Question

我想出了如何在how to drag gridview row from one grid to another的datagridviews之间拖动行，但现在我遇到了问题。我可以将行从gridPODetails拖到DataGridView1。我可以将行从DataGridView1拖回gridPODetails。但之后我一无所获。我希望能够无限地来回拖动，但我只能去那里。可能导致这种情况的原因以及如何纠正？

 private void gridPODetails_MouseDown(object sender, MouseEventArgs e)
        {
            DataGridView.HitTestInfo info = gridPODetails.HitTest(e.X, e.Y);

            if (info.RowIndex >= 0)
            {
                DataRow view = ((DataTable)(gridPODetails.DataSource)).Rows[info.RowIndex];
                if (view != null)
                {
                    gridPODetails.DoDragDrop(view, DragDropEffects.Copy);
                }
            }
        }

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

        private void gridPODetails_DragDrop(object sender, DragEventArgs e)
        {
            DataGridView grid = sender as DataGridView;
            DataTable table = grid.DataSource as DataTable;
            DataRow row = e.Data.GetData(typeof(DataRow)) as DataRow;

            if (row != null && table != null && row.Table != table)
            {
                table.ImportRow(row);
                row.Delete();
            }
        }

        private void dataGridView1_MouseDown(object sender, MouseEventArgs e)
        {
            DataGridView.HitTestInfo info = dataGridView1.HitTest(e.X, e.Y);

            if (info.RowIndex >= 0)
            {
                DataRow view = ((DataTable)(dataGridView1.DataSource)).Rows[info.RowIndex];
                if (view != null)
                {
                    dataGridView1.DoDragDrop(view, DragDropEffects.Copy);
                }
            }
        }

        private void dataGridView1_DragEnter(object sender, DragEventArgs e)
        {
            e.Effect = DragDropEffects.Copy;
        }

        private void dataGridView1_DragDrop(object sender, DragEventArgs e)
        {
            DataGridView grid = sender as DataGridView;
            DataTable table = grid.DataSource as DataTable;
            DataRow row = e.Data.GetData(typeof(DataRow)) as DataRow;

            if (row != null && table != null && row.Table != table)
            {
                table.ImportRow(row);
                row.Delete();
            }
        }

Answer 1

在table.AcceptChanges()之后添加row.Delete()应允许您在表之间向后移动行。

原因可能是因为导入之前删除的行可能会导致问题。

Answer 2

在回答MAW74656关于问题的评论时，如果我打算连接多个网格进行拖放操作，我将把这个方法放在一起。

本质上，我尝试创建一个lambda来将所有这些功能组合在一个方法中 - 如果需要允许多个调用者，它可以像它自己的方法一样完成。

这是：

Func<DataGridView, IEnumerable<Action>> configureDragDrop = grid =>
{
    var dataTable = grid.DataSource as DataTable;

    /* Event handler definitions here - see below */

    grid.MouseDown += mds;
    grid.DragEnter += des;
    grid.DragDrop += dds;

    return new Action[]
    {
        () => grid.MouseDown -= mds,
        () => grid.DragEnter -= des,
        () => grid.DragDrop -= dds,
    };
};

这段代码允许我写这个：

        // form-level field
        private List<Action> removeHandlers = new List<Action>();

        // in the method where `configureDragDrop` is defined
        removeHandlers.AddRange(configureDragDrop(gridPODetails));
        removeHandlers.AddRange(configureDragDrop(dataGridView1));
        removeHandlers.AddRange(configureDragDrop(dataGridView2));
        removeHandlers.AddRange(configureDragDrop(dataGridView3));
        removeHandlers.AddRange(configureDragDrop(dataGridView4));
        removeHandlers.AddRange(configureDragDrop(dataGridView5));
        removeHandlers.AddRange(configureDragDrop(dataGridView6));
        removeHandlers.AddRange(configureDragDrop(dataGridView7));
        // etc

当我关闭我的表单时，我可以在一行中删除所有处理程序：

        Array.ForEach(removeHandlers.ToArray(), rh => rh.Invoke());

事件处理程序看起来与原始代码非常相似 - 刚才是lambda格式。

MouseDown：

            MouseEventHandler mds = (smd, emd) =>
            {
                var info = grid.HitTest(emd.X, emd.Y);
                if (info.RowIndex >= 0)
                {
                    var dr = dataTable.Rows[info.RowIndex];
                    if (dr != null)
                    {
                        grid.DoDragDrop(dr, DragDropEffects.Copy);
                    }
                }
            };

DragEnter：

            DragEventHandler des = (sde, ede) =>
            {
                ede.Effect = DragDropEffects.Copy;
            };

DragDrop：

            DragEventHandler dds = (sdd, edd) =>
            {
                var dr = edd.Data.GetData(typeof(DataRow)) as DataRow;
                if (dr != null)
                {
                    var dst = dataTable;
                    var src = dr.Table;
                    if (dst != src)
                    {
                        dst.ImportRow(dr);
                        dr.Delete();
                        src.AcceptChanges();
                        dst.AcceptChanges();
                    }
                }
            };

我希望这会有所帮助。

拖放在C＃中不起作用

2 个答案: