From 482b6241690f7b116b07d06fb4950754f6fdf584 Mon Sep 17 00:00:00 2001
From: facile pop culture reference <donotem@ilme.no>
Date: Wed, 15 Jul 2026 12:57:53 +0300
Subject: [PATCH] add Screen::area and ::clip to implement Align

---
 dizzle             |  2 +-
 src/draw.rs        | 10 +++++++++-
 src/draw/coord.rs  |  5 +++++
 src/draw/layout.rs | 40 +++++++++++++++++++++++++++++++---------
 src/draw/split.rs  | 17 ++++++++---------
 src/eval.rs        | 24 +++++++++++-------------
 src/term/output.rs | 24 ++++++++++++++++++++----
 7 files changed, 85 insertions(+), 37 deletions(-)

diff --git a/dizzle b/dizzle
index af2a107..0050385 160000
--- a/dizzle
+++ b/dizzle
@@ -1 +1 @@
-Subproject commit af2a10751f87caef8e5526d1f692c941b8de8357
+Subproject commit 0050385e63ea5d3ab9be7c495dae5fc635396cf0
diff --git a/src/draw.rs b/src/draw.rs
index 64738bd..a672576 100644
--- a/src/draw.rs
+++ b/src/draw.rs
@@ -24,7 +24,15 @@ use crate::*;
 pub trait Screen: Xy<Self::Unit> + Wh<Self::Unit> + Send + Sync + Sized {
     type Unit: Coord;
     /// Render drawable in subarea specified by `area`
-    fn show <T: Draw<Self>> (&mut self, content: T) -> Perhaps<XYWH<Self::Unit>>;
+    fn show (&mut self, content: impl Draw<Self>) -> Perhaps<XYWH<Self::Unit>>;
+    /// Get current clipping area
+    fn area (&self) -> XYWH<Self::Unit>;
+    /// Set clipping area
+    fn clip <T> (
+        &mut self,
+        area: impl Into<Option<XYWH<Self::Unit>>>,
+        draw: impl FnOnce(&mut Self)->T
+    ) -> T;
 }
 
 /// Implement the [Draw] trait for a particular drawable and [Screen].
diff --git a/src/draw/coord.rs b/src/draw/coord.rs
index 40d784d..053258e 100644
--- a/src/draw/coord.rs
+++ b/src/draw/coord.rs
@@ -33,3 +33,8 @@ pub trait Coord: Send + Sync + Copy
     /// Convert to [AtomicUsize].
     fn atomic (self) -> AtomicUsize { AtomicUsize::new(self.into()) }
 }
+
+/// TUI works in u16 coordinates.
+impl Coord for u16 {
+    fn plus (self, other: Self) -> Self { self.saturating_add(other) }
+}
diff --git a/src/draw/layout.rs b/src/draw/layout.rs
index 71dca39..e70a449 100644
--- a/src/draw/layout.rs
+++ b/src/draw/layout.rs
@@ -71,16 +71,16 @@ pub trait Layout<S: Screen>: Draw<S> + Sized {
         Push::XY(self, x.into(), y.into())
     }
 
-    fn align (self, azimuth: impl Into<Option<Azimuth>>) -> impl Draw<S> {
+    fn align (self, azimuth: impl Into<Option<Azimuth>>) -> Align<Self> {
         Align(azimuth.into(), self)
     }
-    fn align_c (self) -> impl Draw<S> {
+    fn align_c (self) -> Align<Self> {
         Align(Some(Azimuth::C), self)
     }
-    fn align_x (self) -> impl Draw<S> {
+    fn align_x (self) -> Align<Self> {
         Align(Some(Azimuth::X), self)
     }
-    fn align_y (self) -> impl Draw<S> {
+    fn align_y (self) -> Align<Self> {
         Align(Some(Azimuth::Y), self)
     }
 
@@ -287,8 +287,27 @@ impl_draw!(<T: Screen, I: Draw<T>, X: Into<Option<T::Unit>>,>|self: Pad<T, I, X>
 
 pub struct Align<T>(Option<Azimuth>, T);
 
-impl_draw!(<S: Screen, T: Draw<S>,>|self: Align<T>, _to: S|{
-    todo!()
+impl_draw!(<S: Screen, T: Draw<S>,>|self: Align<T>, to: S|{
+    use Azimuth::*;
+    let XYWH(x0, y0, w0, h0) = to.area();
+    Ok(if let Some(XYWH(x, y, w, h)) = self.1.layout(to.area())? {
+        to.clip(match self.0 {
+            Some(NW) => XYWH(x0, y0, w, h),
+            Some(N)  => todo!(),
+            Some(NE) => todo!(),
+            Some(W)  => todo!(),
+            Some(C)  => todo!(),
+            Some(E)  => todo!(),
+            Some(SW) => todo!(),
+            Some(S)  => XYWH(x0 + w0.sub(w) / 2.into(), (y0 + h0).sub(h), w, h),
+            Some(SE) => todo!(),
+            Some(X)  => todo!(),
+            Some(Y)  => todo!(),
+            None => to.area()
+        }, |to|self.1.draw(to))?
+    } else {
+        None
+    })
 });
 
 /// Where is [0, 0] located?
@@ -315,10 +334,13 @@ pub fn area <S: Screen, T: Draw<S>, U: Into<Option<XYWH<S::Unit>>>> (
     Area(origin.into(), it)
 }
 
-pub struct Area<S: Screen, T: Draw<S>>(Option<XYWH<S::Unit>>, T);
+pub struct Area<S: Screen, T: Draw<S>>(
+    pub Option<XYWH<S::Unit>>,
+    pub T
+);
 
-impl_draw!(<S: Screen, T: Draw<S>,>|self: Area<S, T>, _to: S|{
-    todo!()
+impl_draw!(<S: Screen, T: Draw<S>,>|self: Area<S, T>, to: S|{
+    to.clip(self.0, |to|self.1.draw(to))
 });
 
 pub struct Origin<T>(Option<Azimuth>, T);
diff --git a/src/draw/split.rs b/src/draw/split.rs
index 37ef914..1cee49c 100644
--- a/src/draw/split.rs
+++ b/src/draw/split.rs
@@ -1,27 +1,26 @@
 use super::*;
-use Azimuth::*;
 
-pub const fn east <T: Screen> (a: impl Draw<T>, b: impl Draw<T>) -> impl Draw<T> {
+pub const fn east <S: Screen, A: Draw<S>, B: Draw<S>> (a: A, b: B) -> impl Draw<S> {
     Split::East.half(a, b)
 }
 
-pub const fn north <T: Screen> (a: impl Draw<T>, b: impl Draw<T>) -> impl Draw<T> {
+pub const fn north <S: Screen, A: Draw<S>, B: Draw<S>> (a: A, b: B) -> impl Draw<S> {
     Split::North.half(a, b)
 }
 
-pub const fn west <T: Screen> (a: impl Draw<T>, b: impl Draw<T>) -> impl Draw<T> {
+pub const fn west <S: Screen, A: Draw<S>, B: Draw<S>> (a: A, b: B) -> impl Draw<S> {
     Split::West.half(a, b)
 }
 
-pub const fn south <T: Screen> (a: impl Draw<T>, b: impl Draw<T>) -> impl Draw<T> {
+pub const fn south <S: Screen, A: Draw<S>, B: Draw<S>> (a: A, b: B) -> impl Draw<S> {
     Split::South.half(a, b)
 }
 
-pub const fn above <T: Screen> (a: impl Draw<T>, b: impl Draw<T>) -> impl Draw<T> {
+pub const fn above <S: Screen, A: Draw<S>, B: Draw<S>> (a: A, b: B) -> impl Draw<S> {
     Split::Above.half(a, b)
 }
 
-pub const fn below <T: Screen> (a: impl Draw<T>, b: impl Draw<T>) -> impl Draw<T> {
+pub const fn below <S: Screen, A: Draw<S>, B: Draw<S>> (a: A, b: B) -> impl Draw<S> {
     Split::Below.half(a, b)
 }
 
@@ -47,8 +46,8 @@ impl Split {
     /// let _ = Split::East.half("", "");
     /// let _ = Split::West.half("", "");
     /// ```
-    pub const fn half <T: Screen> (&self, a: impl Draw<T>, b: impl Draw<T>) -> impl Draw<T> {
-        thunk(move|to: &mut T|{
+    pub const fn half <S: Screen, A: Draw<S>, B: Draw<S>> (&self, a: A, b: B) -> impl Draw<S> {
+        thunk(move|to: &mut S|{
             let (area_a, area_b) = to.xywh().split_half(self);
             let (origin_a, origin_b) = self.origins();
             let a = a.align(origin_a);
diff --git a/src/eval.rs b/src/eval.rs
index 423cb64..d103a0a 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -119,19 +119,17 @@ pub fn eval_view <'a, O: Screen + 'a, S> (
         ).draw(output),
 
         // Second `frags.next()` calls returns the namespace member.
-        Some("bsp") => {
-            eval_enum!("bsp", output, state, frags.next(), arg0, Split {
-                "n" => North,
-                "s" => South,
-                "e" => East,
-                "w" => West,
-                "a" => Above,
-                "b" => Below
-            }).half(
-                thunk(move|output: &mut O|{state.interpret(output, &arg0)}),
-                thunk(move|output: &mut O|{state.interpret(output, &arg1)}),
-            ).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(
+            thunk(move|output: &mut O|{state.interpret(output, &arg0)}),
+            thunk(move|output: &mut O|{state.interpret(output, &arg1)}),
+        ).draw(output),
 
         Some("align") => {
             let content = thunk(move|output: &mut O|{state.interpret(output, &arg0)});
diff --git a/src/term/output.rs b/src/term/output.rs
index b91f919..237860b 100644
--- a/src/term/output.rs
+++ b/src/term/output.rs
@@ -1,13 +1,10 @@
 use crate::*;
 use ratatui::{prelude::{Style, Position, Backend, Color}};
 
-/// TUI works in u16 coordinates.
-impl Coord for u16 { fn plus (self, other: Self) -> Self { self.saturating_add(other) } }
-
 impl Screen for Tui {
     type Unit = u16;
     /// Render drawable in subarea specified by `area`
-    fn show <'t, T: Draw<Self>> (&mut self, content: T) -> Perhaps<XYWH<u16>> {
+    fn show (&mut self, content: impl Draw<Self>) -> Perhaps<XYWH<u16>> {
         let previous_area = self.1;
         Ok(if let Some(area) = content.layout(self.1)? {
             self.1 = area;
@@ -21,6 +18,25 @@ impl Screen for Tui {
             None
         })
     }
+
+    /// Get current clipping area
+    fn area (&self) -> XYWH<Self::Unit> {
+        self.1
+    }
+
+    fn clip <T> (
+        &mut self,
+        area: impl Into<Option<XYWH<u16>>>,
+        draw: impl FnOnce(&mut Self)->T
+    ) -> T {
+        let prev = self.1;
+        if let Some(area) = area.into() {
+            self.1 = area.into();
+        }
+        let result = draw(self);
+        self.1 = prev;
+        result
+    }
 }
 
 /// Enable TUI output for state struct.