Function input_sys::libinput_event_gesture_get_scale

pub unsafe extern "C" fn libinput_event_gesture_get_scale(
    event: *mut libinput_event_gesture
) -> f64

@ingroup event_gesture

Return the absolute scale of a pinch gesture, the scale is the division of the current distance between the fingers and the distance at the start of the gesture. The scale begins at 1.0, and if e.g. the fingers moved together by 50% then the scale will become 0.5, if they move twice as far apart as initially the scale becomes 2.0, etc.

For gesture events that are of type @ref LIBINPUT_EVENT_GESTURE_PINCH_BEGIN, this function returns 1.0.

For gesture events that are of type @ref LIBINPUT_EVENT_GESTURE_PINCH_END, this function returns the scale value of the most recent @ref LIBINPUT_EVENT_GESTURE_PINCH_UPDATE event (if any) or 1.0 otherwise.

For all other events this function returns 0.

@note It is an application bug to call this function for events other than @ref LIBINPUT_EVENT_GESTURE_PINCH_BEGIN, @ref LIBINPUT_EVENT_GESTURE_PINCH_END or @ref LIBINPUT_EVENT_GESTURE_PINCH_UPDATE.

@return the absolute scale of a pinch gesture