class NativeMethods
{
[ComImport]
[Guid("0000010D-0000-0000-C000-000000000046")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
interface IViewObject
{
void Draw([MarshalAs(UnmanagedType.U4)] uint dwAspect, int lindex, IntPtr pvAspect, [In] IntPtr ptd, IntPtr hdcTargetDev, IntPtr hdcDraw, [MarshalAs(UnmanagedType.Struct)] ref RECT lprcBounds, [In] IntPtr lprcWBounds, IntPtr pfnContinue, [MarshalAs(UnmanagedType.U4)] uint dwContinue);
}

[StructLayout(LayoutKind.Sequential, Pack = 4)]
struct RECT
{
public int Left;
public int Top;
public int Right;
public int Bottom;
}

public static void GetImage(object obj, Image destination, Color backgroundColor)
{
using (Graphics graphics = Graphics.FromImage(destination))
{
IntPtr deviceContextHandle = IntPtr.Zero;
RECT rectangle = new RECT();

rectangle.Right = destination.Width;
rectangle.Bottom = destination.Height;

graphics.Clear(backgroundColor);

try
{
deviceContextHandle = graphics.GetHdc();

IViewObject viewObject = obj as IViewObject;
viewObject.Draw(1, -1, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero, deviceContextHandle, ref rectangle, IntPtr.Zero, IntPtr.Zero, 0);
}
finally
{
if (deviceContextHandle != IntPtr.Zero)
{
graphics.ReleaseHdc(deviceContextHandle);
}
}
}
}
}

private void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{

Bitmap screenshot = new Bitmap(webBrowser1.Width, webBrowser1.Height);
NativeMethods.GetImage(webBrowser1.ActiveXInstance, screenshot, Color.White);

// 保存图片
screenshot.Save(@"F:\h11.png");
}