用户控件在面板上拖放

我正在制作一个图形编辑器，但在拖放时遇到一些问题Panel。椭圆没有占据我放置它的确切位置，我认为它被放置在大小为 150;150 的 UserControl 中。这是一个短片的链接来说明我的意思：http://gyazo.com/abf5484a31e2d1ce8ebccc49bee9fdb6 http://gyazo.com/abf5484a31e2d1ce8ebccc49bee9fdb6在第一部分中，您可以看到椭圆转到了错误的位置，在电影的结尾，当我画一条线时，椭圆周围似乎有一个块。我该如何解决这个问题？

Form1.cs

public partial class Form1 : Form
{
    bool draw = false;
    int x, y, xe, ye;

    public Form1()
    {
        InitializeComponent();

        menuComboBoxShape.ComboBox.DataSource = Enum.GetValues(typeof(Item));
    }

    public enum Item
    {
        Pencil,
        Rectangle, 
        Ellipse,
    }


    private void panel_MouseDown(object sender, MouseEventArgs e)
    {
        draw = true;
        x = e.X;
        y = e.Y;
    }

    private void panel_MouseUp(object sender, MouseEventArgs e)
    {
        draw = false;
        xe = e.X;
        ye = e.Y;

        Item item; 
        Enum.TryParse<Item>(menuComboBoxShape.ComboBox.SelectedValue.ToString(), out item);

        switch (item)
        {

            case Item.Pencil:
                using (Graphics g = panel.CreateGraphics())
                    using (var pen = new Pen(System.Drawing.Color.Black))     //Create the pen used to draw the line (using statement makes sure the pen is disposed)
                    {
                        g.DrawLine(pen,new Point(x, y), new Point(xe, ye));
                    }
                break;
            case Item.Rectangle:
                RectangleShape recShape = new RectangleShape(x, y, xe - x, ye - y);
                panel.Controls.Add(recShape);
                panel.Invalidate();
                break;
            case Item.Ellipse:
                EllipseShapeTest test = new EllipseShapeTest(x, y, xe - x, ye - y);
                panel.Controls.Add(test);
                panel.Invalidate();
                break;
            default:
                break;
        }
    }
}

EllipseShapeTest.cs

class EllipseShapeTest : UserControl
{
    private int x;
    private int y;
    private int width;
    private int height;

    public EllipseShapeTest(int x, int y, int width, int height)
    {
        setY(y);
        setX(x);
        setWidth(width);
        setHeight(height);
    }

    public int getX() { return x;}
    public int getY() { return y; }
    public int getWidth() { return width; }
    public int getHeight() { return height; }
    public void setX(int newx) { x = newx; }
    public void setY(int newy) { y = newy; }
    public void setWidth(int newwidth) { width = newwidth; }
    public void setHeight(int newheight) { height = newheight; }


    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);
        // Call methods of the System.Drawing.Graphics object.

        // Draw an aqua rectangle in the rectangle represented by the control.
        e.Graphics.DrawEllipse(Pens.Aqua,x,y,width,height);
    }

    protected override void OnMouseMove(MouseEventArgs e)
    {

        // Make the cursor the Hand cursor when the mouse moves  
        // over the button.
        Cursor = Cursors.Hand;

        // Call MyBase.OnMouseMove to activate the delegate. 
        base.OnMouseMove(e);

        if (e.Button == MouseButtons.Left)
        {
            this.Location = new Point(e.X, e.Y);
            Invalidate();
        }
     }

这里有一个Label可拖动的子类。相同的代码应该适用于任何控件，包括您的UserControl.

 public DragLabel()
 {
     //..
     MouseDown += DragLabel_MouseDown;
     MouseMove += DragLabel_MouseMove;
 }

 Point mDown { get; set; }

 void DragLabel_MouseDown(object sender, MouseEventArgs e)
 {
      mDown = e.Location;
 }

 void DragLabel_MouseMove(object sender, MouseEventArgs e)
 {
      if (e.Button == MouseButtons.Left)
      {
           Location = new Point(e.X + Left - mDown.X, e.Y + Top - mDown.Y);
      }
 }

如果您的应用程序需要使多个类可拖动，您可以将该功能放在一个DragController类并在那里注册那些需要它的控件..

至于你的第二个问题：在例子中我们只看到one控制。在这个简单的例子中，应该做的是使 UCBackColor = Color.Transparent。但是一旦你想添加more这样的形状你会撞墙而且，恐怕你必须give up在这样的设计上。看here https://stackoverflow.com/questions/30209473/rectangle-add-mousemove-event/30210637#30210637讨论问题和我建议的解决方案..！

顺便说一句：使用Control to move周围的active形状很好，但所有其他形状都必须是Drawn到背景上。 （当您完全理解最后一段后，这会更有意义；-）