C# WinForm实现窗体上控件自由拖动功能示例

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 WinFormDrag{  public partial class Form1 : Form  {    //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;    public Form1()    {      InitializeComponent();    }    private void Form1_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);        }      }    }    /// <summary>    /// 按下鼠标时    /// </summary>    /// <param name="sender"></param>    /// <param name="e"></param>    private void pb1_MouseDown(object sender, MouseEventArgs e)    {      if (e.Button == MouseButtons.Left)      {        mouseDownPoint = e.Location;        //记录控件的大小        rect = pb1.Bounds;      }    }    /// <summary>    /// 移过时    /// </summary>    /// <param name="sender"></param>    /// <param name="e"></param>    private void pb1_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 - mouseDownPoint.X, e.Location.Y - mouseDownPoint.Y));        this.Refresh();      }    }    /// <summary>    /// 释放鼠标按钮时    /// </summary>    /// <param name="sender"></param>    /// <param name="e"></param>    private void pb1_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          pb1.Location = rect.Location;          this.Refresh();        }        reset();      }    }    //重置变量    private void reset()    {      mouseDownPoint = Point.Empty;      rect = Rectangle.Empty;      isDrag = false;    }    //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(pb1.PointToScreen(p));    }  }}