C＃：在表面拖放控件

Question

有沒有一種方式，可以讓一個控件，如一個文本框，拖動可棄在C＃中？

我希望用戶必須點擊並按住鼠標控制，並拖動它在其表面上和表面內的任何地方拖放的能力。

任何人有任何想法如何實現這一點？

Answer 1

This answer幫了我很多。它在任何類型的控制和容器上都很棒。

Answer 2

如果你控制一個容器（例如面板）中移動，則可以覆蓋onmousedown事件/事件的OnMouseMove，並調整控制的位置屬性。

根據您的問題，它似乎並不認爲你需要完整的拖和拖放（移動不同的控制，甚至應用程序之間的數據）。

Answer 3

如果你想從Silverlight的容器外拖動一個項目，那麼最好的辦法是檢查出silverlight 4 beta

public MainPage() 
{ 
    InitializeComponent(); 
    Loaded += new RoutedEventHandler(MainPage_Loaded); 
    // wire up the various Drop events 
    InstallButton.Drop += new DragEventHandler(InstallButton_Drop); 
    InstallButton.DragOver += new DragEventHandler(InstallButton_DragOver); 
    InstallButton.DragEnter += new DragEventHandler(InstallButton_DragEnter); 
    InstallButton.DragLeave += new DragEventHandler(InstallButton_DragLeave); 
} 

void InstallButton_Drop(object sender, DragEventArgs e) 
{ 
    IDataObject foo = e.Data; // do something with data 
} 

Answer 4

這在VB6中過去很容易。但現在我們真的只有過去被稱爲OleDrag的東西。

不管怎樣，下面的代碼應該告訴您如何。您只需要一個標籤（dragDropLabel），並將AllowDrop屬性的表單（DragDropTestForm）設置爲True。

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Linq; 
using System.Text; 
using System.Windows.Forms; 

namespace DragDropTest 
{ 
    public partial class DragDropTestForm : Form 
    { 
     // Negative offset to drop location, to adjust for position where a drag starts 
     // on a label. 
     private Point _labelOffset; 

     // Save the full type name for a label, since this is used to test for the control type. 
     private string labelTypeName = typeof(Label).FullName; 

     public DragDropTestForm() 
     { 
      InitializeComponent(); 
     } 

     private void dragDropLabel_MouseDown(object sender, MouseEventArgs e) 
     { 
      if (e.Button == MouseButtons.Left) 
      { 
       _labelOffset = new Point(-e.X, -e.Y); 
      } 
     } 

     private void dragDropLabel_MouseMove(object sender, MouseEventArgs e) 
     { 
      const double minimumDragDistance = 4; 
      const double minimumDragDistanceSquared = minimumDragDistance * minimumDragDistance; 

      if (e.Button == MouseButtons.Left) 
      { 
       // Minimum n pixel movement before drag starts. 
       if (((Math.Pow(_labelOffset.X - e.X, 2)) + Math.Pow(_labelOffset.Y - e.Y, 2)) >= minimumDragDistanceSquared) 
       { 
        dragDropLabel.DoDragDrop(dragDropLabel, DragDropEffects.Move); 
       } 
      }  
     } 

     private void DragDropTestForm_DragOver(object sender, DragEventArgs e) 
     { 
      IDataObject data = e.Data; 

      string[] formats = data.GetFormats(); 

      if (formats[0] == labelTypeName) 
      { 
       e.Effect = DragDropEffects.Move; 
      } 
     } 

     private void DragDropTestForm_DragDrop(object sender, DragEventArgs e) 
     { 
      IDataObject data = e.Data; 

      string[] formats = data.GetFormats(); 

      if (formats[0] == labelTypeName) 
      { 
       Label label = (Label) data.GetData(formats[0]); 
       if (label == dragDropLabel) 
       { 
        Point newLocation = new Point(e.X, e.Y); 
        newLocation.Offset(_labelOffset); 
        dragDropLabel.Location = this.PointToClient(newLocation); 
       } 
      } 
     } 
    } 
}