[−][src]Enum druid::Event
An event, propagated downwards during event flow.
Events are things that happen that can change the state of widgets. An important category is events plumbed from the platform windowing system, which includes mouse and keyboard events, but also (in the future) status changes such as window focus changes.
Events can also be higher level concepts indicating state changes within the widget hierarchy, for example when a widget gains or loses focus or "hot" (also known as hover) status.
Events are a key part of what is called "event flow", which is
basically the propagation of an event through the widget hierarchy
through the event
widget method. A container widget will
generally pass the event to its children, mediated through the
WidgetPod
container, which is where most of the event flow logic
is applied (especially the decision whether or not to propagate).
This enum is expected to grow considerably, as there are many, many different kinds of events that are relevant in a GUI.
Variants
Sent to all widgets in a given window when that window is first instantiated.
This should always be the first Event
received, although widgets will
receive LifeCycle::WidgetAdded
first.
Widgets should handle this event if they need to do some addition setup when a window is first created.
WindowSize(Size)
Called on the root widget when the window size changes.
Discussion: it's not obvious this should be propagated to user
widgets. It is propagated through the RootWidget and handled
in the WindowPod, but after that it might be considered better
to just handle it in layout
.
MouseDown(MouseEvent)
Called when a mouse button is pressed.
MouseUp(MouseEvent)
Called when a mouse button is released.
MouseMove(MouseEvent)
Called when the mouse is moved.
The MouseMove
event is propagated to the active widget, if
there is one, otherwise to hot widgets (see HotChanged
).
If a widget loses its hot status due to MouseMove
then that specific
MouseMove
event is also still sent to that widget.
The MouseMove
event is also the primary mechanism for widgets
to set a cursor, for example to an I-bar inside a text widget. A
simple tactic is for the widget to unconditionally call
set_cursor
in the MouseMove handler, as MouseMove
is only
propagated to active or hot widgets.
Wheel(MouseEvent)
Called when the mouse wheel or trackpad is scrolled.
KeyDown(KeyEvent)
Called when a key is pressed.
Note: the intent is for each physical key press to correspond to
a single KeyDown
event. This is sometimes different than the
raw events provided by the platform. In particular, Windows sends
one or both of WM_KEYDOWN (a raw key code) and WM_CHAR (the
Unicode value), depending on the actual key.
KeyUp(KeyEvent)
Called when a key is released.
Because of repeat, there may be a number KeyDown
events before
a corresponding KeyUp
is sent.
Paste(Clipboard)
Called when a paste command is received.
Zoom(f64)
Called when the trackpad is pinched.
The value is a delta.
Timer(TimerToken)
Called on a timer event.
Request a timer event through EventCtx::request_timer()
. That will
cause a timer event later.
Note that timer events from other widgets may be delivered as well. Use
the token returned from the request_timer()
call to filter events more
precisely.
Command(Command)
Called with an arbitrary Command
, submitted from elsewhere in
the application.
Commands can be issued when the user triggers a menu item or an
application-level hotkey, or they can be created dynamically by
Widget
s, at runtime, with EventCtx::submit_command
.
Internal(InternalEvent)
Internal druid event.
This should always be passed down to descendant WidgetPod
s.
Implementations
impl Event
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pub fn transform_scroll(
&self,
offset: Vec2,
viewport: Rect,
force: bool
) -> Option<Event>
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&self,
offset: Vec2,
viewport: Rect,
force: bool
) -> Option<Event>
Transform the event for the contents of a scrolling container.
the force
flag is used to ensure an event is delivered even
if the cursor is out of the viewport, such as if the contents are active
or hot.
Trait Implementations
Auto Trait Implementations
impl !RefUnwindSafe for Event
impl !Send for Event
impl !Sync for Event
impl Unpin for Event
impl !UnwindSafe for Event
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> RoundFrom<T> for T
fn round_from(x: T) -> T
impl<T, U> RoundInto<U> for T where
U: RoundFrom<T>,
U: RoundFrom<T>,
fn round_into(self) -> U
impl<T> Same<T> for T
type Output = T
Should always be Self
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
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fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,