schrodinger.utils.qapplication module¶

Functions for managing the global QApplication instance.

Typical usage:

if __name__ == ‘__main__’:: af2.start_application(MyPanel.panel)

(Note that the start_application function is available from the af2 namespace)

schrodinger.utils.qapplication.ApplicationMode¶: alias of schrodinger.utils.qapplication.RunMode

exception schrodinger.utils.qapplication.CantCreateQApplicationError(msg='', *args, **kwargs)¶

Bases: RuntimeError

__init__(msg='', *args, **kwargs)¶

schrodinger.utils.qapplication.require_application(func=None, create=False, use_qtcore_app=False)¶

Use this decorator on functions that require a QApplication to run. When the decorated function is called, this will check whether a QApplication exists. If it does not, a RuntimeError will be raised unless create=True, which will cause a QApplication to be created.

Parameters

func – the function to decorate
create (bool) – whether to create a QApplication if one does not exist
use_qtcore_app (bool) – Whether to create the application using the QtCore module instead of the QtWidgets module.

schrodinger.utils.qapplication.get_application(create=True, use_qtcore_app=False, offscreen=False)¶

Gets the global QApplication instance. By default, creates one if none exists.

Parameters

create (bool) – Whether to create a new application if none exists.
use_qtcore_app – Whether to create the application using the QtCore module instead of the QtWidgets module.
offscreen – Whether to add -platform offscreen to the QApplication arguments even if a display is present (Linux-only).

Raises

CantCreateQApplicationError – if use_qtcore_app is False but a QCoreApplication already exists. In the opposite case (use_qtcore_app is True but a QApplication already exists), no traceback is thrown (because QApplication is a substitutable subclass of QCoreApplication)
CantCreateQApplicationError – if use_qtcore_app is False and importing QtWidgets fails (e.g. due to missing graphics libraries)

Returns

the application

Return type

QApplication or None

schrodinger.utils.qapplication.is_core_application()¶

Return whether the application instance is a QtCore application (as opposed to a QtWidgets application).

Returns: Whether there is a QtCore application or None if there’s no application
Return type: bool or NoneType

schrodinger.utils.qapplication.start_application(main_callable, use_qtcore_app=False)¶

Begins the application’s event loop using the exec method. The main callable is called via timer from within the event loop. This function is meant to be used when running in standalone scripts as follows:

if __name__ == ‘__main__’:
application.start_application(main)

Using this function to launch standalone scripts/panels more closely mimics the way Python is run under Maestro. For example, a panel may be presented with MyPanel.show() without having to call application.exec().

This is generally intended for use with GUI scripts.

Parameters

main_callable (callable) – the function/method to be run in the event loop, commonly a module level main function or MyPanelClass.panel
use_qtcore_app (bool) – Whether to create the application using the QtCore module instead of the QtWidgets module. Set to True for scripts that are non-GUI and/or need to run on machines that have no display.

schrodinger.utils.qapplication.run_application(main_callable, use_qtcore_app=True)¶

This function is the same as start_application with two important differences:

Creates a QCoreApplication by default

Quits the application as soon as the main_callable function returns
and does a system exit with that return value

This is generally intended for use by non-GUI, commandline scripts.

schrodinger.utils.qapplication.process_events(flags=None)¶

Calls processEvents on the main event loop. Requires an application.

Parameters: flags – passed to processEvents. See QCoreApplication.processEvents for documentation
Raises: RuntimeError – if there is no application

schrodinger.utils.qapplication.quit_application()¶: Quits the application.