Using ctypes with jython

Question

I have a trouble with using ctypes lib in my python script. Here is my code (found on the Internet):

if __name__ == "__main__":
    from ctypes import *
    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 moveCursorInCurrentWindow(x, y):
        # Find the focussed window.
        guiThreadInfo = GUITHREADINFO(cbSize=sizeof(GUITHREADINFO))
        user32.GetGUIThreadInfo(0, byref(guiThreadInfo))
        focussedWindow = guiThreadInfo.hwndFocus

        # Find the screen position of the window.
        windowRect = RECT()
        user32.GetWindowRect(focussedWindow, byref(windowRect))

        # Finally, move the cursor relative to the window.
        user32.SetCursorPos(windowRect.left + x, windowRect.top + y)

    if __name__ == '__main__':
    # Quick test.
        moveCursorInCurrentWindow(100, 100)

The first problem was that python couldn't find the ctypes so i copied the files downloaded from the project site to

netbeans\6.9\jython-2.5.1\Lib\

(yep, im using netbeans) and then it shows this error:

>    from ctypes import *
>  File "C:\Users\k\.netbeans\6.9\jython-2.5.1\Lib\ctypes\__init__.py", line 10, in <module>
>    from _ctypes import Union, Structure, Array

Just like the init file has some errors o_O Help guys! Greetings, Chris

Steven Rumbalski · Accepted Answer · 2011-03-03 21:46:27Z

ctypes in Jython experimental and not complete.

From the jython-users mailing list in a thread titled "ctypes in Jython" Jim Baker (a Jython committer) wrote on November 17, 2010:

There's some experimental support for ctypes in 2.5.2 [the current version], but it's really more of a placeholder at this point.

He then suggests these work arounds:

I do recommend JNA if you can modify your ctypes code. JNA is pretty close to ctypes - JNA's API apparently was significantly influenced by ctypes! JNA also seems to work well with Jython.

The other option is to use something like execnet. For execnet specifically: it allows you to pair Jython with CPython, and it does seem to work well. But its GPL license makes it a non starter for many people. There are other choices out there too.

Further on in the same thread we have this confirming assessment:

I tried the ctypes module in 2.5.2rc2 recently, and found that: 1) There's no ctypes.util.find_library yet 2) ctypes.Structure doesn't support non-scalar types yet

So I agree with the "more of a placeholder" assessment. Still, it's exciting to see it getting started.

Chinmay Kanchi · Accepted Answer · 2011-03-03 21:40:22Z

3

ctypes is not supported in Jython 2.5.1. There has been some experimental support added in 2.5.2, but it's certainly nowhere near complete. Maybe you'll have better luck using JNA with Jython instead. There's a short tutorial here.

answered Mar 3, 2011 at 21:40

Chinmay Kanchi

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Comments

Mr_Pink · Accepted Answer · 2011-03-03 21:39:10Z

1

Jython doesn't yet have full support for ctypes: http://bugs.jython.org/issue1328

You can't simply take the ctypes library compiled for CPython, and plug it into Jython.

answered Mar 3, 2011 at 21:39

Mr_Pink

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1 Comment

Dolda2000 Over a year ago

For the record, ctypes support seems to be much better now, in the Jython 2.7 beta.

Krzysztof Kaczor · Accepted Answer · 2011-03-05 11:46:40Z

0

Ok, thx dudes! I just reconfig my NetBeans, now its using cPython. Everything works. I just had to changed the line user32.SetCursorPos(windowRect.left + x, windowRect.top + y) to: user32.SetCursorPos(c_ulong(windowRect.left + x), c_ulong(windowRect.left + y))

answered Mar 5, 2011 at 11:46

Krzysztof Kaczor

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