iris-ai
1956be3f3d
A widget is asked in two boxes rather than one. Its frame is what a fraction it declares or reports is a fraction of, and it passes through a span, a stack and a scroll unchanged, so `rel(0.5)` is half the same area however many containers sit between: a frame is narrowed only by what is decided above the widget -- a declared length, the root. Its extent is where the drawing goes, given as a `Place` per axis: a part of the parent's own box, measured in frame lengths from where that box starts, which the child either fills or has its answer placed inside. What that buys is that nothing under a container depends on where the container sits. A container reads `extent_len` for the length it divides and nothing about the start, so moving it re-places its children by re-adding that start and draws nobody again; and a fraction is resolved once, against the frame, rather than once per box it is composed through -- a stack sized by a child that reports `rel(0.5)` no longer takes half of half. `Place` replaces `DrawRegion`, `ExtentPlacement`, `widget_within`, `measure_len`, `region()`, `placement()` and `box_of`. Primitives and masks are written in the widget's own box's coordinates alone, so the drawing has one reference rather than two. The placement pin goes with them: reading the extent's length pins that length symbolically, and pins compose only where a child's box is its parent's own. Placing an answer waits for the end of the parent's draw or for the next ask of that child in it, so a span child is one drawing and one move rather than two moves. `Pad` is transparent: its padding goes around what it pads and its child keeps the outer frame, which is where `Outset` was going anyway. A fraction under a pad is now a fraction of the frame rather than of the inset box. Checked: fmt, clippy with -D warnings, 109 suite tests and 20 core tests in debug, the 11 generated cases, and the shrinker at 400 trees of depth 5 over all fifteen cases -- which still finds seed 108 under `reorder`, where a wrapping text measured in one box and drawn in another settles differently warm than cold. `redraw` therefore keeps the baseline's deferral for a box that is not as long as the one the widget was measured in; the plan's step 6 is not done, and the next commit message or the handoff says why.
105 lines
3.9 KiB
Rust
105 lines
3.9 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 len = painter.extent_len();
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let cut = Len::from_parts(Rel::ZERO, Px::from_int(40));
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let top = Place::Within(Some(UiSpan::new(Len::ZERO, cut)));
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let measured = painter
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.widget_at(&self.probe, UiRegion::FULL, [Place::Within(None), top])
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.len(Axis::X);
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let px = measured.apply_leftover().to_px(painter.px_len(Axis::X));
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let below = Place::Within(Some(UiSpan::new(cut, len.y)));
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let place = [Place::Within(None), below];
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match px > Px::from_f32(self.threshold) {
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true => painter.widget_at(&self.wide, UiRegion::FULL, place),
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false => painter.widget_at(&self.narrow, UiRegion::FULL, place),
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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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