output: remove RenderBox

output/src/layout_align.rs

@@ -1,7 +1,7 @@
 //! ```
 //! use ::tengri::{output::*, tui::*};
 //! let area: [u16;4] = [10, 10, 20, 20];
-//! fn test (area: [u16;4], item: &impl Content<TuiOut>, expected: [u16;4]) {
+//! fn test (area: [u16;4], item: &impl Render<TuiOut>, expected: [u16;4]) {
 //!     assert_eq!(Content::layout(item, area), expected);
 //!     assert_eq!(Render::layout(item, area),  expected);
 //! };
@@ -48,33 +48,36 @@ impl<A> Align<A> {
     #[inline] pub const fn se (a: A) -> Self { Self(Alignment::SE,     a) }
 }
 
-impl<E: Output, A: Content<E>> Content<E> for Align<A> {
-    fn content (&self) -> impl Render<E> + '_ {
-        &self.1
-    }
+impl<E: Output, A: Render<E>> Render<E> for Align<A> {
     fn layout (&self, on: E::Area) -> E::Area {
+        self.0.align(on, &self.1)
+    }
+    fn render (&self, to: &mut E) {
+        to.place(self.layout(to.area()), &self.1)
+    }
+}
+
+impl Alignment {
+    fn align <E: Output> (&self, on: E::Area, content: impl Render<E>) -> E::Area {
         use Alignment::*;
-        let it = Render::layout(&self.content(), on).xywh();
+        let it = content.layout(on).xywh();
         let cx = on.x()+(on.w().minus(it.w())/2.into());
         let cy = on.y()+(on.h().minus(it.h())/2.into());
         let fx = (on.x()+on.w()).minus(it.w());
         let fy = (on.y()+on.h()).minus(it.h());
-        let [x, y] = match self.0 {
-            Center => [cx, cy],
-            X =>  [cx, it.y()],
-            Y =>  [it.x(), cy],
-            NW => [on.x(), on.y()],
-            N  => [cx,     on.y()],
-            NE => [fx,     on.y()],
-            W  => [on.x(), cy],
-            E  => [fx,     cy],
-            SW => [on.x(), fy],
-            S  => [cx,     fy],
-            SE => [fx,     fy],
-        }.into();
+        let [x, y] = match self {
+            Center => [cx,     cy],
+            X      => [cx,     it.y()],
+            Y      => [it.x(), cy],
+            NW     => [on.x(), on.y()],
+            N      => [cx,     on.y()],
+            NE     => [fx,     on.y()],
+            W      => [on.x(), cy],
+            E      => [fx,     cy],
+            SW     => [on.x(), fy],
+            S      => [cx,     fy],
+            SE     => [fx,     fy],
+        };
         [x, y, it.w(), it.h()].into()
     }
-    fn render (&self, to: &mut E) {
-        to.place(Content::layout(self, to.area()), &self.content())
-    }
 }

output/src/layout_bsp.rs

@@ -15,7 +15,7 @@ impl<A, B> Bsp<A, B> {
     #[inline] pub const fn a (a: A, b: B) -> Self { Self(Above, a, b) }
     #[inline] pub const fn b (a: A, b: B) -> Self { Self(Below, a, b) }
 }
-impl<E: Output, A: Content<E>, B: Content<E>> Content<E> for Bsp<A, B> {
+impl<E: Output, A: Render<E>, B: Render<E>> Render<E> for Bsp<A, B> {
     fn layout (&self, outer: E::Area) -> E::Area { let [_, _, c] = self.areas(outer); c }
     fn render (&self, to: &mut E) {
         let [area_a, area_b, _] = self.areas(to.area());
@@ -26,11 +26,11 @@ impl<E: Output, A: Content<E>, B: Content<E>> Content<E> for Bsp<A, B> {
         }
     }
 }
-impl<E: Output, A: Content<E>, B: Content<E>> BspAreas<E, A, B> for Bsp<A, B> {
+impl<E: Output, A: Render<E>, B: Render<E>> BspAreas<E, A, B> for Bsp<A, B> {
     fn direction (&self) -> Direction { self.0 }
     fn contents (&self) -> (&A, &B) { (&self.1, &self.2) }
 }
-pub trait BspAreas<E: Output, A: Content<E>, B: Content<E>> {
+pub trait BspAreas<E: Output, A: Render<E>, B: Render<E>> {
     fn direction (&self) -> Direction;
     fn contents (&self) -> (&A, &B);
     fn areas (&self, outer: E::Area) -> [E::Area;3] {

output/src/layout_cond.rs

@@ -6,7 +6,7 @@ impl<A> When<A> {
     /// Create a binary condition.
     pub const fn new (c: bool, a: A) -> Self { Self(c, a) }
 }
-impl<E: Output, A: Render<E>> Content<E> for When<A> {
+impl<E: Output, A: Render<E>> Render<E> for When<A> {
     fn layout (&self, to: E::Area) -> E::Area {
         let Self(cond, item) = self;
         let mut area = E::Area::zero();
@@ -31,7 +31,7 @@ impl<A, B> Either<A, B> {
     /// Create a ternary view condition.
     pub const fn new (c: bool, a: A, b: B) -> Self { Self(c, a, b) }
 }
-impl<E: Output, A: Render<E>, B: Render<E>> Content<E> for Either<A, B> {
+impl<E: Output, A: Render<E>, B: Render<E>> Render<E> for Either<A, B> {
     fn layout (&self, to: E::Area) -> E::Area {
         let Self(cond, a, b) = self;
         if *cond { a.layout(to) } else { b.layout(to) }

output/src/layout_map.rs

@@ -66,7 +66,7 @@ impl_map_direction!(south, y, n);
 impl_map_direction!(west,  x, e);
 impl_map_direction!(north, y, s);
 
-impl<'a, E, A, B, I, F, G> Content<E> for Map<E, A, B, I, F, G> where
+impl<'a, E, A, B, I, F, G> Render<E> for Map<E, A, B, I, F, G> where
     E: Output,
     B: Render<E>,
     I: Iterator<Item = A> + Send + Sync + 'a,
@@ -94,7 +94,7 @@ impl<'a, E, A, B, I, F, G> Content<E> for Map<E, A, B, I, F, G> where
     fn render (&self, to: &mut E) {
         let Self { get_iter, get_item, .. } = self;
         let mut index = 0;
-        let area = Content::layout(self, to.area());
+        let area = Render::layout(self, to.area());
         for item in get_iter() {
             let item = get_item(item, index);
             //to.place(area.into(), &item);
@@ -107,24 +107,24 @@ impl<'a, E, A, B, I, F, G> Content<E> for Map<E, A, B, I, F, G> where
 #[inline] pub fn map_south<O: Output>(
     item_offset: O::Unit,
     item_height: O::Unit,
-    item: impl Content<O>
-) -> impl Content<O> {
+    item: impl Render<O>
+) -> impl Render<O> {
     Push::y(item_offset, Fixed::y(item_height, Fill::x(item)))
 }
 
 #[inline] pub fn map_south_west<O: Output>(
     item_offset: O::Unit,
     item_height: O::Unit,
-    item: impl Content<O>
-) -> impl Content<O> {
+    item: impl Render<O>
+) -> impl Render<O> {
     Push::y(item_offset, Align::nw(Fixed::y(item_height, Fill::x(item))))
 }
 
 #[inline] pub fn map_east<O: Output>(
     item_offset: O::Unit,
     item_width:  O::Unit,
-    item: impl Content<O>
-) -> impl Content<O> {
+    item: impl Render<O>
+) -> impl Render<O> {
     Push::x(item_offset, Align::w(Fixed::x(item_width, Fill::y(item))))
 }
 

output/src/layout_stack.rs

@@ -1,43 +1,44 @@
 use crate::*;
 use Direction::*;
 
-pub struct Stack<'x, E, F> {
-    __: PhantomData<&'x E>,
+pub struct Stack<'x, E, F1> {
+    __: PhantomData<&'x (E, F1)>,
     direction: Direction,
-    callback:  F
+    callback:  F1
 }
-impl<'x, E, F: Fn(&mut dyn FnMut(&dyn Render<E>)) + 'x> Stack<'x, E, F> {
-    pub fn new (direction: Direction, callback: F) -> Self {
+
+impl<'x, E, F1> Stack<'x, E, F1> {
+    pub fn new (direction: Direction, callback: F1) -> Self {
         Self { direction, callback, __: Default::default(), }
     }
-    pub fn above (callback: F) -> Self {
+    pub fn above (callback: F1) -> Self {
         Self::new(Above, callback)
     }
-    pub fn below (callback: F) -> Self {
+    pub fn below (callback: F1) -> Self {
         Self::new(Below, callback)
     }
-    pub fn north (callback: F) -> Self {
+    pub fn north (callback: F1) -> Self {
         Self::new(North, callback)
     }
-    pub fn south (callback: F) -> Self {
+    pub fn south (callback: F1) -> Self {
         Self::new(South, callback)
     }
-    pub fn east (callback: F) -> Self {
+    pub fn east (callback: F1) -> Self {
         Self::new(East, callback)
     }
-    pub fn west (callback: F) -> Self {
+    pub fn west (callback: F1) -> Self {
         Self::new(West, callback)
     }
 }
-impl<'x, E: Output, F: Fn(&mut dyn FnMut(&dyn Render<E>)) + 'x> Content<E> for Stack<'x, E, F> {
+
+impl<'x, E: Output, F1: Fn(&mut dyn FnMut(&dyn Render<E>))> Render<E> for Stack<'x, E, F1> {
     fn layout (&self, to: E::Area) -> E::Area {
         let state = StackLayoutState::<E>::new(self.direction, to);
-        let mut adder = |component: &dyn Render<E>|{
+        (self.callback)(&mut |component: &dyn Render<E>|{
             let StackLayoutState { x, y, w_remaining, h_remaining, .. } = *state.borrow();
             let [_, _, w, h] = component.layout([x, y, w_remaining, h_remaining].into()).xywh();
             state.borrow_mut().grow(w, h);
-        };
-        (self.callback)(&mut adder);
+        });
         let StackLayoutState { w_used, h_used, .. } = *state.borrow();
         match self.direction {
             North | West => { todo!() },
@@ -48,13 +49,12 @@ impl<'x, E: Output, F: Fn(&mut dyn FnMut(&dyn Render<E>)) + 'x> Content<E> for S
     fn render (&self, to: &mut E) {
         let state = StackLayoutState::<E>::new(self.direction, to.area());
         let to = Rc::new(RefCell::new(to));
-        let mut adder = |component: &dyn Render<E>|{
+        (self.callback)(&mut |component: &dyn Render<E>|{
             let StackLayoutState { x, y, w_remaining, h_remaining, .. } = *state.borrow();
             let layout = component.layout([x, y, w_remaining, h_remaining].into());
             state.borrow_mut().grow(layout.w(), layout.h());
             to.borrow_mut().place(layout, component);
-        };
-        (self.callback)(&mut adder);
+        });
     }
 }
 
@@ -115,7 +115,7 @@ impl<E: Output> StackLayoutState<E> {
         //Self { direction, callback, __: Default::default(), }
     //}
 //}
-//impl<'a, E, F1> Content<E> for Stack<'a, E, F1> where
+//impl<'a, E, F1> Render<E> for Stack<'a, E, F1> where
     //E: Output, F1: Fn(&mut dyn FnMut(&'a dyn Render<E>)) + Send + Sync,
 //{
     //fn layout (&self, to: E::Area) -> E::Area {

output/src/layout_xy.rs

@@ -2,9 +2,8 @@
 //! ```
 //! use ::tengri::{output::*, tui::*};
 //! let area: [u16;4] = [10, 10, 20, 20];
-//! fn test (area: [u16;4], item: &impl Content<TuiOut>, expected: [u16;4]) {
-//!     assert_eq!(Content::layout(item, area), expected);
-//!     assert_eq!(Render::layout(item, area),  expected);
+//! fn test (area: [u16;4], item: &impl Render<TuiOut>, expected: [u16;4]) {
+//!     assert_eq!(item.layout(area), expected);
 //! };
 //! test(area, &(), [20, 20, 0, 0]);
 //!
@@ -28,18 +27,20 @@ macro_rules! transform_xy {
             #[inline] pub const fn y  (item: A) -> Self { Self::Y(item)  }
             #[inline] pub const fn xy (item: A) -> Self { Self::XY(item) }
         }
-        impl<E: Output, T: Content<E>> Content<E> for $Enum<T> {
-            fn content (&self) -> impl Render<E> + '_ {
-                match self {
-                    Self::X(item)  => item,
-                    Self::Y(item)  => item,
-                    Self::XY(item) => item,
-                }
+        impl<E: Output, T: Render<E>> Content<E> for $Enum<T> {
+            fn content (&self) -> Option<impl Render<E> + '_> {
+                use $Enum::*;
+                Some(match self { X(item) | Y(item) | XY(item)  => item, })
             }
+        }
+        impl<E: Output, T: Render<E>> Render<E> for $Enum<T> {
             fn layout (&$self, $to: <E as Output>::Area) -> <E as Output>::Area {
                 use $Enum::*;
                 $area
             }
+            fn render (&self, output: &mut E) {
+                output.place(self.layout(output.area()), &self.content())
+            }
         }
     }
 }
@@ -54,13 +55,18 @@ macro_rules! transform_xy_unit {
             #[inline] pub const fn y (y: U, item: A) -> Self { Self::Y(y, item) }
             #[inline] pub const fn xy (x: U, y: U, item: A) -> Self { Self::XY(x, y, item) }
         }
-        impl<E: Output, T: Content<E>> Content<E> for $Enum<E::Unit, T> {
+        impl<E: Output, T: Render<E>> Content<E> for $Enum<E::Unit, T> {
+            fn content (&self) -> Option<impl Render<E> + '_> {
+                use $Enum::*;
+                Some(match self { X(_, c) => c, Y(_, c) => c, XY(_, _, c) => c, })
+            }
+        }
+        impl<E: Output, T: Render<E>> Render<E> for $Enum<E::Unit, T> {
             fn layout (&$self, $to: E::Area) -> E::Area {
                 $layout.into()
             }
-            fn content (&self) -> impl Render<E> + '_ {
-                use $Enum::*;
-                Some(match self { X(_, c) => c, Y(_, c) => c, XY(_, _, c) => c, })
+            fn render (&self, output: &mut E) {
+                output.place(self.layout(output.area()), &self.content())
             }
         }
         impl<U: Coordinate, T> $Enum<U, T> {
@@ -88,12 +94,11 @@ transform_xy!("fill/x" "fill/y" "fill/xy" |self: Fill, to|{
 
 transform_xy_unit!("fixed/x" "fixed/y" "fixed/xy"|self: Fixed, area|{
     let [x, y, w, h] = area.xywh();
-    let fixed_area = match self {
+    let [x, y, w, h] = self.content().layout(match self {
         Self::X(fw, _) => [x, y, *fw, h],
         Self::Y(fh, _) => [x, y, w, *fh],
         Self::XY(fw, fh, _) => [x, y, *fw, *fh],
-    };
-    let [x, y, w, h] = Render::layout(&self.content(), fixed_area.into()).xywh();
+    }.into()).xywh();
     let fixed_area = match self {
         Self::X(fw, _) => [x, y, *fw, h],
         Self::Y(fh, _) => [x, y, w, *fh],
@@ -103,51 +108,41 @@ transform_xy_unit!("fixed/x" "fixed/y" "fixed/xy"|self: Fixed, area|{
 });
 
 transform_xy_unit!("min/x" "min/y" "min/xy"|self: Min, area|{
-    let area = Render::layout(&self.content(), area);
+    let [x, y, w, h] = self.content().layout(area).xywh();
     match self {
-        Self::X(mw, _)      => [area.x(), area.y(), area.w().max(*mw), area.h()],
-        Self::Y(mh, _)      => [area.x(), area.y(), area.w(),          area.h().max(*mh)],
-        Self::XY(mw, mh, _) => [area.x(), area.y(), area.w().max(*mw), area.h().max(*mh)],
-    }
-});
+        Self::X(mw, _)      => [x, y, w.max(*mw), h],
+        Self::Y(mh, _)      => [x, y, w,          h.max(*mh)],
+        Self::XY(mw, mh, _) => [x, y, w.max(*mw), h.max(*mh)], } });
 
 transform_xy_unit!("max/x" "max/y" "max/xy"|self: Max, area|{
     let [x, y, w, h] = area.xywh();
-    Render::layout(&self.content(), match self {
+    self.content().layout(match self {
         Self::X(fw, _) => [x, y, *fw, h],
         Self::Y(fh, _) => [x, y, w, *fh],
-        Self::XY(fw, fh, _) => [x, y, *fw, *fh],
-    }.into())
-});
+        Self::XY(fw, fh, _) => [x, y, *fw, *fh], }.into()) });
 
-transform_xy_unit!("shrink/x" "shrink/y" "shrink/xy"|self: Shrink, area|Render::layout(
-    &self.content(),
+transform_xy_unit!("shrink/x" "shrink/y" "shrink/xy"|self: Shrink, area|self.content().layout(
     [area.x(), area.y(), area.w().minus(self.dx()), area.h().minus(self.dy())].into()));
 
-transform_xy_unit!("expand/x" "expand/y" "expand/xy"|self: Expand, area|Render::layout(
-    &self.content(),
+transform_xy_unit!("expand/x" "expand/y" "expand/xy"|self: Expand, area|self.content().layout(
     [area.x(), area.y(), area.w().plus(self.dx()), area.h().plus(self.dy())].into()));
 
 transform_xy_unit!("push/x" "push/y" "push/xy"|self: Push, area|{
-    let area = Render::layout(&self.content(), area);
-    [area.x().plus(self.dx()), area.y().plus(self.dy()), area.w(), area.h()]
-});
+    let area = self.content().layout(area);
+    [area.x().plus(self.dx()), area.y().plus(self.dy()), area.w(), area.h()] });
 
 transform_xy_unit!("pull/x" "pull/y" "pull/xy"|self: Pull, area|{
-    let area = Render::layout(&self.content(), area);
-    [area.x().minus(self.dx()), area.y().minus(self.dy()), area.w(), area.h()]
-});
+    let area = self.content().layout(area);
+    [area.x().minus(self.dx()), area.y().minus(self.dy()), area.w(), area.h()] });
 
 transform_xy_unit!("margin/x" "margin/y" "margin/xy"|self: Margin, area|{
-    let area = Render::layout(&self.content(), area);
+    let area = self.content().layout(area);
     let dx = self.dx();
     let dy = self.dy();
-    [area.x().minus(dx), area.y().minus(dy), area.w().plus(dy.plus(dy)), area.h().plus(dy.plus(dy))]
-});
+    [area.x().minus(dx), area.y().minus(dy), area.w().plus(dy.plus(dy)), area.h().plus(dy.plus(dy))] });
 
 transform_xy_unit!("padding/x" "padding/y" "padding/xy"|self: Padding, area|{
-    let area = Render::layout(&self.content(), area);
+    let area = self.content().layout(area);
     let dx = self.dx();
     let dy = self.dy();
-    [area.x().plus(dx), area.y().plus(dy), area.w().minus(dy.plus(dy)), area.h().minus(dy.plus(dy))]
-});
+    [area.x().plus(dx), area.y().plus(dy), area.w().minus(dy.plus(dy)), area.h().minus(dy.plus(dy))] });

output/src/output.rs

@@ -1,5 +1,4 @@
 use crate::*;
-use std::ops::Deref;
 
 /// Render target.
 pub trait Output: Send + Sync + Sized {

output/src/output_content.rs

@@ -1,88 +1,60 @@
 use crate::*;
 
 /// Composable renderable with static dispatch.
-pub trait Content<E: Output> {
-    /// Return a [Render]able of a specific type.
-    fn content (&self) -> impl Render<E> + '_ {
-        ()
-    }
-    /// Perform layout. By default, delegates to [Self::content].
-    fn layout (&self, area: E::Area) -> E::Area {
-        self.content().layout(area)
-    }
-    /// Draw to output. By default, delegates to [Self::content].
-    fn render (&self, output: &mut E) {
-        self.content().render(output) 
-    }
-}
-
-/// Every pointer to [Content] is a [Content].
-impl<E: Output, C: Content<E>> Content<E> for &C {
-    fn content (&self) -> impl Render<E> + '_ { (*self).content() }
-    fn layout (&self, area: E::Area) -> E::Area { (*self).layout(area) }
-    fn render (&self, output: &mut E) { (*self).render(output) }
+pub trait Content<E: Output>: Sized {
+    /// Return opaque [Render]able.
+    fn content (&self) -> Option<impl Render<E> + '_> { Option::<()>::None }
 }
 
 /// The platonic ideal unit of [Content]: total emptiness at dead center (e=1vg^sqrt(-1))
-impl<E: Output> Content<E> for () {
-    fn layout (&self, area: E::Area) -> E::Area { area.center().to_area_pos().into() }
-    fn render (&self, _: &mut E) {}
+impl<E: Output> Content<E> for () {}
+
+impl<E: Output> Content<E> for fn(&mut E) {
+    fn content (&self) -> Option<impl Render<E> + '_> {
+        Some(self)
+    }
+}
+
+impl<E: Output, T: Render<E>> Content<E> for fn()->T {
+    fn content (&self) -> Option<impl Render<E> + '_> {
+        Some(self())
+    }
 }
 
 impl<E: Output, T: Content<E>> Content<E> for Option<T> {
-    fn content (&self) -> impl Render<E> + '_ {
-        self.as_ref()
+    fn content (&self) -> Option<impl Render<E> + '_> {
+        if let Some(content) = self {
+            content.content()
+        } else {
+            None
+        }
     }
-    fn layout (&self, area: E::Area) -> E::Area {
-        self.as_ref()
-            .map(|content|content.layout(area))
-            .unwrap_or([0.into(), 0.into(), 0.into(), 0.into(),].into())
-    }
-    fn render (&self, output: &mut E) {
-        self.as_ref()
-            .map(|content|content.render(output));
-    }
-}
-
-/// You can render from a box.
-impl<E: Output> Content<E> for RenderBox<E> {
-    fn content (&self) -> impl Render<E> + '_ { self.deref() }
-    //fn boxed <'b> (self) -> RenderBox<'b, E> where Self: Sized + 'b { self }
 }
 
 /// You can render from an opaque pointer.
 impl<E: Output> Content<E> for &dyn Render<E> where Self: Sized {
-    fn content (&self) -> impl Render<E> + '_ {
+    fn content (&self) -> Option<impl Render<E> + '_> {
         #[allow(suspicious_double_ref_op)]
-        self.deref()
-    }
-    fn layout (&self, area: E::Area) -> E::Area {
-        #[allow(suspicious_double_ref_op)]
-        Render::layout(self.deref(), area)
-    }
-    fn render (&self, output: &mut E) {
-        #[allow(suspicious_double_ref_op)]
-        Render::render(self.deref(), output)
+        Some(self.deref())
     }
 }
 
-/// Implement [Content] with custom rendering for a struct.
-#[macro_export] macro_rules! render {
-    (|$self:ident:$Struct:ident $(<
-        $($L:lifetime),* $($T:ident $(:$Trait:path)?),*
-    >)?, $to:ident | $render:expr) => {
-        impl <$($($L),*)? E: Output, $($T$(:$Trait)?),*> Content<E>
-        for $Struct $(<$($L),* $($T),*>>)? {
-            fn render (&$self, $to: &mut E) { $render }
+/// Implement composable content for a struct.
+#[macro_export] macro_rules! content {
+    // Implement for all [Output]s.
+    (|$self:ident:$Struct:ty| $content:expr) => {
+        impl<E: Output> Content<E> for $Struct {
+            fn content (&$self) -> impl Render<E> + '_ { Some($content) }
         }
     };
+    // Implement for specific [Output].
     ($Output:ty:|
         $self:ident:
-        $Struct:ident $(<$($($L:lifetime)? $($T:ident)? $(:$Trait:path)?),+>)?, $to:ident
-    |$render:expr) => {
+        $Struct:ident$(<$($($L:lifetime)? $($T:ident)? $(:$Trait:path)?),+>)?
+    |$content:expr) => {
         impl $(<$($($L)? $($T)? $(:$Trait)?),+>)? Content<$Output>
         for $Struct $(<$($($L)? $($T)?),+>)? {
-            fn render (&$self, $to: &mut $Output) { $render }
+            fn content (&$self) -> impl Render<$Output> + '_ { $content }
         }
     };
 }

output/src/output_render.rs

@@ -2,46 +2,86 @@ use crate::*;
 
 /// Renderable with dynamic dispatch.
 pub trait Render<E: Output> {
-    /// Compute layout.
-    fn layout (&self, area: E::Area) -> E::Area;
     /// Write data to display.
     fn render (&self, output: &mut E);
-    /// Perform type erasure, turning `self` into an opaque [RenderBox].
+    /// Compute layout.
+    fn layout (&self, area: E::Area) -> E::Area { area }
+
     fn boxed <'a> (self) -> Box<dyn Render<E> + 'a> where Self: Sized + 'a {
         Box::new(self) as Box<dyn Render<E> + 'a>
     }
+    fn rc <'a> (self) -> Rc<dyn Render<E> + 'a> where Self: Sized + 'a {
+        Rc::new(self) as Rc<dyn Render<E> + 'a>
+    }
 }
 
-/// Every [Content] is also a [Render].
-/// However, the converse does not hold true.
-/// Instead, the [Content::content] method returns an
-/// opaque [Render] pointer.
-impl<E: Output, C: Content<E>> Render<E> for C {
-    fn layout (&self, area: E::Area) -> E::Area { Content::layout(self, area) }
-    fn render (&self, output: &mut E) { Content::render(self, output) }
+impl<E: Output> Render<E> for () {
+    fn render (&self, _: &mut E) {}
 }
 
-/// Opaque pointer to a renderable living on the heap.
-///
-/// Return this from [Content::content] to use dynamic dispatch.
-pub type RenderBox<E> = Box<dyn Render<E>>;
+impl<E: Output> Render<E> for fn(&mut E) {
+    fn render (&self, output: &mut E) {
+        self(output)
+    }
+}
 
-/// Implement [Content] with composable content for a struct.
-#[macro_export] macro_rules! content {
-    // Implement for all [Output]s.
-    (|$self:ident:$Struct:ty| $content:expr) => {
-        impl<E: Output> Content<E> for $Struct {
-            fn content (&$self) -> impl Render<E> + '_ { Some($content) }
+impl<'x, E: Output> Render<E> for &(dyn Render<E> + 'x) {
+    fn render (&self, output: &mut E) {
+        (*self).render(output)
+    }
+}
+
+impl<E: Output, R: Render<E>> Render<E> for Box<R> {
+    fn render (&self, output: &mut E) {
+        (**self).render(output)
+    }
+}
+
+impl<E: Output, R: Render<E>> Render<E> for Option<R> {
+    fn render (&self, output: &mut E) {
+        if let Some(render) = self {
+            render.render(output)
+        }
+    }
+}
+
+impl<E: Output, R: Render<E>> Render<E> for &R {
+    fn render (&self, output: &mut E) {
+        (*self).render(output)
+    }
+}
+
+impl<E: Output, R: Render<E>> Render<E> for &mut R {
+    fn render (&self, output: &mut E) {
+        (**self).render(output)
+    }
+}
+
+impl<E: Output, R: Render<E>> Render<E> for [R] {
+    fn render (&self, output: &mut E) {
+        for render in self.iter() {
+            render.render(output)
+        }
+    }
+}
+
+/// Implement custom rendering for a struct.
+#[macro_export] macro_rules! render {
+    (|$self:ident:$Struct:ident $(<
+        $($L:lifetime),* $($T:ident $(:$Trait:path)?),*
+    >)?, $to:ident | $render:expr) => {
+        impl <$($($L),*)? E: Output, $($T$(:$Trait)?),*> Render<E>
+        for $Struct $(<$($L),* $($T),*>>)? {
+            fn render (&$self, $to: &mut E) { $render }
         }
     };
-    // Implement for specific [Output].
     ($Output:ty:|
         $self:ident:
-        $Struct:ident$(<$($($L:lifetime)? $($T:ident)? $(:$Trait:path)?),+>)?
-    |$content:expr) => {
-        impl $(<$($($L)? $($T)? $(:$Trait)?),+>)? Content<$Output>
+        $Struct:ident $(<$($($L:lifetime)? $($T:ident)? $(:$Trait:path)?),+>)?, $to:ident
+    |$render:expr) => {
+        impl $(<$($($L)? $($T)? $(:$Trait)?),+>)? Render<$Output>
         for $Struct $(<$($($L)? $($T)?),+>)? {
-            fn content (&$self) -> impl Render<$Output> + '_ { $content }
+            fn render (&$self, $to: &mut $Output) { $render }
         }
     };
 }

output/src/output_thunk.rs

@@ -11,65 +11,19 @@ impl<E: Output, T: Render<E>, F: Fn()->T> Thunk<E, T, F> {
     }
 }
 impl<E: Output, T: Render<E>, F: Fn()->T> Content<E> for Thunk<E, T, F> {
-    fn content (&self) -> impl Render<E> { (self.1)() }
-}
-
-/// Lazily-evaluated [Render]able with
-/// mandatory stack allocation and dynamic dispatch.
-pub struct ThunkBox<E: Output>(
-    PhantomData<E>,
-    Box<dyn Fn()->Box<dyn Render<E>>>,
-);
-impl<E: Output> ThunkBox<E> {
-    pub const fn new (thunk: Box<dyn Fn()->Box<dyn Render<E>>>) -> Self {
-        Self(PhantomData, thunk)
+    fn content (&self) -> Option<impl Render<E>> {
+        Some((self.1)())
     }
 }
-impl<E: Output> Content<E> for ThunkBox<E> {
-    fn content (&self) -> impl Render<E> { (&self.1)() }
-}
-impl<E: Output> From<Box<dyn Fn()->Box<dyn Render<E>>>> for ThunkBox<E> {
-    fn from (f: Box<dyn Fn()->Box<dyn Render<E>>>) -> Self {
-        Self(PhantomData, f)
-    }
-}
-
-//impl<'a, E: Output, F: Fn()->Box<dyn Render<E> + 'a> + 'a> From<F> for ThunkBox<'a, E> {
-    //fn from (f: F) -> Self {
-        //Self(Default::default(), Box::new(f))
-    //}
-//}
 
 pub struct ThunkRender<E: Output, F: Fn(&mut E)>(PhantomData<E>, F);
 impl<E: Output, F: Fn(&mut E)> ThunkRender<E, F> {
     pub fn new (render: F) -> Self { Self(PhantomData, render) }
 }
-impl<E: Output, F: Fn(&mut E)> Content<E> for ThunkRender<E, F> {
+impl<E: Output, F: Fn(&mut E)> Render<E> for ThunkRender<E, F> {
     fn render (&self, to: &mut E) { (self.1)(to) }
 }
 
-pub struct ThunkLayout<
-    E: Output,
-    F1: Fn(E::Area)->E::Area,
-    F2: Fn(&mut E)
->(
-    PhantomData<E>,
-    F1,
-    F2
-);
-impl<E: Output, F1: Fn(E::Area)->E::Area, F2: Fn(&mut E)> ThunkLayout<E, F1, F2> {
-    pub fn new (layout: F1, render: F2) -> Self { Self(PhantomData, layout, render) }
-}
-impl<E, F1, F2> Content<E> for ThunkLayout<E, F1, F2>
-where
-    E:  Output,
-    F1: Fn(E::Area)->E::Area,
-    F2: Fn(&mut E)
-{
-    fn layout (&self, to: E::Area) -> E::Area { (self.1)(to) }
-    fn render (&self, to: &mut E) { (self.2)(to) }
-}
-
 #[derive(Debug, Default)] pub struct Memo<T, U> {
     pub value: T,
     pub view: Arc<RwLock<U>>

output/src/space.rs

@@ -1,281 +0,0 @@
-use crate::*;
-use Direction::*;
-
-/// A cardinal direction.
-#[derive(Copy, Clone, PartialEq, Debug)]
-#[cfg_attr(test, derive(Arbitrary))]
-pub enum Direction {
-    North, South, East, West, Above, Below
-}
-
-impl Direction {
-    pub fn split_fixed <N: Coordinate> (self, area: impl Area<N>, a: N) -> ([N;4],[N;4]) {
-        let [x, y, w, h] = area.xywh();
-        match self {
-            North => ([x, y.plus(h).minus(a), w, a], [x, y, w, h.minus(a)]),
-            South => ([x, y, w, a], [x, y.plus(a), w, h.minus(a)]),
-            East  => ([x, y, a, h], [x.plus(a), y, w.minus(a), h]),
-            West  => ([x.plus(w).minus(a), y, a, h], [x, y, w.minus(a), h]),
-            Above | Below => (area.xywh(), area.xywh())
-        }
-    }
-}
-
-/// A linear coordinate.
-pub trait Coordinate: Send + Sync + Copy
-    + Add<Self, Output=Self>
-    + Sub<Self, Output=Self>
-    + Mul<Self, Output=Self>
-    + Div<Self, Output=Self>
-    + Ord + PartialEq + Eq
-    + Debug + Display + Default
-    + From<u16> + Into<u16>
-    + Into<usize>
-    + Into<f64>
-{
-    fn zero () -> Self { 0.into() }
-    fn plus (self, other: Self) -> Self;
-    fn minus (self, other: Self) -> Self {
-        if self >= other {
-            self - other
-        } else {
-            0.into()
-        }
-    }
-}
-
-impl Coordinate for u16 {
-    fn plus (self, other: Self) -> Self {
-        self.saturating_add(other)
-    }
-}
-
-pub trait Area<N: Coordinate>: From<[N;4]> + Debug + Copy {
-    fn x (&self) -> N;
-    fn y (&self) -> N;
-    fn w (&self) -> N;
-    fn h (&self) -> N;
-    fn zero () -> [N;4] {
-        [N::zero(), N::zero(), N::zero(), N::zero()]
-    }
-    fn from_position (pos: impl Size<N>) -> [N;4] {
-        let [x, y] = pos.wh();
-        [x, y, 0.into(), 0.into()]
-    }
-    fn from_size (size: impl Size<N>) -> [N;4] {
-        let [w, h] = size.wh();
-        [0.into(), 0.into(), w, h]
-    }
-    fn expect_min (&self, w: N, h: N) -> Usually<&Self> {
-        if self.w() < w || self.h() < h {
-            Err(format!("min {w}x{h}").into())
-        } else {
-            Ok(self)
-        }
-    }
-    fn xy (&self) -> [N;2] {
-        [self.x(), self.y()]
-    }
-    fn wh (&self) -> [N;2] {
-        [self.w(), self.h()]
-    }
-    fn xywh (&self) -> [N;4] {
-        [self.x(), self.y(), self.w(), self.h()]
-    }
-    fn clip_h (&self, h: N) -> [N;4] {
-        [self.x(), self.y(), self.w(), self.h().min(h)]
-    }
-    fn clip_w (&self, w: N) -> [N;4] {
-        [self.x(), self.y(), self.w().min(w), self.h()]
-    }
-    fn clip (&self, wh: impl Size<N>) -> [N;4] {
-        [self.x(), self.y(), wh.w(), wh.h()]
-    }
-    fn set_w (&self, w: N) -> [N;4] {
-        [self.x(), self.y(), w, self.h()]
-    }
-    fn set_h (&self, h: N) -> [N;4] {
-        [self.x(), self.y(), self.w(), h]
-    }
-    fn x2 (&self) -> N {
-        self.x().plus(self.w())
-    }
-    fn y2 (&self) -> N {
-        self.y().plus(self.h())
-    }
-    fn lrtb (&self) -> [N;4] {
-        [self.x(), self.x2(), self.y(), self.y2()]
-    }
-    fn center (&self) -> [N;2] {
-        [self.x().plus(self.w()/2.into()), self.y().plus(self.h()/2.into())]
-    }
-    fn center_x (&self, n: N) -> [N;4] {
-        let [x, y, w, h] = self.xywh();
-        [(x.plus(w / 2.into())).minus(n / 2.into()), y.plus(h / 2.into()), n, 1.into()]
-    }
-    fn center_y (&self, n: N) -> [N;4] {
-        let [x, y, w, h] = self.xywh();
-        [x.plus(w / 2.into()), (y.plus(h / 2.into())).minus(n / 2.into()), 1.into(), n]
-    }
-    fn center_xy (&self, [n, m]: [N;2]) -> [N;4] {
-        let [x, y, w, h] = self.xywh();
-        [(x.plus(w / 2.into())).minus(n / 2.into()), (y.plus(h / 2.into())).minus(m / 2.into()), n, m]
-    }
-    fn centered (&self) -> [N;2] {
-        [self.x().minus(self.w()/2.into()), self.y().minus(self.h()/2.into())]
-    }
-    fn iter_x (&self) -> impl Iterator<Item = N> where N: std::iter::Step {
-        self.x()..(self.x()+self.w())
-    }
-    fn iter_y (&self) -> impl Iterator<Item = N> where N: std::iter::Step {
-        self.y()..(self.y()+self.h())
-    }
-}
-
-impl<N: Coordinate> Area<N> for (N, N, N, N) {
-    fn x (&self) -> N { self.0 }
-    fn y (&self) -> N { self.1 }
-    fn w (&self) -> N { self.2 }
-    fn h (&self) -> N { self.3 }
-}
-
-impl<N: Coordinate> Area<N> for [N;4] {
-    fn x (&self) -> N { self[0] }
-    fn y (&self) -> N { self[1] }
-    fn w (&self) -> N { self[2] }
-    fn h (&self) -> N { self[3] }
-}
-
-pub trait Size<N: Coordinate>: From<[N;2]> + Debug + Copy {
-    fn x (&self) -> N;
-    fn y (&self) -> N;
-    fn w (&self) -> N { self.x() }
-    fn h (&self) -> N { self.y() }
-    fn wh (&self) -> [N;2] { [self.x(), self.y()] }
-    fn clip_w (&self, w: N) -> [N;2] { [self.w().min(w), self.h()] }
-    fn clip_h (&self, h: N) -> [N;2] { [self.w(), self.h().min(h)] }
-    fn expect_min (&self, w: N, h: N) -> Usually<&Self> {
-        if self.w() < w || self.h() < h {
-            Err(format!("min {w}x{h}").into())
-        } else {
-            Ok(self)
-        }
-    }
-    fn zero () -> [N;2] {
-        [N::zero(), N::zero()]
-    }
-    fn to_area_pos (&self) -> [N;4] {
-        let [x, y] = self.wh();
-        [x, y, 0.into(), 0.into()]
-    }
-    fn to_area_size (&self) -> [N;4] {
-        let [w, h] = self.wh();
-        [0.into(), 0.into(), w, h]
-    }
-}
-
-impl<N: Coordinate> Size<N> for (N, N) {
-    fn x (&self) -> N { self.0 }
-    fn y (&self) -> N { self.1 }
-}
-
-impl<N: Coordinate> Size<N> for [N;2] {
-    fn x (&self) -> N { self[0] }
-    fn y (&self) -> N { self[1] }
-}
-
-pub trait HasSize<E: Output> {
-    fn size (&self) -> &Measure<E>;
-    fn width (&self) -> usize {
-        self.size().w()
-    }
-    fn height (&self) -> usize {
-        self.size().h()
-    }
-}
-
-impl<E: Output, T: Has<Measure<E>>> HasSize<E> for T {
-    fn size (&self) -> &Measure<E> {
-        self.get()
-    }
-}
-
-/// A widget that tracks its render width and height
-#[derive(Default)]
-pub struct Measure<E: Output> {
-    _engine: PhantomData<E>,
-    pub x: Arc<AtomicUsize>,
-    pub y: Arc<AtomicUsize>,
-}
-
-impl<E: Output> PartialEq for Measure<E> {
-    fn eq (&self, other: &Self) -> bool {
-        self.x.load(Relaxed) == other.x.load(Relaxed) &&
-            self.y.load(Relaxed) == other.y.load(Relaxed)
-    }
-}
-
-// TODO: 🡘  🡙 ←🡙→ indicator to expand window when too small
-impl<E: Output> Content<E> for Measure<E> {
-    fn render (&self, to: &mut E) {
-        self.x.store(to.area().w().into(), Relaxed);
-        self.y.store(to.area().h().into(), Relaxed);
-    }
-}
-
-impl<E: Output> Clone for Measure<E> {
-    fn clone (&self) -> Self {
-        Self {
-            _engine: Default::default(),
-            x: self.x.clone(),
-            y: self.y.clone(),
-        }
-    }
-}
-
-impl<E: Output> 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: Output> Measure<E> {
-    pub fn new () -> Self {
-        Self {
-            _engine: PhantomData::default(),
-            x: Arc::new(0.into()),
-            y: Arc::new(0.into()),
-        }
-    }
-    pub fn set_w (&self, w: impl Into<usize>) -> &Self {
-        self.x.store(w.into(), Relaxed);
-        self
-    }
-    pub fn set_h (&self, h: impl Into<usize>) -> &Self {
-        self.y.store(h.into(), Relaxed);
-        self
-    }
-    pub fn set_wh (&self, w: impl Into<usize>, h: impl Into<usize>) -> &Self {
-        self.set_w(w);
-        self.set_h(h);
-        self
-    }
-    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 format (&self) -> Arc<str> {
-        format!("{}x{}", self.w(), self.h()).into()
-    }
-    pub fn of <T: Render<E>> (&self, item: T) -> Bsp<Fill<&Self>, T> {
-        Bsp::b(Fill::xy(self), item)
-    }
-}

output/src/space_measure.rs

@@ -16,7 +16,7 @@ impl<E: Output> PartialEq for Measure<E> {
 }
 
 // TODO: 🡘  🡙 ←🡙→ indicator to expand window when too small
-impl<E: Output> Content<E> for Measure<E> {
+impl<E: Output> Render<E> for Measure<E> {
     fn render (&self, to: &mut E) {
         self.x.store(to.area().w().into(), Relaxed);
         self.y.store(to.area().h().into(), Relaxed);

output/src/test.rs

@@ -146,7 +146,7 @@ proptest! {
             ()
         }
     }
-    impl Content<TestOutput> for String {
+    impl Render<TestOutput> for String {
         fn render (&self, to: &mut TestOutput) {
             to.area_mut().set_w(self.len() as u16);
         }
@@ -162,7 +162,7 @@ proptest! {
 #[test] fn test_iter_map () {
     struct Foo;
     impl<T: Output> Content<T> for Foo {}
-    fn _make_map <T: Output, U: Content<T> + Send + Sync> (data: &Vec<U>) -> impl Content<T> {
+    fn _make_map <T: Output, U: Content<T> + Send + Sync> (data: &Vec<U>) -> impl Render<T> {
         Map::new(||data.iter(), |_foo, _index|{})
     }
     let _data = vec![Foo, Foo, Foo];

proc/src/lib.rs

@@ -106,7 +106,7 @@ pub(crate) fn write_quote_to (out: &mut TokenStream2, quote: TokenStream2) {
         //#[tengri_proc::view(SomeOutput)]
         //impl SomeView {
             //#[tengri::view(":view-1")]
-            //fn view_1 (&self) -> impl Content<SomeOutput> + use<'_> {
+            //fn view_1 (&self) -> impl Render<SomeOutput> + use<'_> {
                 //"view-1"
             //}
         //}
@@ -114,7 +114,7 @@ pub(crate) fn write_quote_to (out: &mut TokenStream2, quote: TokenStream2) {
     //let written = quote! { #parsed };
     //assert_eq!(format!("{written}"), format!("{}", quote! {
         //impl SomeView {
-            //fn view_1 (&self) -> impl Content<SomeOutput> + use<'_> {
+            //fn view_1 (&self) -> impl Render<SomeOutput> + use<'_> {
                 //"view-1"
             //}
         //}

tui/examples/tui.rs

@@ -76,25 +76,25 @@ content!(TuiOut: |self: Example|{
 
 //#[tengri_proc::view(TuiOut)]
 //impl Example {
-    //pub fn title (&self) -> impl Content<TuiOut> + use<'_> {
+    //pub fn title (&self) -> impl Render<TuiOut> + use<'_> {
         //Tui::bg(Color::Rgb(60,  10, 10), Push::y(1, Align::n(format!("Example {}/{}:", self.0 + 1, EXAMPLES.len())))).boxed()
     //}
-    //pub fn code (&self) -> impl Content<TuiOut> + use<'_> {
+    //pub fn code (&self) -> impl Render<TuiOut> + use<'_> {
         //Tui::bg(Color::Rgb(10,  60, 10), Push::y(2, Align::n(format!("{}", EXAMPLES[self.0])))).boxed()
     //}
-    //pub fn hello (&self) -> impl Content<TuiOut> + use<'_> {
+    //pub fn hello (&self) -> impl Render<TuiOut> + use<'_> {
         //Tui::bg(Color::Rgb(10, 100, 10), "Hello").boxed()
     //}
-    //pub fn world (&self) -> impl Content<TuiOut> + use<'_> {
+    //pub fn world (&self) -> impl Render<TuiOut> + use<'_> {
         //Tui::bg(Color::Rgb(100, 10, 10), "world").boxed()
     //}
-    //pub fn hello_world (&self) -> impl Content<TuiOut> + use<'_> {
+    //pub fn hello_world (&self) -> impl Render<TuiOut> + use<'_> {
         //"Hello world!".boxed()
     //}
-    //pub fn map_e (&self) -> impl Content<TuiOut> + use<'_> {
+    //pub fn map_e (&self) -> impl Render<TuiOut> + use<'_> {
         //Map::east(5u16, ||0..5u16, |n, _i|format!("{n}")).boxed()
     //}
-    //pub fn map_s (&self) -> impl Content<TuiOut> + use<'_> {
+    //pub fn map_s (&self) -> impl Render<TuiOut> + use<'_> {
         //Map::south(5u16, ||0..5u16, |n, _i|format!("{n}")).boxed()
     //}
 //}

tui/src/tui_content.rs

@@ -5,7 +5,7 @@ macro_rules! impl_content_layout_render {
         layout = $layout:expr;
         render = $render:expr) =>
     {
-        impl Content<$Output> for $Struct {
+        impl Render<$Output> for $Struct {
             fn layout (&$self, $to: [u16;4]) -> [u16;4] { $layout }
             fn render (&$self, $to: &mut $Output) { $render }
         }
@@ -25,19 +25,19 @@ mod tui_string;   pub use self::tui_string::*;
 mod tui_style;    pub use self::tui_style::*;
 mod tui_tryptich; pub use self::tui_tryptich::*;
 
-impl<T: Content<TuiOut>> Content<TuiOut> for std::sync::Arc<T> {
+impl<T: Render<TuiOut>> Render<TuiOut> for std::sync::Arc<T> {
     fn layout (&self, to: [u16;4]) -> [u16;4] {
-        Content::<TuiOut>::layout(&**self, to)
+        Render::<TuiOut>::layout(&**self, to)
     }
     fn render (&self, to: &mut TuiOut) {
-        Content::<TuiOut>::render(&**self, to)
+        Render::<TuiOut>::render(&**self, to)
     }
 }
 
-impl<T: Content<TuiOut>> Content<TuiOut> for Result<T, Box<dyn std::error::Error>> {
-    fn content (&self) -> impl Render<TuiOut> {
-        Bsp::a(self.as_ref().ok(), self.as_ref().err()
-            .map(|e|Tui::fg_bg(Color::Rgb(255,255,255), Color::Rgb(32,32,32), e.to_string())))
+impl<T: Render<TuiOut>> Content<TuiOut> for Result<T, Box<dyn std::error::Error>> {
+    fn content (&self) -> Option<impl Render<TuiOut> + '_> {
+        Some(Bsp::a(self.as_ref().ok(), self.as_ref().err()
+            .map(|e|Tui::fg_bg(Color::Rgb(255,255,255), Color::Rgb(32,32,32), e.to_string()))))
     }
 }
 

tui/src/tui_content/_tui_focus.rs

@@ -243,7 +243,7 @@ impl<T: FocusGrid + HasEnter> FocusOrder for T {
 }
 
 pub trait FocusWrap<T> {
-    fn wrap <W: Content<TuiOut>> (self, focus: T, content: &'_ W) -> impl Content<TuiOut> + '_;
+    fn wrap <W: Content<TuiOut>> (self, focus: T, content: &'_ W) -> impl Render<TuiOut> + '_;
 }
 
 pub fn to_focus_command <T: Send + Sync> (input: &TuiIn) -> Option<FocusCommand<T>> {

tui/src/tui_content/tui_border.rs

@@ -1,40 +1,49 @@
 use crate::*;
 
-pub struct Bordered<S: BorderStyle, W: Content<TuiOut>>(pub bool, pub S, pub W);
-content!(TuiOut: |self: Bordered<S: BorderStyle, W: Content<TuiOut>>|Fill::xy(
-    lay!(When::new(self.0, Border(self.0, self.1)), Padding::xy(1, 1, &self.2))
-));
+pub struct Bordered<S, W>(pub bool, pub S, pub W);
+impl<S: BorderStyle, W: Render<TuiOut>> Content<TuiOut> for Bordered<S, W> {
+    fn content (&self) -> Option<impl Render<TuiOut> + '_> {
+        Some(Fill::xy(
+            lay!(When::new(self.0, Border(self.0, self.1)), Padding::xy(1, 1, &self.2))
+        ))
+    }
+}
 
 pub struct Border<S: BorderStyle>(pub bool, pub S);
-render!(TuiOut: |self: Border<S: BorderStyle>, to| {
-    if self.0 {
-        let area = to.area();
-        if area.w() > 0 && area.y() > 0 {
-            to.blit(&self.1.nw(), area.x(), area.y(), self.1.style());
-            to.blit(&self.1.ne(), area.x() + area.w() - 1, area.y(), self.1.style());
-            to.blit(&self.1.sw(), area.x(), area.y() + area.h() - 1, self.1.style());
-            to.blit(&self.1.se(), area.x() + area.w() - 1, area.y() + area.h() - 1, self.1.style());
-            for x in area.x()+1..area.x()+area.w()-1 {
-                to.blit(&self.1.n(), x, area.y(), self.1.style());
-                to.blit(&self.1.s(), x, area.y() + area.h() - 1, self.1.style());
-            }
-            for y in area.y()+1..area.y()+area.h()-1 {
-                to.blit(&self.1.w(), area.x(), y, self.1.style());
-                to.blit(&self.1.e(), area.x() + area.w() - 1, y, self.1.style());
+impl<S: BorderStyle> Render<TuiOut> for Border<S> {
+    fn layout (&self, area: [u16;4]) -> [u16;4] {
+        self.1.layout(area)
+    }
+    fn render (&self, to: &mut TuiOut) {
+        if self.0 {
+            let area = to.area();
+            if area.w() > 0 && area.y() > 0 {
+                to.blit(&self.1.nw(), area.x(), area.y(), self.1.style());
+                to.blit(&self.1.ne(), area.x() + area.w() - 1, area.y(), self.1.style());
+                to.blit(&self.1.sw(), area.x(), area.y() + area.h() - 1, self.1.style());
+                to.blit(&self.1.se(), area.x() + area.w() - 1, area.y() + area.h() - 1, self.1.style());
+                for x in area.x()+1..area.x()+area.w()-1 {
+                    to.blit(&self.1.n(), x, area.y(), self.1.style());
+                    to.blit(&self.1.s(), x, area.y() + area.h() - 1, self.1.style());
+                }
+                for y in area.y()+1..area.y()+area.h()-1 {
+                    to.blit(&self.1.w(), area.x(), y, self.1.style());
+                    to.blit(&self.1.e(), area.x() + area.w() - 1, y, self.1.style());
+                }
             }
         }
     }
-});
+}
 
-pub trait BorderStyle: Send + Sync + Copy {
+pub trait BorderStyle: Render<TuiOut> + Copy {
     fn enabled (&self) -> bool;
-    fn enclose <W: Content<TuiOut>> (self, w: W) -> impl Content<TuiOut> {
+    fn enclose <W: Render<TuiOut>> (self, w: W) -> impl Render<TuiOut> {
         Bsp::b(Fill::xy(Border(self.enabled(), self)), w)
     }
-    fn enclose2 <W: Content<TuiOut>> (self, w: W) -> impl Content<TuiOut> {
+    fn enclose2 <W: Render<TuiOut>> (self, w: W) -> impl Render<TuiOut> {
         Bsp::b(Margin::xy(1, 1, Fill::xy(Border(self.enabled(), self))), w)
     }
-    fn enclose_bg <W: Content<TuiOut>> (self, w: W) -> impl Content<TuiOut> {
+    fn enclose_bg <W: Render<TuiOut>> (self, w: W) -> impl Render<TuiOut> {
         Tui::bg(self.style().unwrap().bg.unwrap_or(Color::Reset),
             Bsp::b(Fill::xy(Border(self.enabled(), self)), w))
     }
@@ -138,7 +147,7 @@ macro_rules! border {
             fn enabled (&self) -> bool { self.0 }
         }
         #[derive(Copy, Clone)] pub struct $T(pub bool, pub Style);
-        impl Content<TuiOut> for $T {
+        impl Render<TuiOut> for $T {
             fn render (&self, to: &mut TuiOut) {
                 if self.enabled() { let _ = self.draw(to); }
             }

tui/src/tui_content/tui_error.rs

@@ -2,23 +2,26 @@ use crate::*;
 use ratatui::style::Stylize;
 
 // Thunks can be natural error boundaries!
-pub struct ErrorBoundary<O: Output, T: Content<O>>(std::marker::PhantomData<O>, Perhaps<T>);
+pub struct ErrorBoundary<O: Output, T: Render<O>>(
+    std::marker::PhantomData<O>, Perhaps<T>
+);
 
-impl<O: Output, T: Content<O>> ErrorBoundary<O, T> {
+impl<O: Output, T: Render<O>> ErrorBoundary<O, T> {
     pub fn new (content: Perhaps<T>) -> Self {
         Self(Default::default(), content)
     }
 }
 
-impl<T: Content<TuiOut>> Content<TuiOut> for ErrorBoundary<TuiOut, T> {
-    fn content (&self) -> impl Render<TuiOut> + '_ {
-        ThunkRender::new(|to|match self.1.as_ref() {
+impl<T: Render<TuiOut>> Render<TuiOut> for ErrorBoundary<TuiOut, T> {
+    fn render (&self, to: &mut TuiOut) {
+        match self.1.as_ref() {
             Ok(Some(content)) => content.render(to),
             Ok(None) => to.blit(&"empty?", 0, 0, Some(Style::default().yellow())),
-            Err(e) => Content::render(&Tui::fg_bg(
+            Err(e) => Tui::fg_bg(
                 Color::Rgb(255,224,244), Color::Rgb(96,24,24), Bsp::s(
                     Bsp::e(Tui::bold(true, "oops. "), "rendering failed."),
-                    Bsp::e("\"why?\" ", Tui::bold(true, &format!("{e}"))))), to)
-        })
+                    Bsp::e("\"why?\" ", Tui::bold(true, &format!("{e}"))))
+            ).render(to)
+        }
     }
 }

tui/src/tui_content/tui_field.rs

@@ -1,30 +1,30 @@
 use crate::*;
 
 pub struct FieldH<T, U>(pub ItemTheme, pub T, pub U);
-impl<T: Content<TuiOut>, U: Content<TuiOut>> Content<TuiOut> for FieldH<T, U> {
-    fn content (&self) -> impl Render<TuiOut> {
+impl<T: Render<TuiOut>, U: Render<TuiOut>> Content<TuiOut> for FieldH<T, U> {
+    fn content (&self) -> Option<impl Render<TuiOut> + '_> {
         let Self(ItemTheme { darkest, dark, lightest, .. }, title, value) = self;
-        row!(
+        Some(row!(
             Tui::fg_bg(dark.rgb,     darkest.rgb, "▐"),
             Tui::fg_bg(lightest.rgb, dark.rgb,    title),
             Tui::fg_bg(dark.rgb,     darkest.rgb, "▌"),
             Tui::fg_bg(lightest.rgb, darkest.rgb, Tui::bold(true, value)),
-        )
+        ))
     }
 }
 
 pub struct FieldV<T, U>(pub ItemTheme, pub T, pub U);
-impl<T: Content<TuiOut>, U: Content<TuiOut>> Content<TuiOut> for FieldV<T, U> {
-    fn content (&self) -> impl Render<TuiOut> {
+impl<T: Render<TuiOut>, U: Render<TuiOut>> Content<TuiOut> for FieldV<T, U> {
+    fn content (&self) -> Option<impl Render<TuiOut> + '_> {
         let Self(ItemTheme { darkest, dark, lightest, .. }, title, value) = self;
-        Bsp::n(
+        Some(Bsp::n(
             Align::w(Tui::bg(darkest.rgb, Tui::fg(lightest.rgb, Tui::bold(true, value)))),
             Fill::x(Align::w(row!(
                 Tui::bg(darkest.rgb, Tui::fg(dark.rgb,     "▐")),
                 Tui::bg(dark.rgb,    Tui::fg(lightest.rgb, title)),
                 Tui::bg(darkest.rgb, Tui::fg(dark.rgb,     "▌")),
             )))
-        )
+        ))
     }
 }
 
@@ -40,9 +40,9 @@ pub struct Field<T, U> {
     pub value_bg:    Option<ItemColor>,
     pub value_align: Option<Direction>,
 }
-impl<T: Content<TuiOut>, U: Content<TuiOut>> Content<TuiOut> for Field<T, U> {
-    fn content (&self) -> impl Render<TuiOut> {
-        "TODO"
+impl<T: Render<TuiOut>, U: Render<TuiOut>> Content<TuiOut> for Field<T, U> {
+    fn content (&self) -> Option<impl Render<TuiOut> + '_> {
+        Some("TODO")
     }
 }
 

tui/src/tui_content/tui_number.rs

@@ -1,5 +1,13 @@
 use crate::*;
 
-render!(TuiOut: |self: u64, _to|todo!());
+impl Render<TuiOut> for u64 {
+    fn render (&self, _to: &mut TuiOut) {
+        todo!()
+    }
+}
 
-render!(TuiOut: |self: f64, _to|todo!());
+impl Render<TuiOut> for f64 {
+    fn render (&self, _to: &mut TuiOut) {
+        todo!()
+    }
+}

tui/src/tui_content/tui_phat.rs

@@ -12,24 +12,24 @@ impl<T> Phat<T> {
     pub const LO: &'static str = "▄";
     pub const HI: &'static str = "▀";
     /// A phat line
-    pub fn lo (fg: Color, bg: Color) -> impl Content<TuiOut> {
+    pub fn lo (fg: Color, bg: Color) -> impl Render<TuiOut> {
         Fixed::y(1, Tui::fg_bg(fg, bg, RepeatH(Self::LO)))
     }
     /// A phat line
-    pub fn hi (fg: Color, bg: Color) -> impl Content<TuiOut> {
+    pub fn hi (fg: Color, bg: Color) -> impl Render<TuiOut> {
         Fixed::y(1, Tui::fg_bg(fg, bg, RepeatH(Self::HI)))
     }
 }
-impl<T: Content<TuiOut>> Content<TuiOut> for Phat<T> {
-    fn content (&self) -> impl Render<TuiOut> {
+impl<T: Render<TuiOut>> Content<TuiOut> for Phat<T> {
+    fn content (&self) -> Option<impl Render<TuiOut> + '_> {
         let [fg, bg, hi, lo] = self.colors;
         let top = Fixed::y(1, Self::lo(bg, hi));
         let low = Fixed::y(1, Self::hi(bg, lo));
         let content = Tui::fg_bg(fg, bg, &self.content);
-        Min::xy(
+        Some(Min::xy(
             self.width,
             self.height,
             Bsp::s(top, Bsp::n(low, Fill::xy(content)))
-        )
+        ))
     }
 }

tui/src/tui_content/tui_repeat.rs

@@ -2,8 +2,10 @@ use crate::*;
 use ratatui::prelude::Position;
 
 pub struct Repeat<'a>(pub &'a str);
-impl Content<TuiOut> for Repeat<'_> {
-    fn layout (&self, to: [u16;4]) -> [u16;4] { to }
+impl Render<TuiOut> for Repeat<'_> {
+    fn layout (&self, to: [u16;4]) -> [u16;4] {
+        to
+    }
     fn render (&self, to: &mut TuiOut) {
         let [x, y, w, h] = to.area().xywh();
         let a = self.0.len();
@@ -19,8 +21,10 @@ impl Content<TuiOut> for Repeat<'_> {
 }
 
 pub struct RepeatV<'a>(pub &'a str);
-impl Content<TuiOut> for RepeatV<'_> {
-    fn layout (&self, to: [u16;4]) -> [u16;4] { to }
+impl Render<TuiOut> for RepeatV<'_> {
+    fn layout (&self, to: [u16;4]) -> [u16;4] {
+        to
+    }
     fn render (&self, to: &mut TuiOut) {
         let [x, y, _w, h] = to.area().xywh();
         for y in y..y+h {
@@ -32,8 +36,10 @@ impl Content<TuiOut> for RepeatV<'_> {
 }
 
 pub struct RepeatH<'a>(pub &'a str);
-impl Content<TuiOut> for RepeatH<'_> {
-    fn layout (&self, to: [u16;4]) -> [u16;4] { to }
+impl Render<TuiOut> for RepeatH<'_> {
+    fn layout (&self, to: [u16;4]) -> [u16;4] {
+        to
+    }
     fn render (&self, to: &mut TuiOut) {
         let [x, y, w, _h] = to.area().xywh();
         for x in x..x+w {

tui/src/tui_content/tui_scroll.rs

@@ -23,7 +23,7 @@ impl ScrollbarH {
     const ICON_INC: &[char] = &[' ', '🞂', ' '];
 }
 
-impl Content<TuiOut> for ScrollbarV {
+impl Render<TuiOut> for ScrollbarV {
     fn render (&self, to: &mut TuiOut) {
         let [x, y1, _w, h] = to.area().xywh();
         let y2 = y1 + h;
@@ -51,7 +51,7 @@ impl Content<TuiOut> for ScrollbarV {
     }
 }
 
-impl Content<TuiOut> for ScrollbarH {
+impl Render<TuiOut> for ScrollbarH {
     fn render (&self, to: &mut TuiOut) {
         let [x1, y, w, _h] = to.area().xywh();
         let x2 = x1 + w;

tui/src/tui_content/tui_string.rs

@@ -4,24 +4,24 @@ use unicode_width::{UnicodeWidthStr, UnicodeWidthChar};
 
 impl_content_layout_render!(TuiOut: |self: &str, to|
     layout = to.center_xy([width_chars_max(to.w(), self), 1]);
-    render = {let [x, y, w, ..] = Content::layout(self, to.area());
+    render = {let [x, y, w, ..] = Render::layout(self, to.area());
               to.text(self, x, y, w)});
 
 impl_content_layout_render!(TuiOut: |self: String, to|
-    layout = Content::<TuiOut>::layout(&self.as_str(), to);
-    render = Content::<TuiOut>::render(&self.as_str(), to));
+    layout = Render::<TuiOut>::layout(&self.as_str(), to);
+    render = Render::<TuiOut>::render(&self.as_str(), to));
 
 impl_content_layout_render!(TuiOut: |self: Arc<str>, to|
-    layout = Content::<TuiOut>::layout(&self.as_ref(), to);
-    render = Content::<TuiOut>::render(&self.as_ref(), to));
+    layout = Render::<TuiOut>::layout(&self.as_ref(), to);
+    render = Render::<TuiOut>::render(&self.as_ref(), to));
 
 impl_content_layout_render!(TuiOut: |self: std::sync::RwLock<String>, to|
-    layout = Content::<TuiOut>::layout(&self.read().unwrap(), to);
-    render = Content::<TuiOut>::render(&self.read().unwrap(), to));
+    layout = Render::<TuiOut>::layout(&self.read().unwrap(), to);
+    render = Render::<TuiOut>::render(&self.read().unwrap(), to));
 
 impl_content_layout_render!(TuiOut: |self: std::sync::RwLockReadGuard<'_, String>, to|
-    layout = Content::<TuiOut>::layout(&**self, to);
-    render = Content::<TuiOut>::render(&**self, to));
+    layout = Render::<TuiOut>::layout(&**self, to);
+    render = Render::<TuiOut>::render(&**self, to));
 
 fn width_chars_max (max: u16, text: impl AsRef<str>) -> u16 {
     let mut width: u16 = 0;
@@ -61,12 +61,12 @@ impl<'a, T: AsRef<str>> TrimString<T> {
         TrimStringRef(self.0, &self.1)
     }
 }
-impl<'a, T: AsRef<str>> Content<TuiOut> for TrimString<T> {
+impl<'a, T: AsRef<str>> Render<TuiOut> for TrimString<T> {
     fn layout (&self, to: [u16; 4]) -> [u16;4] {
-        Content::layout(&self.as_ref(), to)
+        Render::layout(&self.as_ref(), to)
     }
     fn render (&self, to: &mut TuiOut) {
-        Content::render(&self.as_ref(), to)
+        Render::render(&self.as_ref(), to)
     }
 }
 
@@ -75,7 +75,7 @@ impl<'a, T: AsRef<str>> Content<TuiOut> for TrimString<T> {
 /// Width is computed using [unicode_width].
 pub struct TrimStringRef<'a, T: AsRef<str>>(pub u16, pub &'a T);
 
-impl<T: AsRef<str>> Content<TuiOut> for TrimStringRef<'_, T> {
+impl<T: AsRef<str>> Render<TuiOut> for TrimStringRef<'_, T> {
     fn layout (&self, to: [u16; 4]) -> [u16;4] {
         [to.x(), to.y(), to.w().min(self.0).min(self.1.as_ref().width() as u16), to.h()]
     }

tui/src/tui_content/tui_style.rs

@@ -1,60 +1,70 @@
 use crate::*;
 
 pub trait TuiStyle {
-    fn fg <R: Content<TuiOut>> (color: Color, w: R) -> Foreground<R> {
+    fn fg <R: Render<TuiOut>> (color: Color, w: R) -> Foreground<R> {
         Foreground(color, w)
     }
-    fn bg <R: Content<TuiOut>> (color: Color, w: R) -> Background<R> {
+    fn bg <R: Render<TuiOut>> (color: Color, w: R) -> Background<R> {
         Background(color, w)
     }
-    fn fg_bg <R: Content<TuiOut>> (fg: Color, bg: Color, w: R) -> Background<Foreground<R>> {
+    fn fg_bg <R: Render<TuiOut>> (fg: Color, bg: Color, w: R) -> Background<Foreground<R>> {
         Background(bg, Foreground(fg, w))
     }
-    fn modify <R: Content<TuiOut>> (enable: bool, modifier: Modifier, w: R) -> Modify<R> {
+    fn modify <R: Render<TuiOut>> (enable: bool, modifier: Modifier, w: R) -> Modify<R> {
         Modify(enable, modifier, w)
     }
-    fn bold <R: Content<TuiOut>> (enable: bool, w: R) -> Modify<R> {
+    fn bold <R: Render<TuiOut>> (enable: bool, w: R) -> Modify<R> {
         Self::modify(enable, Modifier::BOLD, w)
     }
-    fn border <R: Content<TuiOut>, S: BorderStyle> (enable: bool, style: S, w: R) -> Bordered<S, R> {
+    fn border <R: Render<TuiOut>, S: BorderStyle> (enable: bool, style: S, w: R) -> Bordered<S, R> {
         Bordered(enable, style, w)
     }
 }
 
 impl TuiStyle for Tui {}
 
-pub struct Foreground<R: Content<TuiOut>>(pub Color, pub R);
-impl<R: Content<TuiOut>> Content<TuiOut> for Foreground<R> {
-    fn content (&self) -> impl Render<TuiOut> { &self.1 }
+pub struct Foreground<R>(pub Color, pub R);
+impl<R: Render<TuiOut>> Render<TuiOut> for Foreground<R> {
+    fn layout (&self, to: [u16;4]) -> [u16;4] {
+        self.1.layout(to)
+    }
     fn render (&self, to: &mut TuiOut) {
-        to.fill_fg(to.area(), self.0);
-        self.1.render(to)
+        let area = self.layout(to.area());
+        to.fill_fg(area, self.0);
+        to.place(area, &self.1);
     }
 }
 
-pub struct Background<R: Content<TuiOut>>(pub Color, pub R);
-impl<R: Content<TuiOut>> Content<TuiOut> for Background<R> {
-    fn content (&self) -> impl Render<TuiOut> { &self.1 }
+pub struct Background<R>(pub Color, pub R);
+impl<R: Render<TuiOut>> Render<TuiOut> for Background<R> {
+    fn layout (&self, to: [u16;4]) -> [u16;4] {
+        self.1.layout(to)
+    }
     fn render (&self, to: &mut TuiOut) {
-        to.fill_bg(to.area(), self.0);
-        self.1.render(to)
+        let area = self.layout(to.area());
+        to.fill_bg(area, self.0);
+        to.place(area, &self.1);
     }
 }
 
-pub struct Modify<R: Content<TuiOut>>(pub bool, pub Modifier, pub R);
-impl<R: Content<TuiOut>> Content<TuiOut> for Modify<R> {
-    fn content (&self) -> impl Render<TuiOut> { &self.2 }
+pub struct Modify<R: Render<TuiOut>>(pub bool, pub Modifier, pub R);
+impl<R: Render<TuiOut>> Render<TuiOut> for Modify<R> {
+    fn layout (&self, to: [u16;4]) -> [u16;4] {
+        self.2.layout(to)
+    }
     fn render (&self, to: &mut TuiOut) {
         to.fill_mod(to.area(), self.0, self.1);
         self.2.render(to)
     }
 }
 
-pub struct Styled<R: Content<TuiOut>>(pub Option<Style>, pub R);
-impl<R: Content<TuiOut>> Content<TuiOut> for Styled<R> {
-    fn content (&self) -> impl Render<TuiOut> { &self.1 }
+pub struct Styled<R: Render<TuiOut>>(pub Option<Style>, pub R);
+impl<R: Render<TuiOut>> Render<TuiOut> for Styled<R> {
+    fn layout (&self, to: [u16;4]) -> [u16;4] {
+        self.1.layout(to)
+    }
     fn render (&self, to: &mut TuiOut) {
-        to.place(self.content().layout(to.area()), &self.content());
+        to.place(self.1.layout(to.area()), &self.1);
         // TODO write style over area
     }
 }

tui/src/tui_content/tui_tryptich.rs

@@ -31,10 +31,10 @@ impl<A, B, C> Tryptich<A, B, C> {
 }
 
 impl<A, B, C> Content<TuiOut> for Tryptich<A, B, C>
-where A: Content<TuiOut>, B: Content<TuiOut>, C: Content<TuiOut> {
-    fn content (&self) -> impl Render<TuiOut> {
+where A: Render<TuiOut>, B: Render<TuiOut>, C: Render<TuiOut> {
+    fn content (&self) -> Option<impl Render<TuiOut> + '_> {
         let Self { top, h, left: (w_a, ref a), middle: (w_b, ref b), right: (w_c, ref c) } = *self;
-        Fixed::y(h, if top {
+        Some(Fixed::y(h, if top {
             Bsp::a(
                 Fill::x(Align::n(Fixed::x(w_b, Align::x(Tui::bg(Color::Reset, b))))),
                 Bsp::a(
@@ -50,7 +50,7 @@ where A: Content<TuiOut>, B: Content<TuiOut>, C: Content<TuiOut> {
                     Fill::xy(Align::e(Fixed::x(w_c, Tui::bg(Color::Reset, c)))),
                 ),
             )
-        })
+        }))
     }
 }
 

tui/src/tui_engine/tui_event.rs

@@ -10,6 +10,7 @@ impl TuiEvent {
     pub fn from_crossterm (event: Event) -> Self {
         Self(event)
     }
+    #[cfg(feature = "dsl")]
     pub fn from_dsl (dsl: impl Dsl) -> Perhaps<Self> {
         Ok(TuiKey::from_dsl(dsl)?.to_crossterm().map(Self))
     }
@@ -17,6 +18,7 @@ impl TuiEvent {
 pub struct TuiKey(Option<KeyCode>, KeyModifiers);
 impl TuiKey {
     const SPLIT: char = '/';
+    #[cfg(feature = "dsl")]
     pub fn from_dsl (dsl: impl Dsl) -> Usually<Self> {
         if let Some(word) = dsl.word()? {
             let word = word.trim();