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实现功能：实现自由拖拽控件，按住鼠标控件拖拽时有黑框显示，松开鼠标控件位置即为黑框位置

实现思路：在按住鼠标时，得到所点击控件的Size以及Location，在鼠标移动时，得到鼠标的坐标，并且在光标坐标处绘制一个与控件大小相同的黑框，松开鼠标时得到黑框的Location，并将黑框的坐标值赋值给控件坐标，即实现了控件拖拽

效果图：

直接上代码，代码中解释的很详细了。我这里是把控件都放在gbConfig容器中的，所以记得加上gbConfig控件的Paint事件

//记录鼠标拖放Point po = Point.Empty;//生成的控件Label lbl = null;//鼠标按下坐标（control控件的相对坐标） Point mouseDownPoint = Point.Empty;//显示拖动效果的矩形 Rectangle rect = Rectangle.Empty;//是否正在拖拽 bool isDrag = false;private void Form1_Load(object sender, EventArgs e){    CreateControls();    this.gbConfig.AllowDrop = true;}/// 
/// 生成三个label控件/// 
private void CreateControls(){    int x = 10;    int y = 20;    int xx = 0;    for (int i = 0; i < 3; i++)    {        string lbltext = "序号" + xx;        string lblname = "lbl" + xx;        lbl = new Label();        lbl.Left = x;        lbl.Top = y;        lbl.Font = new Font("楷书", 14, FontStyle.Bold);        lbl.Name = lblname;        lbl.Text = lbltext;        lbl.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;        lbl.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;        x += lbl.Width + 5;        if (lbl.Width > gbConfig.Width - x)        {            x = 10;            y += lbl.Height + 10;        }        lbl.AllowDrop = false; // 默认为 false,即不可拖动        lbl.MouseDown += new MouseEventHandler(lbl_MouseDown);        lbl.MouseUp += new MouseEventHandler(lbl_MouseUp);        lbl.MouseMove += new MouseEventHandler(lbl_MouseMove);        this.gbConfig.Controls.Add(lbl);        xx++;    }}/// 
/// 鼠标拖动控件操作/// 
/// /// private void lbl_MouseDown(object sender, MouseEventArgs e){    if (e.Button == MouseButtons.Left)    {        lbl = (Label)sender;        //记录控件的大小         rect = lbl.Bounds;        po = e.Location;//鼠标点击时相对于控件的位置进行记录    }}private void lbl_MouseUp(object sender, MouseEventArgs e){    if (e.Button == MouseButtons.Left)    {        if (isDrag)        {            isDrag = false;            //移动control到放开鼠标的地方             lbl.Location = rect.Location;            this.Refresh();        }        reset();    }}private void lbl_MouseMove(object sender, MouseEventArgs e){    if (e.Button == MouseButtons.Left)    {        isDrag = true;        //重新设置rect的位置，跟随鼠标移动         rect.Location = getPointToForm(new Point(e.Location.X - gbConfig.Location.X-po.X, e.Location.Y - gbConfig.Location.Y- po.Y));        this.Refresh();    }}//把相对与control控件的坐标，转换成相对于窗体的坐标。private Point getPointToForm(Point p){    return this.PointToClient(lbl.PointToScreen(p));}//重置变量 private void reset(){    rect = Rectangle.Empty;    isDrag = false;}/// 
/// 绘制黑框/// 
/// /// private void gbConfig_Paint(object sender, PaintEventArgs e){    if (rect != Rectangle.Empty)    {        if (isDrag)        {//画一个和Control一样大小的黑框             e.Graphics.DrawRectangle(Pens.Black, rect);        }        else        {            e.Graphics.DrawRectangle(new Pen(this.BackColor), rect);        }    }}

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