关于颜色
设置form颜色：
public Form1()
  {
  InitializeComponent();
  this.BackColor = System.Drawing.Color.White;//白色
  }

然后：
  [DllImport("user32.dll", CharSet = CharSet.Auto)]
  public static extern IntPtr GetDC(IntPtr hWnd);

  [DllImport("gdi32.dll")]
  public static extern uint GetPixel(IntPtr hDC, int XPos, int YPos);

  [DllImport("user32.dll", CharSet = CharSet.Auto)]
  public static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);


 protected override void OnPaint(PaintEventArgs e)
  {
  base.OnPaint(e);
  IntPtr _DC = GetDC(this.Handle);
  System.Drawing.Graphics formGraphics = e.Graphics;
  System.Drawing.Pen myPen = new System.Drawing.Pen(System.Drawing.Color.Red, 1);//画笔颜色为红色
  formGraphics.DrawLine(myPen, 8, 8 , 14 , 8 );//画一条红线
  uint _ColorLong1 = GetPixel(_DC, 9, 9); //提取线上一点的颜色  
  Color _Color1 = Color.FromArgb((int)_ColorLong1 & 0xFF, (int)(_ColorLong1 & 0xFF00) / 256, (int)(_ColorLong1 & 0xFF0000) / 65536);
  if (_Color1.ToArgb().Equals(Color.Black.ToArgb()))//怎么这时_Color1的ARGB的值为（255，255，255，255）而不是红色的值（255，255，0，0）


请问是怎么回事啊，期待大牛们指导，急啊

------解决方案--------------------
private void Form1_Paint(object sender, PaintEventArgs e)
{
IntPtr _DC = Zgke.SysInfo.WindowsAPI.Win32API.GetDC(this.Handle);
System.Drawing.Graphics formGraphics = e.Graphics;
System.Drawing.Pen myPen = new System.Drawing.Pen(Color.FromArgb(255, 255, 0, 0), 1);//画笔颜色为红色 
formGraphics.DrawLine(myPen, 8, 8, 14, 8);//画一条红线 
// uint _ColorLong1 = GetPixel(_DC, 9, 9); //提取线上一点的颜色

uint _ColorLong1 = Zgke.SysInfo.WindowsAPI.Win32API.GetPixel(_DC, 9, 8); //提取线上一点的颜色
Color _Color1 = Color.FromArgb((int)_ColorLong1 & 0xFF, (int)(_ColorLong1 & 0xFF00) / 256, (int)(_ColorLong1 & 0xFF0000) / 65536);

textBox1.Text = _Color1.ToString();
} 

我获取到的是 A255 R255 G0 B0 是没问题的.