wip: and sweeps right through the codebase

layout/src/measure.rs

@@ -0,0 +1,81 @@
+use crate::*;
+use std::sync::{Arc, atomic::{AtomicUsize, Ordering::Relaxed}};
+
+// TODO: 🡘  🡙 ←🡙→ indicator to expand window when too small
+
+pub trait HasSize<E: Engine> {
+    fn size (&self) -> &Measure<E>;
+}
+
+#[macro_export] macro_rules! has_size {
+    (<$E:ty>|$self:ident:$Struct:ident$(<$($L:lifetime),*$($T:ident$(:$U:path)?),*>)?|$cb:expr) => {
+        impl $(<$($L),*$($T $(: $U)?),*>)? HasSize<$E> for $Struct $(<$($L),*$($T),*>)? {
+            fn size (&$self) -> &Measure<$E> { $cb }
+        }
+    }
+}
+
+/// A widget that tracks its render width and height
+#[derive(Default)]
+pub struct Measure<E: Engine> {
+    _engine: PhantomData<E>,
+    pub x: Arc<AtomicUsize>,
+    pub y: Arc<AtomicUsize>,
+}
+
+impl<E: Engine> Content<E> for Measure<E> {
+    fn render (&self, to: &mut E::Output) {
+        self.x.store(to.area().w().into(), Relaxed);
+        self.y.store(to.area().h().into(), Relaxed);
+    }
+}
+
+impl<E: Engine> Clone for Measure<E> {
+    fn clone (&self) -> Self {
+        Self {
+            _engine: Default::default(),
+            x: self.x.clone(),
+            y: self.y.clone(),
+        }
+    }
+}
+
+impl<E: Engine> std::fmt::Debug for Measure<E> {
+    fn fmt (&self, f: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error> {
+        f.debug_struct("Measure")
+            .field("width",  &self.x)
+            .field("height", &self.y)
+            .finish()
+    }
+}
+
+impl<E: Engine> Measure<E> {
+    pub fn w (&self) -> usize { self.x.load(Relaxed) }
+    pub fn h (&self) -> usize { self.y.load(Relaxed) }
+    pub fn wh (&self) -> [usize;2] { [self.w(), self.h()] }
+    pub fn set_w (&self, w: impl Into<usize>) { self.x.store(w.into(), Relaxed) }
+    pub fn set_h (&self, h: impl Into<usize>) { self.y.store(h.into(), Relaxed) }
+    pub fn set_wh (&self, w: impl Into<usize>, h: impl Into<usize>) { self.set_w(w); self.set_h(h); }
+    pub fn format (&self) -> String { format!("{}x{}", self.w(), self.h()) }
+    pub fn new () -> Self {
+        Self {
+            _engine: PhantomData::default(),
+            x: Arc::new(0.into()),
+            y: Arc::new(0.into()),
+        }
+    }
+}
+
+/// A scrollable area.
+pub struct Scroll<E, F>(pub F, pub Direction, pub u64, PhantomData<E>)
+where
+    E: Engine,
+    F: Send + Sync + Fn(&mut dyn FnMut(&dyn Content<E>)->Usually<()>)->Usually<()>;
+
+//pub trait ContentDebug<E: Engine> {
+    //fn debug <W: Content<E>> (other: W) -> DebugOverlay<E, W> {
+        //DebugOverlay(Default::default(), other)
+    //}
+//}
+
+//impl<E: Engine> ContentDebug<E> for E {}