appJar

The easiest way to create GUIs in Python.

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Written by a teacher, in the classroom, for students.

appJar is designed to run on as many versions of Python as possible - so it should work in your school.

There are no other dependencies - simply download, unzip, and put it in your code folder.
Check out the installation instructions for other ways to get appJar working.

Hello appJar

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GUIs in appJar require three steps.

• First, import the library & create a GUI variable.
  (from now on, we do everything to the GUI variable)

# import the library
from appJar import gui
# create a GUI variable called app
app = gui()

• Then, using the gui variable, add and configure an output widget:
  (if you've tried turtle this will all look very familiar)

# add & configure widgets - widgets get a name, to help referencing them later
app.addLabel("title", "Welcome to appJar")
app.setLabelBg("title", "red")

• Finally, start the GUI:
  (NB. don't put any code after this line)

# start the GUI
app.go()

• And, that's it:

  

Interactivity

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Of course, the whole point of making a GUI, is to be interactive - this requires events.

The idea behind event-driven programming is that each time the user clicks or types (an event) the GUI should respond.

• So, we add some input widgets (Entry Boxes), for the user to type in:

app.addLabelEntry("Username")
app.addLabelSecretEntry("Password")

• Then, we need a function - a block of code to call, when an event happens:

def press(button):
    if button == "Cancel":
        app.stop()
    else:
        usr = app.getEntry("Username")
        pwd = app.getEntry("Password")
        print("User:", usr, "Pass:", pwd)

• Finally, a button to create the event:

# link the buttons to the function called press
app.addButtons(["Submit", "Cancel"], press)

• We now have an interactive GUI:

  

When the user presses a button, the press function is called, passing the name of the button as a parameter.

Appearance counts

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We also want to change the way the GUI looks:

• For starters, you can specify a name and size for your GUI, when you create it:

app = gui("Login Window", "400x200")

• You can change the general appearance of the GUI:

app.setBg("orange")
app.setFont(18)

• You can even specify where you want the cursor to be when the GUI starts:

app.setFocus("Username")

• It now looks a bit better:

  

  (NB. We also set the fg/bg colours on the label - see below)

Make your own

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And, that's all you need to know. Check out:

• All the different input widgets & output widgets available.
• Our support for images and sound.
• How to include toolbars, menubars & statusbars.
• How to create simple pop-ups.
• How to use a grid layout.
• How to use containers for more advanced layouts.

Full code-listing

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Below is the full code-listing for the above GUI:

# import the library
from appJar import gui

# handle button events
def press(button):
    if button == "Cancel":
        app.stop()
    else:
        usr = app.getEntry("Username")
        pwd = app.getEntry("Password")
        print("User:", usr, "Pass:", pwd)

# create a GUI variable called app
app = gui("Login Window", "400x200")
app.setBg("orange")
app.setFont(18)

# add & configure widgets - widgets get a name, to help referencing them later
app.addLabel("title", "Welcome to appJar")
app.setLabelBg("title", "blue")
app.setLabelFg("title", "orange")

app.addLabelEntry("Username")
app.addLabelSecretEntry("Password")

# link the buttons to the function called press
app.addButtons(["Submit", "Cancel"], press)

app.setFocus("Username")

# start the GUI
app.go()

Upcoming in v1.0

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In the upcoming 1.0 release, we're formally introducing a new set of options for buiding your GUI.

These are targetted at our more experienced users:

• Context Managers allow you to create the GUI and any containers, in a visibly more understandable way.
• New functions that allow you to add/get/set widgets all with the same command, including passing configuration paramters.
• New properties for configuring the GUI.

Most of these are already live, and can be used, reducing the above GUI code to:

from appJar import gui 

def press():
    print("User:", app.entry("Username"), "Pass:", app.entry("Password"))

with gui("Login Window", "400x200", bg='orange', font={'size':18}) as app:
    app.label("Welcome to appJar", bg='blue', fg='orange')
    app.entry("Username", label=True, focus=True)
    app.entry("Password", label=True, secret=True)
    app.buttons(["Submit", "Cancel"], [press, app.stop])