用C#实现屏幕吸色功能，附逻辑思维讲解图，功能代码不超过50行即可实现

Point p = new Point();
            p.X = MousePosition.X+10;
            p.Y = MousePosition.Y+10;

            Size s = Screen.PrimaryScreen.Bounds.Size;

if (p.X > s.Width - this.Width)
                p.X -= this.Width + 20;
if (p.Y > s.Height - this.Height)
                p.Y -= this.Height + 20;

this.Location = p;

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

namespace LR.Tools
{
///<summary>
/// LR.Tools 的摘要说明
/// 程序: LR.Tools V1.0版
/// Developer: 狼人
/// QQ:459094521  博客: http://www.cnblogs.com/waw/
/// 编写时间: 2009-01-15
///<summary>

public partial class WinEatColor : LR.Tools.MasterForm
    {
        Form f = new Form();
public WinEatColor()
        {
            f.FormBorderStyle = FormBorderStyle.None;//无边框
            f.Cursor = System.Windows.Forms.Cursors.Cross;
            f.WindowState = FormWindowState.Maximized;
            f.Opacity = 0.01;
            f.ShowInTaskbar = false;
            f.Show();

            InitializeComponent();
        }

private void timer1_Tick(object sender, EventArgs e)
        {
//鼠标的坐标
            this.label1.Text = "鼠标坐标："+MousePosition.X+","+MousePosition.Y;
//显示句柄
            this.label3.Text = "句柄：" + LR.Win32API.WindowAPI.WindowFromPoint(MousePosition);
//当前窗体自动跟随鼠标
            this.MoveForm();
//利用API获取当前鼠标坐标点的像素色
            Color c = LR.Win32API.WindowAPI.GetColorOfScreen(MousePosition);
//显示在网页中显示的编码
            this.textBox1.Text = "#"+c.Name.ToUpper().Substring(2);
//显示RGB三位色
            this.txt_RGB.Text = c.R.ToString() + "," + c.G.ToString() + "," + c.B.ToString();
//设置label的颜色
            this.label6.BackColor = c;
//显示放大镜
            this.ShowPictureBox(MousePosition);
        }

void ShowPictureBox(Point p)
        {
//创建一个画布大小和当前屏幕大小一样
            Bitmap bmp = new Bitmap(20,20);
//在这快画布上建立一个绘图对象
            Graphics g = Graphics.FromImage(bmp);
//截取复制当前屏幕内容
            g.CopyFromScreen(p.X-10, p.Y-10, 0,0, bmp.Size);
//以缩略图的形式就放大镜
            Image pThumbnail = bmp.GetThumbnailImage(this.pictureBox1.Width, this.pictureBox1.Height, null, new IntPtr());
//画放大图
            g.DrawImage(bmp, 10, 10, pThumbnail.Width, pThumbnail.Height);
            g.Dispose();

this.pictureBox1.Image = pThumbnail;
            g = Graphics.FromImage(this.pictureBox1.Image);
            g.DrawRectangle(Pens.Black, this.pictureBox1.Width / 2 - 5, this.pictureBox1.Height / 2 - 5, 10, 10);
            g.Dispose();
        }

void MoveForm()
        {
            Point p = new Point();
            p.X = MousePosition.X+10;
            p.Y = MousePosition.Y+10;

            Size s = Screen.PrimaryScreen.Bounds.Size;

if (p.X > s.Width - this.Width)
                p.X -= this.Width + 20;
if (p.Y > s.Height - this.Height)
                p.Y -= this.Height + 20;

this.Location = p;
        }

private void WinEatColor_Load(object sender, EventArgs e)
        {
        }

private void WinEatColor_KeyUp(object sender, KeyEventArgs e)
        {
if (e.KeyCode == Keys.Escape)
this.timer1.Stop();

            Point pCur = MousePosition;
//方向键微调
            if (e.KeyCode == Keys.Up)
                LR.Win32API.WindowAPI.SetCursorPos(pCur.X, pCur.Y - 1);
if (e.KeyCode == Keys.Left)
                LR.Win32API.WindowAPI.SetCursorPos(pCur.X - 1, pCur.Y);
if (e.KeyCode == Keys.Right)
                LR.Win32API.WindowAPI.SetCursorPos(pCur.X + 1, pCur.Y);
if (e.KeyCode == Keys.Down)
                LR.Win32API.WindowAPI.SetCursorPos(pCur.X, pCur.Y + 1);
        }

private void WinEatColor_Deactivate(object sender, EventArgs e)
        {
this.timer1.Stop();
        }

//重拾
        private void button1_Click(object sender, EventArgs e)
        {
this.timer1.Start();
        }

private void textBox1_MouseEnter(object sender, EventArgs e)
        {
this.textBox1.Focus();
this.textBox1.SelectAll();
this.textBox1.Copy();
        }

private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            LR.Win32API.WindowAPI.MouseMoveWindow(this.Handle);
        }

private void WinEatColor_FormClosed(object sender, FormClosedEventArgs e)
        {
            f.Close();
        }
    }
}