComboBox, Path=SelectedValue}"
             Width="Auto" Height="Auto" HorizontalScrollBarVisibility="Auto" 
VerticalScrollBarVisibility="Auto" />

......但它改变了整个文本.我想,使用Selection属性,我可以将更改限制为仅应用于所选区域.但是如何为下一个尚未输入的文本？

Answer 1

为了根据光标位置设置FontFamily,您需要定义具有依赖项属性的自定义控件,该属性有助于通过覆盖OnTextInput方法来插入新的"运行"部分.

我包含了大部分代码,您需要修改名称空间以适应您的开发环境.

代码使用ViewModel来管理可用字体并管理字体是否更改.此代码只是一个原型,不处理两个控件之间的聚焦问题.

要使用此代码:
1-在RichTectBox中键入一些文本.
2-更改ComboBox中的字体.
3-选项卡返回RichTextBox.
4-输入更多文字.

这是自定义的RichTextBox控件:

using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;

namespace RichTextboxFont.Views
{
  public class RichTextBoxCustom : RichTextBox
  {
    public static readonly DependencyProperty CurrentFontFamilyProperty =
            DependencyProperty.Register("CurrentFontFamily", 
            typeof(FontFamily), typeof  
            (RichTextBoxCustom), 
            new FrameworkPropertyMetadata(new FontFamily("Tahoma"), 
            FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
            new PropertyChangedCallback(OnCurrentFontChanged)));

    public FontFamily CurrentFontFamily
    {
       get
       {
         return (FontFamily)GetValue(CurrentFontFamilyProperty);
       }
       set
       {
         SetValue(CurrentFontFamilyProperty, value);
       }
    }

    private static void OnCurrentFontChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
    {}

    protected override void OnTextInput(TextCompositionEventArgs e)
    {
      ViewModels.MainViewModel mwvm = this.DataContext as ViewModels.MainViewModel;
      if ((mwvm != null) && (mwvm.FontChanged))
      {
        TextPointer textPointer = this.CaretPosition.GetInsertionPosition(LogicalDirection.Forward);
        Run run = new Run(e.Text, textPointer);
        run.FontFamily = this.CurrentFontFamily;
        this.CaretPosition = run.ElementEnd;
        mwvm.FontChanged = false;
      }
      else
      {
         base.OnTextInput(e);
      }
    }
  } 
}

这是XAML:

<Window x:Class="RichTextboxFont.Views.MainView"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:local="clr-namespace:RichTextboxFont.Views" 
  xmlns:ViewModels="clr-namespace:RichTextboxFont.ViewModels" 
  Title="Main Window" 
  Height="400" Width="800">
  <DockPanel>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition/>
        </Grid.RowDefinitions>

        <ComboBox ItemsSource="{Binding Path=Fonts}" 
                  SelectedItem="{Binding Path=SelectedFont, Mode=TwoWay}"/>
        <local:RichTextBoxCustom Grid.Row="1" 
                                 CurrentFontFamily="{Binding Path=SelectedFont, Mode=TwoWay}" 
                                 FontSize="30"/>
    </Grid>
  </DockPanel>
</Window>

这是ViewModel:如果你不使用视图模型,请告诉我,我也会添加基类代码; 否则,google/stackoverflow也可以帮到你.

using System.Collections.ObjectModel;
using System.Windows.Media;

namespace RichTextboxFont.ViewModels
{
  public class MainViewModel : ViewModelBase
  {
    #region Constructor

    public MainViewModel()
    {
       FontFamily f1 = new FontFamily("Georgia");
       _fonts.Add(f1);
       FontFamily f2 = new FontFamily("Tahoma");
       _fonts.Add(f2);
    }

    private ObservableCollection<FontFamily> _fonts = new ObservableCollection<FontFamily>();
    public ObservableCollection<FontFamily> Fonts
    {
      get
      {
         return _fonts;
      }
      set
      {
        _fonts = value;
        OnPropertyChanged("Fonts");
      }
    }

    private FontFamily _selectedFont = new FontFamily("Tahoma");
    public FontFamily SelectedFont
    {
      get
      {
        return _selectedFont;
      }
      set
      {
        _selectedFont = value;
        FontChanged = true;
        OnPropertyChanged("SelectedFont");
      }
    }

    private bool _fontChanged = false;
    public bool FontChanged
    {
      get
      {
         return _fontChanged;
      }
      set
      {
        _fontChanged = value;
        OnPropertyChanged("FontChanged");
      }
    }

  #endregion
  }
}

这是我初始化ViewModel的Window代码隐藏:

using System.Windows;

namespace RichTextboxFont.Views
{
  public partial class MainView : Window
  {
    public MainView()
    {
      InitializeComponent();
      this.DataContext = new ViewModels.MainViewModel();
    }
  }
}