wip: enable stack

src/draw.rs

@@ -94,6 +94,11 @@ pub trait Draw<S: Screen> {
     }
 }
 
+/// The opposite of [thunk]?
+pub fn draw <S: Screen, T: Draw<S>> (item: T) -> impl FnOnce(&mut S) -> Perhaps<XYWH<S::Unit>> {
+    move|to: &mut S|item.draw(to)
+}
+
 pub type Drawn<U> = Perhaps<XYWH<U>>;
 
 impl<S: Screen> Draw<S> for () {

src/draw/layout.rs

@@ -1,5 +1,7 @@
 use crate::*;
 
+impl<S: Screen, T: Draw<S>> Layout<S> for T {}
+
 pub trait Layout<S: Screen>: Draw<S> + Sized {
     fn full_w (self) -> impl Draw<S> {
         Full::W(self)
@@ -11,12 +13,15 @@ pub trait Layout<S: Screen>: Draw<S> + Sized {
         Full::WH(self)
     }
 
+    /// (bsp/e (exact/w 10 "Hello") "World")
     fn exact_w <N: Into<Option<S::Unit>>> (self, x: N) -> impl Draw<S> {
         Exact::W(self, x.into())
     }
+    /// (bsp/s (exact/h 10 "Hello") "World")
     fn exact_h <N: Into<Option<S::Unit>>> (self, y: N) -> impl Draw<S> {
         Exact::H(self, y.into())
     }
+    /// (exact/wh 10 2 "Hello World")
     fn exact_wh <N: Into<Option<S::Unit>>> (self, x: N, y: N) -> impl Draw<S> {
         Exact::WH(self, x.into(), y.into())
     }
@@ -150,8 +155,6 @@ pub trait Layout<S: Screen>: Draw<S> + Sized {
     }
 }
 
-impl<S: Screen, T: Draw<S>> Layout<S> for T {}
-
 /// Use whole drawing area along one or both axes.
 ///
 /// ```
@@ -279,8 +282,24 @@ pub enum Max<T: Screen, I: Draw<T>, X: Into<Option<T::Unit>>> {
     WH(I, X, X),
 }
 
-impl_draw!(<T: Screen, I: Draw<T>, X: Into<Option<T::Unit>>,>|self: Max<T, I, X>, _to: T|{
-    todo!()
+impl_draw!(<T: Screen, I: Draw<T>, X: Into<Option<T::Unit>>,>|self: Max<T, I, X>, to: T|{
+    let area: XYWH<T::Unit> = to.area();
+    let (item, area) = match self {
+        Self::W(item, max_w) => (item, XYWH(
+            area.0, area.1, max_w.into().map(|max|max.min(area.2)).unwrap_or(area.2),
+                            area.3
+        )),
+        Self::H(item, max_h) => (item, XYWH(
+            area.0, area.1, area.2,
+                            max_h.into().map(|max|max.min(area.3)).unwrap_or(area.3)
+        )),
+        Self::WH(item, max_w, max_h) => (item, XYWH(
+            area.0, area.1, max_w.into().map(|max|max.min(area.2)).unwrap_or(area.2),
+                            max_h.into().map(|max|max.min(area.3)).unwrap_or(area.3)
+        )),
+        _ => return Ok(None)
+    };
+    to.clip(area, draw(item))
 });
 
 /// Set size of of drawing area.

src/draw/split.rs

@@ -141,7 +141,6 @@ fn draw_stacks <S: Screen> (
     })
 }
 
-
 fn stack_areas <S: Screen> (
     split: &Split,
     area:  XYWH<S::Unit>,

src/eval.rs

@@ -128,21 +128,25 @@ pub fn eval_view <'a, O: Screen + 'a, S> (
     let arg2  = tail1.head();
     // First `frags.next()` calls returns the namespace.
     match frags.next() {
+
         Some("when") => when(
             state.namespace(arg0?)?.unwrap(),
             thunk(move|output: &mut O|{state.interpret(output, &arg1)})
         ).draw(output),
+
         Some("either") => either(
             state.namespace(arg0?)?.unwrap(),
             thunk(move|output: &mut O|{state.interpret(output, &arg1)}),
             thunk(move|output: &mut O|{state.interpret(output, &arg2)}),
         ).draw(output),
+
         Some("bsp") => eval_enum!("bsp", output, state, frags.next(), arg0, Split {
             "n" => North, "s" => South, "e" => East, "w" => West, "a" => Above, "b" => Below
-        }).half(
+        }).stack(
             thunk(move|output: &mut O|{state.interpret(output, &arg0)}),
             thunk(move|output: &mut O|{state.interpret(output, &arg1)}),
         ).draw(output),
+
         Some("align") => thunk(move|output: &mut O|{
             state.interpret(output, &arg0)
         }).align(eval_enum!("align", output, state, frags.next(), arg0, Azimuth {
@@ -150,24 +154,31 @@ pub fn eval_view <'a, O: Screen + 'a, S> (
             "n" => N, "s" => S, "e" => E, "w" => W, 
             "nw" => NW, "sw" => SW, "ne" => NE, "se" => SE, 
         })).draw(output),
+
         Some("exact") => eval_xy!(
             "exact" => expr, head, output, state, frags.next(), exact_wh, exact_w, exact_h, arg0, arg1, arg2,
         ),
+
         Some("fixed") => eval_xy!(
             "fixed" => expr, head, output, state, frags.next(), exact_wh, exact_w, exact_h, arg0, arg1, arg2,
         ),
+
         Some("min") => eval_xy!(
             "min"   => expr, head, output, state, frags.next(), min_wh, min_w, min_h, arg0, arg1, arg2,
         ),
+
         Some("max") => eval_xy!(
             "max"   => expr, head, output, state, frags.next(), max_wh, max_w, max_h, arg0, arg1, arg2,
         ),
+
         Some("push") => eval_xy!(
             "push"  => expr, head, output, state, frags.next(), push_xy, push_x, push_y, arg0, arg1, arg2,
         ),
+
         Some("fill") => eval_xy!(
             "fill"  => expr, head, output, state, frags.next(), full_wh, full_w, full_h, arg0,
         ),
+
         _ => return Ok(None)
 
     }