/// <summary>
/// 在将对象拖到控件的边界上发生。
/// </summary>
private void treeView_DragOver(object sender, DragEventArgs e)
{
// 计算拖动的位置并移动图片
Point point = this.tempTreeView.PointToClient(new Point(e.X, e.Y));
DragHelper.ImageList_DragMove(point.X - this.tempTreeView.Left, point.Y - this.tempTreeView.Top);
// 取得实际拖拽到目标节点
TreeNode nodeAt = this.tempTreeView.GetNodeAt(this.tempTreeView.PointToClient(new Point(e.X, e.Y)));
if (nodeAt == null)
{
e.Effect = DragDropEffects.None;
}
else
{
e.Effect = DragDropEffects.Move;
if (this.tempDropNode != nodeAt)
{
DragHelper.ImageList_DragShowNolock(false);
this.tempTreeView.SelectedNode = nodeAt;
DragHelper.ImageList_DragShowNolock(true);
this.tempDropNode = nodeAt;
}
TreeNode treeNode = nodeAt;
while (treeNode.Parent != null)
{
if (treeNode.Parent == this.dragNode)
{
e.Effect = DragDropEffects.None;
}
treeNode = treeNode.Parent;
}
}
}
/// <summary>
/// 当指定的计时器间隔已过去而且计时器处于启用状态时发生。
/// </summary>
private void timer_Tick(object sender, EventArgs e)
{
// 取得鼠标位置的节点
Point pt = tempTreeView.PointToClient(Control.MousePosition);
TreeNode node = this.tempTreeView.GetNodeAt(pt);
if (node == null)
{
return;
}
// 如果鼠标靠近顶端，设置向上滚动条
if (pt.Y < 30)
{
if (node.PrevVisibleNode != null)
{
node = node.PrevVisibleNode;
DragHelper.ImageList_DragShowNolock(false);
node.EnsureVisible();
this.tempTreeView.Refresh();
DragHelper.ImageList_DragShowNolock(true);
}
}
// 如果鼠标靠近底端，设置向下滚动条
else if (pt.Y > this.tempTreeView.Size.Height - 30)
{
if (node.NextVisibleNode != null)
{
node = node.NextVisibleNode;
DragHelper.ImageList_DragShowNolock(false);
node.EnsureVisible();
this.tempTreeView.Refresh();
DragHelper.ImageList_DragShowNolock(true);
}
}
}
