RepositoryItemTextEdit.CustomHighlightText Event

Allows you to highlight or custom paint strings within the control’s text. This event is supported in Advanced mode (see RepositoryItemTextEdit.UseAdvancedMode).

Namespace: DevExpress.XtraEditors.Repository

Assembly: DevExpress.XtraEditors.v24.2.dll

Declaration

C#

[DXCategory("Events")]
public event TextEditCustomHighlightTextEventHandler CustomHighlightText

VB.NET

<DXCategory("Events")>
Public Event CustomHighlightText As TextEditCustomHighlightTextEventHandler

Event Data

The CustomHighlightText event's data class is TextEditCustomHighlightTextEventArgs. The following properties provide information specific to this event:

Property	Description
LineIndex	Gets the zero-based index of the currently processed text line for multi-line text. Returns 0 for single-line text.
Text	Gets the currently processed text/text line (for multi-line text).
TextPosition	Gets the position of the currently processed text line within the editor’s text.

The event data class exposes the following methods:

Method	Description
HighlightRange(Int32, Int32, Action<TextEdit.Block>)	Highlights or custom paints a text block at a specified position.
HighlightRange(Int32, Int32, Color, Color)	Highlights a text block at a specific position using custom foreground and background colors.
HighlightRange(Int32, Int32, Color)	Highlights a text block at a specified position using a custom foreground color.
HighlightRanges(String, Action<TextEdit.Block>, CompareOptions)	Highlights or custom paints all text blocks that have the specified content.
HighlightRanges(String, Color, Color, CompareOptions)	Highlights all text blocks that have specified content using custom foreground and background colors.
HighlightRanges(String, Color, CompareOptions)	Highlights all text blocks that have the specified content using a custom foreground color.
HighlightWords(String, Action<TextEdit.Block>, CompareOptions)	Highlights or custom paints whole words.
HighlightWords(String, Color, Color, CompareOptions)	Highlights whole words using custom foreground and background colors.
HighlightWords(String, Color, CompareOptions)	Highlights whole words using a custom foreground color.

Remarks

Run Demo: Memo Edit

You can handle the CustomHighlightText (or TextEdit.CustomHighlightText) event to highlight or paint certain strings within the control’s text in a custom manner.

Use the event’s Text parameter to identify the control’s text. For multi-line text (for example, in a MemoEdit control), the CustomHighlightText event fires repeatedly for each text line, and the Text parameter specifies the currently processed text line.

The HighlightRange, HighlightRanges and HighlightWords methods (available from the event’s e argument) allow you to perform the following tasks.

• Highlight strings with custom foreground and background colors.
• Add padding for text blocks.
• Specify a painter that draws text using custom font settings.
• Specify a painter that replaces text blocks with custom graphics (for instance, icons or smileys).

Example

The following example handles the CustomHighlightText event to highlight and custom paint text in a MemoEdit:

• Strikethrough a text block at the beginning of the text.
• Draw a star icon instead of the ‘star’ string.
• Change the background and foreground colors for individual words and strings.

C#

using DevExpress.XtraEditors;

// Enable Advanced Mode during the control's initialization (for instance, at design time)
memoEdit1.Properties.UseAdvancedMode = DevExpress.Utils.DefaultBoolean.True;

memoEdit1.Text = "The formation of a star begins with gravitational instability within a molecular cloud, caused by regions of higher density—often triggered by compression of clouds by radiation from massive stars \r\n (Wikipedia)";
memoEdit1.Font = new Font("Tahoma", 10);

private void memoEdit1_CustomHighlightText(object sender, TextEditCustomHighlightTextEventArgs e) {
    // Change a word's background color and add padding.
    e.HighlightWords("with", (block) => {
        block.BackColor = Color.Yellow;
        block.Padding = new Padding(5, 0, 5, 0);
    });

    // Change a string's background and foreground colors.
    e.HighlightRanges("cloud", (block) => {
        block.BackColor = Color.Yellow;
        block.ForeColor = Color.Red;
    });

    // Strikethrough text at the beginning of the first line.
    if (e.LineIndex == 0)
        e.HighlightRange(0, 12, (block) => { block.Painter = new MyStrikethroughTextPainter(Color.Gray); });

    // Draw a star icon instead of the 'star' string.
    e.HighlightRanges(
        "Star",
        (block) => {
            block.Painter = new MyImagePainter();
            block.ContentSize = new Size(14, 14);
            block.AllowNavigation = false;
        },
        System.Globalization.CompareOptions.IgnoreCase);
}

public class MyStrikethroughTextPainter : TextEdit.TextEditBlockPainter {
    public MyStrikethroughTextPainter(Color color) {
        Color = color;
    }
    Color Color { get; set; }
    static readonly Font StrikeoutFont = new Font("Tahoma", 10f, FontStyle.Strikeout);
    public override bool DrawForeground(TextEdit.Block block) {
        DrawString(block.Text, StrikeoutFont, block.Segments[0].TextBounds, Color);
        return true;
    }
}

public class MyImagePainter : TextEdit.TextEditBlockPainter {
    static Bitmap img;
    static Bitmap Image {
        get {
            if (img == null) {
                using (var temp = System.Drawing.Image.FromFile("d:\\star.png"))
                    img = new Bitmap(temp);
            }
            return img;
        }
    }
    public override bool DrawForeground(TextEdit.Block block) {
        DrawBitmap(Image, block.Segments[0].Bounds, new RectangleF(Point.Empty, Image.Size));
        return true;
    }
}

VB.NET

Imports DevExpress.XtraEditors

' Enable Advanced Mode during the control's initialization (for instance, at design time).
MemoEdit1.Properties.UseAdvancedMode = DevExpress.Utils.DefaultBoolean.True

MemoEdit1.Text = "The formation of a star begins with gravitational instability within a molecular cloud, caused by regions of higher density—often triggered by compression of clouds by radiation from massive stars " & Constants.vbCrLf & " (Wikipedia)"
MemoEdit1.Font = New Font("Tahoma", 10)


Private Sub MemoEdit1_CustomHighlightText(sender As Object, e As DevExpress.XtraEditors.TextEditCustomHighlightTextEventArgs) Handles MemoEdit1.CustomHighlightText
    ' Change a word's background color and add padding.
    e.HighlightWords("with", Sub(block)
                                    block.BackColor = Color.Yellow
                                    block.Padding = New Padding(5, 0, 5, 0)
                                End Sub)
    ' Change a string's background and foreground colors.
    e.HighlightRanges("cloud", Sub(block)
                                    block.BackColor = Color.Yellow
                                    block.ForeColor = Color.Red
                                End Sub)

    ' Strikethrough text at the beginning of the first line.
    If e.LineIndex = 0 Then e.HighlightRange(0, 12, Sub(block)
                                                        block.Painter = New MyStrikethroughTextPainter(Color.Gray)
                                                    End Sub)

    ' Draw a star icon instead of the 'star' string.
    e.HighlightRanges("Star", Sub(block)
                                    block.Painter = New MyImagePainter()
                                    block.ContentSize = New Size(14, 14)
                                    block.AllowNavigation = False
                                End Sub, System.Globalization.CompareOptions.IgnoreCase)
End Sub

Public Class MyStrikethroughTextPainter
    Inherits TextEdit.TextEditBlockPainter

    Public Sub New(ByVal color As Color)
        color = color
    End Sub

    Private Property Color As Color
    Shared ReadOnly StrikeoutFont As Font = New Font("Tahoma", 10F, FontStyle.Strikeout)

    Public Overrides Function DrawForeground(ByVal block As TextEdit.Block) As Boolean
        DrawString(block.Text, StrikeoutFont, block.Segments(0).TextBounds, Color)
        Return True
    End Function
End Class

Public Class MyImagePainter
    Inherits TextEdit.TextEditBlockPainter

    Shared img As Bitmap

    Private Shared ReadOnly Property Image As Bitmap
        Get
            If img Is Nothing Then
                Using temp = System.Drawing.Image.FromFile("d:\star.png")
                    img = New Bitmap(temp)
                End Using
            End If

            Return img
        End Get
    End Property

    Public Overrides Function DrawForeground(ByVal block As TextEdit.Block) As Boolean
        DrawBitmap(Image, block.Segments(0).Bounds, New RectangleF(Point.Empty, Image.Size))
        Return True
    End Function
End Class