Problem with image column while scrolling

[Andre]

hi 

why are all fields empty when scrolling

 

        private void dgvTaskFactory_ViewCellFormatting(object sender, CellFormattingEventArgs e) {
          if (e.CellElement is GridHeaderCellElement) {
                e.CellElement.TextWrap = true;
                e.CellElement.TextAlignment = ContentAlignment.BottomLeft;
            } else {
                if (e.CellElement is GridCellElement cell) {
                    if (cell.ColumnInfo.Name == ColumnTitle.GridTasklistMail.priority) {
                        cell.DrawText = false;
                        cell.Image = Image.FromFile(Convert.ToInt32(cell.Value.ToString()) == -1 ? "express.png" : "timable.png");
                    } else {
                        cell.Image = null;
                    }
                }
            }

        }

[Dimitar]

Hi Andre,

Thank you for writing. 

A similar code seems to work fine on my side. The only reason can be that there is no column with that name. 

Here is the code I have tested with:

Image img;
public RadForm1()
{
    InitializeComponent();
    img = Image.FromFile(@"C:\img\delete.png");
    radGridView1.ViewCellFormatting += RadGridView1_ViewCellFormatting;
    radGridView1.Columns.Add(new GridViewTextBoxColumn() { Name = "ImageColumn", HeaderText = "Image Column" });
    for (int i = 0; i < 10; i++)
    {
        radGridView1.Rows.Add("Row" + i);
    }
}

private void RadGridView1_ViewCellFormatting(object sender, Telerik.WinControls.UI.CellFormattingEventArgs e)
{
    if (e.CellElement is GridHeaderCellElement)
    {
        e.CellElement.TextWrap = true;
        e.CellElement.TextAlignment = ContentAlignment.BottomLeft;
    }
    else
    {
        if (e.CellElement is GridCellElement cell)
        {
            if (cell.ColumnInfo.Name == "ImageColumn")
            {
                cell.DrawText = false;
                cell.Image = img;
            }
            else
            {
                cell.Image = null;
            }
        }
    }
}

I hope this will be useful. Let me know if you have additional questions.

Regards,
Dimitar
Progress Telerik

[Andre]

hi dimitar

the column name is already correct, because everything is displayed correctly when loading.
the problem occurs only when i have to scroll horizontally. scrolling vertically is no problem i have noticed.

[Dimitar]

Hi Andre,

Ok, I was able to see the issue. We are using UI Virtualization which means that cell elements are reused and you will need to reset the DrawText property as well. Here is the code:

private void RadGridView1_ViewCellFormatting(object sender, Telerik.WinControls.UI.CellFormattingEventArgs e)
{
    //reset the value first
    e.CellElement.DrawText = true;

    if (e.CellElement is GridHeaderCellElement)
    {
        e.CellElement.TextWrap = true;
        e.CellElement.TextAlignment = ContentAlignment.BottomLeft;
    }
    else
    {
        if (e.CellElement is GridDataCellElement cell)
        {
            if (cell.ColumnInfo.Name == "ImageColumn")
            {
                cell.DrawText = false;
                cell.Image = img;
            }
            else
            {
                cell.Image = null;

            }
        }
    }
}

Should you have any other questions do not hesitate to ask.

Regards,
Dimitar
Progress Telerik

[Andre]

hi dimitar

works perfectly !!

many thanks

andré