c#winform【仿QQ收缩窗体】功能实现

        最近客户提出一个需求，要实现类似QQ收缩窗体的功能。具体来说就是拖动窗体标题栏到屏幕顶部，松开鼠标，鼠标移出窗体区域后，窗体会自动收缩到屏幕边上。

        主体功能实现起来相对比较容易，因为我在网上能找到现成的代码，是参考了这篇文章C#中winform窗口做成QQ窗口那样能收缩在电脑屏幕的上方-优快云博客。但是实际使用过程中又遇到一些坑：

1、windows系统有个默认操作，就是拖动窗体到屏幕顶上，自动变成最大化。处理起来相对简单，就是禁止窗口最大化。

this.MaximizeBox = false;

2、收缩后的窗体，虽然有露出一点在界面上，但是比较难找到。处理起来就麻烦点，参照QQ的做法，在桌面右下角增加系统托盘，双击托盘也可以展开窗体。

全部项目代码如下：

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

namespace WindowsFormsApp2
{
    public partial class Form1 : Form
    {
        System.Windows.Forms.Timer StopRectTimer;
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            this.Text = "仿QQ收缩窗体";
            //实现类似QQ一样的面板收缩到屏幕边上
            this.MaximizeBox = false;//禁止最大化，以免拖动标题栏到顶部的时候自动最大化
            StopRectTimer = new System.Windows.Forms.Timer();
            StopRectTimer.Tick += new EventHandler(timer1_Tick);
            StopRectTimer.Interval = 50;
            StopRectTimer.Enabled = true;
            this.TopMost = true;
            StopRectTimer.Start();

            NotifyIcon MyNotifyIcon = new NotifyIcon();//实例化

            MyNotifyIcon.Visible = true;//可见性
            MyNotifyIcon.Text = this.Text;//鼠标放在托盘时显示的文字
            MyNotifyIcon.BalloonTipText = this.Text;//气泡显示的文字
            MyNotifyIcon.ShowBalloonTip(1000);//托盘气泡的显现时间
            MyNotifyIcon.Icon = this.Icon;//托盘的外观（系统）

            ContextMenu cm = new ContextMenu();
            MenuItem mi = new MenuItem("退出");
            mi.Click += Mi_Click;
            cm.MenuItems.Add(mi);//添加托盘菜单项  
            MyNotifyIcon.ContextMenu = cm;//托盘菜单项在图标右键时显示  
            MyNotifyIcon.MouseDoubleClick += MyNotifyIcon_MouseDoubleClick;//托盘的鼠标窗机时间注册方法  
        }

        private void Mi_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void MyNotifyIcon_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            StopRectTimer.Enabled = false;
            switch (this.StopAanhor)
            {
                case AnchorStyles.Top:
                    this.Location = new Point(this.Location.X, 0);
                    break;
                case AnchorStyles.Left:
                    this.Location = new Point(0, this.Location.Y);
                    break;
                case AnchorStyles.Right:
                    this.Location = new Point(Screen.PrimaryScreen.Bounds.Width - this.Width, this.Location.Y);
                    break;
                case AnchorStyles.Bottom:
                    this.Location = new Point(this.Location.X, Screen.PrimaryScreen.Bounds.Height - this.Height);
                    break;
            }
            MethodInvoker mi = new MethodInvoker(async () =>
            {
                // 延迟5秒
                await Task.Delay(5000);
                StopRectTimer.Enabled=true;
            });
            this.BeginInvoke(mi);
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            if (this.Bounds.Contains(Cursor.Position))
            {
                switch (this.StopAanhor)
                {
                    case AnchorStyles.Top:
                        this.Location = new Point(this.Location.X, 0);
                        break;
                    case AnchorStyles.Left:
                        this.Location = new Point(0, this.Location.Y);
                        break;
                    case AnchorStyles.Right:
                        this.Location = new Point(Screen.PrimaryScreen.Bounds.Width - this.Width, this.Location.Y);
                        break;
                    case AnchorStyles.Bottom:
                        this.Location = new Point(this.Location.X, Screen.PrimaryScreen.Bounds.Height - this.Height);
                        break;
                }
            }
            else
            {
                switch (this.StopAanhor)
                {
                    case AnchorStyles.Top:
                        this.Location = new Point(this.Location.X, (this.Height - 8) * (-1));
                        break;
                    case AnchorStyles.Left:
                        this.Location = new Point((-1) * (this.Width - 8), this.Location.Y);
                        break;
                    case AnchorStyles.Right:
                        this.Location = new Point(Screen.PrimaryScreen.Bounds.Width - 8, this.Location.Y);
                        break;
                    case AnchorStyles.Bottom:
                        this.Location = new Point(this.Location.X, (Screen.PrimaryScreen.Bounds.Height - 8));
                        break;
                }
            }

        }

        internal AnchorStyles StopAanhor = AnchorStyles.None;
        private void mStopAnhor()
        {
            if (this.Top <= 0 && this.Left <= 0)
            {
                StopAanhor = AnchorStyles.None;
            }
            else if (this.Top <= 0)
            {
                StopAanhor = AnchorStyles.Top;
            }
            else if (this.Left <= 0)
            {
                StopAanhor = AnchorStyles.Left;
            }
            else if (this.Left >= Screen.PrimaryScreen.Bounds.Width - this.Width)
            {
                StopAanhor = AnchorStyles.Right;
            }
            else if (this.Top >= Screen.PrimaryScreen.Bounds.Height - this.Height)
            {
                StopAanhor = AnchorStyles.Bottom;
            }
            else
            {
                StopAanhor = AnchorStyles.None;
            }
        }

        private void Form1_LocationChanged(object sender, EventArgs e)
        {
            this.mStopAnhor();
        }

    }
}