Bitmask containing various status information on the event. It is not
advised to rely on the contents of the bitmask as this might change in
the future.
The status of the modifier keys is normally tested using event->has_modifier.
The type of click (single, double, triple) is requested using
event<-multiclick
and the button for button-related events using event<-button.
Current definition of the mask-values
control-key 0x1
shift-key 0x2
meta-key 0x4
left-button 0x8
middle-button 0x10
right-button 0x20
single-click 0x40
double-click 0x80
triple-click 0xC0
Identifier for the event. This is either a name occurring in the
event-type hierarchy @event_tree
or an integer. The latter is used for ASCII-type events and represents
the ASCII value. See also
event<-key.
Whether or not an event is of specified type is normally tested using
event->is_a.
Other useful classifications are realised using
event->is_up, event->is_down, event->is_drag, event->has_modifier, event<-click_time
and
event<-click_displacement.
One event requires special treatment. This is the event related to wheel-mice,
mice normally having two buttons and a scroll-wheel. Rotations of the
scroll-wheel are mapped to an
event object with event<-id:
wheel. The rotation is available as
event<-rotation, which is @nil
for all other events. A notch of the wheel is a rotation of 15 degrees.
The value is positive if the wheel is rotated from the user and negative
when rotated towards the user.
In the X11 version, wheel-events are normally mapped to the virtual
mouse-buttons 4 and 5. If the class-variable
event.x11_wheel_mouse = @on
(default in the X11 version), the low-level event handling will map the
button 4 and button 5 events to wheel events.
Horizontal scrolling, e.g., using a
trackpad or tilting the wheel, is mapped to an event with event<-id:
horizontal_wheel. Its event<-rotation is
positive to the right. If a trackpad scrolls diagonally, the event
reports the dominant direction.
The event<-detail
of both events is a wheel_data
object that holds the precise scroll distance in both directions, so a
handler may use
get(Ev, dx, DX) and get(Ev, dy, DY) for smooth
scrolling.
In a window with window<->smooth_scroll @on,
the event<-rotation may be a fraction of a
notch. See there.
The wheel event is handled by class window,
class editor, class list_browser
and class scroll_bar.
The wheel scrolls vertically, a page if Control is held down. As usual,
the wheel with Shift held down scrolls horizontally, as does the wheel
on a horizontal scroll_bar. If the receiver cannot scroll horizontally,
Shift scrolls one line.
- See also
- event
->is_a
