C# how to use WM_GETTEXT / GetWindowText API / Window Title

Question

I want to get the content of the control / handle of an application..

Here's the experimental code..

 Process[] processes = Process.GetProcessesByName("Notepad");         foreach (Process p in processes)         {             StringBuilder sb = new StringBuilder();             IntPtr pFoundWindow = p.MainWindowHandle;              List <IntPtr> s =    GetChildWindows(pFoundWindow);              // function that returns a              //list of handle from child component on a given application.               foreach (IntPtr test in s)              {               // Now I want something here that will return/show                 the text on the notepad..                }               GetWindowText(pFoundWindow, sb,256);             MessageBox.Show(sb.ToString()); // this shows the title.. no problem with that          }  

any idea? I've read some API method like GetWindowText or WM_GETTEXT but I dont know how to use it or apply it on my code.. I need a tutorial or sample code...

Thanks in advance : )

Answer 1

public class GetTextTestClass{      [System.Runtime.InteropServices.DllImport("user32.dll", EntryPoint = "SendMessage", CharSet = System.Runtime.InteropServices.CharSet.Auto)]     public static extern bool SendMessage(IntPtr hWnd, uint Msg, int wParam, StringBuilder lParam);      [System.Runtime.InteropServices.DllImport("user32.dll", SetLastError = true)]     public static extern IntPtr SendMessage(int hWnd, int Msg, int wparam, int lparam);      const int WM_GETTEXT       = 0x000D;     const int WM_GETTEXTLENGTH = 0x000E;      public string GetControlText(IntPtr hWnd){          // Get the size of the string required to hold the window title (including trailing null.)          Int32 titleSize = SendMessage((int)hWnd, WM_GETTEXTLENGTH, 0, 0).ToInt32();          // If titleSize is 0, there is no title so return an empty string (or null)         if (titleSize == 0)             return String.Empty;          StringBuilder title = new StringBuilder(titleSize + 1);          SendMessage(hWnd, (int)WM_GETTEXT, title.Capacity, title);          return title.ToString();     } } 

Answer 2

GetWindowText won't give you the content of edit windows from other applications - it only supports default-managed text [like the captions of labels] across processes to prevent hangs... you'll have to send WM_GETTEXT.

You'll need to use a StringBuilder version of SendMessage:

[DllImport("user32.dll", CharSet = CharSet.Auto)] static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, [Out] StringBuilder lParam);  const int WM_GETTEXT = 0xD; StringBuilder sb = new StringBuilder(65535); // needs to be big enough for the whole text SendMessage(hWnd_of_Notepad_Editor, WM_GETTEXT, sb.Length, sb);