.NET获取当前鼠标所在位置像素的颜色

　　本文主要是获得鼠标当前所在位置像素的颜色。说到这里，大家可能还记得PhotoShop中吸管的功能，就是在图片的某一位置点击一下，就能获得那个位置像素的颜色。此程序和吸管的功能相似，不妨先来看下运行效果图：

 

 

 

　　其代码如下所示：

 

class CallWin32GDIAPI
{
        private const int SM_CXSCREEN = 0x00000000;//屏幕的横坐标
        private const int SM_CYSCREEN = 0x00000001;//纵坐标
        private const int SRCCOPY = 0x00CC0020;//光栅操作一参数

        [DllImport("GDI32.dll", EntryPoint = "DeleteDC")]
        public static extern IntPtr DeleteDC(IntPtr hdc);

        [DllImport("GDI32.dll", EntryPoint = "DeleteObject")]
        public static extern IntPtr DeleteObject(IntPtr hObject);

        [DllImport("GDI32.dll", EntryPoint = "BitBlt")]
        public static extern IntPtr BitBlt(IntPtr hdcDest,int nXDest,int nYDest,
                                           int nWidth,int nHight,IntPtr dhcSRC,
                                           int nXSRC,int nYSRC,int dwRop);

        [DllImport("GDI32.dll", EntryPoint = "CreateCompatibleBitmap")]
        public static extern IntPtr CreateCompatibleBitmap(IntPtr hdc, int nWidth, int nHeight);

        [DllImport("GDI32.dll", EntryPoint = "CreateCompatibleDC")]
        public static extern IntPtr CreateCompatibleDC(IntPtr hdc);

        [DllImport("GDI32.dll",EntryPoint="SelectObject")]
        public static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj);

        [DllImport("User32.dll", EntryPoint = "GetDesktopWindow")]
        public static extern IntPtr GetDesktopWindow();

        [DllImport("User32.dll", EntryPoint = "GetDC")]
        public static extern IntPtr GetDC(IntPtr hWnd);

        [DllImport("User32.dll", EntryPoint = "GetSystemMetrics")]
        public static extern IntPtr GetSystemMetrics(int nIndex);

        [DllImport("User32.dll", EntryPoint = "ReleaseDC")]
        public static extern IntPtr ReleaseDC(IntPtr hWnd,IntPtr hdc);

        /// <summary>
        /// 返回像素的颜色
        /// </summary>
        /// <returns></returns>
        internal static Bitmap GetDesktop()
        {
            //屏幕分辨率宽与高,以像素为单位
            int Xscreen;
            int Yscreen;
            IntPtr hBmp;
            //检索指定窗口句柄
            IntPtr hdcScreen = GetDC(GetDesktopWindow());
            //创建一个与设备兼容的内在设备上下文环境
            IntPtr hdcCompatible = CreateCompatibleDC(hdcScreen);
            //得到屏幕分辨率宽与高,以像素为单位
            Xscreen = (int)GetSystemMetrics(SM_CXSCREEN);
            Yscreen = (int)GetSystemMetrics(SM_CYSCREEN);
            //创建与设备相兼容的位图
            hBmp = CreateCompatibleBitmap(hdcScreen, Xscreen, Yscreen);

            if (hBmp != IntPtr.Zero)
            {
                //将位图对象指定到相关的设备上下文环境中
                IntPtr hOldBmp = (IntPtr)SelectObject(hdcCompatible, hBmp);
                //对位图的像素进行转换
                BitBlt(hdcCompatible, 0, 0, Xscreen, Yscreen, hdcScreen, 0, 0, SRCCOPY);
                //SRCCOPY:将源矩形区域直接拷贝到目标矩形区域
                SelectObject(hdcCompatible, hOldBmp);
                //释放系统资源
                DeleteDC(hdcCompatible);
                ReleaseDC(GetDesktopWindow(), hdcScreen);
                //根据返回的句柄创建位图对象
                Bitmap bmp = System.Drawing.Image.FromHbitmap(hBmp);
                DeleteObject(hBmp);
                //强制进行垃圾回收
                GC.Collect();

                return bmp;
            }
            return null;
        }
    }

　　最后，希望转载的朋友能够尊重作者的劳动成果，加上转载地址：http://www.cnblogs.com/hanyonglu/archive/2011/04/12/2014248.html  谢谢。
 

　　完毕。^_^