iris-ai
c55be21761
An argument that is usually `None` goes last. So `widget_at` and `place_at` take the place first, and `narrow_rel_base` after it. `Place` and `Part` also now say which of the two boxes they decide, since that is the question a caller has to answer to pick between them: `Part` is the child's region, said as a part of the caller's own, and `Within`/`Fill` is what becomes of the placement in it.
104 lines
3.8 KiB
Rust
104 lines
3.8 KiB
Rust
//! A measurement that decides control flow.
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//!
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//! Comparing boxes catches a widget that moved. It does not catch a widget
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//! that measured a child, believed a different answer from the one a cold
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//! start would give, and took the other branch -- which is the same defect
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//! arriving somewhere it cannot be ignored. A widget here branches on what it
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//! measured, so a disagreement shows up as a different tree.
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use iris::harness::Harness;
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use iris::prelude::*;
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/// Measures `probe` across `axis` and draws one of two children on the
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/// answer. Its own configuration never changes, so which child is drawn is a
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/// property of the layout alone.
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struct BranchesOnMeasurement {
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probe: StrongWidget,
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wide: StrongWidget,
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narrow: StrongWidget,
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threshold: f32,
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}
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impl Widget for BranchesOnMeasurement {
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fn draw(&mut self, painter: &mut Painter) -> Size {
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let cut = Len::from_parts(Rel::ZERO, Px::from_int(40));
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let top = Place::Within(Part::From(UiSpan::new(Len::ZERO, cut)));
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let measured = painter
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.widget_at(&self.probe, [Place::Within(Part::WHOLE), top], None)
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.len(Axis::X);
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let px = painter.to_px(measured.apply_leftover(), Axis::X);
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let below = Place::Within(Part::From(UiSpan::new(cut, painter.region_len(Axis::Y))));
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let place = [Place::Within(Part::WHOLE), below];
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match px > Px::from_f32(self.threshold) {
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true => painter.widget_at(&self.wide, place, None),
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false => painter.widget_at(&self.narrow, place, None),
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};
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Size::LEFTOVER
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}
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}
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fn plant(h: &mut Harness, threshold: f32) -> (WidgetId, WidgetId) {
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let words = "the quick brown fox jumps over the lazy dog and keeps running";
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let probe = wtext(words).size(16).wrap(true).add(&mut h.rsc);
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let wide = rect(Color::RED).add(&mut h.rsc);
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let narrow = rect(Color::BLUE).add(&mut h.rsc);
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let branch = BranchesOnMeasurement {
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probe: probe.add_strong(&mut h.rsc),
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wide: wide.add_strong(&mut h.rsc),
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narrow: narrow.add_strong(&mut h.rsc),
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threshold,
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}
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.add(&mut h.rsc);
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let side = rect(Color::GREEN).width(120).add(&mut h.rsc);
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h.set_root((side, branch).span(Dir::RIGHT));
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(wide.id(), narrow.id())
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}
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/// Which of the two branches drew, as a pair a test can compare.
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fn taken(h: &Harness, wide: WidgetId, narrow: WidgetId) -> (bool, bool) {
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(h.region(&wide).is_some(), h.region(&narrow).is_some())
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}
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#[test]
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fn a_branch_taken_on_a_measurement_holds_across_repaints() {
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for threshold in [0.0, 200.0, 400.0, 600.0, 779.0, 780.0, 781.0, 2000.0] {
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let mut h = Harness::new((900, 600));
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let (wide, narrow) = plant(&mut h, threshold);
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let first = taken(&h, wide, narrow);
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assert_ne!(first, (false, false), "threshold {threshold}: neither drew");
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for frame in 0..4 {
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h.rsc.widgets_mut().get_dyn_mut(wide);
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h.rsc.widgets_mut().get_dyn_mut(narrow);
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h.frame();
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assert_eq!(
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taken(&h, wide, narrow),
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first,
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"threshold {threshold}, repaint {frame}: the branch moved when nothing did"
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);
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}
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}
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}
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#[test]
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fn a_branch_taken_on_a_measurement_is_the_one_a_cold_start_takes() {
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for threshold in [0.0, 200.0, 400.0, 600.0, 779.0, 780.0, 781.0, 2000.0] {
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let mut warm = Harness::new((900, 600));
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let (wide, narrow) = plant(&mut warm, threshold);
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warm.resize((640, 480));
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warm.frame();
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warm.rsc.widgets_mut().get_dyn_mut(wide);
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warm.frame();
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let mut cold = Harness::new((640, 480));
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let (cwide, cnarrow) = plant(&mut cold, threshold);
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assert_eq!(
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taken(&warm, wide, narrow),
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taken(&cold, cwide, cnarrow),
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"threshold {threshold}: warm and cold took different branches"
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);
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}
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}
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