c# 可后台截取dx窗口

可以通过使用SharpDX库来后台截取DX窗口。下面是一个示例代码：

using System;
using System.Drawing;
using System.Drawing.Imaging;
using SharpDX;
using SharpDX.Direct3D9;
using SharpDX.Windows;

namespace DXScreenCaptureTest
{
    class Program
    {
        static void Main(string[] args)
        {
            var processName = "myDXProcess"; // 要截取的DX程序进程名
            var adapterIndex = 0; // 显卡索引，如果只有一个显卡则为0

            // 获取DX程序窗口句柄
            IntPtr hWnd = IntPtr.Zero;
            while (true)
            {
                hWnd = User32.FindWindowEx(IntPtr.Zero, hWnd, null, processName);
                if (hWnd == IntPtr.Zero) break;
                if (User32.IsWindowVisible(hWnd))
                {
                    int pid;
                    User32.GetWindowThreadProcessId(hWnd, out pid);
                    if (System.Diagnostics.Process.GetProcessById(pid).ProcessName == processName)
                        break;
                }
            }

            if (hWnd == IntPtr.Zero)
            {
                Console.WriteLine($"未找到进程名为{processName}的DX程序窗口");
                return;
            }

            // 获取DX设备对象
            var config = new PresentParameters()
            {
                BackBufferWidth = 1,
                BackBufferHeight = 1,
                DeviceWindowHandle = hWnd,
                PresentationInterval = PresentInterval.Immediate,
                SwapEffect = SwapEffect.Discard
            };
            var device = new Device(new Direct3D(), adapterIndex, DeviceType.Hardware, IntPtr.Zero, CreateFlags.HardwareVertexProcessing, config);

            // 获取后台缓存表面
            var surface = Surface.CreateOffscreenPlain(device, config.BackBufferWidth, config.BackBufferHeight, Format.A8R8G8B8, Pool.SystemMemory);

            // 截取屏幕并保存到文件
            var bitmap = CaptureSurface(device, surface);
            bitmap.Save("screenshot.png", ImageFormat.Png);

            device.Dispose();
            surface.Dispose();
            bitmap.Dispose();

            Console.WriteLine("截图完成");
        }

        private static Bitmap CaptureSurface(Device device, Surface surface)
        {
            // 将后台缓存表面复制到系统内存表面
            device.GetFrontBufferData(0, surface);

            // 将表面转换为Bitmap
            var dataRectangle = surface.LockRectangle(LockFlags.ReadOnly);
            var bitmap = new Bitmap(dataRectangle.Width, dataRectangle.Height, PixelFormat.Format32bppArgb);
            var bitmapData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);
            Utilities.CopyMemory(bitmapData.Scan0, dataRectangle.DataPointer, dataRectangle.Pitch * dataRectangle.Height);
            surface.UnlockRectangle();
            bitmap.UnlockBits(bitmapData);

            return bitmap;
        }
    }

    static class User32
    {
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);

        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern bool IsWindowVisible(IntPtr hWnd);

        [System.Runtime.InteropServices.DllImport("user32.dll", SetLastError = true)]
        public static extern uint GetWindowThreadProcessId(IntPtr hWnd, out int lpdwProcessId);
    }
}

代码中使用了SharpDX库，需要使用NuGet进行安装。另外，要注意确保程序有足够的权限进行后台截图操作。