How can I make FirstBlock as DependencyProperty?

Question

Hi all,

I have to write a text in the first paragraph of RichtextBox to a TextBlock.

I  tried this:

<TextBlock Text= {Binding ElementName=rtb, Path=Docoment.Blocks[0]} />

This will  not work since FirstBlock is not a dependency property.

How can I do this?

Regards

Agrawal

Answer 1

Hi,

Add in your binding this text UpdateSourceTrigger="PropertyChanged"  after setting this property , the changes made in source will be reflected in Textblock ,

here is the link for that

http://msdn.microsoft.com/en-us/library/system.windows.data.binding.updatesourcetrigger.aspx

and the Binding class

http://msdn.microsoft.com/en-us/library/system.windows.data.binding.aspx

---

Thanks & Regards dhampall

Answer 2

HI dhampall_79(Partner)

Thanks for your replay.

It looks like FirstBlock is not a dependancy property.

So adding any of these attributes will not make any difference .

In order to work like this wi shold make fst block as dependencyproperty.

How can I do that?

Regards

Agrawal

Answer 3

Hi Agarwak,

Try This works fine

<TextBlock x:Name="text1" Grid.Row="0" Text="{Binding ElementName=Para1, Path=Inlines/Text}"></TextBlock>
            <RichTextBox x:Name="RichText" Grid.Row="1">
                <FlowDocument>
                    <Paragraph x:Name="Para1">
                        <Run> 1st Paragraph </Run>
                    </Paragraph>
                    <Paragraph x:Name="Para2">
                        <Run>2st Paragraph</Run>
                    </Paragraph>
                    <Paragraph x:Name="Para3">
                        <Run>3st Paragraph</Run>
                    </Paragraph>
                    <Paragraph x:Name="Para4">
                        <Run>4st Paragraph</Run>
                    </Paragraph>
                </FlowDocument>
            </RichTextBox>

Happy Programming!!!

Answer 4

Hi Srithar 

It will work only for first time not when you change the paragraph any further.

Regards

Agrawal

Answer 5

Hi Agarwal,

This works in all cases

<TextBlock x:Name="text1" Grid.Row="0" 
Text="{Binding Path=Document.Blocks.FirstBlock.Inlines/Text, ElementName=RichText}"></TextBlock>

        <RichTextBox Grid.Row="1" x:Name="RichText">
            <FlowDocument>
                <Paragraph>
                    <Run>1 Paragraph</Run>
                </Paragraph>
                <Paragraph>
                    <Run>2 Paragraph</Run>
                </Paragraph>
                <Paragraph>
                    <Run>3 Paragraph</Run>
                </Paragraph>
                <Paragraph>
                    <Run>4 Paragraph</Run>
                </Paragraph>
                <Paragraph>
                    <Run>5 Paragraph</Run>
                </Paragraph>
            </FlowDocument>
        </RichTextBox>

Happy Programming!!!

Answer 6

Hi Srithar,

 I copy pasted your last post code but still it's not working

 it's only working for first time if we change the First Block content at run time let say

 "1 Paragraph" to "new paragraph" but the textblock show "1 Paragraph" in place of "new  Paragraph"

Regards

Ashish

Answer 7

Hi ashish,

I works fine for me. Even when i change it at runtime it is updated.

Code Behind C#:

RichText.Document.Blocks.Clear();
            RichText.Document.Blocks.Add(new Paragraph(new Run("Changed the First Paragraph")));
            RichText.Document.Blocks.Add(new Paragraph(new Run("WPF is Great")));
            RichText.Document.Blocks.Add(new Paragraph(new Run("How is your day")));
            RichText.Document.Blocks.Add(new Paragraph(new Run("4 Paragraph")));
            RichText.Document.Blocks.Add(new Paragraph(new Run("Last Paragraph")));

Output:

Answer 8

Not sure off the top of my head how best to display the Inlines in the TextBlock, but this'll make FirstBlock bindable, and there's a method in there to pull out the text of FirstBlock.

<StackPanel>
    <WpfApplication300:RichTextBoxEx x:Name="rtb"></WpfApplication300:RichTextBoxEx>
    <TextBlock Text="{Binding ElementName=rtb,Path=FirstBlock,Mode=OneWay}"></TextBlock>
    <TextBlock Text="{Binding ElementName=rtb,Path=FirstBlockText,Mode=OneWay}"></TextBlock>
</StackPanel>

public class RichTextBoxEx : RichTextBox, INotifyPropertyChanged
{
    public RichTextBoxEx()
    {
        this.TextChanged += new TextChangedEventHandler(RichTextBoxEx_TextChanged); // make sure we know when the text changes
    }

    void RichTextBoxEx_TextChanged(object sender, TextChangedEventArgs e)
    {
        FirstBlock = this.Document.Blocks.FirstBlock; // update our dependency property
    }

    public static string GetBlockText(Block block) // get the text from the block
    {                        
        if (block == null) return null;

        TextRange textRange = new TextRange(block.ContentStart, block.ContentEnd);

        return textRange.Text;
    }

    public Block FirstBlock
    {
        get { return (Block) GetValue(FirstBlockProperty); }
        set
        {
            SetValue(FirstBlockProperty, value);

            OnPropertyChanged("FirstBlockText"); // when we set a new first block, update the FirstBlockText property
        }
    }

    public string FirstBlockText
    {
        get { return GetBlockText(FirstBlock); }            
    }

    // Using a DependencyProperty as the backing store for FirstBlock.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty FirstBlockProperty =
        DependencyProperty.Register("FirstBlock", typeof(Block), typeof(RichTextBox));

    #region Implementation of INotifyPropertyChanged

    public event PropertyChangedEventHandler PropertyChanged;

    public void OnPropertyChanged(string name)
    {
        if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(name));
    }

    #endregion
}

Warm regards,

Matt