c#根据窗口句柄获取窗口截图

可以使用C#中的System.Drawing.Bitmap类和Win32 API来获取窗口截图。具体的代码如下：

using System;
using System.Drawing;
using System.Runtime.InteropServices;

public class WindowCapture
{
    [DllImport("User32.dll")]
    public static extern IntPtr GetDC(IntPtr hwnd);

    [DllImport("User32.dll")]
    public static extern void ReleaseDC(IntPtr hwnd, IntPtr dc);

    [DllImport("gdi32.dll")]
    public static extern IntPtr CreateCompatibleBitmap(IntPtr dc, int width, int height);

    [DllImport("gdi32.dll")]
    public static extern IntPtr CreateCompatibleDC(IntPtr dc);

    [DllImport("gdi32.dll")]
    public static extern IntPtr SelectObject(IntPtr dc, IntPtr obj);

    [DllImport("gdi32.dll")]
    public static extern bool BitBlt(IntPtr dcDest, int xDest, int yDest, int wDest, int hDest, IntPtr dcSrc, int xSrc, int ySrc, int rasterOp);

    public static Bitmap CaptureWindow(IntPtr hwnd)
    {
        // 获取窗口的设备上下文
        IntPtr hdcSrc = GetDC(hwnd);
        if (hdcSrc == IntPtr.Zero)
        {
            return null;
        }

        // 创建一个兼容的设备上下文和位图
        IntPtr hdcDest = CreateCompatibleDC(hdcSrc);
        IntPtr hbmDest = CreateCompatibleBitmap(hdcSrc, 100, 100);
        if (hdcDest == IntPtr.Zero || hbmDest == IntPtr.Zero)
        {
            ReleaseDC(hwnd, hdcSrc);
            return null;
        }

        // 将位图选入设备上下文
        IntPtr hbmOld = SelectObject(hdcDest, hbmDest);

        // 复制窗口的内容到位图中
        if (!BitBlt(hdcDest, 0, 0, 100, 100, hdcSrc, 0, 0, 0x00CC0020))
        {
            SelectObject(hdcDest, hbmOld);
            DeleteObject(hbmDest);
            DeleteDC(hdcDest);
            ReleaseDC(hwnd, hdcSrc);
            return null;
        }

        // 恢复设备上下文并释放资源
        SelectObject(hdcDest, hbmOld);
        DeleteObject(hbmDest);
        DeleteDC(hdcDest);
        ReleaseDC(hwnd, hdcSrc);

        // 返回位图
        return Bitmap.FromHbitmap(hbmDest);
    }
}

使用方法：

IntPtr hwnd = // 窗口句柄
Bitmap bmp = WindowCapture.CaptureWindow(hwnd);

其中，hwnd为窗口句柄，bmp为获取到的窗口截图。请注意，此代码仅支持获取窗口的静态截图，无法实时获取窗口的内容。