fix native core dependancies in a different direction than the pass direction

packages/native-core/examples/font_size.rs

@@ -0,0 +1,175 @@
+use dioxus_native_core::exports::shipyard::Component;
+use dioxus_native_core::node_ref::*;
+use dioxus_native_core::prelude::*;
+use dioxus_native_core::real_dom::NodeTypeMut;
+use dioxus_native_core_macro::partial_derive_state;
+
+// All states need to derive Component
+#[derive(Default, Debug, Copy, Clone, Component)]
+struct Size(f64, f64);
+
+/// Derive some of the boilerplate for the State implementation
+#[partial_derive_state]
+impl State for Size {
+    type ParentDependencies = ();
+
+    // The size of the current node depends on the size of its children
+    type ChildDependencies = (Self,);
+
+    type NodeDependencies = (FontSize,);
+
+    // Size only cares about the width, height, and text parts of the current node
+    const NODE_MASK: NodeMaskBuilder<'static> = NodeMaskBuilder::new()
+        // Get access to the width and height attributes
+        .with_attrs(AttributeMaskBuilder::Some(&["width", "height"]))
+        // Get access to the text of the node
+        .with_text();
+
+    fn update<'a>(
+        &mut self,
+        node_view: NodeView<()>,
+        (font_size,): <Self::NodeDependencies as Dependancy>::ElementBorrowed<'a>,
+        _parent: Option<<Self::ParentDependencies as Dependancy>::ElementBorrowed<'a>>,
+        children: Vec<<Self::ChildDependencies as Dependancy>::ElementBorrowed<'a>>,
+        _: &SendAnyMap,
+    ) -> bool {
+        let font_size = font_size.size;
+        let mut width;
+        let mut height;
+        if let Some(text) = node_view.text() {
+            // if the node has text, use the text to size our object
+            width = text.len() as f64 * font_size;
+            height = font_size;
+        } else {
+            // otherwise, the size is the maximum size of the children
+            width = children
+                .iter()
+                .map(|(item,)| item.0)
+                .reduce(|accum, item| if accum >= item { accum } else { item })
+                .unwrap_or(0.0);
+
+            height = children
+                .iter()
+                .map(|(item,)| item.1)
+                .reduce(|accum, item| if accum >= item { accum } else { item })
+                .unwrap_or(0.0);
+        }
+        // if the node contains a width or height attribute it overrides the other size
+        for a in node_view.attributes().into_iter().flatten() {
+            match &*a.attribute.name {
+                "width" => width = a.value.as_float().unwrap(),
+                "height" => height = a.value.as_float().unwrap(),
+                // because Size only depends on the width and height, no other attributes will be passed to the member
+                _ => panic!(),
+            }
+        }
+        // to determine what other parts of the dom need to be updated we return a boolean that marks if this member changed
+        let changed = (width != self.0) || (height != self.1);
+        *self = Self(width, height);
+        changed
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Component)]
+struct FontSize {
+    size: f64,
+}
+
+impl Default for FontSize {
+    fn default() -> Self {
+        Self { size: 16.0 }
+    }
+}
+
+#[partial_derive_state]
+impl State for FontSize {
+    // TextColor depends on the TextColor part of the parent
+    type ParentDependencies = (Self,);
+
+    type ChildDependencies = ();
+
+    type NodeDependencies = ();
+
+    // TextColor only cares about the color attribute of the current node
+    const NODE_MASK: NodeMaskBuilder<'static> =
+        // Get access to the color attribute
+        NodeMaskBuilder::new().with_attrs(AttributeMaskBuilder::Some(&["font-size"]));
+
+    fn update<'a>(
+        &mut self,
+        node_view: NodeView<()>,
+        _node: <Self::NodeDependencies as Dependancy>::ElementBorrowed<'a>,
+        parent: Option<<Self::ParentDependencies as Dependancy>::ElementBorrowed<'a>>,
+        _children: Vec<<Self::ChildDependencies as Dependancy>::ElementBorrowed<'a>>,
+        _context: &SendAnyMap,
+    ) -> bool {
+        let mut new = None;
+        for attr in node_view.attributes().into_iter().flatten() {
+            if attr.attribute.name == "font-size" {
+                new = Some(FontSize {
+                    size: attr.value.as_float().unwrap(),
+                });
+            }
+        }
+        let new = new.unwrap_or(parent.map(|(p,)| *p).unwrap_or_default());
+        // check if the member has changed
+        let changed = new != *self;
+        *self = new;
+        changed
+    }
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let mut rdom: RealDom = RealDom::new([FontSize::to_type_erased(), Size::to_type_erased()]);
+
+    let mut count = 0;
+
+    // intial render
+    let text_id = rdom.create_node(format!("Count: {count}")).id();
+    let mut root = rdom.get_mut(rdom.root_id()).unwrap();
+    // set the color to red
+    if let NodeTypeMut::Element(mut element) = root.node_type_mut() {
+        element.set_attribute(("color", "style"), "red".to_string());
+        element.set_attribute(("font-size", "style"), 1.);
+    }
+    root.add_child(text_id);
+
+    let ctx = SendAnyMap::new();
+    // update the State for nodes in the real_dom tree
+    let _to_rerender = rdom.update_state(ctx);
+
+    // we need to run the vdom in a async runtime
+    tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()?
+        .block_on(async {
+            loop {
+                // update the count and font size
+                count += 1;
+                let mut text = rdom.get_mut(text_id).unwrap();
+                if let NodeTypeMut::Text(mut text) = text.node_type_mut() {
+                    *text = format!("Count: {count}");
+                }
+                if let NodeTypeMut::Element(mut element) =
+                    rdom.get_mut(rdom.root_id()).unwrap().node_type_mut()
+                {
+                    element.set_attribute(("font-size", "style"), count as f64);
+                }
+
+                let ctx = SendAnyMap::new();
+                let _to_rerender = rdom.update_state(ctx);
+
+                // render...
+                rdom.traverse_depth_first(|node| {
+                    let indent = " ".repeat(node.height() as usize);
+                    let font_size = *node.get::<FontSize>().unwrap();
+                    let size = *node.get::<Size>().unwrap();
+                    let id = node.id();
+                    println!("{indent}{id:?} {font_size:?} {size:?}");
+                });
+
+                // wait 1 second
+                tokio::time::sleep(std::time::Duration::from_secs(1)).await;
+            }
+        })
+}