1，目的：
- 获取屏幕上任意位置像素的色值。
2，知识点:
- 热键的注册与注销。
/// <summary>/// 热键注册/// </summary>/// <param name="hWnd">要定义热键的窗口的句柄 </param>/// <param name="id">定义热键ID（不能与其它ID重复） </param>/// <param name="fsModifiers">标识热键是否在按Alt、Ctrl、Shift、Windows等键时才会生效 </param>/// <param name="vk">定义热键的内容 </param>/// <returns>如果函数执行成功，返回值不为0。如果函数执行失败，返回值为0。要得到扩展错误信息，调用GetLastError。</returns>[DllImport("user32.dll", SetLastError = true)]public static extern bool RegisterHotKey(IntPtr hWnd, int id, KeyModifiers fsModifiers, Keys vk);/// <summary>/// 热键注销/// </summary>/// <param name="hWnd">要取消热键的窗口的句柄 </param>/// <param name="id">要取消热键的ID </param>/// <returns></returns>[DllImport("user32.dll", SetLastError = true)]public static extern bool UnregisterHotKey(IntPtr hWnd, int id);- 颜色的获取。
/// <summary>/// 在一个指定设备场景中获取一个像素的RGB值/// </summary>/// <param name="hDC">设备场景的句柄</param>/// <param name="XPos">逻辑坐标中要检查点的X坐标</param>/// <param name="YPos">逻辑坐标中要检查点的Y坐标</param>/// <returns>返回一个32位包含ARGB的UInt</returns>[DllImport("gdi32.dll")]static public extern uint GetPixel(IntPtr hDC, int XPos, int YPos);- 获取的颜色值（32位Uint 数据类型），A ,R,G,B分布如下:
与常规A,R,G,B排序有所区别，而且获取的Alpha部分始终为0。
3，效果展示:
4，代码:
public partial class Form1 : Form{public Form1(){InitializeComponent();}Timer t = new Timer() { Interval = 100 };IntPtr displayHwd;private void Form1_Load(object sender, EventArgs e){APIHelper.RegisterHotKey(this.Handle, 81, KeyModifiers.Shift, Keys.C);this.TopMost = checkBox1.Checked;t.Tick += T_Tick;}private void Form1_FormClosing(object sender, FormClosingEventArgs e){APIHelper.UnregisterHotKey(this.Handle, 81);}/// <summary>/// 获取color从左至右第4个byte作为Blue值/// </summary>/// <param name="color"></param>/// <returns></returns>byte GetBlue(uint color){return (byte)(color>>16);}byte GetGreen(uint color){//向右移动8位return (byte)(color >> 8);}byte GetRed(uint color){return (byte)(color);}byte GetAlpha(uint color){return (byte)(color >> 24);}private void checkBox1_CheckedChanged(object sender, EventArgs e){this.TopMost = checkBox1.Checked;}private void btnExit_Click(object sender, EventArgs e){Application.Exit();}private void btnStart_Click(object sender, EventArgs e){if (btnStart.Text == "开始"){t.Start();btnStart.BackColor = Color.LightGreen;btnStart.Text = "停止";displayHwd= APIHelper.CreateDC("DISPLAY", null, null, IntPtr.Zero);}else{btnStart.Text = "开始";t.Stop();btnStart.BackColor = SystemColors.Control;APIHelper.DeleteDC(displayHwd);}}protected override void WndProc(ref Message m){//WM_HOTKEY=0x0312，热键关联的消息IDconst int WM_HOTKEY = 0x0312;//按快捷键 switch (m.Msg){case WM_HOTKEY:switch (m.WParam.ToInt32()){case 81: //按下的是Shift+C Clipboard.SetText(txtColor.Text);break;}break;}base.WndProc(ref m);}List<string> list = new List<string>();private void T_Tick(object sender, EventArgs e){Point mousePoint= Control.MousePosition;txtPoint.Text = $"X:{mousePoint.X},Y:{mousePoint.Y}";if(Control.MouseButtons== MouseButtons.Left){uint colorVal = APIHelper.GetPixel(displayHwd, mousePoint.X, mousePoint.Y);list.Clear();byte[] bytes = BitConverter.GetBytes(colorVal);BitArray array = new BitArray(bytes);foreach (bool bit in array){if (bit){list.Add("1");}else{list.Add("0");}}list.Reverse();txtMonitor.Text = string.Join(" ", list);byte red = GetRed(colorVal);byte green = GetGreen(colorVal);byte blue = GetBlue(colorVal);byte alpha = GetAlpha(colorVal);panel1.BackColor = Color.FromArgb( red, green, blue);txtColor.Text = ColorTranslator.ToHtml(panel1.BackColor).ToString();txtRGB.Text = $"{red},{green},{blue}";btnStart.Text = "开始";t.Stop();btnStart.BackColor = SystemColors.Control;APIHelper.DeleteDC(displayHwd);}}}[Flags()]public enum KeyModifiers{None = 0,Alt = 1,Ctrl = 2,Shift = 4,WindowsKey = 8}class APIHelper{/// <summary>/// 在一个指定设备场景中获取一个像素的RGB值/// </summary>/// <param name="hDC">设备场景的句柄</param>/// <param name="XPos">逻辑坐标中要检查点的X坐标</param>/// <param name="YPos">逻辑坐标中要检查点的Y坐标</param>/// <returns>返回一个32位包含ARGB的UInt</returns>[DllImport("gdi32.dll")]static public extern uint GetPixel(IntPtr hDC, int XPos, int YPos);/// <summary>/// 为专门设备创建设备场景/// </summary>/// <param name="driverName">如果此参数为DISPLAY则代表整个屏幕的设备场景，如果为WINSPOOL则访问打印机驱动</param>/// <param name="deviceName">所用专门设备的名称</param>/// <param name="output">用null给该参数</param>/// <param name="lpinitData">DEVMODE,该结构保存初始值</param>/// <returns>设备场景的句柄</returns>[DllImport("gdi32.dll")]static public extern IntPtr CreateDC(string driverName, string deviceName, string output, IntPtr lpinitData);/// <summary>/// 在一个指定设备场景中获取一个像素的RGB值/// </summary>/// <param name="DC">设备场景的句柄</param>/// <returns></returns>[DllImport("gdi32.dll")]static public extern bool DeleteDC(IntPtr DC);/// <summary>/// 热键注册/// </summary>/// <param name="hWnd">要定义热键的窗口的句柄 </param>/// <param name="id">定义热键ID（不能与其它ID重复） </param>/// <param name="fsModifiers">标识热键是否在按Alt、Ctrl、Shift、Windows等键时才会生效 </param>/// <param name="vk">定义热键的内容 </param>/// <returns>如果函数执行成功，返回值不为0。如果函数执行失败，返回值为0。要得到扩展错误信息，调用GetLastError。</returns>[DllImport("user32.dll", SetLastError = true)]public static extern bool RegisterHotKey(IntPtr hWnd, int id, KeyModifiers fsModifiers, Keys vk);/// <summary>/// 热键注销/// </summary>/// <param name="hWnd">要取消热键的窗口的句柄 </param>/// <param name="id">要取消热键的ID </param>/// <returns></returns>[DllImport("user32.dll", SetLastError = true)]public static extern bool UnregisterHotKey(IntPtr hWnd, int id);}
