How can I write multiple lines to a textbox using python win32?

Question

I have a C program that has a textbox component. I want to have a python GUI write text to this text box. Currently, I can write to the textbox HWND using:

def winFunc(hwnd, lparam):
    s = win32gui.GetWindowText(hwnd)
    if s == "":
        win32gui.SendMessage(hwnd, win32con.WM_SETTEXT, 0, lparam)

hwnd = win32gui.FindWindow("Graph Program", None)
win32gui.EnumChildWindows(hwnd, winFunc, text)

This code will write text to the textbox but it cannot append text on a newline to the textbox. Is it possible to read in the text that is currently in the textbox or is it possible to add text to a textbox? I am new to using the windows API. Also, Is it possible to write text as a different color? The text box class is RICHEDIT20A.

David Heffernan · Accepted Answer · 2011-08-01 15:59:10Z

1

Appending text

Send an EM_SETSEL message to move the selection to the end of the rich edit control. Use WM_GETTEXTLENGTH to find out how many characters are in the edit control.
Send an EM_REPLACESEL message to replace the selection. If the selection point is at the end of the control, then replacing is the same as appending.

Don't attempt to use WM_GETTEXT & WM_SETTEXT since it rapidly becomes inefficient, not to mention the fact that the formatting is not preserved.

Formatting text

Use the EM_SETCHARFORMAT to format text. More details over at MSDN.

edited Aug 1, 2011 at 15:59

answered Aug 1, 2011 at 15:40

David Heffernan

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5 Comments

gh4x Over a year ago

I still can not find a way to change the text color so that each appended line is a new color in python. I was not able to find a way to call EM_SETCHARFORMAT using python.

gh4x Over a year ago

I was thinking win32gui.SendMessage(hwnd, EM_SETCHARFORMAT, SCF_SELECTION, format) but I also do not know how to (in python) specify a Charformat structure.

David Heffernan Over a year ago

I think you may need to use ctypes structure classes to replicate CHARFORMAT. I would also point out that you are meant to ask one question at a time. You asked about appending text, and formatting it.

gh4x Over a year ago

I have posted a new question to focus on color formatting. stackoverflow.com/questions/6903692/…

David Heffernan Over a year ago

@gh4x Good, I think that's exactly what to do.

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