`Len` is `Px` beside `Rel` beside `Weight`, so the seam `4e28f10` left in
`Span` -- a float length added to a fixed-point cursor -- is gone, and the
sum a span compares against its box is exact.
`Weight` is its own scale, `Fixed<16>`, because a share of what is left over
is not a fraction of anything: a list divides its room by the total of them,
so the range has to hold a whole list's worth while the precision only has to
tell two weights apart. `Rel::ratio` turns two weights into a share on the
finer grid, which is what a span needs and what dividing them on their own
grid would round away.
`AxisAlign` holds a `Rel` rather than a float, which is what the layout was
reading out of it anyway. `Padding` and `Span::gap` hold `Px`, converted
where they are built instead of on every frame. `RegionAlign::rel` is gone;
its one caller wanted a position, and now builds one.
`Fixed` gains `from_num` for a number as it is written in source, `mul_int`
for a length repeated a whole number of times, and `ratio`.
Checked: fmt, clippy, 101 tests, 100 generated seeds in 86 s, all five
shrinker cases at 300 seeds, and all five examples byte-identical at
1920x1200 against `4e28f10`.
With the fuzzer comparing for equality rather than within 0.05 px, four of
the five cases now pass 100 seeds -- `resize-repaint` joins the other three.
`reorder` still fails one seed by one step, so the last of it is in what a
box is measured *in*: `px_len` and the window are still floats.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The shrinker's `reorder` case had two red seeds at depth 5, and neither was
about reordering. A span asks whether anything is left over by comparing its
box in pixels with what its fixed and relative children fill. Where the
parent sized that box from this span's own answer those are the same number,
and the box returns through the chain a few bits off, so 0.00003 px decided
it: warm rounded under and left a leftover-only child undrawn, cold rounded
over and drew it at zero length. Both are stable, and the pixels are the
same either way, which is why nothing but the oracle could see it.
The room to divide is `len * fixed - total.px`, and under `HOLDS_EPSILON_PX`
of it is now none. That moves the boundary off the length boxes land on
rather than making the comparison tolerant: the validity range is still
split at the boundary exactly, as generated seed 16 requires, and what it
gives up is a share of under a twentieth of a pixel. The same margin answers
the `fixed == 0` arm, where the only room is what negative pixels leave.
`tests/unsettled.rs` gets the six-widget tree, shrunk from 266. It needs the
span above the one that divides: without a box composed through it both
trees round the same way and the boundary is never crossed.
Checked: fmt, clippy, 89 tests, 100 generated seeds agreeing in 68.5 s, and
all five shrinker cases at 1000 seeds of depth 6 (159,024 widgets each).
`tabs`, `view`, `minimal`, `text` and `random` render byte-identical at
1920x1200 against the same worktree without the change.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
`.width()` built a `SetSize` whose whole job was to answer `size_hint`, so
every declared length cost a widget, an `ActiveData` and a link of chain to
say one number. It is now a `SizeRule` per axis on `WidgetData`, beside
`region_node`, resolved by `Painter` where the widget is drawn. `SetSize`
and `MaxSize` are gone; `MaxSize` had no caller but its own builders.
That settles which of two answers is the size. A rule wins on the axis it
names and the `Size` returned by `draw` answers the rest, applied once in
`draw_inner` rather than by each widget that could carry one -- so the
widget under a rule never learns of it. `Painter::size_hint` reads the rule
first for the same reason: a rule that beats what a widget would draw has
to beat what it says about itself.
`declared_lens` still falls back to a non-leftover `size_hint`, which is
how an image or a gap gets its own pixel size rather than the whole offer.
That is the offer's business rather than a declaration's, and it falls away
when a widget occupies its reported size inside the box it was offered.
`known` and `declared` are separate because a share is a length to whoever
divides one and not to whoever composes a box: `.width(leftover(3))` is
known without drawing but cannot narrow anything.
Checked: fmt, clippy, 85 tests, and 100 generated seeds agreeing warm
against cold in 67.6 s. `minimal`, `text` and `view` render byte-identical
at 1920x1200; `tabs` differs only in the widget count it prints about
itself, which is two wrapper types smaller.
A local redraw drew a dirty widget in the box it was placed in. When a reader
decided that box from the widget's own answer -- an aligned span sized to its
children, a text at the tail of a row, a scroll's content -- the old answer is a
fixed point of measuring there whatever the content now says, so the layout had
two stable answers and which one it reached depended on the tree's history.
`tests/unsettled.rs` has the two shrunk cases: the four-widget aligned span,
and a scroll placing a pass-through `SetSize` in a box the content decided,
where the span under it was placed once and nothing at its own edge said so.
`ActiveData::offered_px` keeps the pixel size of the box the parent first asked
about the child in, whether through `known_len` or a first `place`, beside `px`,
the box it drew against. A dirty widget whose size reads an axis on which some
reader up its chain gave what it read a box other than the one it asked in is
not drawn locally: the chain is marked and the parent of the highest such
placement draws, since above it every box is a constraint rather than an
answer. The walk goes up the whole reader chain because a pass-through hands a
derived box down unchanged.
`Scroll` read its box's length for the clamp through `px_len`, which records
the reported size as depending on it, and it does not: its size is its
content's. That made every scroll tick a size question asked in a derived box,
at 34x the instructions. `Painter::px_len_for_draw` is the read that records
nothing. Instructions per frame on the depth-8 rig against the previous head:
`many` at 32 dirty 0.66M to 0.74M, at 130 dirty 27.7M to 26.5M, `resize` 15.8M
to 15.0M, `scroll`, `repaint` and `size` unchanged. The shrinking fuzzer passes
200 trees at depth 7 in all four cases, the hundred-seed sweep passes, and the
five reference renders and the resize render are byte-identical.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
The shrinking fuzzer had no case for what `generated.rs` calls a reshuffle,
which was the only thing still failing there. `Case::Reorder` rotates every
span's children after a warm frame and compares against a tree grown that
way -- which needs a span's creation order kept apart from the order its
children are attached in, or the two trees make the same widgets in
different orders and cannot be lined up.
It found a four-widget tree, from 486, and the trace says the layout has
more than one answer rather than one answer reached twice.
Aligned(mid, -, Span[ Text(wrap), OneLine ])
A span measures its children in its own box. Its own box is what its parent
gave it, from the size it reported, from those children. So with the
wrapping text second it is offered `cursor..end` of a span 663.376 wide and
asked for 357.44, which is what it already holds -- the size is valid, the
span reports 663.376 again, and nothing moves. Grown in that order from
scratch the span is offered the window, the text is asked for 334.06 and
answers 318.45, and the span settles at 624.38. Both are stable. Which one
you get depends on what the tree was before.
So this is not a stale drawing kept too long, and no rule about when to
keep one will fix it: it is a circular dependency with two solutions.
`Painter::settle` in `Aligned` -- place into the child's own size without
measuring there -- makes all four cases in `unsettled.rs` pass and breaks
two in `generated.rs`, whether or not the child is drawn first. Not kept;
the shape of the fix is the constraint a container measures under being
something it is given rather than something it ends up with.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Six widgets from 905, and it fails in 0.06s: everything inside a declared
189x176 box is the same size whatever the output is, so a resize may not
reach any of it, and the text still comes out 3.92px narrower warm than
cold.
`tests/trace_unsettled.rs` says why, and it is not what it looked like. A
span measures a content-sized child in the space remaining, is told 167.41,
and then offers that back as the child's box -- so the text is re-broken at
exactly its own longest line, which is a knife edge: warm lands on four
lines and 163.49, cold stays on three and 167.41. Measuring an answer
against itself is unstable precisely at the fixed point.
`Painter::settle` -- move the child's slot, keep the drawing, never measure
again -- is the shape of the fix and does not work yet. In a span it breaks
five cases, because a container child may have laid its own children out as
fractions of the box it drew in, so moving it into a shorter one shrinks
them; reporting a length in pixels does not mean the drawing is positioned
in pixels. In `Aligned` alone it breaks two. Recorded rather than kept: the
condition wants to be something a widget declares, near `OnResize`, rather
than something its caller infers.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Ignoring is for cost, not for status: a fuzzer earns it, a known defect
does not. Hiding this one behind an attribute turns a loud failure into a
quiet one nobody goes looking for.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Reconstructing a generated failure by hand had failed three times: a seed
reproduces a tree of hundreds of widgets, and the printed chain is not
enough to see which part matters. `tests/shrink.rs` grows trees from a
description it can simplify -- drop a child, unwrap a wrapper, shorten a
text, drop a declared length -- and takes the first simplification that
still fails until none does. It lives in the tests; nothing in the library
knows about it.
It works: with the box-length check in `try_reuse` deliberately disabled
it reduced a 96-widget tree to 2. That check is worth keeping, because a
fuzzer that cannot fail is a fuzzer that agrees with everything.
What it found is not what any of this was looking for. Six widgets, shrunk
from 402:
Span[ Stack[ Text("Wrapping"), Aligned(pos,pos,
SetSize(x: 76px, Text("Wrapping shapes", wrap))) ] ]
The wrapping text is one line on the first frame and two after a repaint,
and two is right for a 76px box -- so the *cold* tree is the one that has
not settled. `generated.rs` has been comparing a warm frame against a cold
one and calling the difference a retained-layout defect, while at least
some of it is the first frame shaping a text at a width it was measured in
rather than the one it was given. Retained state is not involved.
`tests/unsettled.rs` is that case by hand, in 0.06s. Both of its tests
fail, so both are ignored with the reason rather than left to break the
build.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
iris-aiandClaude Opus 5