feat: Add basic constraints (macOS)

finestra/src/event.rs

@@ -54,6 +54,8 @@ pub struct ViewTree<State> {
 
     #[cfg(target_os = "macos")]
     dispatcher: StatefulEventDispatcher<State>,
+
+    parent_id: Option<ViewId>,
 }
 
 impl<State: 'static> ViewTree<State> {
@@ -62,6 +64,7 @@ impl<State: 'static> ViewTree<State> {
         Self {
             id_generator: Default::default(),
             registry,
+            parent_id: None,
         }
     }
 
@@ -71,6 +74,7 @@ impl<State: 'static> ViewTree<State> {
             id_generator: Default::default(),
             registry,
             dispatcher,
+            parent_id: None,
         }
     }
 
@@ -80,6 +84,7 @@ impl<State: 'static> ViewTree<State> {
         id
     }
 
+    #[cfg(windows)]
     pub(crate) fn put_event_handlers_with_id(&mut self, id: ViewId, map: EventHandlerMap<State>) -> ViewId {
         self.registry.map.insert(id, map);
         id
@@ -89,6 +94,14 @@ impl<State: 'static> ViewTree<State> {
     pub(crate) fn create_dispatcher(&self) -> Box<dyn EventDispatcher> {
         Box::new(self.dispatcher.clone())
     }
+
+    pub(crate) fn parent_id(&self) -> Option<ViewId> {
+        self.parent_id
+    }
+
+    pub(crate) fn set_parent_id(&mut self, id: ViewId) {
+        self.parent_id = Some(id);
+    }
 }
 
 #[derive(Debug, Default)]

finestra/src/layout/constraints.rs

@@ -0,0 +1,49 @@
+// Copyright (C) 2024 Tristan Gerritsen <tristan@thewoosh.org>
+// All Rights Reserved.
+
+use crate::ViewId;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(crate) struct Constraint {
+    pub alignment: ConstraintAlignment,
+
+    pub reference_id: ViewId,
+    pub reference_alignment: ConstraintAlignment,
+}
+
+#[cfg(target_os = "macos")]
+impl Constraint {
+    pub fn convert(
+            &self,
+            this: &impl crate::platform::macos::LayoutExt,
+            reference: &impl crate::platform::macos::LayoutExt,
+        ) -> cacao::layout::LayoutConstraint {
+        _ = self.reference_alignment; // TODO
+
+        match self.alignment {
+            ConstraintAlignment::Top => {
+                this.layout_constraint_top().constraint_less_than_or_equal_to(reference.layout_constraint_top())
+            }
+
+            ConstraintAlignment::Bottom => {
+                this.layout_constraint_bottom().constraint_less_than_or_equal_to(reference.layout_constraint_bottom())
+            }
+
+            ConstraintAlignment::Left => {
+                this.layout_constraint_left().constraint_less_than_or_equal_to(reference.layout_constraint_left())
+            }
+
+            ConstraintAlignment::Right => {
+                this.layout_constraint_right().constraint_less_than_or_equal_to(reference.layout_constraint_right())
+            }
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) enum ConstraintAlignment {
+    Left,
+    Right,
+    Top,
+    Bottom,
+}

finestra/src/layout/mod.rs

@@ -0,0 +1,6 @@
+// Copyright (C) 2024 Tristan Gerritsen <tristan@thewoosh.org>
+// All Rights Reserved.
+
+mod constraints;
+
+pub(crate) use self::constraints::*;

finestra/src/lib.rs

@@ -11,6 +11,7 @@ pub use euclid;
 mod app;
 mod error;
 mod event;
+mod layout;
 mod platform;
 mod resources;
 mod state;
@@ -19,6 +20,7 @@ mod window;
 
 pub use self::app::*;
 pub use self::error::*;
+pub(crate) use self::layout::*;
 pub use self::resources::*;
 pub use self::state::*;
 pub use self::views::*;