Class MouseEvent

lib/matplotlib/backend_bases.py:1323–1445

A mouse event ('button_press_event', 'button_release_event', \ 'scroll_event', 'motion_notify_event'). A MouseEvent has a number of special attributes in addition to those defined by the parent `Event` and `LocationEvent` classes. Attributes ---------- button : None or `Mo

class MouseEvent(LocationEvent):
    """
    A mouse event ('button_press_event', 'button_release_event', \
'scroll_event', 'motion_notify_event').

    A MouseEvent has a number of special attributes in addition to those
    defined by the parent `Event` and `LocationEvent` classes.

    Attributes
    ----------
    button : None or `MouseButton` or {'up', 'down'}
        The button pressed. 'up' and 'down' are used for scroll events.

        Note that LEFT and RIGHT actually refer to the "primary" and
        "secondary" buttons, i.e. if the user inverts their left and right
        buttons ("left-handed setting") then the LEFT button will be the one
        physically on the right.

        If this is unset, *name* is "scroll_event", and *step* is nonzero, then
        this will be set to "up" or "down" depending on the sign of *step*.

    buttons : None or frozenset
        For 'motion_notify_event', the mouse buttons currently being pressed
        (a set of zero or more MouseButtons);
        for other events, None.

        .. note::
           For 'motion_notify_event', this attribute is more accurate than
           the ``button`` (singular) attribute, which is obtained from the last
           'button_press_event' or 'button_release_event' that occurred within
           the canvas (and thus 1. be wrong if the last change in mouse state
           occurred when the canvas did not have focus, and 2. cannot report
           when multiple buttons are pressed).

           This attribute is not set for 'button_press_event' and
           'button_release_event' because GUI toolkits are inconsistent as to
           whether they report the button state *before* or *after* the
           press/release occurred.

        .. warning::
           On macOS, the Tk backends only report a single button even if
           multiple buttons are pressed.

    key : None or str
        The key pressed when the mouse event triggered, e.g. 'shift'.
        See `KeyEvent`.

        .. warning::
           This key is currently obtained from the last 'key_press_event' or
           'key_release_event' that occurred within the canvas.  Thus, if the
           last change of keyboard state occurred while the canvas did not have
           focus, this attribute will be wrong.  On the other hand, the
           ``modifiers`` attribute should always be correct, but it can only
           report on modifier keys.

    step : float
        The number of scroll steps (positive for 'up', negative for 'down').
        This applies only to 'scroll_event' and defaults to 0 otherwise.