Introduction

Python wrapper around the Java Access Bridge / Windows Access Bridge.

Requirements

• 64-bit Windows
• Java >= 8 (https://docs.aws.amazon.com/corretto/latest/corretto-8-ug/downloads-list.html)
  • If you are doing development install JDK, otherwise JRE is enough
• Python >= 3.8 (https://www.python.org/downloads/release/python-375/)

Enable the Java Access Bridge in windows

C:\path\to\java\bin\jabswitch -enable

Install

pip install java-access-bridge-wrapper

How to use

Import the Java Access Bridge (JAB) wrapper and optionally the context tree

from JABWrapper.jab_wrapper import JavaAccessBridgeWrapper
from JABWrapper.context_tree import ContextNode, ContextTree, SearchElement

The JAB creates an virtual GUI window when it is opened. For the JAB to operate and receive events from the GUI, the calling code needs to implement the windows message pump and call it in a loop. The JABWrapper object needs to be in the same thread.

This can be achieved for example by starting the message pump in a separate thread, where the JAB object is also initialized.

GetMessage = ctypes.windll.user32.GetMessageW
TranslateMessage = ctypes.windll.user32.TranslateMessage
DispatchMessage = ctypes.windll.user32.DispatchMessageW

def pump_background(pipe: queue.Queue):
    try:
        jab_wrapper = JavaAccessBridgeWrapper()
        pipe.put(jab_wrapper)
        message = byref(wintypes.MSG())
        while GetMessage(message, 0, 0, 0) > 0:
            TranslateMessage(message)
            logging.debug("Dispatching msg={}".format(repr(message)))
            DispatchMessage(message)
    except Exception as err:
        pipe.put(None)

def main():
    pipe = queue.Queue()
        thread = threading.Thread(target=pump_background, daemon=True, args=[pipe])
        thread.start()
        jab_wrapper = pipe.get()
        if not jab_wrapper:
            raise Exception("Failed to initialize Java Access Bridge Wrapper")
        time.sleep(0.1) # Wait until the initial messages are parsed, before accessing frames

if __name__ == "__main__":
    main()

Once the JABWrapper object is initialized, attach to some frame and optionally create the context tree to get the element tree of the application.

jab_wrapper.switch_window_by_title("Frame title")
context_tree = ContextTree(jab_wrapper)

Development

Prerequisites

1. Install Invoke, Poetry and the other required dependencies in order to be able to develop and package the library: pip install -Ur requirements.txt.
   • If you want to isolate these from the other projects and not rely on the OS Python, enable a (pyenv) virtual environment first by following these instructions.
2. Now you're ready to set-up Poetry for the first time with inv setup.
   • Check with -h on how to pass credentials for ensuring that both your production PyPI and CI DevPI are configured. You'll find these in our Robocorp > Shared 1Password by searching for keywords like "pypi" (where we recommend a personal token instead) and "devpi".
3. Run inv update so the library gets ready for development.

Testing

Run test script against a simple Swing application.

Set environment variable

set RC_JAVA_ACCESS_BRIDGE_DLL="C:\path\to\Java\bin\WindowsAccessBridge-64.dll"

Update requirements and install the library in development mode

inv update

Run tests

inv test

Packaging

Check linting

inv lint  # apply with '-a'

Building and publishing

inv publish  # '-c' for DevPI

TODO:

• Support for 32-bit Java Access Bridge version
• Implement rest of the utility functions to the JABWrapper