Add Widget and Node

showbits-common/Cargo.toml

@@ -8,5 +8,10 @@ anyhow.workspace = true
 image.workspace = true
 palette.workspace = true
 
+[dependencies.taffy]
+version = "0.4.0"
+default-features = false
+features = ["std", "taffy_tree", "flexbox", "grid", "block_layout"]
+
 [lints]
 workspace = true

showbits-common/src/lib.rs

@@ -1,5 +1,7 @@
-pub use crate::{rect::*, vec2::*, view::*};
+pub use crate::{node::*, rect::*, vec2::*, view::*, widget::*};
 
+mod node;
 mod rect;
 mod vec2;
 mod view;
+mod widget;

showbits-common/src/node.rs

@@ -0,0 +1,30 @@
+use taffy::{NodeId, Style, TaffyResult, TaffyTree};
+
+use crate::Widget;
+
+pub struct Node {
+    layout: Style,
+    children: Vec<NodeId>,
+    widget: Option<Box<dyn Widget>>,
+}
+
+impl Node {
+    pub fn empty() -> Self {
+        Self {
+            layout: Style::default(),
+            children: vec![],
+            widget: None,
+        }
+    }
+
+    pub fn widget<W: Widget + 'static>(mut self, widget: W) -> Self {
+        self.widget = Some(Box::new(widget));
+        self
+    }
+
+    pub fn register(self, tree: &mut TaffyTree<Box<dyn Widget>>) -> TaffyResult<NodeId> {
+        let id = tree.new_with_children(self.layout, &self.children)?;
+        tree.set_node_context(id, self.widget)?;
+        Ok(id)
+    }
+}

showbits-common/src/widget.rs

@@ -0,0 +1,23 @@
+use taffy::{AvailableSpace, Size};
+
+use crate::{Node, View};
+
+pub trait Widget {
+    #[allow(unused_variables)]
+    fn size(&mut self, known: Size<Option<f32>>, available: Size<AvailableSpace>) -> Size<f32> {
+        Size::ZERO
+    }
+
+    fn draw_below(&mut self, view: &mut View<'_>) -> anyhow::Result<()>;
+    fn draw_above(&mut self, view: &mut View<'_>) -> anyhow::Result<()>;
+}
+
+pub trait WidgetExt {
+    fn node(self) -> Node;
+}
+
+impl<W: Widget + 'static> WidgetExt for W {
+    fn node(self) -> Node {
+        Node::empty().widget(self)
+    }
+}