fan fani's questions

 private int SubStractPage()
 {
    
     Image image = CaptureScreen(976, 766, 0, 0, size2);
   
     image.Save(@"C:\ImageTests\screen.jpg", ImageFormat.Jpeg);


     using (Tesseract tesseract = new Tesseract(@"C:\langs", "eng", OcrEngineMode.TesseractLstmCombined))
     {
         tesseract.SetImage(new Image<Bgr, byte>(@"C:\ImageTests\screen.jpg"));
         tesseract.Recognize();
         
         string pages = tesseract.GetUTF8Text().Replace(" ", "");
        
         if( pages.Length == 1 || pages.Length == 0)
         {
             MessageBox.Show(pages);
             return 0;
         }
         else
         {
             if (pages.Length < 10)
             {
            
                 MessageBox.Show(pages);
                 return Convert.ToInt32(pages[pages.Length - 1].ToString()) - 1;
             }
             else 
             {

                 MessageBox.Show(pages);

                 return Convert.ToInt32((pages[pages.Length - 2].ToString() + pages[pages.Length - 1].ToString())) - 1;
             }
         }
        

     }
 }

该方法获取屏幕截图，然后成功从 tesseract 变量的屏幕截图中检索文本。然后我只是在页面中输入没有空格的数字。然后我返回页码最后一位数字或页码最后两位数字的值。但最终，即使页面在返回之前不为 null，也会变为 Null 并引发错误。这和什么有关系呢？

我写了这段代码：

using System.Diagnostics;
using System.Runtime.InteropServices;

namespace AutoPoster
{
    public partial class Form1 : Form
    {
       
        private bool isWriting { get; set; }
        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.F9)
            {
                MessageBox.Show("staring");
                
                WriteThis("Test");
            }
            else if (e.KeyCode == Keys.F4)
            {
                ShowWindow(this.Handle, 1);
                MessageBox.Show("stopping");
                isWriting = false;
            }
        }
        private void button1_Click(object sender, EventArgs e)
        {

        }
        public Form1()
        {
            InitializeComponent();

        }
        private void Form1_Load(object sender, EventArgs e)
        {

        }
        [DllImport("user32.dll")]
        static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
        [DllImport("user32.dll")]
        static extern IntPtr FindWindowEx(IntPtr parentHandle, int childAfter, string className, string windowTitle);
        [DllImport("user32.dll")]
        static extern int SendMessage(IntPtr hWnd, int uMsg, int wParam, string lParam);

        const int WM_CHAR = 0x0102;

        [DllImport("user32.dll")]
        public static extern int SetForegroundWindow(IntPtr hWnd);
        [STAThread]

        private void WriteThis(string letter)
        {
            isWriting = true;
            while (isWriting)
            {
                Process[] processes = Process.GetProcessesByName("notepad");
                foreach (Process proc in processes)
                {
                    SetForegroundWindow(proc.MainWindowHandle);
                    Thread.Sleep(1000);
                    SendKeys.SendWait("T");
                    SendKeys.SendWait($"{letter}");
                    SendKeys.SendWait("{ENTER}");
                    Thread.Sleep(10000);

                }
            }

        }

    }

}

它有一个 WriteThis 方法，可以模拟特定窗口中的击键。当您按 f9 时，它开始工作，当您按 f4 时，它停止。我需要确保在执行此方法期间我看不到它如何打开窗口并执行操作。也就是说，程序必须在后台运行。我如何更改代码或添加一些内容来实现这一点？我知道isWriting我做得不太好。