Merge remote-tracking branch 'upstream/main' into split/17-headless-rig

tests/layout.rs

@@ -32,3 +32,80 @@ fn resizing_relays_out_against_the_new_output() {
     assert_corners!(h, left, (0, 0), (100, 100));
     assert_corners!(h, right, (100, 0), (800, 100));
 }
+
+#[test]
+fn an_empty_widget_takes_a_share_of_a_span() {
+    let mut h = Harness::new((400, 200));
+    let gap = ().add(&mut h.rsc);
+    let right = rect(Color::BLUE).width(100).add(&mut h.rsc);
+    h.set_root((gap, right).span(Dir::RIGHT));
+
+    assert_corners!(h, gap, (0, 0), (300, 200));
+    assert_corners!(h, right, (300, 0), (400, 200));
+}
+
+#[test]
+fn a_child_drawn_twice_moves_once() {
+    let mut h = Harness::new((400, 200));
+    // `Aligned` draws its child twice; listing it twice would move it twice.
+    let inner = rect(Color::BLUE).add(&mut h.rsc);
+    let centered = inner.center().width(200).add(&mut h.rsc);
+    let left = rect(Color::RED).width(100).add(&mut h.rsc);
+    h.set_root((left, centered).span(Dir::RIGHT));
+    assert_corners!(h, inner, (100, 0), (300, 200));
+
+    h.rsc[left].x = Some(Len::abs(150));
+    h.frame();
+
+    assert_corners!(h, inner, (150, 0), (350, 200));
+}
+
+#[test]
+fn a_resize_lands_where_a_cold_start_would() {
+    let build = |h: &mut Harness| {
+        let para = wtext(
+            "Wrapping shapes one source into as many lines as its container leaves room \
+             for, so the height of a paragraph is an answer rather than a setting.",
+        )
+        .size(20)
+        .wrap(true)
+        .pad(16)
+        .add(&mut h.rsc);
+        let below = rect(Color::RED).add(&mut h.rsc);
+        let root = (para, below).span(Dir::DOWN).pad(12);
+        h.set_root(root);
+        (para, below)
+    };
+
+    let mut cold = Harness::new((900, 1200));
+    let (cold_para, cold_below) = build(&mut cold);
+
+    let mut resized = Harness::new((1920, 1200));
+    let (para, below) = build(&mut resized);
+    resized.resize((900, 1200));
+    resized.frame();
+
+    assert_eq!(resized.region(&para), cold.region(&cold_para), "paragraph");
+    assert_eq!(resized.region(&below), cold.region(&cold_below), "below");
+}
+
+#[test]
+fn a_fixed_box_is_drawn_again_rather_than_stretched() {
+    let mut h = Harness::new((400, 400));
+    // The panel fills a stack sized by its sibling, so it is drawn in the
+    // whole box and then placed in the shorter one. Reusing it in that fixed
+    // box afterwards would leave it whatever height it happened to have.
+    let panel = rect(Color::BLUE).add(&mut h.rsc);
+    let leaf = rect(Color::RED).height(100).add(&mut h.rsc);
+    let stack = (panel, leaf)
+        .stack()
+        .size(StackSize::Child(1))
+        .add(&mut h.rsc);
+    h.set_root(stack.align(Align::TOP));
+    assert_corners!(h, panel, (0, 0), (400, 100));
+
+    h.rsc[leaf].y = Some(Len::abs(250));
+    h.frame();
+
+    assert_corners!(h, panel, (0, 0), (400, 250));
+}

tests/remap.rs

@@ -0,0 +1,27 @@
+//! What a drawing can be taken out of, and what it cannot.
+
+use iris::core::{Remap, UiRegion, UiScalar, UiSpan};
+
+/// A box `size` tall whose top is `rel` of the way down the window.
+fn fixed(rel: f32, size: f32) -> UiRegion {
+    UiRegion::new(
+        UiSpan::FULL,
+        UiSpan::new(UiScalar { rel, abs: 0.0 }, UiScalar { rel, abs: size }),
+    )
+}
+
+#[test]
+fn a_fixed_box_can_be_carried_but_not_stretched() {
+    let from = fixed(0.0, 164.0);
+    assert!(Remap::new(from, UiRegion::FULL).is_none());
+    assert!(Remap::new(from, fixed(0.5, 164.0)).is_some());
+    assert!(Remap::new(from, fixed(0.0, 98.0)).is_none());
+}
+
+#[test]
+fn a_relative_box_can_be_stretched_to_any_other() {
+    let remap = Remap::new(UiRegion::FULL, fixed(0.0, 98.0)).expect("relative boxes remap");
+    // A part that filled the window keeps filling what replaced it, which is
+    // exactly what `outside` could not say for a box of a fixed length.
+    assert_eq!(remap.apply(UiRegion::FULL), fixed(0.0, 98.0));
+}

tests/retained.rs

@@ -0,0 +1,252 @@
+//! What a second frame draws again, and what it keeps.
+
+use std::{cell::Cell, rc::Rc};
+
+use iris::harness::{Harness, assert_corners};
+use iris::prelude::*;
+
+/// A leaf that counts its draws and reports whatever size it is given, so a
+/// test can see what the retained path skipped.
+struct Counted {
+    draws: Rc<Cell<usize>>,
+    size: Size,
+    dependence: OnResize,
+}
+
+impl Widget for Counted {
+    fn draw(&mut self, _: &mut Painter) -> Size {
+        self.draws.set(self.draws.get() + 1);
+        self.size
+    }
+
+    fn on_resize(&self, _: Axis) -> OnResize {
+        self.dependence
+    }
+}
+
+struct Counts(Rc<Cell<usize>>);
+
+impl Counts {
+    fn get(&self) -> usize {
+        self.0.get()
+    }
+}
+
+fn counted(h: &mut Harness, size: Size, dependence: OnResize) -> (WeakWidget<Counted>, Counts) {
+    let draws = Rc::new(Cell::new(0));
+    let id = Counted {
+        draws: draws.clone(),
+        size,
+        dependence,
+    }
+    .add(&mut h.rsc);
+    (id, Counts(draws))
+}
+
+/// A fixed-width leaf beside one that takes the rest, so changing the first
+/// hands the second a different box without the output changing.
+fn pair(h: &mut Harness, rest: OnResize) -> (WeakWidget<Counted>, Counts, WidgetId) {
+    let (first, _) = counted(h, Size::from((100, 200)), OnResize::Translate);
+    let (second, draws) = counted(h, Size::REST, rest);
+    h.set_root((first, second).span(Dir::RIGHT));
+    (first, draws, second.id())
+}
+
+#[test]
+fn a_leaf_that_ignores_its_box_is_not_drawn_again_when_the_box_changes() {
+    let mut h = Harness::new((400, 200));
+    let (first, draws, second) = pair(&mut h, OnResize::Scale);
+    let settled = draws.get();
+    assert_corners!(h, second, (100, 0), (400, 200));
+
+    h.rsc[first].size = Size::from((150, 200));
+    h.frame();
+
+    assert_eq!(
+        draws.get(),
+        settled,
+        "its box is a field to write, not a reason to draw"
+    );
+    assert_corners!(h, second, (150, 0), (400, 200));
+}
+
+#[test]
+fn a_leaf_that_depends_on_its_box_is_drawn_again_when_the_box_changes() {
+    let mut h = Harness::new((400, 200));
+    let (first, draws, second) = pair(&mut h, OnResize::Redraw);
+    let settled = draws.get();
+
+    h.rsc[first].size = Size::from((150, 200));
+    h.frame();
+
+    // Twice: once for the span to measure it, once for its real box. A child
+    // that can hint its length is spared the first, and a smaller number here
+    // means someone has made that cheaper rather than broken it.
+    assert_eq!(draws.get(), settled + 2);
+    assert_corners!(h, second, (150, 0), (400, 200));
+}
+
+#[test]
+fn a_span_child_that_declares_its_length_is_drawn_once() {
+    let mut h = Harness::new((400, 200));
+    let (told, told_draws) = counted(&mut h, Size::from((100, 200)), OnResize::Translate);
+    let (asked, asked_draws) = counted(&mut h, Size::from((100, 200)), OnResize::Translate);
+    // The span takes one child's length from its hint and has to draw the
+    // other to find out, so only the second is drawn before it is placed.
+    let hinted = told.width(100).add(&mut h.rsc);
+    h.set_root((hinted, asked).span(Dir::RIGHT));
+
+    assert_eq!(told_draws.get(), 1);
+    assert_eq!(
+        asked_draws.get(),
+        2,
+        "drawn to be measured, then again to be placed"
+    );
+}
+
+#[test]
+fn a_span_relays_out_when_a_child_it_measured_changes() {
+    let mut h = Harness::new((400, 200));
+    let (first, _, second) = pair(&mut h, OnResize::Translate);
+
+    h.rsc[first].size = Size::from((250, 200));
+    h.frame();
+
+    assert_corners!(h, first, (0, 0), (250, 200));
+    assert_corners!(h, second, (250, 0), (400, 200));
+}
+
+#[test]
+fn a_placed_child_survives_the_next_frame() {
+    let mut h = Harness::new((400, 200));
+    // Both children declare a length, so the span places them from their hints
+    // rather than drawing them to find out.
+    let top = rect(Color::RED).height(80).add(&mut h.rsc);
+    let bottom = rect(Color::BLUE).height(120).add(&mut h.rsc);
+    h.set_root((top, bottom).span(Dir::DOWN));
+
+    h.rsc.widgets_mut().get_dyn_mut(top.id());
+    h.frame();
+
+    assert_corners!(h, top, (0, 0), (400, 80));
+    assert_corners!(h, bottom, (0, 80), (400, 200));
+}
+
+/// Lays its child out from the hint alone, never reading what it drew.
+struct FromHint {
+    inner: StrongWidget,
+}
+
+impl Widget for FromHint {
+    fn draw(&mut self, painter: &mut Painter) -> Size {
+        let len = painter.size_hint(&self.inner, Axis::Y).unwrap();
+        let mut region = UiRegion::FULL;
+        region.y.end = region.y.start.offset(len.abs);
+        painter.widget_within(&self.inner, region);
+        Size::REST
+    }
+}
+
+#[test]
+fn a_parent_that_only_read_a_hint_relays_out_when_the_hint_changes() {
+    let mut h = Harness::new((400, 200));
+    let inner = rect(Color::RED).height(80).add(&mut h.rsc);
+    let parent = FromHint {
+        inner: inner.add_strong(&mut h.rsc),
+    }
+    .add(&mut h.rsc);
+    h.set_root(parent);
+    assert_corners!(h, inner, (0, 0), (400, 80));
+
+    h.rsc[inner].y = Some(Len::abs(120));
+    h.frame();
+
+    assert_corners!(h, inner, (0, 0), (400, 120));
+}
+
+/// Reads the output's size, which nothing but its own draw can put right.
+struct ReadsOutput {
+    draws: Rc<Cell<usize>>,
+}
+
+impl Widget for ReadsOutput {
+    fn draw(&mut self, painter: &mut Painter) -> Size {
+        self.draws.set(self.draws.get() + 1);
+        Size::abs(painter.output_size() / 4.0)
+    }
+}
+
+#[test]
+fn a_resize_does_not_redraw_what_the_shader_can_move() {
+    let mut h = Harness::new((400, 200));
+    let (leaf, draws) = counted(&mut h, Size::REST, OnResize::Redraw);
+    h.set_root(leaf);
+    let settled = draws.get();
+
+    h.resize((800, 100));
+    assert!(h.needs_redraw());
+    h.frame();
+
+    assert_eq!(
+        draws.get(),
+        settled,
+        "its box is the same fraction of a different output"
+    );
+    assert_corners!(h, leaf, (0, 0), (800, 100));
+}
+
+#[test]
+fn a_resize_redraws_what_read_the_output() {
+    let mut h = Harness::new((400, 200));
+    let draws = Rc::new(Cell::new(0));
+    let leaf = ReadsOutput {
+        draws: draws.clone(),
+    }
+    .add(&mut h.rsc);
+    h.set_root(leaf);
+    let settled = draws.get();
+
+    h.resize((800, 100));
+    h.frame();
+
+    assert_eq!(draws.get(), settled + 1);
+}
+
+#[test]
+fn narrowing_the_output_reflows_text_and_relays_out_around_it() {
+    let mut h = Harness::new((600, 400));
+    let para = wtext(
+        "Wrapping shapes one source into as many lines as its container leaves \
+        room for, so the height of a paragraph is an answer rather than a setting.",
+    )
+    .size(20)
+    .wrap(true)
+    .add(&mut h.rsc);
+    let below = rect(Color::RED).add(&mut h.rsc);
+    h.set_root((para, below).span(Dir::DOWN));
+    let top = h.region(&below).expect("drew nothing").top_left.y;
+
+    h.resize((300, 400));
+    h.frame();
+
+    let lower = h.region(&below).expect("drew nothing").top_left.y;
+    assert!(lower > top, "same words, half the width: {top} -> {lower}");
+}
+
+#[test]
+fn a_change_two_levels_under_its_reader_still_reaches_it() {
+    let mut h = Harness::new((400, 400));
+    // Every wrapper up to the outer pad read the size below it, so the outer
+    // pad is what draws again -- and the span it hands the box to is the same
+    // size as before, which is what lets a draw reuse its way past the leaf.
+    let (leaf, _) = counted(&mut h, Size::abs((100, 100).into()), OnResize::Redraw);
+    let padded = leaf.pad(10).add(&mut h.rsc);
+    let below = rect(Color::RED).add(&mut h.rsc);
+    h.set_root((padded, below).span(Dir::DOWN).pad(12));
+    assert_corners!(h, below, (12, 132), (388, 388));
+
+    h.rsc[leaf].size = Size::abs((100, 200).into());
+    h.frame();
+
+    assert_corners!(h, below, (12, 232), (388, 388));
+}