我正在试图制作一个程序,允许将文件拖放到ListView
。我使用ListView.InsertionMark
来确定插入文件的位置。当我放弃文件时,InsertionMark
不会消失,因为DragLeave
事件未触发;如果我将拖放效果更改为DragDropEffects.None
,则释放鼠标时将触发DragLeave
事件。这是为什么发生?DragDropEffects.Link拖放效果为什么DragLeave没有被触发?
此外,文档中还提到“如果键盘或鼠标按钮状态有变化,则会引发QueryContinueDrag
事件并确定是继续拖动,删除数据还是取消基于该值的操作的Action
财产的事件的QueryContinueDragEventArgs
“。但QueryContinueDrag
事件也未触发。
public partial class MainForm : Form
{
private ListView listView1 = new ListView();
public MainForm()
{
InitializeComponent();
this.Controls.Add(listView1);
listView1.Dock = DockStyle.Fill;
listView1.View = View.Details;
listView1.Columns.Add("Test");
listView1.Items.Add("0");
listView1.AllowDrop = true;
listView1.DragEnter += listView1_DragEnter;
listView1.DragOver += listView1_DragOver;
listView1.DragLeave += listView1_DragLeave;
listView1.DragDrop += listView1_DragDrop;
listView1.GiveFeedback += listView1_GiveFeedback;
listView1.QueryContinueDrag += listView1_QueryContinueDrag;
}
private void listView1_DragEnter(object sender, DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.FileDrop))
{
e.Effect = DragDropEffects.Link | DragDropEffects.Scroll;
}
else
{
e.Effect = DragDropEffects.None;
}
}
private void listView1_DragOver(object sender, DragEventArgs e)
{
// This is not done, only to show this problem.
listView1.InsertionMark.Index = 0;
listView1.InsertionMark.AppearsAfterItem = true;
}
private void listView1_DragLeave(object sender, EventArgs e)
{
listView1.InsertionMark.Index = -1;
}
private void listView1_DragDrop(object sender, DragEventArgs e)
{
// listView1.InsertionMark.Index = -1; // Is this really necessary?
}
private void listView1_QueryContinueDrag(object sender, QueryContinueDragEventArgs e)
{
this.Text = "listView1_QueryContinueDrag";
}
private void listView1_GiveFeedback(object sender, GiveFeedbackEventArgs e)
{
this.Text = "listView1_GiveFeedback";
}
}
我必须手动设置listView1.InsertionMark.Index = -1
隐藏InsertionMark
?无论如何触发DragLeave
事件时,拖放效果是DragDropEffects.Link
?
但是,如果我不设置'e.Effect = DragDropEffects.Link | DragDropEffects.Scroll',当删除文件时,'DragLeave'事件被触发。 – EFanZh
@EFanZh - 如果你正在谈论代码的分支,你可以将效果设置为None,那么就不会发生拖放操作。如果释放鼠标按钮,这将有效地强制取消该操作。 –