Table Of Contents
New in version 1.3.0.
Changed in version 1.9.2: The interactive launcher has been deprecated.
InteractiveLauncher provides a user-friendly python shell
interface to an
App so that it can be prototyped and debugged
The Kivy API intends for some functions to only be run once or before the
main EventLoop has started. Methods that can normally be called during the
course of an application will work as intended, but specifically overriding
methods such as
on_touch() dynamically leads to trouble.
Creating an InteractiveLauncher¶
Take your existing subclass of
App (this can be production code) and
pass an instance to the
from kivy.interactive import InteractiveLauncher from kivy.app import App from kivy.uix.button import Button class MyApp(App): def build(self): return Button(text='Hello Shell') launcher = InteractiveLauncher(MyApp()) launcher.run()
After pressing enter, the script will return. This allows the interpreter to
continue running. Inspection or modification of the
App can be done
safely through the InteractiveLauncher instance or the provided
SafeMembrane class instances.
If you want to test this example, start Python without any file to have already an interpreter, and copy/paste all the lines. You’ll still have the interpreter at the end + the kivy application running.
IPython provides a fast way to learn the Kivy API. The
and all of it’s attributes, including methods and the entire widget tree,
can be quickly listed by using the ‘.’ operator and pressing ‘tab’. Try this
code in an Ipython shell.
from kivy.interactive import InteractiveLauncher from kivy.app import App from kivy.uix.widget import Widget from kivy.graphics import Color, Ellipse class MyPaintWidget(Widget): def on_touch_down(self, touch): with self.canvas: Color(1, 1, 0) d = 30. Ellipse(pos=(touch.x - d/2, touch.y - d/2), size=(d, d)) class TestApp(App): def build(self): return Widget() i = InteractiveLauncher(TestApp()) i.run() i. # press 'tab' to list attributes of the app i.root. # press 'tab' to list attributes of the root widget # App is boring. Attach a new widget! i.root.add_widget(MyPaintWidget()) i.safeIn() # The application is now blocked. # Click on the screen several times. i.safeOut() # The clicks will show up now # Erase artwork and start over i.root.canvas.clear()
All of the proxies used in the module store their referent in the
_ref attribute, which can be accessed directly if needed, such as
for getting doc strings.
type() will access the
proxy, not its referent.
Directly Pausing the Application¶
SafeMembrane hold internal
references to the
EventLoop‘s ‘safe’ and ‘confirmed’
threading.Event objects. You can use their safing methods to control
the application manually.
SafeMembrane.safeIn() will cause the application to pause and
SafeMembrane.safeOut() will allow a paused application
to continue running. This is potentially useful for scripting actions into
functions that need the screen to update etc.
The pausing is implemented via the
and occurs before the start of each frame.
Adding Attributes Dynamically¶
This module uses threading and object proxies to encapsulate the running
App. Deadlocks and memory corruption can occur if making direct
references inside the thread without going through the provided proxy(s).
InteractiveLauncher can have attributes added to it exactly like a
normal object and if these were created from outside the membrane, they will
not be threadsafe because the external references to them in the python
interpreter do not go through InteractiveLauncher’s membrane behavior,
To threadsafe these external references, simply assign them to
SafeMembrane instances of themselves like so:
from kivy.interactive import SafeMembrane interactiveLauncher.attribute = myNewObject # myNewObject is unsafe myNewObject = SafeMembrane(myNewObject) # myNewObject is now safe. Call at will. myNewObject.method()
Unit tests, examples, and a better explanation of which methods are safe in a running application would be nice. All three would be excellent.
Could be re-written with a context-manager style i.e.
with safe: foo()
Any use cases besides compacting code?
SafeMembrane(ob, *args, **kwargs)¶
This help is for a proxy object. Did you want help on the proxy’s referent instead? Try using help(<instance>._ref)
The SafeMembrane is a threadsafe proxy that also returns attributes as new thread-safe objects and makes thread-safe method calls, preventing thread-unsafe objects from leaking into the user’s environment.
Provides a thread-safe entry point for interactive launching.
Provides a thread-safe exit point for interactive launching.