/// <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();
}
}
