RichTextBox自定义控件

Question

I'm trying to create a new custom control, which inherits from RichTextBox. The reason for this is to add custom buffering to the control (eg only append text every x milliseconds and/or buffer.Length > x).

I've managed to create the control and add it to the xaml Window, however it doesn't seem to actually operate as a RichTextBox properly - text doesn't display after being appended, and the cursor doesn't change icon when hovered over the control .

It seems to be fairly simple code, so I'm not sure where I'm going wrong.

CBufferedTextBox.cs:

public class CBufferedTextBox : RichTextBox
{
    const int MAX_LENGTH = 2048;
    const int TIMER_LENGTH = 1000;

    DispatcherTimer m_timer = new DispatcherTimer();

    DispatcherTimer Timer
    {
        get { return m_timer; }
    }

    StringBuilder m_currentText = new StringBuilder();

    StringBuilder CurrentText
    {
        get { return m_currentText; }
    }


    static CBufferedTextBox()
    {
        DefaultStyleKeyProperty.OverrideMetadata( typeof( CBufferedTextBox ), new FrameworkPropertyMetadata( typeof( CBufferedTextBox ) ) );
    }


    public CBufferedTextBox()
    {
        Loaded += CBufferedTextBox_Loaded;
    }

    public CBufferedTextBox( FlowDocument document )
        : base( document )
    {
    }


    public new void AppendText( string strText )
    {
        CurrentText.Append( strText );

        if( !strText.EndsWith( Environment.NewLine ) )
        {
            CurrentText.AppendLine();
        }

        if( CurrentText.Length > MAX_LENGTH )
        {
            Flush();
        }
    }

    void CBufferedTextBox_Loaded( object sender, RoutedEventArgs e )
    {
        Timer.Interval = new TimeSpan( TIMER_LENGTH );
        Timer.Tick += new EventHandler( Timer_Tick );
        Timer.Start();
    }

    void Timer_Tick( object sender, EventArgs e )
    {
        Flush();
    }

    void Flush()
    {
        Timer.Stop();
        this.BeginInvokeIfRequired( o =>
        {
            if( CurrentText.Length > 0 )
            {
                base.AppendText( CurrentText.ToString() );

                // Clear
                CurrentText.Remove( 0, CurrentText.Length );

                ScrollToEnd();
            }

            Timer.Start();
        } );
    }
}

Generic.xaml:

<Style TargetType="{x:Type local:CBufferedTextBox}" BasedOn="{StaticResource {x:Type RichTextBox}}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:CBufferedTextBox}">
                <Border Background="{TemplateBinding Background}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}">
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Thanks, Rich

Answer 1

Well of course not, you completely have overriden the Style and especially the ControlTemplate . Your Control just consists of a Border, thats all. No text input, no text display no nothing. You need to implement at least the bare basics in your template, to let your CBufferedTextBox behave like you expect.

I also want to point out, that your new void AppendText is pretty dangerous and might not do what you expect. In your Flush method you call the AppendText of the RichtText box not yours. Also new is not the same as override. The RichTextBox will never call your method internally, even if it is of your new type CBufferedTextBox.