Richtextbox wpf 绑定 - 开卷题库

小开

Create a UserControl which has a RichTextBox named RTB. Now add the following dependency property:

    public FlowDocument Document
{
get { return (FlowDocument)GetValue(DocumentProperty); }
set { SetValue(DocumentProperty, value); }
}


public static readonly DependencyProperty DocumentProperty =
DependencyProperty.Register("Document", typeof(FlowDocument), typeof(RichTextBoxControl), new PropertyMetadata(OnDocumentChanged));


private static void OnDocumentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
RichTextBoxControl control = (RichTextBoxControl) d;
FlowDocument document = e.NewValue as FlowDocument;
if (document  == null)
{
control.RTB.Document = new FlowDocument(); //Document is not amused by null :)
}
else
{
control.RTB.Document = document;
}
}

This solution is probably that "proxy" solution you saw somewhere.. However.. RichTextBox simply does not have Document as DependencyProperty... So you have to do this in another way...

HTH

小开

I can give you an ok solution and you can go with it, but before I do I'm going to try to explain why Document is not a DependencyProperty to begin with.

During the lifetime of a RichTextBox control, the Document property generally doesn't change. The RichTextBox is initialized with a FlowDocument. That document is displayed, can be edited and mangled in many ways, but the underlying value of the Document property remains that one instance of the FlowDocument. Therefore, there is really no reason it should be a DependencyProperty, ie, Bindable. If you have multiple locations that reference this FlowDocument, you only need the reference once. Since it is the same instance everywhere, the changes will be accessible to everyone.

I don't think FlowDocument supports document change notifications, though I am not sure.

That being said, here's a solution. Before you start, since RichTextBox doesn't implement INotifyPropertyChanged and Document is not a DependencyProperty, we have no notifications when the RichTextBox's Document property changes, so the binding can only be OneWay.

Create a class that will provide the FlowDocument. Binding requires the existence of a DependencyProperty, so this class inherits from DependencyObject.

class HasDocument : DependencyObject
{
public static readonly DependencyProperty DocumentProperty =
DependencyProperty.Register("Document",
typeof(FlowDocument),
typeof(HasDocument),
new PropertyMetadata(new PropertyChangedCallback(DocumentChanged)));


private static void DocumentChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
Debug.WriteLine("Document has changed");
}


public FlowDocument Document
{
get { return GetValue(DocumentProperty) as FlowDocument; }
set { SetValue(DocumentProperty, value); }
}
}

Create a Window with a rich text box in XAML.

<Window x:Class="samples.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Flow Document Binding" Height="300" Width="300"
>
<Grid>
<RichTextBox Name="richTextBox" />
</Grid>
</Window>

Give the Window a field of type HasDocument.

HasDocument hasDocument;

Window constructor should create the binding.

hasDocument = new HasDocument();


InitializeComponent();


Binding b = new Binding("Document");
b.Source = richTextBox;
b.Mode = BindingMode.OneWay;
BindingOperations.SetBinding(hasDocument, HasDocument.DocumentProperty, b);

If you want to be able to declare the binding in XAML, you would have to make your HasDocument class derive from FrameworkElement so that it can be inserted into the logical tree.

Now, if you were to change the Document property on HasDocument, the rich text box's Document will also change.

FlowDocument d = new FlowDocument();
Paragraph g = new Paragraph();
Run a = new Run();
a.Text = "I showed this using a binding";
g.Inlines.Add(a);
d.Blocks.Add(g);


hasDocument.Document = d;

小开

最佳答案

There is a much easier way!

You can easily create an attached DocumentXaml (or DocumentRTF) property which will allow you to bind the RichTextBox's document. It is used like this, where Autobiography is a string property in your data model:

<TextBox Text="{Binding FirstName}" />
<TextBox Text="{Binding LastName}" />
<RichTextBox local:RichTextBoxHelper.DocumentXaml="{Binding Autobiography}" />

Voila! Fully bindable RichTextBox data!

The implementation of this property is quite simple: When the property is set, load the XAML (or RTF) into a new FlowDocument. When the FlowDocument changes, update the property value.

This code should do the trick:

using System.IO;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
public class RichTextBoxHelper : DependencyObject
{
public static string GetDocumentXaml(DependencyObject obj)
{
return (string)obj.GetValue(DocumentXamlProperty);
}


public static void SetDocumentXaml(DependencyObject obj, string value)
{
obj.SetValue(DocumentXamlProperty, value);
}


public static readonly DependencyProperty DocumentXamlProperty =
DependencyProperty.RegisterAttached(
"DocumentXaml",
typeof(string),
typeof(RichTextBoxHelper),
new FrameworkPropertyMetadata
{
BindsTwoWayByDefault = true,
PropertyChangedCallback = (obj, e) =>
{
var richTextBox = (RichTextBox)obj;


// Parse the XAML to a document (or use XamlReader.Parse())
var xaml = GetDocumentXaml(richTextBox);
var doc = new FlowDocument();
var range = new TextRange(doc.ContentStart, doc.ContentEnd);


range.Load(new MemoryStream(Encoding.UTF8.GetBytes(xaml)),
DataFormats.Xaml);


// Set the document
richTextBox.Document = doc;


// When the document changes update the source
range.Changed += (obj2, e2) =>
{
if (richTextBox.Document == doc)
{
MemoryStream buffer = new MemoryStream();
range.Save(buffer, DataFormats.Xaml);
SetDocumentXaml(richTextBox,
Encoding.UTF8.GetString(buffer.ToArray()));
}
};
}
});
}

The same code could be used for TextFormats.RTF or TextFormats.XamlPackage. For XamlPackage you would have a property of type byte[] instead of string.

The XamlPackage format has several advantages over plain XAML, especially the ability to include resources such as images, and it is more flexible and easier to work with than RTF.

It is hard to believe this question sat for 15 months without anyone pointing out the easy way to do this.

小开

I have tuned up previous code a little bit. First of all range.Changed hasn't work for me. After I changed range.Changed to richTextBox.TextChanged it turns out that TextChanged event handler can invoke SetDocumentXaml recursively, so I've provided protection against it. I also used XamlReader/XamlWriter instead of TextRange.

public class RichTextBoxHelper : DependencyObject
{
private static HashSet<Thread> _recursionProtection = new HashSet<Thread>();


public static string GetDocumentXaml(DependencyObject obj)
{
return (string)obj.GetValue(DocumentXamlProperty);
}


public static void SetDocumentXaml(DependencyObject obj, string value)
{
_recursionProtection.Add(Thread.CurrentThread);
obj.SetValue(DocumentXamlProperty, value);
_recursionProtection.Remove(Thread.CurrentThread);
}


public static readonly DependencyProperty DocumentXamlProperty = DependencyProperty.RegisterAttached(
"DocumentXaml",
typeof(string),
typeof(RichTextBoxHelper),
new FrameworkPropertyMetadata(
"",
FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
(obj, e) => {
if (_recursionProtection.Contains(Thread.CurrentThread))
return;


var richTextBox = (RichTextBox)obj;


// Parse the XAML to a document (or use XamlReader.Parse())


try
{
var stream = new MemoryStream(Encoding.UTF8.GetBytes(GetDocumentXaml(richTextBox)));
var doc = (FlowDocument)XamlReader.Load(stream);


// Set the document
richTextBox.Document = doc;
}
catch (Exception)
{
richTextBox.Document = new FlowDocument();
}


// When the document changes update the source
richTextBox.TextChanged += (obj2, e2) =>
{
RichTextBox richTextBox2 = obj2 as RichTextBox;
if (richTextBox2 != null)
{
SetDocumentXaml(richTextBox, XamlWriter.Save(richTextBox2.Document));
}
};
}
)
);
}

小开

Here's a VB.Net version of Lolo's answer:

Public Class RichTextBoxHelper
Inherits DependencyObject


Private Shared _recursionProtection As New HashSet(Of System.Threading.Thread)()


Public Shared Function GetDocumentXaml(ByVal depObj As DependencyObject) As String
Return DirectCast(depObj.GetValue(DocumentXamlProperty), String)
End Function


Public Shared Sub SetDocumentXaml(ByVal depObj As DependencyObject, ByVal value As String)
_recursionProtection.Add(System.Threading.Thread.CurrentThread)
depObj.SetValue(DocumentXamlProperty, value)
_recursionProtection.Remove(System.Threading.Thread.CurrentThread)
End Sub


Public Shared ReadOnly DocumentXamlProperty As DependencyProperty = DependencyProperty.RegisterAttached("DocumentXaml", GetType(String), GetType(RichTextBoxHelper), New FrameworkPropertyMetadata("", FrameworkPropertyMetadataOptions.AffectsRender Or FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, Sub(depObj, e)
RegisterIt(depObj, e)
End Sub))


Private Shared Sub RegisterIt(ByVal depObj As System.Windows.DependencyObject, ByVal e As System.Windows.DependencyPropertyChangedEventArgs)
If _recursionProtection.Contains(System.Threading.Thread.CurrentThread) Then
Return
End If
Dim rtb As RichTextBox = DirectCast(depObj, RichTextBox)
Try
rtb.Document = Markup.XamlReader.Parse(GetDocumentXaml(rtb))
Catch
rtb.Document = New FlowDocument()
End Try
' When the document changes update the source
AddHandler rtb.TextChanged, AddressOf TextChanged
End Sub


Private Shared Sub TextChanged(ByVal sender As Object, ByVal e As TextChangedEventArgs)
Dim rtb As RichTextBox = TryCast(sender, RichTextBox)
If rtb IsNot Nothing Then
SetDocumentXaml(sender, Markup.XamlWriter.Save(rtb.Document))
End If
End Sub

End Class

小开

This VB.Net version works for my situation. I removed thread collection semaphore, instead using RemoveHandler and AddHandler. Also, since a FlowDocument can only be bound to one RichTextBox at a time, I put in a check that the RichTextBox's IsLoaded=True. Let's begin with how I used the class in a MVVM app which uses ResourceDictionary instead of Window.

    ' Loaded and Unloaded events seems to be the only way to initialize a control created from a Resource Dictionary
' Loading document here because Loaded is the last available event to create a document
Private Sub Rtb_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
' only good place to initialize RichTextBox.Document with DependencyProperty
Dim rtb As RichTextBox = DirectCast(sender, RichTextBox)
Try
rtb.Document = RichTextBoxHelper.GetDocumentXaml(rtb)
Catch ex As Exception
Debug.WriteLine("Rtb_Loaded: Message:" & ex.Message)
End Try
End Sub


' Loaded and Unloaded events seems to be the only way to initialize a control created from a Resource Dictionary
' Free document being held by RichTextBox.Document by assigning New FlowDocument to RichTextBox.Document. Otherwise we'll see an of "Document belongs to another RichTextBox"
Private Sub Rtb_Unloaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
Dim rtb As RichTextBox = DirectCast(sender, RichTextBox)
Dim fd As New FlowDocument
RichTextBoxHelper.SetDocumentXaml(rtb, fd)
Try
rtb.Document = fd
Catch ex As Exception
Debug.WriteLine("PoemDocument.PoemDocumentView.PoemRtb_Unloaded: Message:" & ex.Message)
End Try
End Sub


Public Class RichTextBoxHelper
Inherits DependencyObject


Public Shared Function GetDocumentXaml(ByVal depObj As DependencyObject) As FlowDocument
Return depObj.GetValue(DocumentXamlProperty)
End Function


Public Shared Sub SetDocumentXaml(ByVal depObj As DependencyObject, ByVal value As FlowDocument)
depObj.SetValue(DocumentXamlProperty, value)
End Sub


Public Shared ReadOnly DocumentXamlProperty As DependencyProperty = DependencyProperty.RegisterAttached("DocumentXaml", GetType(FlowDocument), GetType(RichTextBoxHelper), New FrameworkPropertyMetadata(Nothing, FrameworkPropertyMetadataOptions.AffectsRender Or FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, Sub(depObj, e)
RegisterIt(depObj, e)
End Sub))




Private Shared Sub RegisterIt(ByVal depObj As System.Windows.DependencyObject, ByVal e As System.Windows.DependencyPropertyChangedEventArgs)
Dim rtb As RichTextBox = DirectCast(depObj, RichTextBox)
If rtb.IsLoaded Then
RemoveHandler rtb.TextChanged, AddressOf TextChanged
Try
rtb.Document = GetDocumentXaml(rtb)
Catch ex As Exception
Debug.WriteLine("RichTextBoxHelper.RegisterIt: ex:" & ex.Message)
rtb.Document = New FlowDocument()
End Try
AddHandler rtb.TextChanged, AddressOf TextChanged
Else
Debug.WriteLine("RichTextBoxHelper: Unloaded control ignored:" & rtb.Name)
End If
End Sub


' When a RichTextBox Document changes, update the DependencyProperty so they're in sync.
Private Shared Sub TextChanged(ByVal sender As Object, ByVal e As TextChangedEventArgs)
Dim rtb As RichTextBox = TryCast(sender, RichTextBox)
If rtb IsNot Nothing Then
SetDocumentXaml(sender, rtb.Document)
End If
End Sub


End Class

小开

I know this is an old post, but check out the Extended WPF Toolkit. It has a RichTextBox that supports what you are tryign to do.

小开

Guys why bother with all the faff. This works perfectly. No code required

<RichTextBox>
<FlowDocument>
<Paragraph>
<Run Text="{Binding Mytextbinding}"/>
</Paragraph>
</FlowDocument>
</RichTextBox>

小开

 <RichTextBox>
<FlowDocument PageHeight="180">
<Paragraph>
<Run Text="{Binding Text, Mode=TwoWay}"/>
</Paragraph>
</FlowDocument>
</RichTextBox>

This seems to be the easiest way by far and isn't displayed in any of these answers.

In the view model just have the Text variable.

小开

Most of my needs were satisfied by this answer https://stackoverflow.com/a/2989277/3001007 by krzysztof. But one issue with that code (i faced was), the binding won't work with multiple controls. So I changed _recursionProtection with a Guid based implementation. So it's working for Multiple controls in same window as well.

 public class RichTextBoxHelper : DependencyObject
{
private static List<Guid> _recursionProtection = new List<Guid>();


public static string GetDocumentXaml(DependencyObject obj)
{
return (string)obj.GetValue(DocumentXamlProperty);
}


public static void SetDocumentXaml(DependencyObject obj, string value)
{
var fw1 = (FrameworkElement)obj;
if (fw1.Tag == null || (Guid)fw1.Tag == Guid.Empty)
fw1.Tag = Guid.NewGuid();
_recursionProtection.Add((Guid)fw1.Tag);
obj.SetValue(DocumentXamlProperty, value);
_recursionProtection.Remove((Guid)fw1.Tag);
}


public static readonly DependencyProperty DocumentXamlProperty = DependencyProperty.RegisterAttached(
"DocumentXaml",
typeof(string),
typeof(RichTextBoxHelper),
new FrameworkPropertyMetadata(
"",
FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
(obj, e) =>
{
var richTextBox = (RichTextBox)obj;
if (richTextBox.Tag != null && _recursionProtection.Contains((Guid)richTextBox.Tag))
return;




// Parse the XAML to a document (or use XamlReader.Parse())


try
{
string docXaml = GetDocumentXaml(richTextBox);
var stream = new MemoryStream(Encoding.UTF8.GetBytes(docXaml));
FlowDocument doc;
if (!string.IsNullOrEmpty(docXaml))
{
doc = (FlowDocument)XamlReader.Load(stream);
}
else
{
doc = new FlowDocument();
}


// Set the document
richTextBox.Document = doc;
}
catch (Exception)
{
richTextBox.Document = new FlowDocument();
}


// When the document changes update the source
richTextBox.TextChanged += (obj2, e2) =>
{
RichTextBox richTextBox2 = obj2 as RichTextBox;
if (richTextBox2 != null)
{
SetDocumentXaml(richTextBox, XamlWriter.Save(richTextBox2.Document));
}
};
}
)
);
}

For completeness sake, let me add few more lines from original answer https://stackoverflow.com/a/2641774/3001007 by ray-burns. This is how to use the helper.

<RichTextBox local:RichTextBoxHelper.DocumentXaml="{Binding Autobiography}" />

小开

Here is my solution based on Ray Burns answer with DataBinding and conversion of a XAML-string to a RichTextBox-Document:

ViewModel

    TestText = @"<FlowDocument xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""><Paragraph><Bold>Hello World!</Bold></Paragraph></FlowDocument>";

View

<RichTextBox local:RichTextBoxHelper.DocumentXaml="{Binding TestText}"/>

RichTextBoxHelper

public class RichTextBoxHelper : DependencyObject
{
public static string GetDocumentXaml(DependencyObject obj) { return (string) obj.GetValue(DocumentXamlProperty); }


public static void SetDocumentXaml(DependencyObject obj,
string value)
{
obj.SetValue(DocumentXamlProperty, value);
}


public static readonly DependencyProperty DocumentXamlProperty = DependencyProperty.RegisterAttached
(
"DocumentXaml",
typeof(string),
typeof(RichTextBoxHelper),
new FrameworkPropertyMetadata
{
BindsTwoWayByDefault = true,
PropertyChangedCallback = (obj,
e) =>
{
var    richTextBox = (RichTextBox) obj;
var    xaml        = GetDocumentXaml(richTextBox);
Stream sm          = new MemoryStream(Encoding.UTF8.GetBytes(xaml));
richTextBox.Document = (FlowDocument) XamlReader.Load(sm);
sm.Close();
}
}
);
}