Owner-Drawn Cells | ComponentOne True DBGrid for WinForms

Owner-Drawn Cells

In This Topic

For cases where complex per-cell customizations need to be performed you can render the contents of the cell by writing a handler for the OwnerDrawCell event. This event is raised as needed to display the contents of cells that have their OwnerDraw property set to True.

To create the owner-drawn cells in the above illustration, complete the following:

Set the OwnerDraw property to True for the First column either in the designer or in code:

In the Designer

Open the C1TrueDBGrid Designer by selecting Designer from the C1TrueDBGrid Tasks menu.
Select the First column in the grid by clicking on it in the right pane.

The column can also be selected by choosing First from the drop-down list in the toolbar.
Click the Display Column tab in the left pane.
Set the OwnerDraw property to True.
Click OK to close the editor.

In Code

Add the following code to the Form_Load event:

Visual Basic	Copy Code
Me.C1TrueDBGrid1.Splits(0).DisplayColumns("First").OwnerDraw = True

C#	Copy Code
this.c1TrueDBGrid1.Splits[0].DisplayColumns["First"].OwnerDraw = true;

Declare the structure RECT in the general declarations of the form:

Visual Basic	Copy Code
Public Structure RECT Dim Left As Long Dim Top As Long Dim Right As Long Dim Bottom As Long End Structure

C#	Copy Code
public struct RECT{ long Left; long Top; long Right; long Bottom; }

Implement the OwnerDrawCell event as follows:

Visual Basic	Copy Code
Private Sub C1TrueDBGrid1_OwnerDrawCell(ByVal sender As Object, ByVal e As C1.Win.C1TrueDBGrid.OwnerDrawCellEventArgs) Handles C1TrueDBGrid1.OwnerDrawCell If e.Col = 0 Then ' Create a gradient brush, blue to red. Dim pt1, pt2 As Point pt1 = New Point(e.CellRect.X, e.CellRect.Y) pt2 = New Point(e.CellRect.Right, e.CellRect.Y) Dim linGrBrush As System.Drawing.Drawing2D.LinearGradientBrush linGrBrush = New System.Drawing.Drawing2D.LinearGradientBrush(pt1, pt2, Color.Blue, Color.Red) Dim rt As RectangleF rt = New RectangleF(e.CellRect.X, e.CellRect.Y, e.CellRect.Width, e.CellRect.Height) ' Fill the cell rectangle with the gradient. e.Graphics.FillRectangle(linGrBrush, e.CellRect) Dim whiteBR As Brush whiteBR = New SolidBrush(Color.White) Dim dispCol As C1.Win.C1TrueDBGrid.C1DisplayColumn dispCol = Me.C1TrueDBGrid1.Splits(0).DisplayColumns(e.Col) ' Center the text horizontally. Dim sfmt As New StringFormat() sfmt.Alignment = StringAlignment.Center ' Draw the text. e.Graphics.DrawString(dispCol.DataColumn.CellText(e.Row), dispCol.Style.Font, whiteBR, rt, sfmt) whiteBR.Dispose() ' Let the grid know the event was handled. e.Handled = True End If End Sub

Visual Basic

Copy Code

Private Sub C1TrueDBGrid1_OwnerDrawCell(ByVal sender As Object, ByVal e As C1.Win.C1TrueDBGrid.OwnerDrawCellEventArgs) Handles C1TrueDBGrid1.OwnerDrawCell
    If e.Col = 0 Then
 
        ' Create a gradient brush, blue to red.
        Dim pt1, pt2 As Point
        pt1 = New Point(e.CellRect.X, e.CellRect.Y)
        pt2 = New Point(e.CellRect.Right, e.CellRect.Y)
        Dim linGrBrush As System.Drawing.Drawing2D.LinearGradientBrush
        linGrBrush = New System.Drawing.Drawing2D.LinearGradientBrush(pt1, pt2, Color.Blue, Color.Red)
 
        Dim rt As RectangleF
        rt = New RectangleF(e.CellRect.X, e.CellRect.Y, e.CellRect.Width, e.CellRect.Height)
 
        ' Fill the cell rectangle with the gradient.
        e.Graphics.FillRectangle(linGrBrush, e.CellRect)
 
        Dim whiteBR As Brush
        whiteBR = New SolidBrush(Color.White)
        Dim dispCol As C1.Win.C1TrueDBGrid.C1DisplayColumn
        dispCol = Me.C1TrueDBGrid1.Splits(0).DisplayColumns(e.Col)
 
        ' Center the text horizontally.
        Dim sfmt As New StringFormat()
        sfmt.Alignment = StringAlignment.Center
 
        ' Draw the text.
        e.Graphics.DrawString(dispCol.DataColumn.CellText(e.Row), dispCol.Style.Font, whiteBR, rt, sfmt)
        whiteBR.Dispose()
 
        ' Let the grid know the event was handled.
        e.Handled = True
    End If
End Sub

C#	Copy Code
private void C1TrueDBGrid1_OwnerDrawCell(object sender, C1.Win.C1TrueDBGrid.OwnerDrawCellEventArgs e) { if ( e.Col = 0 ) { // Create a gradient brush, blue to red. Point pt1, pt2; pt1 = new Point[e.CellRect.X, e.CellRect.Y]; pt2 = new Point[e.CellRect.Right, e.CellRect.Y]; System.Drawing.Drawing2D.LinearGradientBrush linGrBrush; linGrBrush = new System.Drawing.Drawing2D.LinearGradientBrush(pt1, pt2, Color.Blue, Color.Red); RectangleF rt; rt = new RectangleF(e.CellRect.X, e.CellRect.Y, e.CellRect.Width, e.CellRect.Height); // Fill the cell rectangle with the gradient. e.Graphics.FillRectangle(linGrBrush, e.CellRect); Brush whiteBR; whiteBR = new SolidBrush(Color.White); C1.Win.C1TrueDBGrid.C1DisplayColumn dispCol; dispCol = this.c1TrueDBGrid1.Splits[0].DisplayColumns[e.Col]; // Center the text horizontally. StringFormat sfmt = new StringFormat(); sfmt.Alignment = StringAlignment.Center; // Draw the text. e.Graphics.DrawString(dispCol.DataColumn.CellText[e.Row], dispCol.Style.Font, whiteBR, rt, sfmt); whiteBR.Dispose(); // Let the grid know the event was handled. e.Handled = true; } }

Copy Code

private void C1TrueDBGrid1_OwnerDrawCell(object sender,  C1.Win.C1TrueDBGrid.OwnerDrawCellEventArgs e) 
{
    if ( e.Col = 0 ) 
    {
        // Create a gradient brush, blue to red.
        Point pt1, pt2;
        pt1 = new Point[e.CellRect.X, e.CellRect.Y];
        pt2 = new Point[e.CellRect.Right, e.CellRect.Y];
        System.Drawing.Drawing2D.LinearGradientBrush linGrBrush;
        linGrBrush = new System.Drawing.Drawing2D.LinearGradientBrush(pt1, pt2, Color.Blue, Color.Red);
 
        RectangleF rt;
        rt = new RectangleF(e.CellRect.X, e.CellRect.Y, e.CellRect.Width, e.CellRect.Height);
 
        // Fill the cell rectangle with the gradient.
        e.Graphics.FillRectangle(linGrBrush, e.CellRect);
 
        Brush whiteBR;
        whiteBR = new SolidBrush(Color.White);
        C1.Win.C1TrueDBGrid.C1DisplayColumn dispCol;
        dispCol = this.c1TrueDBGrid1.Splits[0].DisplayColumns[e.Col];
 
        // Center the text horizontally.
        StringFormat  sfmt = new StringFormat();
        sfmt.Alignment = StringAlignment.Center;
 
        // Draw the text.
        e.Graphics.DrawString(dispCol.DataColumn.CellText[e.Row], dispCol.Style.Font, whiteBR, rt, sfmt);
        whiteBR.Dispose();
 
        // Let the grid know the event was handled.
        e.Handled = true;
    }
 
}

There are a couple key points worth noting in this example:

If the Handled property is set to True, the grid will not fill in the cell's background, nor will it display cell text or graphics. Therefore, you are responsible for filling in the entire cell, even if there is no data to display.
Even a relatively simple example such as the one illustrated here requires a fair amount of coding, so consider using background bitmaps instead of owner-drawn cells if possible.