CPF/CPF.Windows/ScreenImpl.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Text;
using CPF.Drawing;
using CPF.Platform;
using static CPF.Windows.UnmanagedMethods;

namespace CPF.Windows
{
    public class ScreenImpl : Screen
    {
        private readonly IntPtr _hMonitor;
        public ScreenImpl(Rect bounds, Rect workingArea, bool primary, IntPtr hMonitor) : base(bounds, workingArea, primary)
        {
            this._hMonitor = hMonitor;
        }

        //public IReadOnlyList<Screen> GetAllScreens()
        //{
        //    var ScreenCount = GetSystemMetrics(SystemMetric.SM_CMONITORS);
        //    List<Screen> screens = new List<Screen>();
        //    EnumDisplayMonitors(IntPtr.Zero, IntPtr.Zero,
        //        (IntPtr monitor, IntPtr hdcMonitor, ref Rect lprcMonitor, IntPtr data) =>
        //        {
        //            screens.Add(FromMonitor(monitor, hdcMonitor));
        //            return true;
        //        }, IntPtr.Zero);
        //    return screens;
        //}

        public static Screen FromMonitor(IntPtr monitor, IntPtr hdc)
        {
            MONITORINFO monitorInfo = MONITORINFO.Create();
            if (GetMonitorInfo(monitor, ref monitorInfo))
            {
                RECT bounds = monitorInfo.rcMonitor;
                RECT workingArea = monitorInfo.rcWork;
                Rect cBounds = new Rect(bounds.left, bounds.top, bounds.right - bounds.left,
                    bounds.bottom - bounds.top);
                Rect cWorkArea =
                    new Rect(workingArea.left, workingArea.top, workingArea.right - workingArea.left,
                        workingArea.bottom - workingArea.top);

                return new ScreenImpl(cBounds, cWorkArea, monitorInfo.dwFlags == 1,
                     monitor);
            }
            return null;
        }

        public override int GetHashCode()
        {
            return (int)_hMonitor;
        }

        public override bool Equals(object obj)
        {
            return (obj is ScreenImpl screen) ? this._hMonitor == screen._hMonitor : base.Equals(obj);
        }

        public override Bitmap Screenshot()
        {
            IntPtr desktopHwnd = GetDesktopWindow();
            IntPtr desktopDc = GetWindowDC(desktopHwnd);
            IntPtr memDc = CreateCompatibleDC(desktopDc);

            try
            {
                // 3. 创建DIBSection (24位真彩色位图)
                BITMAPINFOHEADER bmi = new BITMAPINFOHEADER
                {
                    biSize = (uint)Marshal.SizeOf(typeof(BITMAPINFOHEADER)),
                    biWidth = (int)Bounds.Width,
                    biHeight = -(int)Bounds.Height,  // 负值表示自顶向下DIB
                    biPlanes = 1,
                    biBitCount = 24,
                    biCompression = 0,   // BI_RGB
                    biSizeImage = (uint)(((int)Bounds.Width * 3 + 3) & ~3) * (uint)Bounds.Height // 行对齐到4字节
                }
                ;

                IntPtr hBitmap = CreateDIBSection(desktopDc, ref bmi, 0, out var bitsPtr, IntPtr.Zero, 0);

                // 4. 将屏幕内容复制到位图
                IntPtr oldBitmap = SelectObject(memDc, hBitmap);
                BitBlt(memDc, 0, 0, (int)Bounds.Width, (int)Bounds.Height, desktopDc, 0, 0, TernaryRasterOperations.SRCCOPY | TernaryRasterOperations.CAPTUREBLT);
                SelectObject(memDc, oldBitmap);

                // 5. 构造BMP文件
                using (MemoryStream ms = new MemoryStream())
                {
                    // 5.1 计算文件大小
                    uint pixelDataSize = bmi.biSizeImage;
                    uint fileSize = (uint)(Marshal.SizeOf(typeof(BITMAPFILEHEADER)) +
                    (Marshal.SizeOf(typeof(BITMAPINFOHEADER))) +
                    pixelDataSize);

                    // 5.2 创建文件头
                    BITMAPFILEHEADER fileHeader = new BITMAPFILEHEADER
                    {
                        bfType = 0x4D42, // "BM"
                        bfSize = fileSize,
                        bfOffBits = (uint)(Marshal.SizeOf(typeof(BITMAPFILEHEADER)) +
(Marshal.SizeOf(typeof(BITMAPINFOHEADER))))
                    }
                    ;

                    // 5.3 写入文件头
                    byte[] fileHeaderBytes = StructureToBytes(fileHeader);
                    ms.Write(fileHeaderBytes, 0, fileHeaderBytes.Length);

                    // 5.4 写入信息头
                    byte[] infoHeaderBytes = StructureToBytes(bmi);
                    ms.Write(infoHeaderBytes, 0, infoHeaderBytes.Length);

                    // 5.5 写入像素数据 (直接从DIBSection内存复制)
                    byte[] pixelData = new byte[pixelDataSize];
                    Marshal.Copy(bitsPtr, pixelData, 0, (int)pixelDataSize);
                    ms.Write(pixelData, 0, pixelData.Length);

                    ms.Position = 0;

                    Bitmap bitmap = new Bitmap(ms);
                    return bitmap;
                }
            }
            finally
            {
                // 6. 清理资源
                ReleaseDC(desktopHwnd, desktopDc);
                DeleteDC(memDc);
            }
        }

        // 辅助方法：结构体转字节数组
        private static byte[] StructureToBytes<T>(T structure) where T : struct
        {
            int size = Marshal.SizeOf(typeof(T));
            byte[] bytes = new byte[size];
            IntPtr ptr = Marshal.AllocHGlobal(size);
            try
            {
                Marshal.StructureToPtr(structure, ptr, false);
                Marshal.Copy(ptr, bytes, 0, size);
                return bytes;
            }
            finally
            {
                Marshal.FreeHGlobal(ptr);
            }
        }
    }
}