Getting UI text from external app in C#

Question

Is it possible to get UI text from an external application in C#.

In particular, is there a way to read Unicode text from a label (I assume it's a normal Windows label control) from an external Win32 app that was written by a 3rd party? The text is visible, but not selectable by mouse in the UI.

I assume there is some accessibility API (e.g. meant for screen readers) that allows this.

Edit: Currently looking into using something like the Managed Spy App but would still appreciate any other leads.

Answer 1

If you just care about the standard Win32 label, then WM_GETTEXT will work fine, as outlined in the other answers.

--

There is an accessibility API - UIAutomation - for standard labels, it too uses WM_GETTEXT behind the scenes. One advantage to it, however, is that it can get text from several other types of controls, including most system controls, and often UI using non-system controls - including WPF, text in IE and Firefox, and others.

// compile as:
// csc file.cs /r:UIAutomationClient.dll /r:UIAutomationTypes.dll /r:WindowsBase.dll
using System.Windows.Automation;
using System.Windows.Forms;
using System;

class Test
{
    public static void Main()
    {
        // Get element under pointer. You can also get an AutomationElement from a
            // HWND handle, or by navigating the UI tree.
        System.Drawing.Point pt = Cursor.Position;
        AutomationElement el = AutomationElement.FromPoint(new System.Windows.Point(pt.X, pt.Y));
        // Prints its name - often the context, but would be corresponding label text for editable controls. Can also get the type of control, location, and other properties.
        Console.WriteLine( el.Current.Name );
    }
}