Add explicit orthogonal span sizing

tests/layout.rs

@@ -20,6 +20,33 @@ fn a_span_gives_each_child_the_width_it_asked_for() {
     assert_corners!(h, right, (100, 0), (400, 200));
 }
 
+#[test]
+fn a_full_ortho_span_reports_relative_full() {
+    let mut h = Harness::new((400, 200));
+    let child = rect(Color::RED).height(40).add(&mut h.rsc);
+    let span = (child,)
+        .span(Dir::RIGHT)
+        .ortho(OrthoSize::Full)
+        .add(&mut h.rsc);
+    h.set_root(span);
+
+    assert_eq!(h.render.active[&span.id()].size.y, Len::rel(1.0));
+}
+
+#[test]
+fn a_children_ortho_span_reports_its_tallest_fixed_child() {
+    let mut h = Harness::new((400, 200));
+    let short = rect(Color::RED).height(40).add(&mut h.rsc);
+    let tall = rect(Color::BLUE).height(70).add(&mut h.rsc);
+    let span = (short, tall)
+        .span(Dir::RIGHT)
+        .ortho(OrthoSize::Children)
+        .add(&mut h.rsc);
+    h.set_root(span);
+
+    assert_eq!(h.render.active[&span.id()].size.y, Len::px(70.0));
+}
+
 #[test]
 fn resizing_relays_out_against_the_new_output() {
     let mut h = Harness::new((400, 200));
@@ -158,7 +185,12 @@ fn a_box_with_a_fixed_length_can_be_stretched_on_its_other_axis() {
     let inner = rect(Color::BLUE).add(&mut h.rsc);
     let row = inner.pad(10).height(40).add(&mut h.rsc);
     let filler = rect(Color::GREEN).add(&mut h.rsc);
-    let column = (row, filler).span(Dir::DOWN).add(&mut h.rsc);
+    // This column is an item in a row, so it takes the width left for it
+    // rather than asking for a full row-width in addition to the bar.
+    let column = (row, filler)
+        .span(Dir::DOWN)
+        .ortho(OrthoSize::Children)
+        .add(&mut h.rsc);
     let bar = rect(Color::RED).width(100).add(&mut h.rsc);
     h.set_root((bar, column).span(Dir::RIGHT));
     assert_corners!(h, inner, (110, 10), (390, 30));