feat(list_column): button list items

src/widget/list/list_column.rs

@@ -0,0 +1,188 @@
+// Copyright 2022 System76 <info@system76.com>
+// SPDX-License-Identifier: MPL-2.0
+
+use crate::widget::container::Catalog;
+use crate::widget::{button, column, container, divider, row, space::vertical};
+use crate::{Apply, Element, theme};
+use iced::{Length, Padding};
+
+/// A button list item for use in a [`ListColumn`].
+pub struct ListButton<'a, Message> {
+    content: Element<'a, Message>,
+    on_press: Option<Message>,
+    selected: bool,
+}
+
+/// Creates a [`ListButton`] with the given content.
+pub fn button<'a, Message>(content: impl Into<Element<'a, Message>>) -> ListButton<'a, Message> {
+    ListButton {
+        content: content.into(),
+        on_press: None,
+        selected: false,
+    }
+}
+
+impl<'a, Message: 'static> ListButton<'a, Message> {
+    pub fn on_press(mut self, on_press: Message) -> Self {
+        self.on_press = Some(on_press);
+        self
+    }
+
+    pub fn on_press_maybe(mut self, on_press: Option<Message>) -> Self {
+        self.on_press = on_press;
+        self
+    }
+
+    pub fn selected(mut self, selected: bool) -> Self {
+        self.selected = selected;
+        self
+    }
+}
+
+pub enum ListItem<'a, Message> {
+    Element(Element<'a, Message>),
+    Button(ListButton<'a, Message>),
+}
+
+/// A trait for types that can be added to a [`ListColumn`].
+pub trait IntoListItem<'a, Message> {
+    fn into_list_item(self) -> ListItem<'a, Message>;
+}
+
+impl<'a, Message, T> IntoListItem<'a, Message> for T
+where
+    T: Into<Element<'a, Message>>,
+{
+    fn into_list_item(self) -> ListItem<'a, Message> {
+        ListItem::Element(self.into())
+    }
+}
+
+impl<'a, Message> IntoListItem<'a, Message> for ListButton<'a, Message> {
+    fn into_list_item(self) -> ListItem<'a, Message> {
+        ListItem::Button(self)
+    }
+}
+
+#[must_use]
+pub struct ListColumn<'a, Message> {
+    list_item_padding: Padding,
+    style: theme::Container<'a>,
+    children: Vec<ListItem<'a, Message>>,
+}
+
+#[inline]
+pub fn list_column<'a, Message: 'static>() -> ListColumn<'a, Message> {
+    ListColumn::default()
+}
+
+pub fn with_capacity<'a, Message: 'static>(capacity: usize) -> ListColumn<'a, Message> {
+    let cosmic_theme::Spacing {
+        space_xxs, space_m, ..
+    } = theme::spacing();
+
+    ListColumn {
+        list_item_padding: [space_xxs, space_m].into(),
+        style: theme::Container::List,
+        children: Vec::with_capacity(capacity),
+    }
+}
+
+impl<Message: 'static> Default for ListColumn<'_, Message> {
+    fn default() -> Self {
+        with_capacity(4)
+    }
+}
+
+impl<'a, Message: Clone + 'static> ListColumn<'a, Message> {
+    #[inline]
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Adds an element to the list column.
+    #[allow(clippy::should_implement_trait)]
+    pub fn add(mut self, item: impl IntoListItem<'a, Message>) -> Self {
+        self.children.push(item.into_list_item());
+        self
+    }
+
+    /// Sets the style variant of this [`ListColumn`].
+    #[inline]
+    pub fn style(mut self, style: <crate::Theme as Catalog>::Class<'a>) -> Self {
+        self.style = style;
+        self
+    }
+
+    pub fn list_item_padding(mut self, padding: impl Into<Padding>) -> Self {
+        self.list_item_padding = padding.into();
+        self
+    }
+
+    #[must_use]
+    pub fn into_element(self) -> Element<'a, Message> {
+        let padding = self.list_item_padding;
+        let count = self.children.len();
+        let last_index = count.saturating_sub(1);
+        let radius_s = theme::active().cosmic().radius_s();
+
+        // Ensure minimum height of 32
+        let content_row = |content| {
+            row![container(content), vertical().height(32)].align_y(iced::Alignment::Center)
+        };
+
+        self.children
+            .into_iter()
+            .enumerate()
+            .fold(
+                column::with_capacity((2 * count).saturating_sub(1)),
+                |mut col, (i, item)| {
+                    if i > 0 {
+                        col = col.push(divider::horizontal::default());
+                    }
+
+                    match item {
+                        ListItem::Element(content) => {
+                            col.push(content_row(content).padding(padding).width(Length::Fill))
+                        }
+                        ListItem::Button(ListButton {
+                            content,
+                            on_press,
+                            selected,
+                        }) => col.push(
+                            content_row(content)
+                                .apply(button::custom)
+                                .padding(padding)
+                                .width(Length::Fill)
+                                .on_press_maybe(on_press)
+                                .selected(selected)
+                                .class(theme::Button::ListItem(get_radius(
+                                    radius_s,
+                                    i == 0,
+                                    i == last_index,
+                                ))),
+                        ),
+                    }
+                },
+            )
+            .width(Length::Fill)
+            .apply(container)
+            .class(self.style)
+            .into()
+    }
+}
+
+impl<'a, Message: Clone + 'static> From<ListColumn<'a, Message>> for Element<'a, Message> {
+    fn from(column: ListColumn<'a, Message>) -> Self {
+        column.into_element()
+    }
+}
+
+fn get_radius(radius: [f32; 4], first: bool, last: bool) -> [f32; 4] {
+    match (first, last) {
+        (true, true) => radius,
+        (true, false) => [radius[0], radius[1], 0.0, 0.0],
+        (false, true) => [0.0, 0.0, radius[2], radius[3]],
+        (false, false) => [0.0, 0.0, 0.0, 0.0],
+    }
+}