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use std::any::Any;
use std::collections::hash_map::DefaultHasher;
use std::future::Future;
use std::hash::{Hash, Hasher};
use futures::Stream;
use crate::node::component_node::{Runtime, State};
use crate::node::Node;
use crate::style::builder::StyleBuilder;
use crate::widget::Context as WidgetContext;
/// A re-usable component for defining a fragment of a user interface.
/// Components are the main building block for user interfaces in pixel-widgets.
///
/// The examples in this repository all implement some kind of `Component`,
/// check them out if you just want to read some code.
pub trait Component {
/// Mutable state associated with this `Component`.
type State: 'static + Any + Send + Sync;
/// The message type this `Component` will receive from it's view.
type Message: 'static;
/// The message type this `Component` submits to its parent.
type Output: 'static;
/// Create a new `State` for the `Component`.
/// This will be called only once when the `Component` is first created.
fn mount(&self) -> Self::State;
/// Generate the view for the `Component`.
/// This will be called just in time before ui rendering.
/// When the `Component` is updated,
/// the view will be invalidated and the runtime will have to call this function again.
fn view<'a>(&'a self, state: &'a Self::State) -> Node<'a, Self::Message>;
/// Update the `Component` state in response to the `message`.
/// Asynchronous operations can be submitted to the `context`,
/// which will result in more `update` calls in the future.
/// Messages for the parent `Component` or root can also be submitted through the `context`.
fn update(
&self,
_message: Self::Message,
_state: State<Self::State>,
_context: Context<Self::Message, Self::Output>,
) {
}
/// Returns a `StyleBuilder` with styling information scoped to this component.
/// This method will be called when you call
/// [`StyleBuilder::component()`](../style/builder/struct.StyleBuilder.html#method.component)
/// when building your style.
fn style() -> StyleBuilder {
StyleBuilder::default()
}
/// Converts the component into a `Node`. This is used by the library to
/// instantiate the component in a user interface.
fn into_node<'a>(self) -> Node<'a, Self::Output>
where
Self: 'a + Sized,
{
Node::from_component(self)
}
/// Converts the component into a `Node` and sets a style class to it.
fn class<'a>(self, class: &'a str) -> Node<'a, Self::Output>
where
Self: 'a + Sized,
{
let mut node = self.into_node();
node.set_class(class);
node
}
/// Converts the component into a `Node` and sets a custom key to it.
fn key<'a, K>(self, key: K) -> Node<'a, Self::Output>
where
Self: 'a + Sized,
K: Hash,
{
let mut hasher = DefaultHasher::new();
key.hash(&mut hasher);
let mut node = self.into_node();
node.set_key(hasher.finish());
node
}
}
/// Allows for message passing between components
pub struct Context<'a, Message, Output> {
widget_context: &'a mut WidgetContext<Output>,
runtime: &'a mut Runtime<Message>,
}
impl<'a, Message, Output> Context<'a, Message, Output> {
pub(crate) fn new(widget_context: &'a mut WidgetContext<Output>, runtime: &'a mut Runtime<Message>) -> Self {
Self {
widget_context,
runtime,
}
}
/// Push a message to the parent.
pub fn push(&mut self, message: Output) {
self.widget_context.push(message);
}
/// Push multiple messages to the parent using an iterator.
pub fn extend<I: IntoIterator<Item = Output>>(&mut self, iter: I) {
self.widget_context.extend(iter);
}
/// Returns the cursor position
pub fn cursor(&self) -> (f32, f32) {
self.widget_context.cursor()
}
/// Submits a messsage to self in the future.
pub fn wait<F: 'static + Future<Output = Message> + Send + Sync + Unpin>(&mut self, fut: F) {
self.runtime.wait(fut);
}
/// Submits a stream of messages to self in the future.
pub fn stream<S: 'static + Stream<Item = Message> + Send + Sync + Unpin>(&mut self, stream: S) {
self.runtime.stream(stream);
}
}