2 files changed, 108 insertions(+), 0 deletions(-)

A src/list.rs
M src/main.rs

@@ 0,0 1,107 @@
+//! Simple list view widget.
+
+use std::sync::Arc;
+
+use druid::kurbo::{Point, Rect, Size};
+
+use druid::{
+    Action, BaseState, BoxConstraints, Data, Env, Event, EventCtx, LayoutCtx, PaintCtx, UpdateCtx,
+    Widget, WidgetPod,
+};
+
+pub struct List<T: Data, F: FnMut() -> Box<dyn Widget<T>>> {
+    closure: F,
+    children: Vec<WidgetPod<T, Box<dyn Widget<T>>>>,
+}
+
+impl<T: Data, F: FnMut() -> Box<dyn Widget<T>>> List<T, F> {
+    pub fn new(closure: F) -> Self {
+        List {
+            closure,
+            children: Vec::new(),
+        }
+    }
+}
+
+impl<T: Data, F: FnMut() -> Box<dyn Widget<T>>> Widget<Arc<Vec<T>>> for List<T, F> {
+    fn paint(
+        &mut self,
+        paint_ctx: &mut PaintCtx,
+        _base_state: &BaseState,
+        data: &Arc<Vec<T>>,
+        env: &Env,
+    ) {
+        for (child, child_data) in self.children.iter_mut().zip(data.iter()) {
+            child.paint_with_offset(paint_ctx, child_data, env);
+        }
+    }
+
+    fn layout(
+        &mut self,
+        layout_ctx: &mut LayoutCtx,
+        bc: &BoxConstraints,
+        data: &Arc<Vec<T>>,
+        env: &Env,
+    ) -> Size {
+        let mut width = bc.min().width;
+        let mut y = 0.0;
+        for (child, child_data) in self.children.iter_mut().zip(data.iter()) {
+            let child_bc = BoxConstraints::new(
+                Size::new(bc.min().width, 0.0),
+                Size::new(bc.max().width, std::f64::INFINITY),
+            );
+            let child_size = child.layout(layout_ctx, &child_bc, child_data, env);
+            let rect = Rect::from_origin_size(Point::new(0.0, y), child_size);
+            child.set_layout_rect(rect);
+            width = width.max(child_size.width);
+            y += child_size.height;
+        }
+        bc.constrain(Size::new(width, y))
+    }
+
+    fn event(
+        &mut self,
+        event: &Event,
+        ctx: &mut EventCtx,
+        data: &mut Arc<Vec<T>>,
+        env: &Env,
+    ) -> Option<Action> {
+        let mut action = None;
+        let mut new_data = Vec::with_capacity(data.len());
+        let mut any_changed = false;
+        for (child, child_data) in self.children.iter_mut().zip(data.iter()) {
+            let mut d = child_data.to_owned();
+            action = Action::merge(action, child.event(event, ctx, &mut d, env));
+            if !any_changed && !child_data.same(&d) {
+                any_changed = true;
+            }
+            new_data.push(d);
+        }
+        if any_changed {
+            *data = Arc::new(new_data);
+        }
+        action
+    }
+
+    fn update(
+        &mut self,
+        ctx: &mut UpdateCtx,
+        _old_data: Option<&Arc<Vec<T>>>,
+        data: &Arc<Vec<T>>,
+        env: &Env,
+    ) {
+        for (child, child_data) in self.children.iter_mut().zip(data.iter()) {
+            child.update(ctx, child_data, env);
+        }
+        let len = self.children.len();
+        if len > data.len() {
+            self.children.truncate(data.len())
+        } else if len < data.len() {
+            for child_data in &data[len..] {
+                let mut child = WidgetPod::new((self.closure)());
+                child.update(ctx, child_data, env);
+                self.children.push(child);
+            }
+        }
+    }
+}

@@ 4,6 4,7 @@ use druid::{LensWrap, UiMain, UiState};
 
 mod app_state;
 mod interp_pane;
+mod list;
 
 use app_state::{lenses, AppState, InterpPt};
 use interp_pane::InterpPane;