Create module boundaries for `pane_grid` logic

1 files changed, 128 insertions, 0 deletions

diff --git a/native/src/widget/pane_grid/node.rs b/native/src/widget/pane_grid/node.rs
new file mode 100644
index 00000000..a9aa7fdc
--- /dev/null
+++ b/native/src/widget/pane_grid/node.rs
@@ -0,0 +1,128 @@
+use crate::{
+    pane_grid::{Pane, Split},
+    Rectangle, Size,
+};
+
+use std::collections::HashMap;
+
+#[derive(Debug, Clone, Hash)]
+pub enum Node {
+    Split {
+        kind: Split,
+        ratio: u32,
+        a: Box<Node>,
+        b: Box<Node>,
+    },
+    Pane(Pane),
+}
+
+impl Node {
+    pub fn find(&mut self, pane: &Pane) -> Option<&mut Node> {
+        match self {
+            Node::Split { a, b, .. } => {
+                a.find(pane).or_else(move || b.find(pane))
+            }
+            Node::Pane(p) => {
+                if p == pane {
+                    Some(self)
+                } else {
+                    None
+                }
+            }
+        }
+    }
+
+    pub fn split(&mut self, kind: Split, new_pane: Pane) {
+        *self = Node::Split {
+            kind,
+            ratio: 500_000,
+            a: Box::new(self.clone()),
+            b: Box::new(Node::Pane(new_pane)),
+        };
+    }
+
+    pub fn update(&mut self, f: &impl Fn(&mut Node)) {
+        match self {
+            Node::Split { a, b, .. } => {
+                a.update(f);
+                b.update(f);
+            }
+            _ => {}
+        }
+
+        f(self);
+    }
+
+    pub fn remove(&mut self, pane: &Pane) -> Option<Pane> {
+        match self {
+            Node::Split { a, b, .. } => {
+                if a.pane() == Some(*pane) {
+                    *self = *b.clone();
+                    Some(self.first_pane())
+                } else if b.pane() == Some(*pane) {
+                    *self = *a.clone();
+                    Some(self.first_pane())
+                } else {
+                    a.remove(pane).or_else(|| b.remove(pane))
+                }
+            }
+            Node::Pane(_) => None,
+        }
+    }
+
+    pub fn regions(
+        &self,
+        spacing: f32,
+        size: Size,
+    ) -> HashMap<Pane, Rectangle> {
+        let mut regions = HashMap::new();
+
+        self.compute_regions(
+            spacing / 2.0,
+            &Rectangle {
+                x: 0.0,
+                y: 0.0,
+                width: size.width,
+                height: size.height,
+            },
+            &mut regions,
+        );
+
+        regions
+    }
+
+    pub fn pane(&self) -> Option<Pane> {
+        match self {
+            Node::Split { .. } => None,
+            Node::Pane(pane) => Some(*pane),
+        }
+    }
+
+    pub fn first_pane(&self) -> Pane {
+        match self {
+            Node::Split { a, .. } => a.first_pane(),
+            Node::Pane(pane) => *pane,
+        }
+    }
+
+    fn compute_regions(
+        &self,
+        halved_spacing: f32,
+        current: &Rectangle,
+        regions: &mut HashMap<Pane, Rectangle>,
+    ) {
+        match self {
+            Node::Split { kind, ratio, a, b } => {
+                let ratio = *ratio as f32 / 1_000_000.0;
+                let (region_a, region_b) =
+                    kind.apply(current, ratio, halved_spacing);
+
+                a.compute_regions(halved_spacing, &region_a, regions);
+                b.compute_regions(halved_spacing, &region_b, regions);
+            }
+            Node::Pane(pane) => {
+                let _ = regions.insert(*pane, *current);
+            }
+        }
+    }
+}