issue with cellPaint-event

[Froggie]

Hello!

I have a issue with the cellPaint-Event (virtualmodus is off).
In the Event I call a method where I draw the Background and the text of a cell. If the first cell of the current row has a special Tag, then I want to draw the text across all columns.
Therefore I use the bounds-Property of the RowElement.
But instead of drawing the text from the first cell across all other columns, the text is drawn within each cell. Why does this happen?
I explicitly set the Graphics.Clip to the Bounds of the RowElement.

See attached image for the issue.
There is also another issue where the background is drawn "behind" the scrollbar.

Just by the way: Can I set a ColumnSpan for a specific cell?

Here is my code for painting the cell:

private void drawTitle(GridViewCellPaintEventArgs e)
{
    var groupText = grid.Rows[e.Cell.RowIndex].Cells[0].Tag as string;
    var font = new Font(SystemFonts.MessageBoxFont, FontStyle.Regular | FontStyle.Underline);

    //region to draw is the entire row
    e.Graphics.Clip = new System.Drawing.Region(e.Cell.RowElement.Bounds);
    e.Graphics.Clear(Color.PeachPuff);
    e.Graphics.DrawString(groupText, font, Brushes.Blue, Point.Empty);

    e.Cell.RowElement.DrawBorder = false;
    e.Cell.RowElement.BorderWidth = 0;
    e.Cell.DisableHTMLRendering = true;
    e.Cell.CanFocus = false;
}

Thanks in advance!

[Jack]

Hello Froggie,

The CellPaint event is optimized for painting inside grid cells. When you want to paint across the whole row, you should use the RowPaint event. Please note that Fonts are expensive system resources and you should avoid creating new font instances when painting. I recommend using a single instance for all paint events. 

Please consider the following code snippet which contains my modifications:

void radGridView1_CellFormatting(object sender, CellFormattingEventArgs e)
{
    e.CellElement.RowElement.DrawBorder = false;
    e.CellElement.RowElement.BorderWidth = 0;
    e.CellElement.DisableHTMLRendering = true;
    e.CellElement.CanFocus = false;
}

Font font = new Font(SystemFonts.MessageBoxFont, FontStyle.Regular | FontStyle.Underline);

void radGridView1_RowPaint(object sender, GridViewRowPaintEventArgs e)
{
    Rectangle rect = new Rectangle(0, 0, e.Row.Size.Width, e.Row.Size.Height);
    string groupText = "e.Row.RowInfo.Cells[0].Tag as string";

    //region to draw is the entire row
    e.Graphics.Clip = new System.Drawing.Region(rect);
    e.Graphics.Clear(Color.PeachPuff);
    e.Graphics.DrawString(groupText, font, Brushes.Blue, Point.Empty);
}

I hope it helps.
 
Greetings,
Jack
the Telerik team

[Froggie]

Hallo!
Thanks for your help. That worked for me.

But I don't understand why the Bounds of a Rowelement in a CellPaint-event is not working. My understanding is that the e.Cell.RowElemant refers to the row which the cell belongs to. So the following two snippets should return the same result:

//in cellPaint
e.Graphics.Clip = new System.Drawing.Region(e.Cell.RowElement.Bounds);
// in rowPaint
Rectangle rect = new Rectangle(0, 0, e.Row.Size.Width, e.Row.Size.Height);
e.Graphics.Clip = new System.Drawing.Region(rect);

Are my expectations wrong? Or am I missing something?

Thanks in advance!

[Jack]

Hello Froggie,

When handling the CellPaint event, the Graphics object is translated to the location of the cell element. The Bounds property is relative to the parent element, by default its value is 0, 0 and this causes the observed issue. As suggested before, I recommend using the RowPaint event instead.
 
All the best,
Jack
the Telerik team