C # how to use WM_GETTEXT / GetWindowText API

Question

I want to get the contents of an application control / descriptor.

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 read some API method like GetWindowText or WM_GETTEXT, but I don’t know how to use it or apply it on my code. I need a tutorial or sample code ...

Thank you 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 will not give you the contents of editing windows from other applications - it only supports default-controlled text [for example, label labels] through processes to prevent freezes ... you will need to send WM_GETTEXT.

You will need to use the SendMessage version of the StringBuilder version:

 [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); 

Answer 3

See http://pinvoke.net/default.aspx/user32/GetWindowText.html , as well as the MSDN documentation. Below you will find a short code example on how to use the GetWindowText method.