wip: component playground; Align primitive

crates/tek_test/src/main.rs

@@ -0,0 +1,50 @@
+use tek_core::*;
+
+pub fn main () -> Usually<()> {
+    Tui::run(Arc::new(RwLock::new(Demo::new())))?;
+    Ok(())
+}
+
+pub struct Demo {
+    index: usize,
+    items: Vec<Box<dyn Component<Tui>>>
+}
+
+impl Demo {
+    fn new () -> Self {
+        let items = vec![];
+        Self { index: 0, items }
+    }
+}
+
+impl Handle<Tui> for Demo {
+    fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
+        match from.event() {
+            key!(KeyCode::PageUp) => {
+                self.index = (self.index + 1) % self.items.len();
+                Ok(Some(true))
+            },
+            key!(KeyCode::PageDown) => {
+                self.index = if self.index > 1 {
+                    self.index - 1
+                } else {
+                    self.items.len() - 1
+                };
+                Ok(Some(true))
+            },
+            _ =>  Ok(None)
+        }
+    }
+}
+
+impl Layout<Tui> for Demo {
+    fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
+        Align::Center(self.items[self.index]).layout(area)
+    }
+}
+
+impl Render<Tui> for Demo {
+    fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
+        Align::Center(self.items[self.index]).render(to)
+    }
+}