Trait cursive_core::view::View
source · [−]pub trait View: Any + AnyView {
fn draw(&self, printer: &Printer<'_, '_>);
fn layout(&mut self, _: Vec2) { ... }
fn needs_relayout(&self) -> bool { ... }
fn required_size(&mut self, constraint: Vec2) -> Vec2 { ... }
fn on_event(&mut self, _: Event) -> EventResult { ... }
fn call_on_any<'a>(&mut self, _: &Selector<'_>, _: AnyCb<'a>) { ... }
fn focus_view(
&mut self,
_: &Selector<'_>
) -> Result<EventResult, ViewNotFound> { ... }
fn take_focus(
&mut self,
source: Direction
) -> Result<EventResult, CannotFocus> { ... }
fn important_area(&self, view_size: Vec2) -> Rect { ... }
fn type_name(&self) -> &'static str { ... }
}
Expand description
Main trait defining a view behaviour.
This is what you should implement to define a custom View.
Required Methods
Provided Methods
Called once the size for this view has been decided.
It can be used to pre-compute the configuration of child views.
View groups should propagate the information to their children.
At this point, the given size is final and cannot be negociated.
It is guaranteed to be the size available for the call to draw()
.
fn needs_relayout(&self) -> bool
fn needs_relayout(&self) -> bool
Should return true
if the view content changed since the last call
to layout()
.
This is mostly an optimisation for views where the layout phase is expensive.
- Views can ignore it and always return true (default implementation). They will always be assumed to have changed.
- View Groups can ignore it and always re-layout their children.
- If they call
required_size
orlayout
with stable parameters, the children may cache the result themselves and speed up the process anyway.
- If they call
fn required_size(&mut self, constraint: Vec2) -> Vec2
fn required_size(&mut self, constraint: Vec2) -> Vec2
Returns the minimum size the view requires with the given restrictions.
This is the main way a view communicate its size to its parent.
Some views have a fixed size, and will ignore the constraint
parameter entirely.
Some views are flexible, and may adapt fully or partially to the constraints.
Default implementation always return (1,1)
.
fn on_event(&mut self, _: Event) -> EventResult
fn on_event(&mut self, _: Event) -> EventResult
Called when an event is received (key press, mouse event, …).
You can return an EventResult
:
EventResult::Ignored
means the event was not processed and may be sent to another view.EventResult::Consumed
means the event was consumed and should not be sent to any other view. It may in addition include a callback to be run.
The default implementation just ignores any event.
fn call_on_any<'a>(&mut self, _: &Selector<'_>, _: AnyCb<'a>)
fn call_on_any<'a>(&mut self, _: &Selector<'_>, _: AnyCb<'a>)
Runs a closure on the view identified by the given selector.
See Finder::call_on
for a nicer interface, implemented for all
views.
If the selector doesn’t find a match, the closure will not be run.
View groups should implement this to forward the call to each children.
Default implementation is a no-op.
fn focus_view(&mut self, _: &Selector<'_>) -> Result<EventResult, ViewNotFound>
fn focus_view(&mut self, _: &Selector<'_>) -> Result<EventResult, ViewNotFound>
Moves the focus to the view identified by the given selector.
Returns Ok(_)
if the view was found and selected.
A callback may be included, it should be run on &mut Cursive
.
Default implementation simply returns Err(ViewNotFound)
.
fn take_focus(&mut self, source: Direction) -> Result<EventResult, CannotFocus>
fn take_focus(&mut self, source: Direction) -> Result<EventResult, CannotFocus>
Attempt to give this view the focus.
source
indicates where the focus comes from.
When the source is unclear (for example mouse events),
Direction::none()
can be used.
Returns Ok(_)
if the focus was taken.
Returns Err(_)
if this view does not take focus (default implementation).
fn important_area(&self, view_size: Vec2) -> Rect
fn important_area(&self, view_size: Vec2) -> Rect
What part of the view is important and should be visible?
When only part of this view can be visible, this helps determine which part.
It is given the view size (same size given to layout
).
Default implementation return the entire view.
Implementations
sourceimpl dyn View
impl dyn View
sourcepub fn downcast_ref<T: Any>(&self) -> Option<&T>
pub fn downcast_ref<T: Any>(&self) -> Option<&T>
Attempts to downcast self
to a concrete type.
sourcepub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T>
pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T>
Attempts to downcast self
to a concrete type.