private void ListDragSource_MouseMove(object sender, MouseEventArgs e)
{
//注意这里的严密性, 最好不使用e.Button == MouseButtons.Left, 因为e.Button还可能具有其他的属性
if ((e.Button & MouseButtons.Left) == MouseButtons.Left)
{
// If the mouse moves outside the rectangle, start the drag.
//这里做得太好了，防止意外的拖拽，不是说鼠标动了一下就要拖拽!
if (dragBoxFromMouseDown != Rectangle.Empty &&
!dragBoxFromMouseDown.Contains(e.X, e.Y))
{
// Create custom cursors for the drag-and-drop operation.
try
{
MyNormalCursor = new Cursor("3dwarro.cur");
MyNoDropCursor = new Cursor("3dwno.cur");
}
catch
{
// An error occurred while attempting to load the cursors, so use
// standard cursors.
UseCustomCursorsCheck.Checked = false;
}
finally
{
// The screenOffset is used to account for any desktop bands
// that may be at the top or left side of the screen when
// determining when to cancel the drag drop operation.
screenOffset = SystemInformation.WorkingArea.Location;
// Proceed with the drag-and-drop, passing in the list item.
DragDropEffects dropEffect = ListDragSource.DoDragDrop(ListDragSource.Items[indexOfItemUnderMouseToDrag], DragDropEffects.All | DragDropEffects.Link);
//拖拽结束后继续执行!
// If the drag operation was a move then remove the item.
if (dropEffect == DragDropEffects.Move)
{
ListDragSource.Items.RemoveAt(indexOfItemUnderMouseToDrag);
// Selects the previous item in the list as long as the list has an item.
if (indexOfItemUnderMouseToDrag > 0)
{
ListDragSource.SelectedIndex = indexOfItemUnderMouseToDrag - 1;
}
else if (ListDragSource.Items.Count > 0)
{
// Selects the first item.
ListDragSource.SelectedIndex = 0;
}
}
// Dispose of the cursors since they are no longer needed.
if (MyNormalCursor != null)
{
MyNormalCursor.Dispose();
}
if (MyNoDropCursor != null)
{
MyNoDropCursor.Dispose();
}
}
}
}
}
private void ListDragSource_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
if (dragBoxFromMouseDown != Rectangle.Empty &&
!dragBoxFromMouseDown.Contains(e.X, e.Y))
{
screenOffset = SystemInformation.WorkingArea.Location;
DragDropEffects dropEffect = ListDragSource.DoDragDrop(ListDragSource.Items[indexOfItemUnderMouseToDrag], DragDropEffects.All | DragDropEffects.Link);
}
}
}
private void ListDragSource_MouseDown(object sender, MouseEventArgs e)
{
indexOfItemUnderMouseToDrag = ListDragSource.IndexFromPoint(e.X, e.Y);
if (indexOfItemUnderMouseToDrag != ListBox.NoMatches)
{
// 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;
}
}
