Introduce `keyboard::on_key_press` and `on_key_release`

Also rename `subscription::events*` to `event::listen*`.

1 files changed, 59 insertions, 0 deletions

diff --git a/futures/src/event.rs b/futures/src/event.rs
new file mode 100644
index 00000000..214d2d40
--- /dev/null
+++ b/futures/src/event.rs
@@ -0,0 +1,59 @@
+//! Listen to runtime events.
+use crate::core::event::{self, Event};
+use crate::core::window;
+use crate::subscription::{self, Subscription};
+use crate::MaybeSend;
+
+/// Returns a [`Subscription`] to all the ignored runtime events.
+///
+/// This subscription will notify your application of any [`Event`] that was
+/// not captured by any widget.
+pub fn listen() -> Subscription<Event> {
+    listen_with(|event, status| match status {
+        event::Status::Ignored => Some(event),
+        event::Status::Captured => None,
+    })
+}
+
+/// Creates a [`Subscription`] that listens and filters all the runtime events
+/// with the provided function, producing messages accordingly.
+///
+/// This subscription will call the provided function for every [`Event`]
+/// handled by the runtime. If the function:
+///
+/// - Returns `None`, the [`Event`] will be discarded.
+/// - Returns `Some` message, the `Message` will be produced.
+pub fn listen_with<Message>(
+    f: fn(Event, event::Status) -> Option<Message>,
+) -> Subscription<Message>
+where
+    Message: 'static + MaybeSend,
+{
+    #[derive(Hash)]
+    struct EventsWith;
+
+    subscription::filter_map(
+        (EventsWith, f),
+        move |event, status| match event {
+            Event::Window(window::Event::RedrawRequested(_)) => None,
+            _ => f(event, status),
+        },
+    )
+}
+
+/// Creates a [`Subscription`] that produces a message for every runtime event,
+/// including the redraw request events.
+///
+/// **Warning:** This [`Subscription`], if unfiltered, may produce messages in
+/// an infinite loop.
+pub fn listen_raw<Message>(
+    f: fn(Event, event::Status) -> Option<Message>,
+) -> Subscription<Message>
+where
+    Message: 'static + MaybeSend,
+{
+    #[derive(Hash)]
+    struct RawEvents;
+
+    subscription::filter_map((RawEvents, f), f)
+}