datagridview cellpainting event

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i use cellpainting event every time i drag item from my listbox to datagridview.
when i drag item from the listbox my previous cellpainting event in datagridview disappears.
How can i keep the cellpainting events on the datagridview?

here is my code:

C#

public int x;
public int y;

C#

private void dataGridView1_DragDrop(object sender, DragEventArgs e)
      {
          Point p = this.dataGridView1.PointToClient(new Point(e.X, e.Y));
          DataGridView.HitTestInfo info = this.dataGridView1.HitTest(p.X, p.Y);

          if (info.RowIndex != -1 && info.ColumnIndex != -1)
          {
              Object value = (Object)e.Data.GetData(typeof(string));
              this.dataGridView1.Rows[info.RowIndex].Cells[info.ColumnIndex].Value = value;

              x = info.RowIndex;
              y = info.ColumnIndex;

                  dataGridView1.CellPainting += new DataGridViewCellPaintingEventHandler(dataGridView1_CellPainting);

              dataGridView1.Invalidate();

          }
      }

C#

protected void dataGridView1_CellPainting(object sender,DataGridViewCellPaintingEventArgs e)
       {

           if (e.RowIndex == x && e.ColumnIndex >= y && e.ColumnIndex < y + 4)
           {
               e.Graphics.FillRectangle(Brushes.Red, e.CellBounds);
               e.PaintContent(e.CellBounds);
               e.Handled = true;
           }
       }

Posted 28-Apr-12 3:50am

yehiad

Updated 28-Apr-12 4:28am

v2

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[no name] 28-Apr-12 10:03am

What have you tried? What errors are you getting? Where is the code that demonstrates your problem?

1 solution

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OriginalGriff · Answer 1 · 2012-04-28T04:41:00

Why are you adding an event handler every time you drop an item?
Wouldn't it make more sense to have just the single one handler, particularly since you are putting them all to the same handler method.
Instead, set up the handler once, in form load, or at design time, and try setting the row and column first:

C#

private void dataGridView1_DragDrop(object sender, DragEventArgs e)
      {
          Point p = this.dataGridView1.PointToClient(new Point(e.X, e.Y));
          DataGridView.HitTestInfo info = this.dataGridView1.HitTest(p.X, p.Y);
          if (info.RowIndex != -1 && info.ColumnIndex != -1)
          {
              Object value = (Object)e.Data.GetData(typeof(string));
              x = info.RowIndex;
              y = info.ColumnIndex;
              this.dataGridView1.Rows[info.RowIndex].Cells[info.ColumnIndex].Value = value;
          }
      }

"i drag Courses from the listbox into timetable(datagridview). when i did it like u worte, still the previous cellpainting event in datagridview disappears and only last event appears."

Which is exactly what I would expect - that is what you have asked it to do.
If you want to preserve previous cells as well, you need to replace your "x" and "y" with a list (or other collection) to hold the ones you want to highlight:

C#

  private List<Point> makeRed = new List<Point>();
  private void dataGridView1_DragDrop(object sender, DragEventArgs e)
  {
      Point p = this.dataGridView1.PointToClient(new Point(e.X, e.Y));
      DataGridView.HitTestInfo info = this.dataGridView1.HitTest(p.X, p.Y);
      if (info.RowIndex != -1 && info.ColumnIndex != -1)
      {
          Object value = (Object)e.Data.GetData(typeof(string));
          makeRed.Add(new Point(e.RowIndex, e.ColumnIndex));
          this.dataGridView1.Rows[info.RowIndex].Cells[info.ColumnIndex].Value = value;
      }
  }
private void dataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
{
    if (makeRed.Contains(new Point(e.RowIndex, e.ColumnIndex)))
    {
        e.Graphics.FillRectangle(Brushes.Red, e.CellBounds);
        e.PaintContent(e.CellBounds);
        e.Handled = true;
    }
}