Question

I have copied some code and modified it to suit my application. And I will continue to tweak and clean up the code until I am statisfied with it. But I have encountered a little error. I have two datagridviews and wish to move datagridrows from one to another. However, while the drag&drop events all fire, the dataGridView_Routes_DragDrop() will execute the log command because there is no data in e.Data.GetData. What have I done wrong? Am I missing something? I’ve tried to look through several guides but nothing specifically covers this issue.

How can I get the datagrid pass the dragged datagridrow over to the other datagrid?

    /* Drag & Drop */
    private Rectangle dragBoxFromMouseDown;
    private int rowIndexFromMouseDown;
    private void dataGridView_Trips_MouseMove(object sender, MouseEventArgs e)
    {
        if ((e.Button & MouseButtons.Left) == MouseButtons.Left)
        {
            // If the mouse moves outside the rectangle, start the drag.
            if (dragBoxFromMouseDown != Rectangle.Empty && !dragBoxFromMouseDown.Contains(e.X, e.Y))
            {
                // Proceed with the drag and drop, passing in the list item.                    
                DragDropEffects dropEffect = dataGridView_Trips.DoDragDrop(dataGridView_Trips.Rows[rowIndexFromMouseDown], DragDropEffects.Copy);
            }
        }
    }

    private void dataGridView_Trips_MouseDown(object sender, MouseEventArgs e)
    {
        // Get the index of the item the mouse is below.
        rowIndexFromMouseDown = dataGridView_Trips.HitTest(e.X, e.Y).RowIndex;
        if (rowIndexFromMouseDown != -1)
        {
            // Remember the point where the mouse down occurred. 
            // The DragSize indicates the size that the mouse can move 
            // before a drag event should be started.                
            Size dragSize = SystemInformation.DragSize;

            // Create a rectangle using the DragSize, with the mouse position being
            // at the center of the rectangle.
            dragBoxFromMouseDown = new Rectangle(new Point(e.X - (dragSize.Width / 2), e.Y - (dragSize.Height / 2)), dragSize);
        }
        else
            // Reset the rectangle if the mouse is not over an item in the ListBox.
            dragBoxFromMouseDown = Rectangle.Empty;
    }

    private void dataGridView_Routes_DragOver(object sender, DragEventArgs e)
    {
        e.Effect = DragDropEffects.Copy;
    }

    private void dataGridView_Routes_DragDrop(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(typeof(DataRowView)))
        {
            // The mouse locations are relative to the screen, so they must be 
            // converted to client coordinates.
            Point clientPoint = dataGridView_Routes.PointToClient(new Point(e.X, e.Y));

            // If the drag operation was a copy then add the row to the other control.
            if (e.Effect == DragDropEffects.Copy)
            {
                DataGridViewRow rowToMove = e.Data(typeof(DataGridViewRow)) as DataGridViewRow;
                dataGridView_Routes.Rows.Add(rowToMove);
            }
        }
        else
        {
            log("Geen data! #01", "Fout");
        }
    }
    /* End Drag & Drop */

Answer 1

I don’t know. But the following function has been adjusted and it works as intended. Not quite sure how the previous code broke.

EDIT: The typeof was written with DataViewRow instead of DataGridViewRow. Fail.

private void dataGridView_Routes_DragDrop(object sender, DragEventArgs e)
    {
        try
        {
            if (e.Data.GetDataPresent(typeof(DataGridViewRow)))
            {

                // The mouse locations are relative to the screen, so they must be 
                // converted to client coordinates.
                Point clientPoint = dataGridView_Routes.PointToClient(new Point(e.X, e.Y));

                // If the drag operation was a copy then add the row to the other control.
                if (e.Effect == DragDropEffects.Copy)
                {
                    DataGridViewRow Row = (DataGridViewRow)e.Data.GetData(typeof(DataGridViewRow));
                    dataGridView_Routes.Rows.Add(Row.Cells[0].Value, Row.Cells[1].Value, Row.Cells[2].Value);
                }
            }
            else
            {
                log("Geen data! #01", "Fout");
            }
        }
        catch (Exception msg)
        {
            log(msg.Message,"Fout");
        }
    }