From f5b88932b4bc24496a0478038c760c63f50642db Mon Sep 17 00:00:00 2001 From: iris <2+iris@noreply.localhost> Date: Sun, 6 Sep 2026 19:59:39 -0400 Subject: [PATCH] iris: a widget's move slot has one owner -- move_applied + repositioned `mov` accumulates a delta onto the slot and `reposition` overwrote it, and both legitimately land on one widget in one frame: `List::place`'s Bottom-known branch offers a row a same-size box that has moved (`mov`), then corrects the placement inside it when the row's cached height no longer matches what the row reports (`reposition`). That is what a wrapped transcript row hit, and what the `move_applied == ZERO` debug assert was standing in for -- an assert against a case that happens is not a guarantee, it is a crash. The slot means `move_applied + repositioned` now, both halves recorded on `ActiveData`, so `reposition` adds the move rather than dropping it and stays idempotent. The assert it replaces is a `debug_assert_eq!` that the slot still holds that sum on entry -- i.e. that nothing but those two ever wrote it. Test: `a_widget_moved_by_its_parent_and_then_placed_inside_it_lands_at_the_placement`, which draws the child at the offered position (-100px) rather than the placement (100px) without the fix. Verified against the `.wrap(true)` repro from docs/IRIS_TODO.md (draws correctly, no panic) and an emulator bench run with assertions live. --- docs/IRIS_TODO.md | 37 +++++++++---- iris/core/src/ui/active.rs | 13 +++++ iris/core/src/ui/render_state.rs | 30 ++++++++--- iris/src/layout_tests.rs | 93 ++++++++++++++++++++++++++++++++ 4 files changed, 155 insertions(+), 18 deletions(-) diff --git a/docs/IRIS_TODO.md b/docs/IRIS_TODO.md index da62fa6..d3fc0f9 100644 --- a/docs/IRIS_TODO.md +++ b/docs/IRIS_TODO.md @@ -591,17 +591,23 @@ agent ticks it here with the evidence. that. Fixed in `iris/src/widget/rect.rs`; the reason is written at the definition. Suspect the same cause for anything else tinted with a background rect. -- [ ] **A wrapped transcript row trips `reposition`'s debug assert.** - *"widget ... is both moved by its parent's own layout (`mov`) and - repositioned within it"*, raised from `List::place`. Repro: change - `.wrap(!verbatim)` to `.wrap(true)` in `transcript-ui/src/row.rs`'s - `build_block` and run `iris/run-headless.sh transcript --shot - /tmp/x.png -- -p transcript-ui`. Survives the `Rect` fix above and is - not specific to any block kind -- it appears once the row is tall - enough. The shipping configuration does not reach it (verbatim blocks - do not wrap) and the Android bench runs clean with assertions live, - but it is a real disagreement about who owns a widget's move slot and - should be settled before more of P1 leans on `List`. +- [x] **A wrapped transcript row tripped `reposition`'s debug assert.** + Settled 2026-09-06 by giving the move slot one owner instead of two. + `mov` accumulates a delta on it, `reposition` overwrote it, and both + legitimately land on one widget in one frame: `List::place`'s + Bottom-known branch offers a row a same-size box that has *moved* + (`mov`), then corrects the placement inside it when the row's cached + height no longer matches what the row reports (`reposition`). The + slot now always means `move_applied + repositioned` + (`ActiveData::repositioned`, `iris/core/src/ui/render_state.rs`), so + `reposition` adds the move rather than dropping it -- the assert is + gone and the arithmetic is right. Test: + `a_widget_moved_by_its_parent_and_then_placed_inside_it_lands_at_the_placement` + in `layout_tests.rs`, which lands the child at the *offered* position + (-100px) instead of the placement (100px) without the fix, and a + `debug_assert_eq!` in `reposition` that nothing but those two ever + writes the slot. Verified with the `.wrap(true)` repro (draws, no + panic) and an emulator bench run with assertions live. - [ ] **Desktop colours are washed out: the winit surface is sRGB and the shader writes the palette's bytes as linear.** Mocha Crust (17,17,27) is drawn as (73,73,91), measured off @@ -624,6 +630,15 @@ agent ticks it here with the evidence. backend too -- `./run-headless.sh transcript --shot /tmp/x.png -- -p transcript-ui --features iris/force-gles`. +- [ ] **The bench report pane draws over the transcript rows instead of + replacing them.** Visible on the emulator for the first time now that + glyphs render there (`/tmp/emu-final.png`, 2026-09-06): after a bench + run the report's lines and the transcript's occupy the same rows in the + top third of the screen, both legible, neither on top. Pre-existing -- + the same overlap is in a screenshot taken before the move-slot fix -- so + it is its own item, most likely the report pane not masking or not + claiming its region. + ## Build (for the port) Widgets `RUST.md`'s "The port, in order (decided 2026-09-05)" needs and diff --git a/iris/core/src/ui/active.rs b/iris/core/src/ui/active.rs index 3b702cc..c6e0675 100644 --- a/iris/core/src/ui/active.rs +++ b/iris/core/src/ui/active.rs @@ -53,4 +53,17 @@ pub struct ActiveData { /// after a finger pan (2026-09-06). Reset to zero whenever the widget /// is really redrawn, since `draw_inner` zeroes the slot then too. pub move_applied: Vec2, + /// The offset the last `Painter::reposition` placed this widget's + /// content at *within* `region`, in window pixels. The move slot has + /// exactly one owner and one meaning: + /// `move_offsets[move_slot] == move_applied + repositioned`. `mov` + /// adds to the first, `reposition` overwrites the second (it + /// recomputes `from` afresh every call, so repeating it must land on + /// the same answer rather than drifting), and both then rewrite the + /// slot from the sum -- which is what lets a parent both move a child + /// with its own layout and place it inside that moved region in one + /// frame. `List::place`'s Bottom-known branch does exactly that once a + /// row's blocks wrap. Reset to zero on a real redraw, with + /// `move_applied` and the slot itself. + pub repositioned: Vec2, } diff --git a/iris/core/src/ui/render_state.rs b/iris/core/src/ui/render_state.rs index 14f3cb5..b14f6db 100644 --- a/iris/core/src/ui/render_state.rs +++ b/iris/core/src/ui/render_state.rs @@ -380,6 +380,7 @@ impl UiRenderState { move_slot, own_mask, move_applied: Vec2::ZERO, + repositioned: Vec2::ZERO, }; // remove old children that weren't kept @@ -442,12 +443,8 @@ impl UiRenderState { let Some(active) = self.active.get(&id) else { return; }; - debug_assert!( - active.move_applied == Vec2::ZERO, - "widget {id:?} is both moved by its parent's own layout (`mov`) and repositioned \ - within it; the two write the same slot with different conventions -- see \ - `ActiveData::move_applied`" - ); + let move_applied = active.move_applied; + let repositioned = active.repositioned; let from = active .size .to_uivec2(self.density) @@ -457,8 +454,27 @@ impl UiRenderState { let from_px = from.top_left().to_abs(self.output_size); let to_px = to.top_left().to_abs(self.output_size); let delta = to_px - from_px; + // Not `delta` alone: a parent may have `mov`ed this widget to a + // region that itself moved earlier in the same frame, and that + // part of the slot is `move_applied`'s, not this call's. Writing + // `delta` on its own dropped it and put the content back at the + // pre-move position. `from` is computed against `active.region`, + // which `mov` already updated, so `delta` is purely the placement + // inside the region and the two summands never overlap. let entry = rsc.ui_mut().move_offsets.get_mut(slot); - entry.delta = [delta.x, delta.y]; + debug_assert_eq!( + entry.delta, + [ + move_applied.x + repositioned.x, + move_applied.y + repositioned.y + ], + "widget {id:?}'s move slot was written by something other than `mov`/`reposition`; \ + the slot is theirs and means `move_applied + repositioned` -- see `ActiveData`" + ); + entry.delta = [move_applied.x + delta.x, move_applied.y + delta.y]; + if let Some(active) = self.active.get_mut(&id) { + active.repositioned = delta; + } self.mov_count += 1; } diff --git a/iris/src/layout_tests.rs b/iris/src/layout_tests.rs index b56ce70..be2ef9c 100644 --- a/iris/src/layout_tests.rs +++ b/iris/src/layout_tests.rs @@ -562,3 +562,96 @@ fn a_size_independent_widget_moved_by_its_parent_has_the_hit_box_it_is_drawn_at( after.top_left ); } + +/// A parent that both `mov`s a child (its own layout moved the box it +/// offers) and `reposition`s it inside that box in the same frame -- what +/// `List::place`'s Bottom-known branch does once a row's cached height +/// stops matching what the row reports, which is reachable as soon as a +/// transcript row's blocks wrap (docs/IRIS_TODO.md's "Found by P1a"). +struct MoveThenPlace { + inner: StrongWidget, + /// Where the child is *offered* a (constant-size) box, moved between + /// frames by the test. + offer_top: f32, + /// Where the child is then placed within this widget's own region. + place_top: f32, +} + +impl Widget for MoveThenPlace { + fn draw(&mut self, painter: &mut Painter) -> Size { + let offer = UiRegion::new( + UiSpan::FULL, + UiSpan::new( + UiScalar::abs(self.offer_top), + UiScalar::abs(self.offer_top + 40.0), + ), + ); + painter.widget_within(&self.inner, offer); + let place = UiRegion::new( + UiSpan::FULL, + UiSpan::new( + UiScalar::abs(self.place_top), + UiScalar::abs(self.place_top + 40.0), + ), + ); + painter.reposition(&self.inner, place); + Size::default() + } +} + +/// `mov` accumulates a delta onto a widget's move slot and `reposition` +/// overwrites it, and both can legitimately land on one widget in one +/// frame (see `MoveThenPlace`). `reposition` used to write its own delta +/// alone, which dropped the move and put the child back at the position +/// the offered box had *before* it moved; a `debug_assert!` that +/// `move_applied` was zero hid that behind a panic instead of fixing it. +/// The slot has one owner and one meaning now -- +/// `move_applied + repositioned` -- so the child stays where it was +/// placed however its offered box moves. Fails at the offer's position +/// (200) rather than the placement's (100) without that. +#[test] +fn a_widget_moved_by_its_parent_and_then_placed_inside_it_lands_at_the_placement() { + let mut rsc = TestRsc { + ui: UiData::default(), + }; + let rect = rsc.ui.widgets.add_strong(Rect::new(UiColor::WHITE)); + let child = rsc.ui.widgets.add_strong(Sized { + inner: rect.any(), + x: None, + y: Some(Len::abs(40.0)), + }); + let child_w = child.weak(); + let parent = rsc.ui.widgets.add_strong(MoveThenPlace { + inner: child.any(), + offer_top: 0.0, + place_top: 100.0, + }); + let parent_w = parent.weak(); + let root = parent.any(); + + let mut render = UiRenderState::new(); + render.resize((200.0, 400.0)); + render.update(&root, &mut rsc); + let before = render.window_region(&child_w, &rsc).unwrap(); + assert!( + (before.top_left.y - 100.0).abs() < 0.01, + "the child should be drawn where it was placed, not where it was offered: {before:?}" + ); + + // Move the offered box without changing its size (the `mov` fast path) + // and place the child at the same spot as before. Marking the parent + // dirty is what a real container's own content change does; the child + // itself is untouched, which is the case `mov` exists for. + { + let parent = rsc.ui.widgets.get_mut(&parent_w).unwrap(); + parent.offer_top = 200.0; + } + rsc.ui.widgets.needs_redraw.insert(parent_w.id()); + render.update(&root, &mut rsc); + let after = render.window_region(&child_w, &rsc).unwrap(); + assert!( + (after.top_left.y - 100.0).abs() < 0.01, + "the placement did not change, so neither should the child: before={before:?} \ + after={after:?}" + ); +}