移植的WinForms拖放到WPF拖放 [英] Porting WinForms drag and drop to WPF drag and drop
问题描述
我从的WinForms到WPF移植我的计划，并遇到了一些问题拖放。它应该允许从一个TreeView拖（它就像一个文件浏览器），以打开该文件的文本框。不过，WPF的版本就像一个复制和粘贴树型视图的标题文本自动。我想我只是有一些混了？可能是数据对象的东西。
全功能的，相关的WinForms code：
私人无效treeView1_MouseMove（对象发件人，发送MouseEventArgs E）
{
如果（e.Button = MouseButtons.Left！）回报;
树节点节点= treeView1.GetNodeAt（e.Location）;
如果（节点！= NULL）treeView1.DoDragDrop（节点，DragDropEffects.Move）;
}
文本框[I] .DragDrop + =（0，EE）=＆GT;
{
如果（ee.Data.GetData present（typeof运算（树节点）））
{
树节点节点=（树节点）ee.Data.GetData（typeof运算（树节点））;
（（文本框）O）。文= File.ReadAllLines（pathRoot + node.Parent.FullPath）;
...
在WPF code，应该做同样的事情：
私人无效TreeView_ previewMouseLeftButtonDown（对象发件人，MouseButtonEventArgs E）
{
树型视图项目= e.Source为树型视图;
如果（项目！= NULL）
{
数据对象数据对象=新的数据对象（）;
dataObject.SetData（DataFormats.StringFormat，GetFullPath（项目））;
DragDrop.DoDragDrop（项目，数据对象，DragDropEffects.Move）;
}
}
//textbox[i].$p$pviewDrop + = textbox_Drop;
私人无效textbox_Drop（对象发件人，DragEventArgs E）
{
树型视图节点=（树型视图）e.Data.GetData（typeof运算（树型视图））; //空值？
（（文本框）发件人）。文=;
//这是正在执行但随后该节点的标题文本被粘贴
//同时，该怎样访问我通过数据对象？
}
问题：在我的WPF的版本，我设置文本框的文本为空（作为测试），它发生，但事后TreeViewItem的标题文本被粘贴，这是不是我想要的。
问题：什么是正确的方式来口本的WinForms code到WPF？为什么被粘贴的文本在WPF版本？我如何prevent是什么？我使用了正确的事件？我如何访问数据对象在 textbox_Drop 让像我在的WinForms版本中那样我可以打开该文件？为什么在WPF的版本是树型视图节点总是空？
问题：在我的WPF的版本，我设置文本框的文本为空（作为测试），它发生，但事后TreeViewItem的标题文本被粘贴，这是不是我想要的。
我觉得父UI元素是处理（因此覆盖）的删除事件，使你没有得到你所期望的结果。作为事实上，试图重新您的问题的时候，我甚至不能让我的TextBox.Drop事件激发。但是，使用文本框的previewDrop事件，我能得到什么（我认为）是您预期的结果。试试这个：
私人无效textBox1_ previewDrop（对象发件人，DragEventArgs E）
{
文本框TB =发件人的文本框;
如果（TB！= NULL）
{
//如果数据对象包含字符串数据，将其解压缩。
如果（e.Data.GetData present（DataFormats.StringFormat））
{
字符串文件名= e.Data.GetData（DataFormats.StringFormat）的字符串;
使用（StreamReader的S = File.OpenText（文件名））
{
（（文本框）发件人）。文= s.ReadToEnd（）;
}
}
}
e.Handled =真实; //一定要设置为true
}
我认为，code段应回答你们大多数人都提出，除了这一个问题：
为什么在WPF的版本是树型视图节点总是空？
在数据对象要传递的DragDrop事件不支持将一个树型视图。在您的code（和我），我们指定的数据格式将是 DataFormats.StringFormat 不能转换为树型视图。
I am porting my program from WinForms to WPF and have ran into some issues with the drag and drop. It should allow for dragging from a TreeView (it is like a file explorer) to a textbox which opens the file. However, the WPF version acts like a copy-and-paste of the TreeViewItem's header text automatically. I think I just have something mixed up? Possibly the DataObject stuff.
The fully functional, relevant WinForms code:
private void treeView1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button != MouseButtons.Left) return;
TreeNode node = treeView1.GetNodeAt(e.Location);
if (node != null) treeView1.DoDragDrop(node, DragDropEffects.Move);
}
textbox[i].DragDrop += (o, ee) =>
{
if (ee.Data.GetDataPresent(typeof(TreeNode)))
{
TreeNode node = (TreeNode)ee.Data.GetData(typeof(TreeNode));
((Textbox)o).Text = File.ReadAllLines(pathRoot + node.Parent.FullPath);
...
The WPF code that should do the same thing:
private void TreeView_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
TreeViewItem item = e.Source as TreeViewItem;
if (item != null)
{
DataObject dataObject = new DataObject();
dataObject.SetData(DataFormats.StringFormat, GetFullPath(item));
DragDrop.DoDragDrop(item, dataObject, DragDropEffects.Move);
}
}
//textbox[i].PreviewDrop += textbox_Drop;
private void textbox_Drop(object sender, DragEventArgs e)
{
TreeViewItem node = (TreeViewItem)e.Data.GetData(typeof(TreeViewItem)); //null?
((Textbox)sender).Text = "";
//this is being executed BUT then the node's header text is being pasted
//also, how do I access the DataObject I passed?
}
Problem: In my WPF version, I am setting the textbox's text to empty (as a test), which occurs, but afterwards the TreeViewItem's header text is being pasted which is not what I want.
Questions: What is the correct way to port this WinForms code to WPF? Why is the text being pasted in the WPF version? How do I prevent that? Am I using the correct events? How do I access the DataObject in textbox_Drop so that I can open the file like I did in the WinForms version? Why is TreeViewItem node always null in the WPF version?
Problem: In my WPF version, I am setting the textbox's text to empty (as a test), which occurs, but afterwards the TreeViewItem's header text is being pasted which is not what I want.
I think a parent UI element is handling (and therefore overriding) the Drop event so you're not getting the results you expect. As a matter of fact, when trying to recreate your issue, I couldn't even get my TextBox.Drop event to fire. However, using the TextBox's PreviewDrop event, I was able to get what (I think) is your expected result. Try this:
private void textBox1_PreviewDrop(object sender, DragEventArgs e)
{
TextBox tb = sender as TextBox;
if (tb != null)
{
// If the DataObject contains string data, extract it.
if (e.Data.GetDataPresent(DataFormats.StringFormat))
{
string fileName = e.Data.GetData(DataFormats.StringFormat) as string;
using (StreamReader s = File.OpenText(fileName))
{
((TextBox)sender).Text = s.ReadToEnd();
}
}
}
e.Handled = true; //be sure to set this to true
}
I think that code snippet should answer most of the questions you posed except for this one:
Why is TreeViewItem node always null in the WPF version?
The DataObject you are passing in the DragDrop event does not support passing a TreeViewItem. In your code (and mine) we specify that the data format will be DataFormats.StringFormat which cannot be cast to a TreeViewItem.
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