C#獲取鼠標所指像素的顏色

1.創建一個C# Windows應用程序

2.添加一個Windows表單Label到Form1.cs

3.單擊label1控件然後更改Text屬性為空字符

4.更改BorderStyle屬性為FixedSingle

5.右鍵單擊Form1.cs，然後點擊VIEw Code

添加下面Using語句到Form1.cs源碼的頂部

6.using System.Runtime.InteropServices;

注意該步驟添加必要的引用來調用InteropServices函數和方法

7.private Bitmap myBitmap;

添加下面的Win32APICall 類到Form1.cs中的Form1類後面

public class Win32APICall
{
[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 bool BitBlt(IntPtr hdcDest,int nXDest,
int nYDest,int nWidth,int nHeight,IntPtr hdcSrc,
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 hgdiobjBmp);
[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 int GetSystemMetrics(int nIndex);
[DllImport("user32.dll",EntryPoint="ReleaseDC")]
public static extern IntPtr ReleaseDC(IntPtr hWnd,IntPtr hDC);
public static Bitmap GetDesktop()
{
　 int screenX;
　 int screenY;
　 IntPtr hBmp;
　 IntPtr hdcScreen = GetDC(GetDesktopWindow());
　 IntPtr hdcCompatible = CreateCompatibleDC(hdcScreen);
　 screenX = GetSystemMetrics(0);
　 screenY = GetSystemMetrics(1);
　 hBmp = CreateCompatibleBitmap(hdcScreen, screenX, screenY);
　 if (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 = System.Drawing.Image.FromHbitmap(hBmp);
　　　DeleteObject(hBmp);
　　　GC.Collect();
　　　return bmp;
　 }
　 return null;
　 }
}

該步驟添加用於調用非托管Windows GDI API函數所需的變量，結構和DllImport語句

8.添加下面代碼到在第二步創建的標簽的MouseDown 事件中

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

9.添加下面代碼到第二步創建的標簽的MouseUp 事件中

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

10.點擊運行，單擊並保持鼠標按鈕在標簽上保持按下狀態，在桌面拖動鼠標指針，然後釋放鼠標按鈕來捕獲顏色