How to retrieve the selected text from the active window

Question

I am trying to create a simple open source utility for windows using Python that can perform user-defined actions on the selected text of the currently active window. The utility should be activated using a pre-defined keyboard shortcut.

Usage is partially outlined in the following example:

1. The user selects some text using the mouse or the keyboard (in any application window)
2. The user presses a pre-defined keyboard shortcut
3. The selected text is retrieved by our utility or copied to clipboard (both approaches should be fine)
4. The keyboard shortcut-dependent action is performed on the selected text

What puzzles me is step 3. How the selected text is retrieved from the active window. This should work with all applications.

I use the pywin32 module.

Thanks in advance for your answers and tips.

Update #1:

Turns out that there are two approaches to accomplish the task:

1. Find the active window, then send a message/keystroke (Ctrl-C) to it in order to copy the selected text to the clipboard. Then the utility can work on the text by accessing it using the clipboard-related functions.
2. Find the active Window, then retrieve the selected text directly (without copying it to clipboard). This seems more difficult than the 1st approach.

As starting points:

Get the active window ID as Anurag Uniyal has pointed out in his reply.

Or get the window object with the following code:

import win32ui
wnd = win32ui.GetForegroundWindow()
print wnd.GetWindowText()

Corinthians

Can you clarify whether or not this utility is actually creating the active window or is this active window from a different application? – Tontine

The "active window" is a window from a different application. This utility should run in the background (or systray) and should be activated with a pre-defined keystroke. – Corinthians

Have you figure out how to retrieve the selected text ? – Epicanthus

Have you figure out how to retrieve the selected text ??? – Sudatory

Answer 1

the code below will work only on simple text boxes (just did it in VB6, and ported to python)

edit: it was tested only on python 2.6

from ctypes import *
import win32gui
import win32api
import win32con


user32 = windll.user32
kernel32 = windll.kernel32

class RECT(Structure):
 _fields_ = [
     ("left", c_ulong),
     ("top", c_ulong),
     ("right", c_ulong),
     ("bottom", c_ulong)
 ]

class GUITHREADINFO(Structure):
 _fields_ = [
     ("cbSize", c_ulong),
     ("flags", c_ulong),
     ("hwndActive", c_ulong),
     ("hwndFocus", c_ulong),
     ("hwndCapture", c_ulong),
     ("hwndMenuOwner", c_ulong),
     ("hwndMoveSize", c_ulong),
     ("hwndCaret", c_ulong),
     ("rcCaret", RECT)
 ]



def get_selected_text_from_front_window(): # As String
    ''' vb6 to python translation '''

    gui = GUITHREADINFO(cbSize=sizeof(GUITHREADINFO))
    txt=''
    ast_Clipboard_Obj=None
    Last_Clipboard_Temp = -1


    user32.GetGUIThreadInfo(0, byref(gui))

    txt = GetCaretWindowText(gui.hwndCaret, True)

    '''
    if Txt = "" Then
        LastClipboardClip = ""
        Last_Clipboard_Obj = GetClipboard
        Last_Clipboard_Temp = LastClipboardFormat
        SendKeys "^(c)"
        GetClipboard
        Txt = LastClipboardClip
        if LastClipboardClip <> "" Then Txt = LastClipboardClip
        RestoreClipboard Last_Clipboard_Obj, Last_Clipboard_Temp
        print "clbrd: " + Txt
    End If
    '''    
    return txt



def GetCaretWindowText(hWndCaret, Selected = False): # As String

    startpos =0
    endpos =0

    txt = ""

    if hWndCaret:

        buf_size = 1 + win32gui.SendMessage(hWndCaret, win32con.WM_GETTEXTLENGTH, 0, 0)
        if buf_size:
            buffer = win32gui.PyMakeBuffer(buf_size)
            win32gui.SendMessage(hWndCaret, win32con.WM_GETTEXT, buf_size, buffer)
            txt = buffer[:buf_size]

        if Selected and buf_size:
            selinfo  = win32gui.SendMessage(hWndCaret, win32con.EM_GETSEL, 0, 0)
            endpos   = win32api.HIWORD(selinfo)
            startpos = win32api.LOWORD(selinfo)
            return txt[startpos: endpos]

    return txt

if __name__ == '__main__':
    print get_selected_text_from_front_window()

Caesarea

I tested your code with Python 3 , it only returns <memory at 0x014775E0>, no text . – Epicanthus

Me too, I tested your code with 3.7.3 python, return an empty string – Satanic

Answer 2

It won't be trivial but here is the starting point

import win32gui
hwnd = win32gui.GetForegroundWindow()
print win32gui.GetWindowText(hwnd)

Maybe you will have to use FindWindow,FindWindowEx to get child windows with focus

edit: also while experimenting use spy++ to see how it retrieves information about various windows, see hwnd, window class etc

basically if you can find a example in C/C++/C# it won't be difficult to translate that into pywin32 equivalent, so in a way it is win32 api specific question

Langham

I've been getting the active window object with the following: import win32ui wnd = win32ui.GetForegroundWindow() print wnd.GetWindowText() But I have difficulties in getting to the selected text from there. Thanks for the tips. I will look into spy++. – Corinthians

Hello,I have question about basically if you can find a example in C/C++/C# it won't be difficult to translate that into pywin32 equivalent, so in a way it is win32 api specific question Can i use same for 64 bit machines? – Sudatory

Answer 3

You're far better off using the Ctrl-C method. Fetching text directly will work for something like an edit control, but is useless for retrieving text that an application has painted directly on its own window.

Tiossem

Thanks. This assumes that all applications, which support text selection, make use of the clipboard. This is probably true for 99.99% of the applications, but do you happen to know if this is the rule? – Corinthians

Keep in mind there are a few applications that do support clipboard copy of text, but assign a different meaning to Ctrl+C than "clipboard copy." One example that comes to mind is the command shell (cmd.exe). – Snatch

Answer 4

It appears that while the clipboard and associated copy and paste shortcuts are ubiquitous, they must be added to applications by developers. The best bet is to use a listener to capture when ctrl+c is activated, check that the clipboard is not in use and has data on it, and then manipulate the data from there.
You can check out Microsoft's dev page here:

https://learn.microsoft.com/en-us/windows/win32/dataxchg/using-the-clipboard#implementing-the-cut-copy-and-paste-commands

Blen

Can you provide an example code using pywin32? Windows api is not easy enough for most python developers. – Zygophyllaceous

I would suggest looking over example #2 programcreek.com/python/example/104590/win32api.keybd_event I am currently working with pynput for listening pypi.org/project/pynput – Blen