【PC微信探祕】C#截圖PC微信登陸二維碼

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace L017CaptureWeChatQrcode
{
    public partial class Form1 : Form
    {
        //微信進程
        Process WxProcess = null;
        Boolean Init()
        {
            WxProcess = null;
            Process[] processes = Process.GetProcesses();
            foreach (Process process in processes)
            {
                if (process.ProcessName == "WeChat")
                {
                    WxProcess = process;
                    break;
                }
            }
            if (WxProcess == null)
            {
                MessageBox.Show("微信沒有找到！");
                return false;
            }
            return true;
        }

        public Form1()
        {
            InitializeComponent();
        }

        private void Button1_Click(object sender, EventArgs e)
        {
            if (Init() == false) return;

            //   1）獲取設備上下文句柄：GetWindowDC-- > ReleaseDC
            IntPtr windowDCHandle = GetWindowDC(IntPtr.Zero);
            if (windowDCHandle == IntPtr.Zero)
            {
                MessageBox.Show("獲取設備上下文句柄失敗！");
                return;
            }

            //   2）獲取指定窗口邊界和尺寸：GetWindowRect，
            Rectangle rectangle = new Rectangle();
            if (GetWindowRect(WxProcess.MainWindowHandle, ref rectangle) == 0)
            {
                MessageBox.Show("獲取指定窗口邊界和尺寸失敗！");
                return;
            };

            //	注意C#中的Rectangle與C++中RECT區別
            //3）計算窗口大小
            int width = rectangle.Width - rectangle.X;
            int height = rectangle.Height - rectangle.Y;

            //   4）創建一個設備上下文相關的位圖：CreateCompatibleBitmap->DeleteObject
            IntPtr compatibleBitmapHandle = CreateCompatibleBitmap(windowDCHandle, width, height);
            if (compatibleBitmapHandle == IntPtr.Zero)
            {
                MessageBox.Show("創建一個設備上下文相關的位圖失敗！");
                return;
            }

            //   5）創建一個內存上下文兼容的句柄：CreateCompatibleDC->DeleteDC
            IntPtr compatibleDCHandle = CreateCompatibleDC(windowDCHandle);
            if (compatibleDCHandle == IntPtr.Zero)
            {
                MessageBox.Show("創建一個內存上下文兼容的句柄失敗！");
                return;
            }

            //   6）選擇一個設備上下文對象：SelectObject
            if (SelectObject(compatibleDCHandle, compatibleBitmapHandle) == IntPtr.Zero)
            {
                MessageBox.Show("選擇一個設備上下文對象失敗！");
                return;
            }

            //   7）拷貝窗口到設備上下文：PrintWindow
            if (PrintWindow(WxProcess.MainWindowHandle, compatibleDCHandle, 0) == 0)
            {
                MessageBox.Show("拷貝窗口到設備上下文失敗！");
                return;
            }

            this.pictureBox1.Width = width;
            this.pictureBox1.Height = height;
            this.pictureBox1.Image = Image.FromHbitmap(compatibleBitmapHandle);

            this.pictureBox1.Image.Save(Environment.CurrentDirectory + "\\Wx.png", ImageFormat.Png);

            int qrWidth = 197;
            int qrHeight = 197;

            Image qrImage = new Bitmap(qrWidth, qrHeight);
            Graphics graphics = Graphics.FromImage(qrImage);
            graphics.DrawImage(Image.FromHbitmap(compatibleBitmapHandle),
                new Rectangle(0, 0, qrWidth, qrHeight),
                new Rectangle(40, 80, qrWidth, qrHeight),
                GraphicsUnit.Pixel);
            graphics.Dispose();

            this.pictureBox2.Width = qrWidth;
            this.pictureBox2.Height = qrHeight;
            this.pictureBox2.Image = qrImage;


            //   8）清理垃圾
            DeleteObject(compatibleBitmapHandle);
            DeleteDC(compatibleDCHandle);
            ReleaseDC(WxProcess.MainWindowHandle, windowDCHandle);
        }

        [DllImport("Gdi32.dll")]
        public static extern int DeleteDC(IntPtr hdc);

        [DllImport("Gdi32.dll")]
        public static extern int DeleteObject(IntPtr ho);

        [DllImport("User32.dll")]
        public static extern int PrintWindow(IntPtr hwnd, IntPtr hdcBlt, UInt32 nFlags);

        [DllImport("Gdi32.dll")]
        public static extern IntPtr SelectObject(IntPtr hdc, IntPtr h);

        [DllImport("Gdi32.dll")]
        public static extern IntPtr CreateCompatibleDC(IntPtr hdc);

        [DllImport("Gdi32.dll")]
        public static extern IntPtr CreateCompatibleBitmap(IntPtr hdc, int cx, int cy);

        [DllImport("User32.dll")]
        public static extern int GetWindowRect(IntPtr hWnd, ref Rectangle lpRect);

        [DllImport("User32.dll")]
        public static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);

        [DllImport("User32.dll")]
        public static extern IntPtr GetWindowDC(IntPtr hWnd);
    }

}

示例來源：
網易雲課堂《2019 PC 微信探祕》

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