Add sidebars

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

zed/src/workspace/sidebar.rs

@@ -0,0 +1,93 @@
+use crate::Settings;
+use gpui::{
+    elements::{
+        Align, ConstrainedBox, Container, Flex, MouseEventHandler, ParentElement as _, Svg,
+    },
+    AnyViewHandle, AppContext, Element as _, ElementBox,
+};
+
+pub struct Sidebar {
+    side: Side,
+    items: Vec<Item>,
+    active_item_ix: Option<usize>,
+}
+
+#[derive(Clone, Copy)]
+pub enum Side {
+    Left,
+    Right,
+}
+
+struct Item {
+    icon_path: &'static str,
+    view: AnyViewHandle,
+}
+
+impl Sidebar {
+    pub fn new(side: Side) -> Self {
+        Self {
+            side,
+            items: Default::default(),
+            active_item_ix: None,
+        }
+    }
+
+    pub fn add_item(&mut self, icon_path: &'static str, view: AnyViewHandle) {
+        self.items.push(Item { icon_path, view });
+    }
+
+    pub fn toggle_item(&mut self, item_ix: usize) {
+        if self.active_item_ix == Some(item_ix) {
+            self.active_item_ix = None;
+        } else {
+            self.active_item_ix = Some(item_ix)
+        }
+    }
+
+    pub fn active_item(&self) -> Option<&AnyViewHandle> {
+        self.active_item_ix
+            .and_then(|ix| self.items.get(ix))
+            .map(|item| &item.view)
+    }
+
+    pub fn render(&self, settings: &Settings, cx: &AppContext) -> ElementBox {
+        let side = self.side;
+        let line_height = cx.font_cache().line_height(
+            cx.font_cache().default_font(settings.ui_font_family),
+            settings.ui_font_size,
+        );
+
+        Container::new(
+            Flex::column()
+                .with_children(self.items.iter().enumerate().map(|(item_ix, item)| {
+                    let theme = if Some(item_ix) == self.active_item_ix {
+                        &settings.theme.active_sidebar_icon
+                    } else {
+                        &settings.theme.sidebar_icon
+                    };
+                    enum SidebarButton {}
+                    MouseEventHandler::new::<SidebarButton, _>(item.view.id(), cx, |_| {
+                        ConstrainedBox::new(
+                            Align::new(
+                                ConstrainedBox::new(
+                                    Svg::new(item.icon_path).with_color(theme.color).boxed(),
+                                )
+                                .with_height(line_height)
+                                .boxed(),
+                            )
+                            .boxed(),
+                        )
+                        .with_height(line_height + 16.0)
+                        .boxed()
+                    })
+                    .on_click(move |cx| {
+                        cx.dispatch_action("workspace:toggle_sidebar_item", (side, item_ix))
+                    })
+                    .boxed()
+                }))
+                .boxed(),
+        )
+        .with_style(&settings.theme.sidebar)
+        .boxed()
+    }
+}