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# coding: utf-8
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"""
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Support for creating GUI apps and starting event loops.
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IPython's GUI integration allows interative plotting and GUI usage in IPython
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session. IPython has two different types of GUI integration:
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1. The terminal based IPython supports GUI event loops through Python's
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PyOS_InputHook. PyOS_InputHook is a hook that Python calls periodically
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whenever raw_input is waiting for a user to type code. We implement GUI
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support in the terminal by setting PyOS_InputHook to a function that
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iterates the event loop for a short while. It is important to note that
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in this situation, the real GUI event loop is NOT run in the normal
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manner, so you can't use the normal means to detect that it is running.
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2. In the two process IPython kernel/frontend, the GUI event loop is run in
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the kernel. In this case, the event loop is run in the normal manner by
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calling the function or method of the GUI toolkit that starts the event
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loop.
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In addition to starting the GUI event loops in one of these two ways, IPython
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will *always* create an appropriate GUI application object when GUi
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integration is enabled.
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If you want your GUI apps to run in IPython you need to do two things:
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1. Test to see if there is already an existing main application object. If
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there is, you should use it. If there is not an existing application object
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you should create one.
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2. Test to see if the GUI event loop is running. If it is, you should not
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start it. If the event loop is not running you may start it.
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This module contains functions for each toolkit that perform these things
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in a consistent manner. Because of how PyOS_InputHook runs the event loop
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you cannot detect if the event loop is running using the traditional calls
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(such as ``wx.GetApp.IsMainLoopRunning()`` in wxPython). If PyOS_InputHook is
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set These methods will return a false negative. That is, they will say the
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event loop is not running, when is actually is. To work around this limitation
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we proposed the following informal protocol:
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* Whenever someone starts the event loop, they *must* set the ``_in_event_loop``
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attribute of the main application object to ``True``. This should be done
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regardless of how the event loop is actually run.
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* Whenever someone stops the event loop, they *must* set the ``_in_event_loop``
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attribute of the main application object to ``False``.
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* If you want to see if the event loop is running, you *must* use ``hasattr``
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to see if ``_in_event_loop`` attribute has been set. If it is set, you
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*must* use its value. If it has not been set, you can query the toolkit
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in the normal manner.
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* If you want GUI support and no one else has created an application or
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started the event loop you *must* do this. We don't want projects to
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attempt to defer these things to someone else if they themselves need it.
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The functions below implement this logic for each GUI toolkit. If you need
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to create custom application subclasses, you will likely have to modify this
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code for your own purposes. This code can be copied into your own project
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so you don't have to depend on IPython.
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"""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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from IPython.core.getipython import get_ipython
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#-----------------------------------------------------------------------------
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# wx
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#-----------------------------------------------------------------------------
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def get_app_wx(*args, **kwargs):
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"""Create a new wx app or return an exiting one."""
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import wx
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app = wx.GetApp()
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if app is None:
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if 'redirect' not in kwargs:
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kwargs['redirect'] = False
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app = wx.PySimpleApp(*args, **kwargs)
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return app
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def is_event_loop_running_wx(app=None):
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"""Is the wx event loop running."""
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# New way: check attribute on shell instance
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ip = get_ipython()
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if ip is not None:
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if ip.active_eventloop and ip.active_eventloop == 'wx':
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return True
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# Fall through to checking the application, because Wx has a native way
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# to check if the event loop is running, unlike Qt.
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# Old way: check Wx application
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if app is None:
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app = get_app_wx()
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if hasattr(app, '_in_event_loop'):
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return app._in_event_loop
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else:
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return app.IsMainLoopRunning()
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def start_event_loop_wx(app=None):
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"""Start the wx event loop in a consistent manner."""
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if app is None:
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app = get_app_wx()
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if not is_event_loop_running_wx(app):
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app._in_event_loop = True
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app.MainLoop()
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app._in_event_loop = False
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else:
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app._in_event_loop = True
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#-----------------------------------------------------------------------------
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# qt4
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#-----------------------------------------------------------------------------
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def get_app_qt4(*args, **kwargs):
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"""Create a new qt4 app or return an existing one."""
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from IPython.external.qt_for_kernel import QtGui
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app = QtGui.QApplication.instance()
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if app is None:
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if not args:
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args = ([''],)
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app = QtGui.QApplication(*args, **kwargs)
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return app
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def is_event_loop_running_qt4(app=None):
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"""Is the qt4 event loop running."""
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# New way: check attribute on shell instance
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ip = get_ipython()
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if ip is not None:
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return ip.active_eventloop and ip.active_eventloop.startswith('qt')
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# Old way: check attribute on QApplication singleton
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if app is None:
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app = get_app_qt4([''])
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if hasattr(app, '_in_event_loop'):
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return app._in_event_loop
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else:
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# Does qt4 provide a other way to detect this?
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return False
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def start_event_loop_qt4(app=None):
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"""Start the qt4 event loop in a consistent manner."""
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if app is None:
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app = get_app_qt4([''])
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if not is_event_loop_running_qt4(app):
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app._in_event_loop = True
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app.exec_()
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app._in_event_loop = False
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else:
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app._in_event_loop = True
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#-----------------------------------------------------------------------------
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# Tk
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#-----------------------------------------------------------------------------
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#-----------------------------------------------------------------------------
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# gtk
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#-----------------------------------------------------------------------------
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