Implement `pure::Responsive` in `iced_lazy`

2 files changed, 396 insertions, 1 deletions

diff --git a/lazy/src/pure.rs b/lazy/src/pure.rs
index 9cea807e..dc500e5e 100644
--- a/lazy/src/pure.rs
+++ b/lazy/src/pure.rs
@@ -1 +1,31 @@
-pub mod component;
+mod component;
+mod responsive;
+
+pub use component::Component;
+pub use responsive::Responsive;
+
+use iced_native::Size;
+use iced_pure::Element;
+
+/// Turns an implementor of [`Component`] into an [`Element`] that can be
+/// embedded in any application.
+pub fn component<'a, C, Message, Renderer>(
+    component: C,
+) -> Element<'a, Message, Renderer>
+where
+    C: Component<Message, Renderer> + 'a,
+    C::State: 'static,
+    Message: 'a,
+    Renderer: iced_native::Renderer + 'a,
+{
+    component::view(component)
+}
+
+pub fn responsive<'a, Message, Renderer>(
+    f: impl Fn(Size) -> Element<'a, Message, Renderer> + 'a,
+) -> Responsive<'a, Message, Renderer>
+where
+    Renderer: iced_native::Renderer,
+{
+    Responsive::new(f)
+}
diff --git a/lazy/src/pure/responsive.rs b/lazy/src/pure/responsive.rs
new file mode 100644
index 00000000..2b77873f
--- /dev/null
+++ b/lazy/src/pure/responsive.rs
@@ -0,0 +1,365 @@
+use iced_native::event;
+use iced_native::layout::{self, Layout};
+use iced_native::mouse;
+use iced_native::renderer;
+use iced_native::{Clipboard, Length, Point, Rectangle, Shell, Size};
+use iced_pure::overlay;
+use iced_pure::widget::horizontal_space;
+use iced_pure::widget::tree::{self, Tree};
+use iced_pure::{Element, Widget};
+
+use ouroboros::self_referencing;
+use std::cell::{Ref, RefCell, RefMut};
+use std::marker::PhantomData;
+use std::ops::Deref;
+
+/// A widget that is aware of its dimensions.
+///
+/// A [`Responsive`] widget will always try to fill all the available space of
+/// its parent.
+#[allow(missing_debug_implementations)]
+pub struct Responsive<'a, Message, Renderer> {
+    view: Box<dyn Fn(Size) -> Element<'a, Message, Renderer> + 'a>,
+    content: RefCell<Content<'a, Message, Renderer>>,
+}
+
+impl<'a, Message, Renderer> Responsive<'a, Message, Renderer>
+where
+    Renderer: iced_native::Renderer,
+{
+    /// Creates a new [`Responsive`] widget with a closure that produces its
+    /// contents.
+    ///
+    /// The `view` closure will be provided with the current [`Size`] of
+    /// the [`Responsive`] widget and, therefore, can be used to build the
+    /// contents of the widget in a responsive way.
+    pub fn new(
+        view: impl Fn(Size) -> Element<'a, Message, Renderer> + 'a,
+    ) -> Self {
+        Self {
+            view: Box::new(view),
+            content: RefCell::new(Content {
+                size: Size::ZERO,
+                layout: layout::Node::new(Size::ZERO),
+                element: Element::new(horizontal_space(Length::Units(0))),
+            }),
+        }
+    }
+}
+
+struct Content<'a, Message, Renderer> {
+    size: Size,
+    layout: layout::Node,
+    element: Element<'a, Message, Renderer>,
+}
+
+impl<'a, Message, Renderer> Content<'a, Message, Renderer> {
+    fn update(
+        &mut self,
+        tree: &mut Tree,
+        renderer: &Renderer,
+        new_size: Size,
+        view: &dyn Fn(Size) -> Element<'a, Message, Renderer>,
+    ) {
+        if self.size == new_size {
+            return;
+        }
+
+        self.element = view(new_size);
+        self.size = new_size;
+        self.layout = self
+            .element
+            .as_widget()
+            .layout(renderer, &layout::Limits::new(Size::ZERO, self.size));
+
+        tree.diff(&self.element);
+    }
+
+    fn resolve<R, T>(
+        &mut self,
+        tree: &mut Tree,
+        renderer: R,
+        layout: Layout<'_>,
+        view: &dyn Fn(Size) -> Element<'a, Message, Renderer>,
+        f: impl FnOnce(
+            &mut Tree,
+            R,
+            Layout<'_>,
+            &mut Element<'a, Message, Renderer>,
+        ) -> T,
+    ) -> T
+    where
+        R: Deref<Target = Renderer>,
+    {
+        self.update(tree, renderer.deref(), layout.bounds().size(), view);
+
+        let content_layout = Layout::with_offset(
+            layout.position() - Point::ORIGIN,
+            &self.layout,
+        );
+
+        f(tree, renderer, content_layout, &mut self.element)
+    }
+}
+
+struct State {
+    tree: RefCell<Tree>,
+}
+
+impl<'a, Message, Renderer> Widget<Message, Renderer>
+    for Responsive<'a, Message, Renderer>
+where
+    Renderer: iced_native::Renderer,
+{
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<State>()
+    }
+
+    fn state(&self) -> tree::State {
+        tree::State::new(State {
+            tree: RefCell::new(Tree::empty()),
+        })
+    }
+
+    fn width(&self) -> Length {
+        Length::Fill
+    }
+
+    fn height(&self) -> Length {
+        Length::Fill
+    }
+
+    fn layout(
+        &self,
+        _renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        layout::Node::new(limits.max())
+    }
+
+    fn on_event(
+        &mut self,
+        tree: &mut Tree,
+        event: iced_native::Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        renderer: &Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+    ) -> event::Status {
+        let state = tree.state.downcast_mut::<State>();
+        let mut content = self.content.borrow_mut();
+
+        content.resolve(
+            &mut state.tree.borrow_mut(),
+            renderer,
+            layout,
+            &self.view,
+            |tree, renderer, layout, element| {
+                element.as_widget_mut().on_event(
+                    tree,
+                    event,
+                    layout,
+                    cursor_position,
+                    renderer,
+                    clipboard,
+                    shell,
+                )
+            },
+        )
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut Renderer,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+    ) {
+        let state = tree.state.downcast_ref::<State>();
+        let mut content = self.content.borrow_mut();
+
+        content.resolve(
+            &mut state.tree.borrow_mut(),
+            renderer,
+            layout,
+            &self.view,
+            |tree, renderer, layout, element| {
+                element.as_widget().draw(
+                    tree,
+                    renderer,
+                    style,
+                    layout,
+                    cursor_position,
+                    viewport,
+                )
+            },
+        )
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        let state = tree.state.downcast_ref::<State>();
+        let mut content = self.content.borrow_mut();
+
+        content.resolve(
+            &mut state.tree.borrow_mut(),
+            renderer,
+            layout,
+            &self.view,
+            |tree, renderer, layout, element| {
+                element.as_widget().mouse_interaction(
+                    tree,
+                    layout,
+                    cursor_position,
+                    viewport,
+                    renderer,
+                )
+            },
+        )
+    }
+
+    fn overlay<'b>(
+        &'b self,
+        tree: &'b mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+    ) -> Option<overlay::Element<'b, Message, Renderer>> {
+        let state = tree.state.downcast_ref::<State>();
+
+        let overlay = OverlayBuilder {
+            content: self.content.borrow(),
+            tree: state.tree.borrow_mut(),
+            types: PhantomData,
+            overlay_builder: |content, tree| {
+                content.element.as_widget().overlay(tree, layout, renderer)
+            },
+        }
+        .build();
+
+        let has_overlay = overlay.with_overlay(|overlay| {
+            overlay.as_ref().map(overlay::Element::position)
+        });
+
+        has_overlay
+            .map(|position| overlay::Element::new(position, Box::new(overlay)))
+    }
+}
+
+impl<'a, Message, Renderer> From<Responsive<'a, Message, Renderer>>
+    for Element<'a, Message, Renderer>
+where
+    Renderer: iced_native::Renderer + 'a,
+    Message: 'a,
+{
+    fn from(responsive: Responsive<'a, Message, Renderer>) -> Self {
+        Self::new(responsive)
+    }
+}
+
+#[self_referencing]
+struct Overlay<'a, 'b, Message, Renderer> {
+    content: Ref<'a, Content<'b, Message, Renderer>>,
+    tree: RefMut<'a, Tree>,
+    types: PhantomData<Message>,
+
+    #[borrows(content, mut tree)]
+    #[covariant]
+    overlay: Option<overlay::Element<'this, Message, Renderer>>,
+}
+
+impl<'a, 'b, Message, Renderer> Overlay<'a, 'b, Message, Renderer> {
+    fn with_overlay_maybe<T>(
+        &self,
+        f: impl FnOnce(&overlay::Element<'_, Message, Renderer>) -> T,
+    ) -> Option<T> {
+        self.borrow_overlay().as_ref().map(f)
+    }
+
+    fn with_overlay_mut_maybe<T>(
+        &mut self,
+        f: impl FnOnce(&mut overlay::Element<'_, Message, Renderer>) -> T,
+    ) -> Option<T> {
+        self.with_overlay_mut(|overlay| overlay.as_mut().map(f))
+    }
+}
+
+impl<'a, 'b, Message, Renderer> overlay::Overlay<Message, Renderer>
+    for Overlay<'a, 'b, Message, Renderer>
+where
+    Renderer: iced_native::Renderer,
+{
+    fn layout(
+        &self,
+        renderer: &Renderer,
+        bounds: Size,
+        position: Point,
+    ) -> layout::Node {
+        self.with_overlay_maybe(|overlay| {
+            let vector = position - overlay.position();
+
+            overlay.layout(renderer, bounds).translate(vector)
+        })
+        .unwrap_or_default()
+    }
+
+    fn draw(
+        &self,
+        renderer: &mut Renderer,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+    ) {
+        self.with_overlay_maybe(|overlay| {
+            overlay.draw(renderer, style, layout, cursor_position);
+        });
+    }
+
+    fn mouse_interaction(
+        &self,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        self.with_overlay_maybe(|overlay| {
+            overlay.mouse_interaction(
+                layout,
+                cursor_position,
+                viewport,
+                renderer,
+            )
+        })
+        .unwrap_or_default()
+    }
+
+    fn on_event(
+        &mut self,
+        event: iced_native::Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        renderer: &Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+    ) -> event::Status {
+        self.with_overlay_mut_maybe(|overlay| {
+            overlay.on_event(
+                event,
+                layout,
+                cursor_position,
+                renderer,
+                clipboard,
+                shell,
+            )
+        })
+        .unwrap_or_else(|| iced_native::event::Status::Ignored)
+    }
+}