1 files changed, 265 insertions, 0 deletions
diff --git a/pure/src/widget/scrollable.rs b/pure/src/widget/scrollable.rs
new file mode 100644
index 00000000..f9a51200
--- /dev/null
+++ b/pure/src/widget/scrollable.rs
@@ -0,0 +1,265 @@
+use crate::overlay;
+use crate::widget::tree::{self, Tree};
+use crate::{Element, Widget};
+
+use iced_native::event::{self, Event};
+use iced_native::layout::{self, Layout};
+use iced_native::mouse;
+use iced_native::renderer;
+use iced_native::widget::scrollable;
+use iced_native::{Clipboard, Length, Point, Rectangle, Shell, Vector};
+
+pub use iced_style::scrollable::{Scrollbar, Scroller, StyleSheet};
+
+/// A widget that can vertically display an infinite amount of content with a
+/// scrollbar.
+#[allow(missing_debug_implementations)]
+pub struct Scrollable<'a, Message, Renderer> {
+    height: Length,
+    scrollbar_width: u16,
+    scrollbar_margin: u16,
+    scroller_width: u16,
+    on_scroll: Option<Box<dyn Fn(f32) -> Message>>,
+    style_sheet: Box<dyn StyleSheet + 'a>,
+    content: Element<'a, Message, Renderer>,
+}
+
+impl<'a, Message, Renderer: iced_native::Renderer>
+    Scrollable<'a, Message, Renderer>
+{
+    /// Creates a new [`Scrollable`].
+    pub fn new(content: impl Into<Element<'a, Message, Renderer>>) -> Self {
+        Scrollable {
+            height: Length::Shrink,
+            scrollbar_width: 10,
+            scrollbar_margin: 0,
+            scroller_width: 10,
+            on_scroll: None,
+            style_sheet: Default::default(),
+            content: content.into(),
+        }
+    }
+
+    /// Sets the height of the [`Scrollable`].
+    pub fn height(mut self, height: Length) -> Self {
+        self.height = height;
+        self
+    }
+
+    /// Sets the scrollbar width of the [`Scrollable`] .
+    /// Silently enforces a minimum value of 1.
+    pub fn scrollbar_width(mut self, scrollbar_width: u16) -> Self {
+        self.scrollbar_width = scrollbar_width.max(1);
+        self
+    }
+
+    /// Sets the scrollbar margin of the [`Scrollable`] .
+    pub fn scrollbar_margin(mut self, scrollbar_margin: u16) -> Self {
+        self.scrollbar_margin = scrollbar_margin;
+        self
+    }
+
+    /// Sets the scroller width of the [`Scrollable`] .
+    ///
+    /// It silently enforces a minimum value of 1.
+    pub fn scroller_width(mut self, scroller_width: u16) -> Self {
+        self.scroller_width = scroller_width.max(1);
+        self
+    }
+
+    /// Sets a function to call when the [`Scrollable`] is scrolled.
+    ///
+    /// The function takes the new relative offset of the [`Scrollable`]
+    /// (e.g. `0` means top, while `1` means bottom).
+    pub fn on_scroll(mut self, f: impl Fn(f32) -> Message + 'static) -> Self {
+        self.on_scroll = Some(Box::new(f));
+        self
+    }
+
+    /// Sets the style of the [`Scrollable`] .
+    pub fn style(
+        mut self,
+        style_sheet: impl Into<Box<dyn StyleSheet + 'a>>,
+    ) -> Self {
+        self.style_sheet = style_sheet.into();
+        self
+    }
+}
+
+impl<'a, Message, Renderer> Widget<Message, Renderer>
+    for Scrollable<'a, Message, Renderer>
+where
+    Renderer: iced_native::Renderer,
+{
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<scrollable::State>()
+    }
+
+    fn state(&self) -> tree::State {
+        tree::State::new(scrollable::State::new())
+    }
+
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(&self.content)]
+    }
+
+    fn diff(&self, tree: &mut Tree) {
+        tree.diff_children(std::slice::from_ref(&self.content))
+    }
+
+    fn width(&self) -> Length {
+        self.content.as_widget().width()
+    }
+
+    fn height(&self) -> Length {
+        self.height
+    }
+
+    fn layout(
+        &self,
+        renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        scrollable::layout(
+            renderer,
+            limits,
+            Widget::<Message, Renderer>::width(self),
+            self.height,
+            |renderer, limits| {
+                self.content.as_widget().layout(renderer, limits)
+            },
+        )
+    }
+
+    fn on_event(
+        &mut self,
+        tree: &mut Tree,
+        event: Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        renderer: &Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+    ) -> event::Status {
+        scrollable::update(
+            tree.state.downcast_mut::<scrollable::State>(),
+            event,
+            layout,
+            cursor_position,
+            clipboard,
+            shell,
+            self.scrollbar_width,
+            self.scrollbar_margin,
+            self.scroller_width,
+            &self.on_scroll,
+            |event, layout, cursor_position, clipboard, shell| {
+                self.content.as_widget_mut().on_event(
+                    &mut tree.children[0],
+                    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,
+    ) {
+        scrollable::draw(
+            tree.state.downcast_ref::<scrollable::State>(),
+            renderer,
+            layout,
+            cursor_position,
+            self.scrollbar_width,
+            self.scrollbar_margin,
+            self.scroller_width,
+            self.style_sheet.as_ref(),
+            |renderer, layout, cursor_position, viewport| {
+                self.content.as_widget().draw(
+                    &tree.children[0],
+                    renderer,
+                    style,
+                    layout,
+                    cursor_position,
+                    viewport,
+                )
+            },
+        )
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        _viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        scrollable::mouse_interaction(
+            tree.state.downcast_ref::<scrollable::State>(),
+            layout,
+            cursor_position,
+            self.scrollbar_width,
+            self.scrollbar_margin,
+            self.scroller_width,
+            |layout, cursor_position, viewport| {
+                self.content.as_widget().mouse_interaction(
+                    &tree.children[0],
+                    layout,
+                    cursor_position,
+                    viewport,
+                    renderer,
+                )
+            },
+        )
+    }
+
+    fn overlay<'b>(
+        &'b self,
+        tree: &'b mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+    ) -> Option<overlay::Element<'b, Message, Renderer>> {
+        self.content
+            .as_widget()
+            .overlay(
+                &mut tree.children[0],
+                layout.children().next().unwrap(),
+                renderer,
+            )
+            .map(|overlay| {
+                let bounds = layout.bounds();
+                let content_layout = layout.children().next().unwrap();
+                let content_bounds = content_layout.bounds();
+                let offset = tree
+                    .state
+                    .downcast_ref::<scrollable::State>()
+                    .offset(bounds, content_bounds);
+
+                overlay.translate(Vector::new(0.0, -(offset as f32)))
+            })
+    }
+}
+
+impl<'a, Message, Renderer> From<Scrollable<'a, Message, Renderer>>
+    for Element<'a, Message, Renderer>
+where
+    Message: 'a + Clone,
+    Renderer: 'a + iced_native::Renderer,
+{
+    fn from(
+        text_input: Scrollable<'a, Message, Renderer>,
+    ) -> Element<'a, Message, Renderer> {
+        Element::new(text_input)
+    }
+}