C#实现磁性窗体（吸附、剥离、移动）

最近做东西需要用到这个，网上找了一下有不少人实现了，比如这位兄弟
http://blog.csdn.net/mngzilin/article/details/5549119
但是有个问题，子窗体无法脱离父窗体独立运动，所以自己重写了一个，初步试了一下，效果挺不错的
可以改进，加入吸附桌面边缘等功能

using System;  
using System.Drawing;  
using System.Collections.Generic;  
using System.Windows.Forms;  
  
namespace TinyBook  
{  
    public enum MagneticLocation  
    {  
        Left = 0,  
        Right = 1,  
        Top = 2,  
        Bottom = 3  
    }  
  
    public enum MagneticState  
    {  
        Adsorbent, // 吸附  
        Separation // 分离  
    }  
  
    public class MagneticManager  
    {  
        public class ChildFormInfo  
        {  
            public Form Child { get; set; }  
            public MagneticLocation Location { get; set; }  
            public MagneticState State { get; set; }  
            public bool CutstomSetLocation { get; set; }  
        }  
  
        public int Step { get; set; }  
  
        private Form m_mainForm = null;  
        private List<ChildFormInfo> m_childs= new List<ChildFormInfo>();  
  
        public MagneticManager(Form form)  
        {  
            m_mainForm = form;  
            form.LocationChanged += MainForm_LocationChanged;  
            form.SizeChanged += MainForm_SizeChanged;  
            form.FormClosed += MainForm_FormClosed;  
            Step = 20;  
        }  
  
        public void addChild(Form childForm, MagneticLocation loc)  
        {  
            foreach (ChildFormInfo info in m_childs)  
            {  
                if (info.Child == childForm)  
                {  
                    return;  
                }  
            }  
  
            ChildFormInfo childInfo = new ChildFormInfo();  
            childInfo.Child = childForm;  
            childInfo.Location = loc;  
            childInfo.State = MagneticState.Adsorbent;  
            childInfo.CutstomSetLocation = false;  
            childForm.LocationChanged += ChildForm_LocationChanged;  
            childForm.SizeChanged += ChildForm_SizeChanged;  
            childForm.FormClosed += ChildForm_FormClosed;  
  
            m_childs.Add(childInfo);  
            adsorbentChild(childInfo);  
        }  
  
        private ChildFormInfo getInfo(Form form)  
        {  
            if (form == null)  
            {  
                return null;  
            }  
  
            foreach (ChildFormInfo info in m_childs)  
            {  
                if (info.Child == form)  
                {  
                    return info;  
                }  
            }  
  
            return null;  
        }  
  
        private Point getLocation(ChildFormInfo info)  
        {  
            Point pos = Point.Empty;  
  
            switch (info.Location)  
            {  
                case MagneticLocation.Left:  
                    pos = new Point(m_mainForm.Left - info.Child.Width + 14, m_mainForm.Top);  
                    break;  
                case MagneticLocation.Right:  
                    pos = new Point(m_mainForm.Right - 14, m_mainForm.Top);  
                    break;  
                case MagneticLocation.Top:  
                    pos = new Point(m_mainForm.Left, m_mainForm.Top - info.Child.Height);  
                    break;  
                case MagneticLocation.Bottom:  
                    pos = new Point(m_mainForm.Left, m_mainForm.Bottom);  
                    break;  
                default:  
                    break;  
            }  
  
            return pos;  
        }  
  
        private void setChildLocation(ChildFormInfo info, Point location)  
        {  
            if (info.Child == null)  
            {  
                return;  
            }  
  
            info.CutstomSetLocation = true;  
            info.Child.Location = location;  
            info.CutstomSetLocation = false;  
        }  
  
        private void setChildLocation(ChildFormInfo info, int x, int y)  
        {  
            setChildLocation(info, new Point(x, y));  
        }  
  
        private void resetChildLocation(ChildFormInfo info)  
        {  
            if (info.Child == null)  
            {  
                return;  
            }  
  
            Point pos = getLocation(info);  
            setChildLocation(info, pos);  
        }  
  
        private void adsorbentChild(ChildFormInfo info)  
        {  
            info.State = MagneticState.Adsorbent;  
            resetChildLocation(info);  
        }  
  
        private void separationChild(ChildFormInfo info)  
        {  
            info.State = MagneticState.Separation;  
        }  
  
        private void MainForm_LocationChanged(object sender, EventArgs e)  
        {  
            foreach (ChildFormInfo info in m_childs)  
            {  
                if (info.State == MagneticState.Adsorbent)  
                {  
                    resetChildLocation(info);  
                }  
            }  
        }  
  
        private void MainForm_SizeChanged(object sender, EventArgs e)  
        {  
            foreach (ChildFormInfo info in m_childs)  
            {  
                if (info.State == MagneticState.Adsorbent)  
                {  
                    resetChildLocation(info);  
                }  
            }  
        }  
  
        private void MainForm_FormClosed(object sender, EventArgs e)  
        {  
        }  
  
        private void ChildForm_LocationChanged(object sender, EventArgs e)  
        {  
            ChildFormInfo info = getInfo(sender as Form);  
  
            if (info == null)  
            {  
                return;  
            }  
  
            if (info.CutstomSetLocation == true)  
            {  
                return;  
            }  
  
            Point location = getLocation(info);  
  
            if (info.Child.Left > location.X && info.Location == MagneticLocation.Right)  
            {  
                if (info.Child.Left - location.X > Step)  
                {  
                    separationChild(info);  
                }  
                else  
                {  
                    adsorbentChild(info);  
                }  
            }  
            else if (info.Child.Left < location.X && info.Location == MagneticLocation.Left)  
            {  
                if (info.Child.Left - location.X < -Step)  
                {  
                    separationChild(info);  
                }  
                else  
                {  
                    adsorbentChild(info);  
                }  
            }  
            if (info.Child.Top > location.Y && info.Location == MagneticLocation.Bottom)  
            {  
                if (info.Child.Top - location.Y > Step)  
                {  
                    separationChild(info);  
                }  
                else  
                {  
                    adsorbentChild(info);  
                }  
            }  
            else if (info.Child.Top < location.Y && info.Location == MagneticLocation.Top)  
            {  
                if (info.Child.Top - location.Y < -Step)  
                {  
                    separationChild(info);  
                }  
                else  
                {  
                    adsorbentChild(info);  
                }  
            }  
        }  
  
        private void ChildForm_SizeChanged(object sender, EventArgs e)  
        {  
            ChildFormInfo info = getInfo(sender as Form);  
  
            if (info != null && info.State == MagneticState.Adsorbent)  
            {  
                resetChildLocation(info);  
            }  
        }  
  
        private void ChildForm_FormClosed(object sender, EventArgs e)  
        {  
            ChildFormInfo info = getInfo(sender as Form);  
  
            if (info != null)  
            {  
                m_childs.Remove(info);  
            }  
        }  
    }  
}