don't crash on add track/scene

src/view/split.rs

@@ -0,0 +1,110 @@
+use crate::{core::*, view::*};
+
+pub struct If<'a>(pub bool, pub &'a (dyn Render + Sync));
+
+impl<'a> Render for If<'a> {
+    fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+        match self.0 {
+            true  => self.1 as &dyn Render,
+            false => &() as &dyn Render
+        }.render(buf, area)
+    }
+}
+
+pub struct IfElse<'a>(pub bool, pub &'a (dyn Render + Sync), pub &'a (dyn Render + Sync));
+
+impl<'a> Render for IfElse<'a> {
+    fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+        match self.0 {
+            true  => self.1 as &dyn Render,
+            false => &() as &dyn Render
+        }.render(buf, area)
+    }
+}
+
+#[derive(Copy, Clone)]
+pub enum Direction { Down, Right }
+
+impl Direction {
+    pub fn split <'a, const N: usize> (&self, items: [&'a (dyn Render + Sync);N]) -> Split<'a, N> {
+        Split(*self, items)
+    }
+    pub fn split_focus <'a> (&self, index: usize, items: Renderables<'a>, style: Style) -> SplitFocus<'a> {
+        SplitFocus(*self, index, items, style)
+    }
+    pub fn is_down (&self) -> bool {
+        match self { Self::Down => true, _ => false }
+    }
+    pub fn is_right (&self) -> bool {
+        match self { Self::Right => true, _ => false }
+    }
+}
+
+pub struct Split<'a, const N: usize>(
+    pub Direction, pub [&'a (dyn Render + Sync);N]
+);
+
+impl<'a, const N: usize> Split<'a, N> {
+    pub fn down (items: [&'a (dyn Render + Sync);N]) -> Self {
+        Self(Direction::Down, items)
+    }
+    pub fn right (items: [&'a (dyn Render + Sync);N]) -> Self {
+        Self(Direction::Right, items)
+    }
+}
+
+impl<'a, const N: usize> Render for Split<'a, N> {
+    fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+        let Rect { mut x, mut y, mut width, mut height } = area;
+        for item in self.1 {
+            if width == 0 || height == 0 {
+                break
+            }
+            let result = item.render(buf, Rect { x, y, width, height })?;
+            match self.0 {
+                Direction::Down => {
+                    y = y + result.height;
+                    height = height.saturating_sub(result.height);
+                },
+                Direction::Right => {
+                    x = x + result.width;
+                    width = width.saturating_sub(result.width);
+                },
+            }
+        }
+        Ok(area)
+    }
+}
+
+type Renderables<'a> = &'a [JackDevice];
+
+pub struct SplitFocus<'a>(pub Direction, pub usize, pub Renderables<'a>, pub Style);
+
+impl<'a> Render for SplitFocus<'a> {
+    fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
+        let Rect { mut x, mut y, mut width, mut height } = area;
+        let mut results = vec![];
+        for item in self.2.iter() {
+            if width == 0 || height == 0 {
+                break
+            }
+            let result = item.render(buf, Rect { x, y, width, height })?;
+            results.push(result);
+            match self.0 {
+                Direction::Down => {
+                    y = y + result.height;
+                    height = height.saturating_sub(result.height);
+                },
+                Direction::Right => {
+                    x = x + result.width;
+                    width = width.saturating_sub(result.width);
+                },
+            }
+        }
+        results
+            .get(self.1)
+            .map(|focused|Lozenge(self.3).draw(buf, Rect { width, ..*focused }))
+            .transpose()?;
+        Ok(area)
+    }
+}