julia interface for accessing Qt via PyCall and PySide



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A julia package connecting julia to the Qt UI framework via Steven G. Johnson's PyCall connection to Python (https://github.com/stevengj/PyCall.jl) and the PySide libraries of the Qt Project (http://qt-project.org/wiki/PySide).

(An alternative could be to use PyQt, but PySide proved easy to install and does a better job with the seamless conversion of python objects into julia objects.)

This package doesn't provide much beyond:

  • configures PyCall's event loop integration

  • a few convenience functions

  • some examples illustrating the basic usage.


  • Download and install PySide
  • For some examples, install SciPy (Ubuntu: apt-get install python-scipy)
  • For some examples, download and install PyQtGraph

A basic "hello world" example

This example illustrates how to use the PyCall interface to produce a basic GUI with a parent container, layout, button, callback and dialog:

using PySide			# imports Qt, QtCore (Qt is QtGui)

w = Qt.QWidget()		# constructors
w[:setWindowTitle]("Hello world example") # w.setWindowTitle() is w[:setWindowTitle] in PyCall
lyt = Qt.QVBoxLayout(w)

btn = Qt.QPushButton("Click me", w)

qconnect(btn, :clicked) do	# qconnect convenience to connect to a signal
  msg = Qt.QMessageBox(btn)
  msg[:setWindowTitle]("A message for you...")
  msg[:setText]("Hello world!")
  msg[:setInformativeText]("Thanks for clicking.")
  msg[:setIcon](Qt.QMessageBox()[:Information])   # how to pick out Qt::QMessageBox::Information enumeration
  convert(Function, msg[:exec])()       # Sometimes, one must must convert to a function (or call qexec(msg))

raise(w)			# show and raise widget

PyCall objects have many methods accessible through ., but not all. The [:symbol' notation can access the remainder. This allows access to most of the functionality of PySide.

A (slightly) more convenient interface

We also provide a slightly more convenient interface for common tasks. For example, the "hello world" example could be written as:

using PySide			# imports Qt, QtCore (Qt is QtGui)

w = Widget()
setWindowTitle(w, "Hello world example (redux)") # methodName(object, args...)
lyt = VBoxLayout(w)		# we require a parent for all but Widget, MainWindow
setLayout(w, lyt)

btn = Button(w)
setText(btn, "Click me")
push!(lyt, btn)			# alternative to addWidget(lyt, btn)

qconnect(btn, :clicked) do	# also change_slot(btn, () -> MessageBox(...))
  MessageBox(btn, "Hi there", :Information)


The constructors have some conveniences. As un-parented objects can go out of scope, we require a parent to be passed in to all but the top-level objects (Widget or MainWindow).

The methods have the basic signature methodName(object, args...). Alternatively, one can call as object[:methodName](args...). The latter is possible even if a convenience method is not created.

The main point of this is to simplify some tasks, but also to give each widget a type so we can write some generic methods, these being:

  • get_value and set_value to retrieve the main value for selection

  • get_items and set_items to get/set the items to select from

  • change_slot to connect a slot to the most typical event.

There are other examples in the examples directory.

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Last Touched

6 months ago


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