C#版的颜色拾取器 原理实现以及 源码

【实例简介】

颜色拾取器实例
【实例截图】

【核心代码】

   public partial class FrmGetColor : Form
    {
        public FrmGetColor()
        {
            InitializeComponent();
        }

        #region 定义快捷键
        //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。        
        [DllImport("user32.dll", SetLastError = true)]
        public static extern bool RegisterHotKey(
        IntPtr hWnd,                //要定义热键的窗口的句柄            
        int id,                     //定义热键ID（不能与其它ID重复）                       
        KeyModifiers fsModifiers,   //标识热键是否在按Alt、Ctrl、Shift、Windows等键时才会生效         
        Keys vk                     //定义热键的内容            
    );
        [DllImport("user32.dll", SetLastError = true)]
        public static extern bool UnregisterHotKey(
            IntPtr hWnd,                //要取消热键的窗口的句柄            
            int id                      //要取消热键的ID            
        );
        //定义了辅助键的名称（将数字转变为字符以便于记忆，也可去除此枚举而直接使用数值）        
        [Flags()]
        public enum KeyModifiers
        {
            None = 0,
            Alt = 1,
            Ctrl = 2,
            Shift = 4,
            WindowsKey = 8
        }
        #endregion



          [DllImport("gdi32.dll")]   
          static public extern uint GetPixel(IntPtr hDC,int XPos,int YPos);   
          [DllImport("gdi32.dll")]   
          static public extern  IntPtr CreateDC(string driverName,string deviceName,string output,IntPtr lpinitData);   
          [DllImport("gdi32.dll")]   
          static public extern bool DeleteDC(IntPtr DC);   
          static public byte GetRValue(uint color)   
          {   
              return (byte)color;   
          }   
          static public byte GetGValue(uint color)   
          {   
              return ((byte)(((short)(color))>>8));   
          }    
          static public byte GetBValue(uint color)   
          {   
             return ((byte)((color)>>16));   
          }    
          static public byte GetAValue(uint color)   
          {   
             return ((byte)((color)>>24));   
          }    
          public Color GetColor(Point screenPoint)   
          {   
              IntPtr displayDC = CreateDC("DISPLAY",null,null,IntPtr.Zero);   
              uint   colorref   =   GetPixel(displayDC,screenPoint.X,screenPoint.Y);   
              DeleteDC(displayDC);   
              byte   Red   =   GetRValue(colorref);   
              byte   Green   =   GetGValue(colorref);   
              byte   Blue   =   GetBValue(colorref);   
              return Color.FromArgb(Red,   Green,   Blue);   
          }   

        private void FrmGetColor_Load(object sender, EventArgs e)
        {
            this.TopMost = true;
        }

        private void checkBox1_CheckedChanged(object sender, EventArgs e)
        {
            if (checkBox1.Checked == true)
            {
                this.TopMost = true;
            }
            else
            {
                this.TopMost = false;
            }
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            txtPoint.Text=Control.MousePosition.X.ToString() "," Control.MousePosition.Y.ToString();
            Point pt = new Point(Control.MousePosition.X, Control.MousePosition.Y);
            Color cl = GetColor(pt);
            panel1.BackColor = cl;
            txtRGB.Text = cl.R   ","   cl.G   ","   cl.B;
            txtColor.Text = ColorTranslator.ToHtml(cl).ToString();
            RegisterHotKey(Handle, 81, KeyModifiers.Ctrl, Keys.F);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            AboutBox1 ab = new AboutBox1();
            ab.ShowDialog();
        }

        private void label3_Click(object sender, EventArgs e)
        {
            System.Diagnostics.Process.Start("http://www.mrbccd.com");
        }
        protected override void WndProc(ref Message m)
        {
            const int WM_HOTKEY = 0x0312;
            //按快捷键     
            switch (m.Msg)
            {
                case WM_HOTKEY:
                    switch (m.WParam.ToInt32())
                    {
                        case 81:    //按下的是CTRL F     
                            Clipboard.SetText(txtColor.Text.Trim());
                            break;
                    }
                    break;
            }
            base.WndProc(ref m);
        }

        private void FrmGetColor_Leave(object sender, EventArgs e)
        {

        }

        private void FrmGetColor_FormClosed(object sender, FormClosedEventArgs e)
        {
            //注销Id号为81的热键设定    
            UnregisterHotKey(Handle, 81);
        }
    }