C# 在C中验证TreeView拖放操作的最佳方法#
我想验证是否允许拖放操作。有效项可以来自我们的另一个“控件”,也可以来自自定义树视图的内部。目前我有:C# 在C中验证TreeView拖放操作的最佳方法#,c#,validation,user-controls,treeview,C#,Validation,User Controls,Treeview,我想验证是否允许拖放操作。有效项可以来自我们的另一个“控件”,也可以来自自定义树视图的内部。目前我有: bool CanDrop(DragEventArgs e) { bool allow = false; Point point = tree.PointToClient(new Point(e.X, e.Y)); TreeNode target = tree.GetNodeAt(point); if (target != null) {
bool CanDrop(DragEventArgs e)
{
bool allow = false;
Point point = tree.PointToClient(new Point(e.X, e.Y));
TreeNode target = tree.GetNodeAt(point);
if (target != null)
{
if (CanWrite(target)) //user permissions
{
if (e.Data.GetData(typeof(DataInfoObject)) != null) //from internal application
{
DataInfoObject info = (DataInfoObject)e.Data.GetData(typeof(DataInfoObject));
DragDataCollection data = info.GetData(typeof(DragDataCollection)) as DragDataCollection;
if (data != null)
{
allow = true;
}
}
else if (tree.SelectedNode.Tag.GetType() != typeof(TreeRow)) //node belongs to this & not a root node
{
if (TargetExistsInNode(tree.SelectedNode, target) == false)
{
if (e.Effect == DragDropEffects.Copy)
{
allow = true;
}
else if (e.Effect == DragDropEffects.Move)
{
allow = true;
}
}
}
}
}
return allow;
}
我已经将所有的检查代码移到了这个方法中,试图改进一些东西,但对我来说,这仍然是可怕的
太多的逻辑,太多的事情要做,我希望treeview会自己做(例如,“TargetExistsInNode”检查被拖动的节点是否被拖动到它的一个子节点)
验证控件输入的最佳方法是什么?我使用TreeNode.Tag属性存储组成逻辑的小型“controller”对象。例如:
class TreeNodeController {
Entity data;
virtual bool IsReadOnly { get; }
virtual bool CanDrop(TreeNodeController source, DragDropEffects effect);
virtual bool CanDrop(DataInfoObject info, DragDropEffects effect);
virtual bool CanRename();
}
class ParentNodeController : TreeNodeController {
override bool IsReadOnly { get { return data.IsReadOnly; } }
override bool CanDrop(TreeNodeController source, DragDropEffect effect) {
return !IsReadOnly && !data.IsChildOf(source.data) && effect == DragDropEffect.Move;
}
virtual bool CanDrop(DataInfoObject info, DragDropEffects effect) {
return info.DragDataCollection != null;
}
override bool CanRename() {
return !data.IsReadOnly && data.HasName;
}
}
class LeafNodeController : TreeNodeController {
override bool CanDrop(TreeNodeController source, DragDropEffect effect) {
return false;
}
}
那么我的坎德罗普应该是这样的:
bool CanDrop(DragDropEventArgs args) {
Point point = tree.PointToClient(new Point(e.X, e.Y));
TreeNode target = tree.GetNodeAt(point);
TreeNodeController targetController = target.Tag as TreeNodeController;
DataInfoObject info = args.GetData(typeof(DataInfoObject)) as DataInfoObject;
TreeNodeController sourceController = args.GetData(typeof(TreeNodeController)) as TreeNodeController;
if (info != null) return targetController.CanDrop(info, e.Effect);
if (sourceController != null) return targetController.CanDrop(sourceController, e.Effect);
return false;
}
现在,对于我添加到树中的每一类对象,我都可以通过选择将哪个TreeNodeController放入标记对象中来专门化行为。这并不是严格地回答您的问题,但我在您的代码中发现了一个bug。
DragDropEffects
设置了flags属性,因此可以将e.Effect
设置为复制和移动的按位组合。在这种情况下,代码将错误地返回false