better-genshin-impact/Vision.WindowCapture/BitBlt/BitBltCapture.cs

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Reflection.Metadata;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using Vanara.Extensions;
using Vanara.PInvoke;

namespace Vision.WindowCapture.BitBlt
{
    public class BitBltCapture : IWindowCapture
    {
        private IntPtr _hWnd;
        public bool IsCapturing { get; private set; }

        public void Start(IntPtr hWnd)
        {
            _hWnd = hWnd;
            IsCapturing = true;
        }

        public Bitmap? Capture()
        {
            if (_hWnd == IntPtr.Zero)
            {
                return null;
            }

            User32.GetWindowRect(_hWnd, out var windowRect);
            var width = windowRect.right - windowRect.left;
            var height = windowRect.bottom - windowRect.top;

            var hdcSrc = User32.GetWindowDC(_hWnd);
            var hdcDest = Gdi32.CreateCompatibleDC(hdcSrc);
            var hBitmap = Gdi32.CreateCompatibleBitmap(hdcSrc, width, height);
            var hOld = Gdi32.SelectObject(hdcDest, hBitmap);
            Gdi32.BitBlt(hdcDest, 0, 0, width, height, hdcSrc, 0, 0, Gdi32.RasterOperationMode.SRCCOPY);
            Gdi32.SelectObject(hdcDest, hOld);
            Gdi32.DeleteDC(hdcDest);
            User32.ReleaseDC(_hWnd, hdcSrc);

            var bitmap = hBitmap.ToBitmap();
            Gdi32.DeleteObject(hBitmap);
            return bitmap;
        }

        public void Stop()
        {
            _hWnd = IntPtr.Zero;
            IsCapturing = false;
        }
    }
}