的DragDrop和dragEnter事件射擊兩次

我有下面的代碼中，我試圖實現一個拖放功能：的DragDrop和dragEnter事件射擊兩次

public Location_Alert() 
    { 
     InitializeComponent(); 
     #region Form Initialization 
     Recur_Txt.Text = "1"; 
     End_Date.Value = Start_Date.Value.Add(new TimeSpan(1,0,0,0)); 
     Recur_Time_Txt.Text = DateTime.Now.Add(new TimeSpan(0,15,0)).ToString("HH:mm"); 
     Location_Alert_Timer.Tick += new EventHandler(Location_Alert_Timer_Tick);//allow for timed recurrences in code 
     this.DragEnter += new DragEventHandler(Location_Alert_DragEnter);//set up monitoring for a Drag event, changing the cursor as users drags file(s) onto the form. 
     this.DragDrop +=new DragEventHandler(Location_Alert_DragDrop);//set up monitoring for a Drop event, allowing user to drag file onto the form 
     #endregion 
    } 

    private void Location_Alert_DragDrop(object sender, DragEventArgs e) 
    { 
     string[] files = (string[])e.Data.GetData(DataFormats.FileDrop); 
     if (files.Length == 1) 
     { 
      int i = 0; 
      int ii = -1; 
      foreach(string file in files) 
      { 
       if (file.Contains("enot")) 
       { 
        if (ii == -1) 
        { 
         ii = i; 
        } 
       } 
       i++; 
      } 
      ImportFile(files[ii]); 
     } 
     else 
     { 
      MessageBox.Show("This application only supports a single drag and drop file, only the first *.enot file will be imported."); 
      int i = 0; 
      int ii = -1; 
      foreach (string file in files) 
      { 
       if (file.Contains("enot")) 
       { 
        if (ii == -1) 
        { 
         ii = i; 
        } 
       } 
       i++; 
      } 
      ImportFile(files[ii]); 
     } 
    } 

    private void Location_Alert_DragEnter(object sender, DragEventArgs e) 
    { 
     if (e.Data.GetDataPresent(DataFormats.FileDrop)) 
     { 
      int i = 0; 
      int ii = -1; 
      string[] files = (string[])e.Data.GetData(DataFormats.FileDrop); 
      foreach (string file in files) 
      { 
       if (file.Contains("enot")) 
       { 
        if (ii == -1) 
        { 
         ii = i; 
        } 
       } 
       i++; 
      } 
      if (ii != -1) 
      { 
       e.Effect = DragDropEffects.Copy; 
      } 
      else 
      { 
       e.Effect = DragDropEffects.None; 
      } 
     } 
    }

和的DragDrop和的dragenter事件總是激發兩次。我的蜱蟲事件沒有，我不確定這背後的原因。除非用戶遇到異常，否則額外的火災不會引起問題。這將處理異常兩次，在這種情況下意味着將2個消息框返回給用戶。

來源

2014-11-20 Jacrys

有沒有機會讓事件連線兩次？一旦來自設計師，一旦在構造函數中？嘗試評論構造函數的線路，看看它是否仍然有效。 – LarsTech 2014-11-20 22:42:49

@LarsTech有答案：事件構造函數是在我的設計器視圖以及我的窗體構造函數中聲明的。

來源

2014-11-21 15:12:18 Jacrys

即使dragEnter被調用了兩次，dragDrop總是被調用一次，如果你在dragEnter中放入e.Effect = DragDropEffects.Copy。

private void Location_Alert_DragDrop(object sender, DragEventArgs e) 
{ 
    ToDo(); 
} 
private void Location_Alert_DragEnter(object sender, DragEventArgs e) 
{ 
    e.Effect = DragDropEffects.Copy; 
}

來源

2017-09-02 13:01:17

的DragDrop和dragEnter事件射擊兩次

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