A speck of dust is small and there is never only one, so the brush had three
things wrong with it: the list stopped at sixteen and the seventeenth repair
pushed the first one out of the shader, the size was a choice of three buttons,
and one gesture laid exactly one spot — a scratch across a hundred pixels was a
dozen clicks.
The cap is gone rather than raised. SkSL indexes a uniform array by a constant
only (the trick the tone curve's mixer already uses), so HEAL_SKSL carried
sixteen unrolled blocks and the list was trimmed to fit them. The shader is now
built for the count it is handed — healSkSL(n), with healUniforms returning
(n * 2 + 1) * 4 floats, the same declaration order for any n — and the renderer
caches one compiled effect per count (exportEngine's healEffectFor). readHeal
no longer slices and the app appends whatever a gesture reported. No repair is
dropped to make room for a later one: the speck healed first is the speck that
stays healed.
The wheel is the size now. wheelHealR multiplies the radius by
exp(-deltaY * 0.0015), so a trackpad's small deltas and a mouse's 100px notch
are the same gesture at two speeds, bounded at 0.3% and 25% of the photo's
width — below the first a spot is finer than the pixels it is drawn on, past
the second it would borrow its patch from off the frame. S, M and L are gone,
and because there is nothing left to point at, the HEAL chip's own readout is
the size: the number the brush is set to is the number on the chip.
The pointer paints. Down starts a stroke, move adds a point every HEAL_SPACING
(0.6) radii of travel, and up turns the whole run into spots in one report — so
a stroke is one undo step however long it was, and the trail drawn while the
pointer is down is a preview of that run, in the accent, cleared the moment the
spots land. The part of a stroke that leaves the photo lays nothing down, and
the pointer is captured so a stroke that runs past the edge ends where the
pointer does rather than leaving a spot hanging at the frame.
The wheel had to be stopped, not merely claimed. The heal layer is a child of
the stage, and the stage has its own wheel listener that zooms the photo, so a
wheel over the brush grew the brush AND zoomed the view: the probe caught it as
a cursor circle 15% wider than the readout it was drawing. The layer's listener
(native, because React's own onWheel is passive) now stops propagation — while
the brush is up, the wheel sizes the brush and nothing else.
One number moved that none of the three asks mentioned, and it is what the
probe's remaining failure was about. The feather band was 45% of the radius,
and that band is the only place the pixels being repaired are mixed back into
the patch, so with the default 6px brush it left a ring of the speck's own edge
one pixel inside the circle (115 in a field of 150) — which the preview's own
JPEG then rang around, reading 177 a pixel off the centre of a repair that
should be flat. Narrowing the band to the outer 15% copies the patch over
everything inside 0.85r: sub-pixel at the default brush, still a soft edge at a
big one, and that pixel now reads 151.
Verified:
heal-skia-lab.cjs (scratchpad, Node + the full CanvasKit build) — 27 PASS,
0 FAIL: the shader for a count compiles through RuntimeEffect.Make and its
uniform block is (n * 2 + 1) * 4 floats (n=1 -> 12, n=40 -> 324); a single
spot copies the donor exactly and leaves the rest of the frame untouched,
pixel for pixel; forty spots are carried whole with the first and the last
both drawn; three spots in one run each borrow their own patch; readHeal
clamps and drops zero-radius spots and no longer trims the list;
wheelHealR grows, shrinks and clamps at both ends (0.3% and 25%); the
search finds a patch and still refuses a brush that covers the frame.
heal-probe.cjs (scratchpad, the rebuilt app at http://localhost:8090) —
48 PASS, 0 FAIL, no page errors: the circle under the cursor is exactly
the size the chip reads, before and after a wheel, and the wheel grows,
shrinks, stops at 25% and at 0.3% and returns to where it started; there
are no size chips left; one click is one spot, the speck reads 151 at its
centre and its four neighbours are field too; a drag shows at least three
trail circles, lays exactly that many spots, clears the trail on release,
and UNDO takes the whole stroke back at once while leaving the repair made
before it alone; REDO repaints it; a bigger brush takes a ten-pixel blob;
twenty-five spots are carried with the first healed speck still first and
still healed; every speck is gone after a reload; CLEAR brings them all
back and lays no spot of its own; the chip goes amber only while spots are
on the photo.
Regressions against the rebuilt app, 0 fail: landing-test.cjs 172,
pro-gate-test.cjs 27, award-column-probe.cjs 18, otp-code-probe.cjs 10,
tone-curve-probe.cjs 42; backend npm test 180 passed, 0 failed.
web tsc --noEmit clean.
ponytail: a stroke's repairs land when the pointer comes up, not under it as
they are painted — a live repair would mean recompiling the pass and re-cutting
the preview per point mid-gesture; the trail is what the pointer has drawn, and
it is drawn in the accent so the difference reads. The list is uncapped, so a
runaway stroke pays one shader compile per distinct count it reaches, cached
for the rest of the session: a ceiling would have to come back with the trim.
The search still has no colour-matching term, so the donor is chosen by
resemblance alone, and the spots still live in the rendered photo's
coordinates, so re-cropping or re-rotating after healing slides them.
3dtours
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