Question

我正在做一些非常简单的事情。

我有一个列表框，其事件设置如下：

    public Form1()
    {
        InitializeComponent();
        this.listBox1.AllowDrop = true;
        this.listBox1.DragEnter += new DragEventHandler(listBox1_DragEnter);
        this.listBox1.DragDrop += new DragEventHandler(listBox1_DragDrop);
    }

    void listBox1_DragDrop(object sender, DragEventArgs e)
    {
       //code to add labelText to Items of ListBox
    }

    void listBox1_DragEnter(object sender, DragEventArgs e)
    {
        //set DragDropEffects;
    }

现在我有一个标签，代码如下：

    private void label1_MouseDown(object sender, MouseEventArgs e)
    {
        DoDragDrop((sender as Label).Text, DragDropEffects.Copy);
        //this.label1.DoDragDrop((sender as Label).Text, DragDropEffects.Copy);
        //used one of them at a time.

    }

但没有任何反应。 listbox DragEnter事件永远不会激活。事实上，拖延永远不会发生。每当我尝试拖动标签（文本）时，不允许出现窗口光标，而不是'DragDropEffects.Copy的光标

拖放不会发生..

当我修改列表框（以及相关代码）以接受从任何其他窗口中删除的文件时，这非常有效。

所以..am无法从保存在表单上的控件执行拖动到保存在同一表单上的另一个控件。

我错过了什么吗？我正在运行Windows XP。

我经历了this和this

请帮忙......

Answer 1

您的代码确实有效。您只需在事件处理程序中设置正确的拖动效果。

void listBox1_DragDrop(object sender, DragEventArgs e)
{
  e.Effect = DragDropEffects.Copy;
}

void listBox1_DragEnter(object sender, DragEventArgs e)
{
  e.Effect = DragDropEffects.Copy;
}

Answer 2

检查ListBox.AllowDrop是否设置为TRUE

Answer 3

以下是您需要的示例以及所有代码（在此处为发现此帖的人添加）。

#region Initial Values
//Constructor:
public Form1() {
   InitializeComponent();
}

private void Form1_Load( object sender, EventArgs e ) {
   InitialValues();
}

private void InitialValues() {
   PrepareDragAndDrop();
}
#endregion Initial Values

#region Drag & Drop

private void PrepareDragAndDrop() {
   //For the object that receives the other dragged element:
   TheSamplListBox.AllowDrop = true;
   TheSamplListBox.DragEnter += TheSamplListBox_DragEnter;
   TheSamplListBox.DragLeave += TheSamplListBox_DragLeave;
   TheSamplListBox.DragDrop  += TheSamplListBox_DragDrop;

   //For the object that will be dragged:
   TheSampleLabel.MouseDown += ( sender, args ) => DoDragDrop( TheSampleLabel.Text, DragDropEffects.Copy );
}

private void TheSamplListBox_DragEnter( object theReceiver, DragEventArgs theEventData ) {
   theEventData.Effect = DragDropEffects.Copy;

   //Only the code above is strictly for the Drag & Drop. The following is for user feedback:
   //You can use [TheSamplListBox] but this approach allows for multiple receivers of the same type:
   var theReceiverListBox = (ListBox) theReceiver;

   theReceiverListBox.BackColor = Color.LightSteelBlue;
}

private void TheSamplListBox_DragLeave( object theReceiver, EventArgs theEventData ) {
   //No code here for the Drag & Drop. The following is for user feedback:
   //You can use [TheSamplListBox] but this approach allows for multiple receivers of the same type:
   var theReceiverListBox = (ListBox) theReceiver;

   theReceiverListBox.BackColor = Color.White;
}

private void TheSamplListBox_DragDrop( object theReceiver, DragEventArgs theEventData ) {
   //You can use [TheSamplListBox] but this approach allows for multiple receivers of the same type:
   var theReceiverListBox = (ListBox) theReceiver;

   //Get the data being dropped. In this case, a string:
   var theStringBeingDropped = theEventData.Data.GetData( "System.String" );

   //Add the string to the ListBox:
   theReceiverListBox.Items.Add( theStringBeingDropped );

   //Only the code above is strictly for the Drag & Drop. The following is for user feedback:
   theReceiverListBox.BackColor = Color.White;
}
#endregion Drag & Drop

将一个控件拖放到winform中的另一个控件

3 个答案: