IconMorphPlan class

Recipe for a IconicMorph — how the source glyph becomes the target.

The choreography the user feels — a travelling "worm", not a cross-fade:

1. One real line of the SOURCE is the hero — e.g. the user's shoulders arc, picked by sourceAnchor. The worm rests on it.
2. Its head launches along the line's own tangent and flies a smooth quintic-Hermite curve (flightLaunch, flightLand, flightBow, flightBias) over to the entry of a real TARGET line — e.g. the face's smile, picked by heroAnchor — arriving along the target's tangent so it eases in, never cutting across.
3. The worm slides onto the target, the tail catching up (headLead) and drawing the smile on. Mechanically: a fixed-length window slides by arc length along one master path (source → flight → target).
4. Meanwhile the source's other contours (the head ring) leave — by default they un-draw / retract (MorphExit.trim) rather than fade — and the target's others (brackets, eyes, nose) draw on (MorphAssemble — trim / scale / 3D flip), assembling the new icon around the line that travelled.

Everything is a tunable here so the SAME engine drives any pair of icons. This is pure data — the geometry it produces lives in MorphGeometry, the painting in IconicMorphPainter.

Annotations

• @immutable

Constructors

IconMorphPlan({Duration duration = IconMotion.iconMorph, Curve curve = IconicEase.flight, int samples = 200, Offset? heroAnchor, int? heroTargetIndex, Offset? sourceAnchor = const Offset(12, 20), int? sourceIndex, double flightLaunch = 1.5, double flightLand = 1.5, double flightBow = -0.40, double flightBias = 0.5, double flightRunway = 2.0, double headLead = 2.2, double headFade = 0.45, double flipStart = 0.55, double flipStagger = 0.1, double exitTaper = 0.5, double exitFade = 0.75, double assembleFade = 0.35, double taperFloor = 1, double assembleTaper = 0.18, double perspective = 0.0028, MorphAssemble assemble = MorphAssemble.trim, MorphExit exit = MorphExit.trim, bool flipSource = false, bool flipTarget = false})

const

Properties

assemble → MorphAssemble

How the ARRIVING (target) non-hero contours assemble — MorphAssemble.trim (draw-on, the default), MorphAssemble.scale (zoom in), or MorphAssemble.flip3d (the 3D flip). Governs the NEW glyph only.

final

assembleFade → double

Emergence span (0..1) — the share of an arriving contour's own draw over which its ALPHA ramps from nothing to full. The mirror of exitFade.

final

assembleTaper → double

Nib press-down (0..1) — the fraction of an arriving contour's draw-on (MorphAssemble.trim) over which its stroke weight ramps from taperFloor up to full, the mirror of exitTaper. Like it, inert unless taperFloor is lowered below 1. Default 0.18.

final

curve → Curve

The worm's temporal ease — the velocity profile the head and tail ride along the master path. Defaults to IconicEase.flight (peak velocity at the first frame, long soft settle — the signature). Direction-aware: a reverse play mirrors it so the worm still launches fast and lands slow going backward. Swap in IconicEase.snap for a spring launch or any Curve of your own.

final

duration → Duration

Total play time. Prefer IconMotion constants for consistent timing.

final

exit → MorphExit

How the LEAVING (source) non-hero contours disappear — MorphExit.trim (un-draw / retract, the default), MorphExit.fade (alpha fade), or MorphExit.scale (shrink + fade). Governs the OLD glyph only, independent of assemble.

final

exitFade → double

Dissolve span (0..1) — a leaving contour's ALPHA fades to nothing over the last 1 - exitFade of the whole animation. This is the whole vanish. Default 0.75 = a quarter of the morph, ≈160 ms at the default duration.

final

exitTaper → double

Pen-lift taper (0..1) — the point in a leaving contour's exit after which its STROKE WEIGHT starts easing down toward taperFloor.

final

flightBias → double

Bow position — where along the flight the flightBow hump peaks (0..1; 0.5 = mid). Shift toward 0 to fatten the launch side, toward 1 the landing.

final

flightBow → double

Lateral bow — signed swing perpendicular to the head→entry chord, as a fraction of the gap (≈ -0.8…0.8; 0 = no swing). When the two tangents near-oppose, a straight flight has to reverse hard through the middle (the "sharp turn"); a bow swings the whole path wide to ONE side instead, turning that reversal into a single broad arc. Sign picks the side (CW vs CCW); you own the magnitude so it never balloons. Added as a bump that's flat at both ends, so it never disturbs the launch/landing tangents.

final

flightLand → double

Landing breathing — the quintic landing-velocity as a fraction of the gap (≈0.15–0.9). Higher = it eases IN more gradually onto the target tangent (a longer, gentler touchdown). Split from flightLaunch so take-off and landing can breathe independently.

final

flightLaunch → double

Launch breathing — the quintic launch-velocity as a fraction of the head→entry gap (≈0.15–0.9). Higher = the flight eases OUT more gradually off the source tangent (a longer, gentler take-off runway).

final

flightRunway → double

Runway — a STRAIGHT breathing segment (viewBox units, e.g. ~20 at a 24 viewBox) along the tangent at EACH end before the curve is allowed to bend. The launch leaves dead-straight for this far, then curves; the landing arrives dead-straight for the last stretch. 0 = the curve bends immediately off the tangent (no straight runway). Clamped to ≤ 45% of the head→entry gap.

final

flipSource → bool

Reverse the resolved SOURCE hero line (swap its head/tail) AFTER the default "head on the right" orientation — so the worm launches from the other end of the source line. Use per-direction when the default end reads wrong.

final

flipStagger → double

Per-contour flip-in delay (auto-normalized to the contour count).

final

flipStart → double

When the target's non-hero contours start flipping in (0..1).

final

flipTarget → bool

Reverse the resolved TARGET hero line (swap entry/head) AFTER the default "entry on the left" orientation — so the worm lands lying the other way.

final

hashCode → int

The hash code for this object.

no setter, override

headFade → double

Window 0..headFade over which the source's non-hero contours LEAVE as the morph runs — it caps whichever exit choreography is active (un-draw, fade, or shrink), NOT just a fade. Default 0.45; the trim un-draw then caps at 0.35 and fade/scale at 0.18, so a smaller headFade tightens the active exit.

final

headLead → double

How much the worm's head leads its tail in time (>1). 1 = head and tail move together (it slides rigidly); higher = the head launches ahead and the tail catches up, so the worm stretches out over the flight and draws the target on as the tail lands.

final

heroAnchor → Offset?

Viewbox-space point used to pick the hero TARGET contour: the contour whose centroid is nearest this anchor becomes the morph's destination line — e.g. Offset(12, 16) for a mouth. Order-independent, so it's the robust selector.

final

heroTargetIndex → int?

Explicit hero target contour index — wins over heroAnchor when set.

final

perspective → double

3D perspective strength for the flip-in (used only when assemble is MorphAssemble.flip3d; see Projector3D).

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

samples → int

Points the hero source + target lines are each resampled to. More = a smoother morph at a little more cost. >= 2.

final

sourceAnchor → Offset?

Viewbox-space point used to pick the hero SOURCE contour — the line that morphs into the target. Defaults to the glyph's lower edge Offset(12, 20), e.g. the user's shoulders arc.

final

sourceIndex → int?

Explicit hero source contour index — wins over sourceAnchor when set.

final

taperFloor → double

Ink floor (0..1) — how thin a taper may ever take the stroke, at either end. Default 1: stroke weight is never touched.

final

Methods

copyWith({Duration? duration, Curve? curve, int? samples, Offset? heroAnchor, int? heroTargetIndex, Offset? sourceAnchor, int? sourceIndex, double? flightLaunch, double? flightLand, double? flightBow, double? flightBias, double? flightRunway, double? headLead, double? headFade, double? flipStart, double? flipStagger, double? exitTaper, double? exitFade, double? assembleFade, double? taperFloor, double? assembleTaper, double? perspective, MorphAssemble? assemble, MorphExit? exit, bool? flipSource, bool? flipTarget}) → IconMorphPlan

Returns a copy with selected fields overridden. Useful for tuning a base plan without mutating it — e.g. a slider can override flightBow while keeping all other fields from the original.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

resolveHeroTarget(List<IconContour> targets) → int

Which target contour the source morphs INTO.

resolveSource(List<IconContour> sources) → int

Which source contour is the one that morphs (the rest fade out).

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

override