一 短消息提示

短消息提示Toast:
用于呈现一条短消息，提示完成后即可自动消失；
特点：
① 弹出式窗口；
② 短文本，可以折行显示；
③ 根据文本长度，自动调整大小；
④ 约1.5后，自动消失；

二 弹出窗口

在Winform中，所有的窗口都用Form实现，比如：
① 常规窗口Window;
② 对话框窗口Dialog；
③ 悬浮窗口FloatWindow;
④ 工具提示Tooltip;
⑤ 弹出式窗口Popup（如菜单窗口、下拉列表窗口）；

自定义一个Form类，即可定义一个窗口

public class myToast:Form
{

}

本窗口不需要边框，位置和大小都是自己控制的。
创建并显示窗口

myToast toast=new myToast();
toast.ShowMessage("This is a totas!");

子窗体代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Text;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace 弹窗提示
{
    public partial class Toast : Form
    {
        private string message;
        public Toast()
        {
            //无边框
            this.FormBorderStyle = FormBorderStyle.None;
            //背景白色
            this.BackColor = Color.White;
        }

        public void ShowMessage(string message)
        {
            this.message = message;

            //手动指定位置
            this.StartPosition = FormStartPosition.Manual;
            this.Location = new Point(0, 0);
            this.Size = new Size(300, 100);

            //显示窗口
            this.Show();
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

            Graphics g = e.Graphics;
            int w = this.Width, h = this.Height;
            Rectangle rect = new Rectangle(0, 0, w, h);
            rect.Inflate(-4, -4);

            //平滑绘制，反锯齿
            g.SmoothingMode = SmoothingMode.HighQuality;
            g.TextRenderingHint = TextRenderingHint.AntiAliasGridFit;

            if(message!=null)
            {
                StringFormat sf = new StringFormat();
                sf.Alignment = StringAlignment.Center;
                sf.LineAlignment = StringAlignment.Center;

                Brush brush = new SolidBrush(Color.Black);
                g.DrawString(message, this.Font, brush, rect, sf);
                brush.Dispose();
            }
        }
    }
}

父窗体代码

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 弹窗提示
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Toast toast = new Toast();
            toast.ShowMessage("This is a toast!");
        }
    }
}

三 窗口位置

toast窗口显示时，相当于主窗口位置居中。
① 找到主窗口，得到主窗口的位置；
② 计算toast窗口的位置；

toast窗口显示时，不剥夺主窗口的焦点，需要重写ShowWithoutActivation

protected override bool ShowWithoutActivation
{
   get
   {
      return true;
   }
}

1 要点与细节

① 已知一个控件Control,可以得到它所在的窗口;

Form form=ctrl.FindForm();

子窗体代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Text;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace 窗口位置
{
    public partial class Toast : Form
    {
        private string message;
        public Toast()
        {
            this.FormBorderStyle = FormBorderStyle.None;
            this.BackColor = Color.White;
            this.ShowInTaskbar = false;
        }
        //owner 可以是子窗口也可以是控件
        public void ShowMessage(Control owner,string message)
        {
            this.message = message;

            this.StartPosition = FormStartPosition.Manual;
            this.Size = new Size(300, 100);

            //找到owner所在的顶级窗口
            Form form = owner.FindForm();
            this.Owner = form;

            //使toast窗口相对主窗口居中
            Rectangle fr = new Rectangle(form.Location, form.Size);
            int x = fr.X + (fr.Width - this.Width) / 2;
            int y = fr.Y + (fr.Width - this.Height) / 2;
            this.Location = new Point(x, y);

            this.Show();
        }

        //焦点控制：本窗口不剥夺主窗口的焦点
        //否则，当toast窗口激活时，主窗口焦点被剥夺
        protected override bool ShowWithoutActivation
        {
            get { return true; }
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

            Graphics g = e.Graphics;
            int w = this.Width, h = this.Height;
            Rectangle rect = new Rectangle(0, 0, w, h);
            rect.Inflate(-4, -4);

            //平滑绘制，反锯齿
            g.SmoothingMode = SmoothingMode.HighQuality;
            g.TextRenderingHint = TextRenderingHint.AntiAliasGridFit;

            if(message!=null)
            {
                StringFormat sf = new StringFormat();
                sf.Alignment = StringAlignment.Center;
                sf.LineAlignment = StringAlignment.Center;

                Brush brush = new SolidBrush(Color.Black);
                g.DrawString(message, this.Font, brush, rect, sf);
                brush.Dispose();
            }
        }
    }
}

父窗体代码

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 窗口位置
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Toast toast = new Toast();
            toast.ShowMessage(button1, "中国人民解放军！");
        }
    }
}

四 窗口大小

Toast的窗口的大小，应该根据消息长度来调整，比如：

toast.ShowMessage(button1,"成功");
toast.ShowMessage(button1,"思密达");
toast.ShowMessage(button1,"编程是一种艺术");

使用Graphics.MeasureString()可以测算文本的尺寸

Graphics g=this.CreateGraphics();
SizeF size=g.MeasureString(str,this.Font,300);
g.Dispose();

注意，临时创建的Graphics用完之后需要手工销毁。