/// <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>
/// 当用户开始拖动节点时发生。
/// </summary>
private void treeView_ItemDrag(object sender, ItemDragEventArgs e)
{
// 取得拖动的节点，并选中它。
this.dragNode = (TreeNode)e.Item;
this.tempTreeView.SelectedNode = this.dragNode;
//this.nodeImage = //知道被拖动的节点，就应该知道节点的图标是什么？
// 重新设置拖动节点的图标
this.imageListDrag.Images.Clear();
this.imageListDrag.ImageSize = new Size(this.dragNode.Bounds.Size.Width + this.tempTreeView.Indent, this.dragNode.Bounds.Height);
// 创建新图标
// 这个图标将包含被拖动的树节点的图象
Bitmap bitmap = new Bitmap(this.dragNode.Bounds.Width + this.tempTreeView.Indent, this.dragNode.Bounds.Height);
Graphics graphics = Graphics.FromImage(bitmap);
// 在图标里包含被拖动节点的图象
if (this.imageListTreeView != null)
{
graphics.DrawImage(this.imageListTreeView.Images[0], 0, 0);
}
// 把被拖动节点的标签
graphics.DrawString(this.dragNode.Text,
this.tempTreeView.Font,
new SolidBrush(this.tempTreeView.ForeColor),
(float)this.tempTreeView.Indent, 1.0f);
this.imageListDrag.Images.Add(bitmap);
Point point = this.tempTreeView.PointToClient(Control.MousePosition);
int dxHotspot = point.X + this.tempTreeView.Indent - this.dragNode.Bounds.Left;
int dyHotspot = point.Y - this.dragNode.Bounds.Top;
// 开始拖拽图象
if (DragHelper.ImageList_BeginDrag(this.imageListDrag.Handle, 0, dxHotspot, dyHotspot))
{
// 开始
this.tempTreeView.DoDragDrop(bitmap, DragDropEffects.Move);
// 结束
DragHelper.ImageList_EndDrag();
}
}
/// <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);
}
}
}
/// <summary>
/// 在完成拖放操作时发生，所有具体移动操作都发生在这里。
/// </summary>
private void treeView_DragDrop(object sender, DragEventArgs e)
{
// Unlock updates
DragHelper.ImageList_DragLeave(this.tempTreeView.Handle);
// 取得目标节点
TreeNode nodeAt = this.tempTreeView.GetNodeAt(this.tempTreeView.PointToClient(new Point(e.X, e.Y)));
// 如果拖拽的节点不等于目标节点，则增加拖拽的节点为目标节点的子节点。
if (this.dragNode != nodeAt)
{
//委托出去做持久化操作，如果持久化成功，才能移动，否则不移动。
if (this.ProcessDragNode != null && this.ProcessDragNode(this.dragNode, nodeAt))
{
if (this.dragNode.Parent == null)
{
this.tempTreeView.Nodes.Remove(this.dragNode);
}
else
{
this.dragNode.Parent.Nodes.Remove(this.dragNode);
}
// 把拖拽的节点增加到目标节点上。
nodeAt.Nodes.Add(this.dragNode);
nodeAt.ExpandAll();
this.dragNode = null;
this.timer.Enabled = false;
}
else
{
MessageUtil.ShowTips("持久化失败，不能移动节点！");
}
}
}
/// <summary>
/// 在将对象拖出控件的边界时发生。
/// </summary>
private void treeView_DragLeave(object sender, EventArgs e)
{
DragHelper.ImageList_DragLeave(this.tempTreeView.Handle);
this.timer.Enabled = false;
}
/// <summary>
/// 在将对象拖入控件的边界时发生。
/// </summary>
private void treeView_DragEnter(object sender, DragEventArgs e)
{
DragHelper.ImageList_DragEnter(this.tempTreeView.Handle, e.X - this.tempTreeView.Left, e.Y - this.tempTreeView.Top);
this.timer.Enabled = true;
}
