将项目从DataGridView拖放到面板上
本文关键字:拖放 项目 DataGridView | 更新日期: 2023-09-27 18:15:33
我一直在寻找DataGridView
中拖放的解决方案,但我发现的只是重新排序项目。
但是我所拥有的是一个DataGridView
绑定到一个SQL服务器数据库使用LINQ实体和重新排序是不适用的,所有我想要的是从DataGridView
拖拽一个项目,并把它放在一个面板上以相同的形式。我该怎么做呢?
我找到的允许重新排序的代码:
private Rectangle dragBoxFromMouseDown;
private int rowIndexFromMouseDown;
private int rowIndexOfItemUnderMouseToDrop;
private void dgvResult_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 = dgvResult.DoDragDrop(
dgvResult.Rows[rowIndexFromMouseDown],
DragDropEffects.Move);
}
}
}
private void dgvResult_MouseDown(object sender, MouseEventArgs e)
{
// Get the index of the item the mouse is below.
rowIndexFromMouseDown = dgvResult.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 dgvResult_DragOver(object sender, DragEventArgs e)
{
e.Effect = DragDropEffects.Move;
}
private void dgvResult_DragDrop(object sender, DragEventArgs e)
{
// The mouse locations are relative to the screen, so they must be
// converted to client coordinates.
Point clientPoint = dgvResult.PointToClient(new Point(e.X, e.Y));
// Get the row index of the item the mouse is below.
rowIndexOfItemUnderMouseToDrop =
dgvResult.HitTest(clientPoint.X, clientPoint.Y).RowIndex;
// If the drag operation was a move then remove and insert the row.
if (e.Effect == DragDropEffects.Move)
{
DataGridViewRow rowToMove = e.Data.GetData(
typeof(DataGridViewRow)) as DataGridViewRow;
dgvResult.Rows.RemoveAt(rowIndexFromMouseDown);
dgvResult.Rows.Insert(rowIndexOfItemUnderMouseToDrop, rowToMove);
}
}
任何在DataGridView
内拖放的尝试都会抛出一个异常:
不能以编程方式删除行,除非DataGridView被数据绑定到支持更改通知并允许删除的IBindingList。
你没有解释你想用Panel
中的行做什么,所以我编了一些东西…
你要做的第一件事是设置面板的AllowDrop = true
。然后编写DragEnter
和DragDrop
事件的脚本:
private void panel1_DragEnter(object sender, DragEventArgs e)
{
// we indicate that we allow dropping
e.Effect = DragDropEffects.Copy;
}
private void panel1_DragDrop(object sender, DragEventArgs e)
{
// the mousemove has packed a row as data, so we unpack it:
DataGridViewRow row = e.Data.GetData( typeof(DataGridViewRow)) as DataGridViewRow;
// not sure what to do with it - store it in the tag
panel1.Tag = row;
// let the paint show something
panel1.Invalidate();
}
private void panel1_Paint(object sender, PaintEventArgs e)
{
// if we hava data in the tag we cast them to DataGridViewRow..
// ..and display the content of the 2nd cell
if (panel1.Tag != null)
e.Graphics.DrawString( ((DataGridViewRow)panel1.Tag).Cells[1].Value.ToString(),
this.Font, Brushes.DarkRed, 8, 8);
}
注意,你可以删除dgvResult_DragDrop
&dgvResult_DragOver
事件,因为我们不想掉在DGV上。
当然,绘制动作几乎是随机的。