1.创建个C# windows应用

　　2.添加个windows表单Label到Form1.cs

　　3.单击label1Control控件然后更改Text属性为空

　　4.更改BorderStyle属性为FixedSingle

　　5.右键单击Form1.cs然后点击View Code

　　添加下面Using语句到Form1.cs源码顶部

　　6.using .Runtime.InteropServices;

　　注意该步骤添加必要引用来InteropServices和思路方法

　　7.private Bitmap myBitmap;

　　添加下面Win32APICall 类到Form1.cs中Form1类后面

public Win32APICall
{
[DllImport("gdi32.dll",EntryPo="DeleteDC")]
public extern IntPtr DeleteDC(IntPtr hdc);
[DllImport("gdi32.dll",EntryPo="DeleteObject")]
public extern IntPtr DeleteObject(IntPtr hObject);
[DllImport("gdi32.dll",EntryPo="BitBlt")]
public extern bool BitBlt(IntPtr hdcDest, nXDest,
nYDest, nWidth, nHeight,IntPtr hdcSrc,
nXSrc, nYSrc, dwRop);
[DllImport ("gdi32.dll",EntryPo="CreateCompatibleBitmap")]
public extern IntPtr CreateCompatibleBitmap(IntPtr hdc,
nWidth, nHeight);
[DllImport ("gdi32.dll",EntryPo="CreateCompatibleDC")]
public extern IntPtr CreateCompatibleDC(IntPtr hdc);
[DllImport ("gdi32.dll",EntryPo="SelectObject")]
public extern IntPtr SelectObject(IntPtr hdc,IntPtr hgdiobjBmp);
[DllImport("user32.dll", EntryPo="GetDesktopWindow")]
public extern IntPtr GetDesktopWindow;
[DllImport("user32.dll",EntryPo="GetDC")]
public extern IntPtr GetDC(IntPtr hWnd);
[DllImport("user32.dll",EntryPo="GetMetrics")]
public extern GetMetrics( nIndex);
[DllImport("user32.dll",EntryPo="ReleaseDC")]
public extern IntPtr ReleaseDC(IntPtr hWnd,IntPtr hDC);
public Bitmap GetDesktop
{
　 screenX;
　 screenY;
　 IntPtr hBmp;
　 IntPtr hdcScreen = GetDC(GetDesktopWindow);
　 IntPtr hdcCompatible = CreateCompatibleDC(hdcScreen);
　 screenX = GetMetrics(0);
　 screenY = GetMetrics(1);
　 hBmp = CreateCompatibleBitmap(hdcScreen, screenX, screenY);
　 (hBmp!=IntPtr.Zero)
　 {
　　　IntPtr hOldBmp = (IntPtr) SelectObject(hdcCompatible, hBmp);
　　　BitBlt(hdcCompatible, 0, 0,screenX,screenY, hdcScreen, 0, 0,13369376);
　　　SelectObject(hdcCompatible, hOldBmp);
　　　DeleteDC(hdcCompatible);
　　　ReleaseDC(GetDesktopWindow, hdcScreen);
　　　Bitmap bmp = .Drawing.Image.FromHbitmap(hBmp);
　　　DeleteObject(hBmp);
　　　GC.Collect;
　　　 bmp;
　 }
　 null;
　 }
}该步骤添加用于非托管windows GDI API所需变量结构和DllImport语句

　　8.添加下面代码到在第 2步创建标签MouseDown 事件中

　　private void label1_MouseDown(object sender, .Windows.Forms.MouseEventArgs e){　　myBitmap = Win32APICall.GetDesktop;}

　　9.添加下面代码到第 2步创建标签MouseUp 事件中

　　private void label1_MouseUp(object sender, .Windows.Forms.MouseEventArgs e){　　Color myColor = myBitmap.GetPixel(MousePosition.X,MousePosition.Y);　　label1.BackColor = myColor;}

　　10.点击运行单击并保持鼠标按钮在标签上保持按下状态在桌面拖动鼠标指针然后释放鼠标按钮来捕获颜色