win32-automation-agent/Domain/DesktopHandler.cs

using AutoAgent.Domain.Exceptions;
using System.Drawing;
using System.Drawing.Imaging;
using System.Text;

namespace AutoAgent.Domain
{
    public static class DesktopHandler
    {
        private static Rectangle GetCaptureArea(IntPtr hwnd, Models.Point pt, Models.AreaSize size)
        {
            Rectangle area;

            if (hwnd == IntPtr.Zero)
            {
                area = Rectangle.FromLTRB(User32Dll.GetSystemMetrics(76), 
                                          User32Dll.GetSystemMetrics(77), 
                                          User32Dll.GetSystemMetrics(78), 
                                          User32Dll.GetSystemMetrics(79));
            }
            else
            {
                if (User32Dll.GetClientRect(hwnd, out var rect))
                {
                    User32Dll.RECT br = new () { X = rect.Right, Y = rect.Bottom };

                    if (User32Dll.ClientToScreen(hwnd, ref rect) && User32Dll.ClientToScreen(hwnd, ref br))
                    {
                        area = new Rectangle(rect.X, rect.Y, br.X - rect.X, br.Y - rect.Y);
                    }
                    else
                    {
                        throw new CaptureAreaException($"Could not convert client coordinates to screen coordinates for HWND: {hwnd}");
                    }
                }
                else
                {
                    throw new CaptureAreaException($"Failed to get client rectangle for HWND: {hwnd}");
                }
            }

            if (size.Width > 0 && size.Height > 0)
            {
                area = new Rectangle(
                    Math.Max(area.X, area.X + pt.X),
                    Math.Max(area.Y, area.Y + pt.Y),
                    Math.Min(size.Width, area.Right - pt.X),
                    Math.Min(size.Height, area.Bottom - pt.Y));
            }

            if (area.Width <= 0 || area.Height <= 0)
            {
                throw new CaptureAreaException($"Final capture rectangle has invalid dimensions: {area}");
            }

            return area;
        }

        private static bool GetWindowInfo(ref Models.WindowInfo data, IntPtr hwnd)
        {
            int length = User32Dll.GetWindowTextLength(hwnd);

            if (length > 0)
            {
                var sb = new StringBuilder(length + 1);
                User32Dll.GetWindowText(hwnd, sb, sb.Capacity);
                data.Title = sb.ToString();

                if (User32Dll.GetCursorPos(out var pt) && User32Dll.ScreenToClient(hwnd, ref pt))
                {
                    data.CursorPosition = new Models.Point { X = pt.X, Y = pt.Y };
                }

                if (User32Dll.GetWindowRect(hwnd, out var wRect))
                {
                    var rect = Rectangle.FromLTRB(wRect.Left, wRect.Top, wRect.Right, wRect.Bottom);
                    data.WindowPosition = new Models.Point { X = rect.X, Y = rect.Y };
                    data.WindowSize = new Models.AreaSize { Width = rect.Width, Height = rect.Height };
                }

                if (User32Dll.GetClientRect(hwnd, out var cRect))
                {
                    var rect = Rectangle.FromLTRB(cRect.Left, cRect.Top, cRect.Right, cRect.Bottom);
                    data.ContentSize = new Models.AreaSize { Width = rect.Width, Height = rect.Height };
                }

                return true;
            }

            return false;
        }

        private static bool TryGetWindowInfo(IntPtr hwnd, ref IntPtr foreground, out Models.WindowInfo info)
        {
            info = new();

            if (User32Dll.IsWindowVisible(hwnd))
            {
                info.Hwnd = hwnd.ToInt32();

                if ((info.ThreadId = (int)User32Dll.GetWindowThreadProcessId(hwnd, out uint pid)) != 0)
                {
                    info.Pid = (int)pid;

                    if (GetWindowInfo(ref info, hwnd))
                    {
                        info.IsActive = foreground.ToInt32() == info.Hwnd;
                        return true;
                    }
                }
            }

            return false;
        }

        public static Task<IEnumerable<Models.WindowInfo>> GetWindows(ushort max = 0, IEnumerable<int>? whitelist = null)
        {
            if (max == 0) max = UInt16.MaxValue;
            if (whitelist == null) whitelist = Array.Empty<int>();

            return Task.Run(() =>
            {
                var foreground = User32Dll.GetForegroundWindow();
                List<Models.WindowInfo> container = new();

                User32Dll.EnumWindows(delegate (IntPtr hwnd, IntPtr lParam)
                {
                    bool found = true;
                    if (container.Count >= max) return false;

                    foreach (var w in whitelist)
                    {
                        if (w == hwnd.ToInt32())
                        {
                            found = true;
                            break;
                        }
                        found = false;
                    }

                    if (found && TryGetWindowInfo(hwnd, ref foreground, out var info))
                    {
                        container.Add(info);
                    }
                    
                    return true;
                }, IntPtr.Zero);

                return (IEnumerable<Models.WindowInfo>)container;
            });
        }

        public static Task<(Models.AreaSize size, byte[] pngImage)> GetScreenshot(Models.Point pos, Models.AreaSize size, IntPtr hwnd = 0)
        {
            return Task.Run(() =>
            {
                Rectangle area = GetCaptureArea(hwnd, pos, size);

                using (Bitmap screenshot = new Bitmap(area.Width, area.Height, PixelFormat.Format32bppArgb))
                {
                    using (Graphics g = Graphics.FromImage(screenshot))
                    {
                        g.CopyFromScreen(area.X, area.Y, 0, 0, area.Size, CopyPixelOperation.SourceCopy);
                    }

                    using (MemoryStream ms = new MemoryStream())
                    {
                        screenshot.Save(ms, ImageFormat.Png);

                        return (new Models.AreaSize { Width = screenshot.Width, Height = screenshot.Height }, ms.ToArray());
                    }
                }
            });
        }

        public static Task<(byte r, byte g, byte b)> GetPixelColor(Models.Point pos, IntPtr hwnd = 0)
        {
            return Task.Run(() =>
            {
                Rectangle area = GetCaptureArea(hwnd, pos, new Models.AreaSize { Width = 1, Height = 1 });

                using (Bitmap screenPixel = new Bitmap(1, 1))
                {
                    using (Graphics g = Graphics.FromImage(screenPixel))
                    {
                        g.CopyFromScreen(area.Left, area.Top, 0, 0, screenPixel.Size);
                    }

                    var color = screenPixel.GetPixel(0, 0);
                    return (color.R, color.G, color.B);
                }
            });
        }
    }
}