Mouse Events

Interactive visualization is one of the most powerful aspect of Python.

Click Events

The click events can be captured by clicked. Use connect() method to connect a callback function to the event. The callback function must accept a single argument of type MouseEvent.

from whitecanvas import new_canvas
from whitecanvas.types import MouseEvent

canvas = new_canvas("matplotlib:qt")

@canvas.mouse.clicked.connect
def _on_click(ev: MouseEvent):
    print("pos:", ev.pos)  # the (x, y) coordinate
    print("button", ev.button)  # mouse button enum
    print("modifiers", ev.modifiers)  # mouse modifier enums

Double-click events are very similar. They can be captured by double_clicked.

from whitecanvas import new_canvas
from whitecanvas.types import MouseEvent

canvas = new_canvas("matplotlib:qt")

@canvas.mouse.double_clicked.connect
def _on_click(ev: MouseEvent):
    print("pos:", ev.pos)  # the (x, y) coordinate
    print("button", ev.button)  # mouse button enum
    print("modifiers", ev.modifiers)  # mouse modifier enums

It is useful to filter the mouse button and modifier inside the callback function.

@canvas.mouse.clicked.connect
def _on_click(ev: MouseEvent):
    if ev.button == "left":
        print("left button clicked")
    if ev.modifiers == "ctrl":
        print("ctrl key is pressed")

Move Events

Mouse move events need a different architecture. Unlike other events, the callback function must be a generator function. every time the mouse moves, the generator proceeds.

from whitecanvas import new_canvas
from whitecanvas.types import MouseEvent

canvas = new_canvas("matplotlib:qt")

@canvas.mouse.moved.connect
def _on_move(ev: MouseEvent):
    if ev.type != "press":
        return
    print("pressed")
    yield
    while ev.type == "move":
        print("moved to:", ev.pos)
        yield
    print("released")

Emulating Mouse Events

Mouse events can be emulated by the emulate_* methods.

• emulate_click()
• emulate_double_click()
• emulate_hover()
• emulate_drag()

from whitecanvas import new_canvas
from whitecanvas.types import MouseEvent

canvas = new_canvas("matplotlib:qt")
canvas.mouse.emulate_click((100, 100), button="left")
canvas.mouse.emulate_double_click((100, 100), button="left", modifiers="ctrl")
canvas.mouse.emulate_hover([(100, 100), (100, 101), (100, 102)])
canvas.mouse.emulate_drag([(100, 100), (100, 101), (100, 102)], button="left")