How to: Custom paint column headers, summary footer, footer cells and indicator cells

• Nov 13, 2018
• 3 minutes to read

The following example custom paints column headers, summary footer, footer cells and indicator cells via the TreeList.CustomDrawColumnHeader, TreeList.CustomDrawFooter, TreeList.CustomDrawFooterCell and TreeList.CustomDrawNodeIndicator events.

Three functions are declared that implement custom painting. These are used to draw the background of the raised and sunken elements, and to paint the text with the predefined alignment within elements.

The image below shows the result.

C#

using System.Drawing.Drawing2D;
using DevExpress.XtraTreeList;
//...

// Custom paints the column headers.
private void treeList1_CustomDrawColumnHeader(object sender, DevExpress.XtraTreeList.CustomDrawColumnHeaderEventArgs e) {
    if (e.Pressed)
        paintSunkenBackground(e);
    else
        paintRaisedBackground(e);
    if (e.ColumnType == HitInfoType.Column)
        paintHAlignedText(e, e.Column.GetCaption(), StringAlignment.Near);
    e.Handled = true;
}

// Custom paints the summary footer.
private void treeList1_CustomDrawFooter(object sender, DevExpress.XtraTreeList.CustomDrawEventArgs e) {
    paintRaisedBackground(e);
    e.Handled = true;
}

// Custom paints the cells of the summary footer.
private void treeList1_CustomDrawFooterCell(object sender, DevExpress.XtraTreeList.CustomDrawFooterCellEventArgs e) {
    if (e.Text == String.Empty) return;
    paintSunkenBackground(e);
    paintHAlignedText(e, e.Text, StringAlignment.Far);
    e.Handled = true;
}

// Custom paints the indicator cells.
private void treeList1_CustomDrawNodeIndicator(object sender, DevExpress.XtraTreeList.CustomDrawNodeIndicatorEventArgs e) {
    paintRaisedBackground(e);
    e.Handled = true;
}

// Custom draw methods:

// Paints the background of raised elements.
private void paintRaisedBackground(CustomDrawEventArgs e)
{
    Brush brush = e.Cache.GetGradientBrush(e.Bounds, Color.Yellow, Color.Gold, LinearGradientMode.Vertical);
    e.Cache.FillRectangle(brush, e.Bounds);
    e.Cache.DrawRectangle(e.Cache.GetPen(Color.LightGray), e.Bounds);
}

// Paints the background of sunken elements.
private void paintSunkenBackground(CustomDrawEventArgs e)
{
    Brush brush = e.Cache.GetGradientBrush(e.Bounds, Color.CornflowerBlue, Color.LightGray, LinearGradientMode.Vertical);
    e.Cache.FillRectangle(brush, e.Bounds);
    e.Cache.DrawRectangle(e.Cache.GetPen(Color.LightGray), e.Bounds);
}

// Paints the aligned text.
private void paintHAlignedText(CustomDrawEventArgs e, String text, StringAlignment align)
{
    Brush textBrush = e.Cache.GetSolidBrush(Color.Black);

    StringFormat outStringFormat = e.Appearance.GetStringFormat();
    outStringFormat.Alignment = align;
    outStringFormat.LineAlignment = StringAlignment.Center;
    outStringFormat.FormatFlags = StringFormatFlags.NoWrap;
    outStringFormat.Trimming = StringTrimming.EllipsisCharacter;

    e.Cache.DrawString(text, e.Appearance.Font, textBrush, e.Bounds, outStringFormat);
}

VB.NET

Imports System.Drawing.Drawing2D
Imports DevExpress.XtraTreeList
'...


' Custom paints the column headers.
Private Sub TreeList1_CustomDrawColumnHeader(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.CustomDrawColumnHeaderEventArgs) _
Handles TreeList1.CustomDrawColumnHeader
    If e.Pressed Then
        paintSunkenBackground(e)
    Else
        paintRaisedBackground(e)
    End If
    If e.ColumnType = HitInfoType.Column Then
        paintHAlignedText(e, e.Column.GetCaption(), StringAlignment.Near)
    End If
    e.Handled = True
End Sub

' Custom paints the summary footer.
Private Sub TreeList1_CustomDrawFooter(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.CustomDrawEventArgs) _
Handles TreeList1.CustomDrawFooter
    paintRaisedBackground(e)
    e.Handled = True
End Sub

' Custom paints the cells of the summary footer.
Private Sub TreeList1_CustomDrawFooterCell(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.CustomDrawFooterCellEventArgs) _
Handles TreeList1.CustomDrawFooterCell
    If e.Text = String.Empty Then
        Return
    End If
    paintSunkenBackground(e)
    paintHAlignedText(e, e.Text, StringAlignment.Far)
    e.Handled = True
End Sub

' Custom paints indicator cells.
Private Sub TreeList1_CustomDrawNodeIndicator(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.CustomDrawNodeIndicatorEventArgs) _
Handles TreeList1.CustomDrawNodeIndicator
    paintRaisedBackground(e)
    e.Handled = True
End Sub

' Custom draw methods:

' Paints the background of raised elements.
Private Sub paintRaisedBackground(ByVal e As CustomDrawEventArgs)
    Dim brush As Brush = e.Cache.GetGradientBrush(e.Bounds, Color.Yellow, Color.Gold, LinearGradientMode.Vertical)
    e.Cache.FillRectangle(brush, e.Bounds)
    e.Cache.DrawRectangle(e.Cache.GetPen(Color.LightGray), e.Bounds)
End Sub

' Paints the background of sunken elements.
Private Sub paintSunkenBackground(ByVal e As CustomDrawEventArgs)
    Dim brush As Brush = e.Cache.GetGradientBrush(e.Bounds, Color.CornflowerBlue, Color.LightGray, LinearGradientMode.Vertical)
    e.Cache.FillRectangle(brush, e.Bounds)
    e.Cache.DrawRectangle(e.Cache.GetPen(Color.LightGray), e.Bounds)
End Sub

' Paints the aligned text.
Private Sub paintHAlignedText(ByVal e As CustomDrawEventArgs, ByVal text As String, ByVal align As StringAlignment)
    Dim textBrush As Brush = e.Cache.GetSolidBrush(Color.Black)

    Dim outStringFormat As StringFormat = e.Appearance.GetStringFormat()
    outStringFormat.Alignment = align
    outStringFormat.LineAlignment = StringAlignment.Center
    outStringFormat.FormatFlags = StringFormatFlags.NoWrap
    outStringFormat.Trimming = StringTrimming.EllipsisCharacter

    e.Cache.DrawString(text, e.Appearance.Font, textBrush, e.Bounds, outStringFormat)
End Sub