custom_events.md

TkEasyGUI > Custom Events

In addition to the unique events of the element, you can use custom events available in Tkinter. There are several ways to bind them.

Simple bind

After creating the element, bind the event with the bind method. The event name will be in the format of "f{key}{handle_name}".

import TkEasyGUI as sg
# (1) create Element
canvas = sg.Canvas(size=(400, 400), key="-canvas-")
window = sg.Window("Canvas", layout=[[canvas]], finalize=True)

# (2) bind custom events
canvas.bind("<ButtonPress>", "press")
canvas.bind("<ButtonRelease>", "release")
canvas.bind("<Motion>", "motion")

# (3) event loop
while True:
    event, values = window.read()
    if event == "-canvas-press":
        print(canvas.user_bind_event) # get event data
        print("x=", canvas.user_bind_event.x)
        print("y=", canvas.user_bind_event.y)
        break
    elif event == "-canvas-relase":
        pass
    elif event == "-canvas-motion":
        pass

Multiple bind - using bind_events method

When creating an element, you can specify multiple events using the bind_events method.

canvas = sg.Canvas(size=(400, 400), key="-canvas-").bind_events({
    "<ButtonPress>": "press",
    "<ButtonRelease>": "release",
    "<Motion>": "motion",
})

Set custom events in constructor

Within the constructor, you can specify bind_events as an argument.

canvas = sg.Canvas(
    size=(400, 400),
    key="-canvas-",
    bind_events={
        "<ButtonPress>": "mousedown",
        "<ButtonRelease>": "mouseup",
        "<Motion>": "mousemove"
    }
)

Samples:

• /tests/paint_eg.py
• /tests/paint_compatible.py

Event Hook

You can hook an event before a system event occurs. This mechanism is utilized within elements like FileBrowse.

import TkEasyGUI as eg

window = eg.Window("Event Hook Test", layout=[
    [eg.Button("OK")],
    [eg.Button("Cancel")],
])
# register event hook
window.register_event_hooks({
    "OK": [
        lambda event, values: print("#OK#hook1:", event, values),
        lambda event, values: print("#OKhook#2:", event, values),
        lambda event, values: print("#OKhook#3:", event, values),
    ],
    "Cancel": [
        lambda event, values: print("#Cancel#hook#1:", event, values),
        lambda event, values: print("#Cancel#hook#2:", event, values),
        lambda event, values: True, # stop event propagation
        lambda event, values: print("#Cancel#hook#3:", event, values),
    ]
})
while window.is_alive():
    event, values = window.read()
    print(event, values)
    if event == "OK":
        break
    elif event == "Cancel":
        break
    elif event == "Cancel-stopped":
        break
window.close()

Samples:

• /tests/event_hooks.py