kas-widgets 0.17.1

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License in the LICENSE-APACHE file or at:
//     https://www.apache.org/licenses/LICENSE-2.0

//! Event adapters

use super::{AdaptConfigCx, AdaptEventCx};
#[allow(unused)] use kas::Events;
use kas::event::{ConfigCx, Event, EventCx, IsUsed};
use kas::{Id, Widget};
use kas::{autoimpl, impl_self};
use std::fmt::Debug;

#[impl_self]
mod AdaptEvents {
    /// Wrapper with configure / update / message handling callbacks.
    ///
    /// This type is constructed by some [`AdaptWidget`](super::AdaptWidget) methods.
    #[autoimpl(Deref, DerefMut using self.inner)]
    #[autoimpl(Viewport using self.inner where W: trait)]
    #[derive_widget]
    pub struct AdaptEvents<W: Widget> {
        /// The inner widget
        #[widget]
        pub inner: W,
        on_configure: Option<Box<dyn Fn(&mut AdaptConfigCx, &mut W)>>,
        on_update: Option<Box<dyn Fn(&mut AdaptConfigCx, &mut W, &W::Data)>>,
        message_handlers: Vec<Box<dyn Fn(&mut AdaptEventCx, &mut W, &W::Data)>>,
    }

    impl<W: Widget> AdaptEvents<W> {
        /// Construct
        #[inline]
        pub fn new(inner: W) -> Self {
            AdaptEvents {
                inner,
                on_configure: None,
                on_update: None,
                message_handlers: vec![],
            }
        }

        /// Call the given closure on [configuration]
        ///
        /// Specifically, the closure is called after [`Events::post_configure`].
        ///
        /// [configuration]: Events#configuration
        #[must_use]
        pub fn on_configure<F>(mut self, f: F) -> Self
        where
            F: Fn(&mut AdaptConfigCx, &mut W) + 'static,
        {
            self.on_configure = Some(Box::new(f));
            self
        }

        /// Call the given closure on [update]
        ///
        /// The closure is called after the [`Self::on_configure`] handler
        /// during [configuration] and after [`Events::update`] during [update].
        ///
        /// [configuration]: Events#configuration
        /// [update]: Events#update
        #[must_use]
        pub fn on_update<F>(mut self, f: F) -> Self
        where
            F: Fn(&mut AdaptConfigCx, &mut W, &W::Data) + 'static,
        {
            self.on_update = Some(Box::new(f));
            self
        }

        /// Add a handler on message of type `M`
        ///
        /// The child index may be inferred via [`EventCx::last_child`].
        /// (Note: this is only possible since `AdaptEvents` is a special "thin" wrapper.)
        ///
        /// Where access to input data is required, use [`Self::on_messages`] instead.
        #[must_use]
        pub fn on_message<M, H>(self, handler: H) -> Self
        where
            M: Debug + 'static,
            H: Fn(&mut AdaptEventCx, &mut W, M) + 'static,
        {
            self.on_messages(move |cx, w, _data| {
                if let Some(m) = cx.try_pop() {
                    handler(cx, w, m);
                }
            })
        }

        /// Add a child handler to map messages of type `M` to `N`
        ///
        /// # Example
        ///
        /// ```
        /// use kas::messages::Select;
        /// use kas_widgets::{AdaptWidget, Row, Tab};
        ///
        /// #[derive(Clone, Debug)]
        /// struct MsgSelectIndex(usize);
        ///
        /// let tabs = Row::new([Tab::new("A")])
        ///     .map_message(|index, Select| MsgSelectIndex(index));
        /// ```
        pub fn map_message<M, N, H>(self, handler: H) -> Self
        where
            M: Debug + 'static,
            N: Debug + 'static,
            H: Fn(usize, M) -> N + 'static,
        {
            self.on_messages(move |cx, _, _| {
                if let Some(index) = cx.last_child() {
                    if let Some(m) = cx.try_pop() {
                        cx.push(handler(index, m));
                    }
                }
            })
        }

        /// Add a generic message handler
        ///
        /// The child index may be inferred via [`EventCx::last_child`].
        /// (Note: this is only possible since `AdaptEvents` is a special "thin" wrapper.)
        #[must_use]
        pub fn on_messages<H>(mut self, handler: H) -> Self
        where
            H: Fn(&mut AdaptEventCx, &mut W, &W::Data) + 'static,
        {
            self.message_handlers.push(Box::new(handler));
            self
        }
    }

    impl<W: Widget> Widget for AdaptEvents<W> {
        type Data = W::Data;

        // NOTE: internal widget methods are used here to call additional event
        // handlers. This is not otherwise supported by #[derive_widget].

        fn _configure(&mut self, cx: &mut ConfigCx, data: &Self::Data, id: Id) {
            self.inner._configure(cx, data, id);

            if let Some(ref f) = self.on_configure {
                let mut cx = AdaptConfigCx::new(cx, self.inner.id());
                f(&mut cx, &mut self.inner);
            }
            if let Some(ref f) = self.on_update {
                let mut cx = AdaptConfigCx::new(cx, self.inner.id());
                f(&mut cx, &mut self.inner, data);
            }
        }

        fn _update(&mut self, cx: &mut ConfigCx, data: &Self::Data) {
            self.inner._update(cx, data);

            if let Some(ref f) = self.on_update {
                let mut cx = AdaptConfigCx::new(cx, self.inner.id());
                f(&mut cx, &mut self.inner, data);
            }
        }

        fn _send(&mut self, cx: &mut EventCx, data: &Self::Data, id: Id, event: Event) -> IsUsed {
            let is_used = self.inner._send(cx, data, id, event);

            if cx.has_msg() {
                let mut cx = AdaptEventCx::new(cx, self.inner.id());
                for handler in self.message_handlers.iter() {
                    handler(&mut cx, &mut self.inner, data);
                }
            }

            is_used
        }

        fn _replay(&mut self, cx: &mut EventCx, data: &Self::Data, id: Id) {
            self.inner._replay(cx, data, id);

            if cx.has_msg() {
                let mut cx = AdaptEventCx::new(cx, self.inner.id());
                for handler in self.message_handlers.iter() {
                    handler(&mut cx, &mut self.inner, data);
                }
            }
        }
    }
}