Takes a screenshot of a Windows Forms control using BitBlt, making it work with CefSharp's WinForms.ChromiumWebBrowser

ControlSnapshot.cs

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Windows.Forms;

public class ControlSnapshot
{
    public static Bitmap Snapshot(Control c)
    {
        int width = 0, height = 0;
        IntPtr hwnd = IntPtr.Zero;
        IntPtr dc = IntPtr.Zero;
        c.Invoke(new MethodInvoker(() => {
            width = c.ClientSize.Width;
            height = c.ClientSize.Height;
            hwnd = c.Handle;
            dc = GetDC(hwnd);
        }));
        Bitmap bmp = new Bitmap(width, height, PixelFormat.Format32bppRgb);
        if (dc != IntPtr.Zero) {
            try {
                using (Graphics g = Graphics.FromImage(bmp)) {
                    IntPtr bdc = g.GetHdc();
                    try {
                        BitBlt(bdc, 0, 0, width, height, dc, 0, 0, TernaryRasterOperations.SRCCOPY);
                    } finally {
                        g.ReleaseHdc(bdc);
                    }
                }
            } finally {
                ReleaseDC(hwnd, dc);
            }
        }
        return bmp;
    }

    [DllImport("user32.dll", SetLastError = true)]
    public static extern IntPtr GetDC(IntPtr hWnd);

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

    [DllImport("gdi32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool BitBlt(IntPtr hdc, int nXDest, int nYDest, int nWidth, int nHeight, IntPtr hdcSrc, int nXSrc, int nYSrc, TernaryRasterOperations dwRop);

    public enum TernaryRasterOperations : uint
    {
        /// <summary>dest = source</summary>
        SRCCOPY = 0x00CC0020,
        /// <summary>dest = source OR dest</summary>
        SRCPAINT = 0x00EE0086,
        /// <summary>dest = source AND dest</summary>
        SRCAND = 0x008800C6,
        /// <summary>dest = source XOR dest</summary>
        SRCINVERT = 0x00660046,
        /// <summary>dest = source AND (NOT dest)</summary>
        SRCERASE = 0x00440328,
        /// <summary>dest = (NOT source)</summary>
        NOTSRCCOPY = 0x00330008,
        /// <summary>dest = (NOT src) AND (NOT dest)</summary>
        NOTSRCERASE = 0x001100A6,
        /// <summary>dest = (source AND pattern)</summary>
        MERGECOPY = 0x00C000CA,
        /// <summary>dest = (NOT source) OR dest</summary>
        MERGEPAINT = 0x00BB0226,
        /// <summary>dest = pattern</summary>
        PATCOPY = 0x00F00021,
        /// <summary>dest = DPSnoo</summary>
        PATPAINT = 0x00FB0A09,
        /// <summary>dest = pattern XOR dest</summary>
        PATINVERT = 0x005A0049,
        /// <summary>dest = (NOT dest)</summary>
        DSTINVERT = 0x00550009,
        /// <summary>dest = BLACK</summary>
        BLACKNESS = 0x00000042,
        /// <summary>dest = WHITE</summary>
        WHITENESS = 0x00FF0062,
        /// <summary>
        /// Capture window as seen on screen.  This includes layered windows
        /// such as WPF windows with AllowsTransparency="true"
        /// </summary>
        CAPTUREBLT = 0x40000000
    }
}