Highlight Search Results in RadTreeView

Environment

Product Version	Product	Author
2020.1.113	RadTreeView for WinForms	Todor Vyagov

Description

This tutorial demonstrates how to highlight search results in RadTreeView.

Solution

The desired text highlight effect can be achieved by setting the TextParams highlightRanges and highlightColor properties just before the paint cycle of TreeNodeContentElement.

• First, we need to create a custom TreeNodeElement by subscribing to the CreateNodeElement event of RadTreeView.

• The custom TreeNodeElement has three main highlight related properties: HighlightText, HighlightTextColor, HighlightCompareOptions. It has also a custom TreeNodeContentElement (this is the element that holds the text).

• To modify the TextParams of TreeNodeContentElement we need to override the CreateTextParams method and there we can add our hightlightRanges and set the highlightColor. The GetSearchHighlightRanges method is responsible for creating the highlightRanges and considers the HightlightText and HighlightCompareOptions.

• Last, but not least we need to update the HighlightText when the text of a text box is changed and force the RadTreeView to repaint.

A full code snippet is illustrated below:

public RadForm1()
{
    InitializeComponent();

    this.radTreeView1.CreateNodeElement += radTreeView1_CreateNodeElement;
    this.radTextBox1.TextChanged += radTextBox1_TextChanged; 
}

private void radTextBox1_TextChanged(object sender, EventArgs e)
{
    HighlightTreeNodeElement.HighlightText = this.radTextBox1.Text;
    this.radTreeView1.Refresh();
}

private void radTreeView1_CreateNodeElement(object sender, CreateTreeNodeElementEventArgs e)
{
    e.NodeElement = new HighlightTreeNodeElement();
}

public class HighlightTreeNodeElement : TreeNodeElement
{
    public static string HighlightText { get; set; }

    public static Color HighlightTextColor { get; set; }

    public static CompareOptions HighlightCompareOptions { get; set; }

    static HighlightTreeNodeElement()
    {
        HighlightText = string.Empty;
        HighlightTextColor = Color.FromArgb(128, Color.Aqua);
        HighlightCompareOptions = CompareOptions.OrdinalIgnoreCase;
    }

    protected override Type ThemeEffectiveType
    {
        get
        {
            return typeof(TreeNodeElement);
        }
    }

    protected override TreeNodeContentElement CreateContentElement()
    {
        HighlightTreeNodeContentElement contentElement = new HighlightTreeNodeContentElement();
        contentElement.ShouldHandleMouseInput = false;
        return contentElement;
    }
}

public class HighlightTreeNodeContentElement : TreeNodeContentElement
{
    protected override Type ThemeEffectiveType
    {
        get
        {
            return typeof(TreeNodeContentElement);
        }
    }

    protected override TextParams CreateTextParams()
    {
        TextParams textParams = base.CreateTextParams();
        if (!string.IsNullOrEmpty(HighlightTreeNodeElement.HighlightText))
        {
            List<CharacterRange> ranges = this.GetSearchHighlightRanges();
            if (ranges.Count > 0)
            {
                textParams.highlightRanges = ranges.ToArray();
                textParams.highlightColor = HighlightTreeNodeElement.HighlightTextColor;
            }
        }

        return textParams;
    }

    private List<CharacterRange> GetSearchHighlightRanges()
    {
        List<CharacterRange> ranges = new List<CharacterRange>();
        string criteria = HighlightTreeNodeElement.HighlightText;

        int index = -1;
        CompareOptions options = HighlightTreeNodeElement.HighlightCompareOptions;
        string text = this.Text;
        do
        {
            if (index + 1 >= text.Length)
            {
                break;
            }

            index = System.Threading.Thread.CurrentThread.CurrentUICulture.CompareInfo.IndexOf(text, criteria, index + 1, options);

            if (index >= 0)
            {
                if ((options & CompareOptions.IgnoreSymbols) == CompareOptions.IgnoreSymbols)
                {
                    int rangeLength = 0;
                    int criteriaLength = criteria.Length;
                    int currentIndex = index;

                    while (criteriaLength > 0 && currentIndex < text.Length)
                    {
                        if (Char.IsLetterOrDigit(text[currentIndex]))
                        {
                            criteriaLength--;
                        }

                        rangeLength++;
                        currentIndex++;
                    }

                    ranges.Add(new CharacterRange(index, rangeLength));
                }
                else
                {
                    ranges.Add(new CharacterRange(index, criteria.Length));
                }
            }
        }
        while (index >= 0 && ranges.Count < 32);

        return ranges;
    }
}

Public Sub New()
    InitializeComponent()
    AddHandler Me.RadTreeView1.CreateNodeElement, AddressOf radTreeView1_CreateNodeElement
    AddHandler Me.RadTextBox1.TextChanged, AddressOf radTextBox1_TextChanged
End Sub

Private Sub radTextBox1_TextChanged(ByVal sender As Object, ByVal e As EventArgs)
    HighlightTreeNodeElement.HighlightText = Me.RadTextBox1.Text
    Me.RadTreeView1.Refresh()
End Sub

Private Sub radTreeView1_CreateNodeElement(ByVal sender As Object, ByVal e As CreateTreeNodeElementEventArgs)
    e.NodeElement = New HighlightTreeNodeElement()
End Sub

Public Class HighlightTreeNodeElement
Inherits TreeNodeElement

    Public Shared Property HighlightText As String
    Public Shared Property HighlightTextColor As Color
    Public Shared Property HighlightCompareOptions As CompareOptions

    Shared Sub New()
        HighlightText = String.Empty
        HighlightTextColor = Color.FromArgb(128, Color.Aqua)
        HighlightCompareOptions = CompareOptions.OrdinalIgnoreCase
    End Sub

    Protected Overrides ReadOnly Property ThemeEffectiveType As Type
        Get
            Return GetType(TreeNodeElement)
        End Get
    End Property

    Protected Overrides Function CreateContentElement() As TreeNodeContentElement
        Dim contentElement As HighlightTreeNodeContentElement = New HighlightTreeNodeContentElement()
        contentElement.ShouldHandleMouseInput = False
        Return contentElement
    End Function
End Class

Public Class HighlightTreeNodeContentElement
Inherits TreeNodeContentElement

    Protected Overrides ReadOnly Property ThemeEffectiveType As Type
        Get
            Return GetType(TreeNodeContentElement)
        End Get
    End Property

    Protected Overrides Function CreateTextParams() As TextParams
        Dim textParams As TextParams = MyBase.CreateTextParams()

        If Not String.IsNullOrEmpty(HighlightTreeNodeElement.HighlightText) Then
            Dim ranges As List(Of CharacterRange) = Me.GetSearchHighlightRanges()

            If ranges.Count > 0 Then
                textParams.highlightRanges = ranges.ToArray()
                textParams.highlightColor = HighlightTreeNodeElement.HighlightTextColor
            End If
        End If

        Return textParams
    End Function

    Private Function GetSearchHighlightRanges() As List(Of CharacterRange)
        Dim ranges As List(Of CharacterRange) = New List(Of CharacterRange)()
        Dim criteria As String = HighlightTreeNodeElement.HighlightText
        Dim index As Integer = -1
        Dim options As CompareOptions = HighlightTreeNodeElement.HighlightCompareOptions
        Dim text As String = Me.Text

        Do

            If index + 1 >= text.Length Then
                Exit Do
            End If

            index = System.Threading.Thread.CurrentThread.CurrentUICulture.CompareInfo.IndexOf(text, criteria, index + 1, options)

            If index >= 0 Then

                If (options And CompareOptions.IgnoreSymbols) = CompareOptions.IgnoreSymbols Then
                    Dim rangeLength As Integer = 0
                    Dim criteriaLength As Integer = criteria.Length
                    Dim currentIndex As Integer = index

                    While criteriaLength > 0 AndAlso currentIndex < text.Length

                        If Char.IsLetterOrDigit(text(currentIndex)) Then
                            criteriaLength -= 1
                        End If

                        rangeLength += 1
                        currentIndex += 1
                    End While

                    ranges.Add(New CharacterRange(index, rangeLength))
                Else
                    ranges.Add(New CharacterRange(index, criteria.Length))
                End If
            End If
        Loop While index >= 0 AndAlso ranges.Count < 32

        Return ranges
    End Function