any_borders

Internally, geometry construction, painting, and animation preparation have been reworked, with corner-specific behavior separated from the shared engine.

New

• Finite offset values on decorations and borders, defaulting to 0.0. Negative values inset the path and positive values outset it. Each layer uses the sum of its decoration and border offsets, preserving configured corner profiles. Offsets support interpolation.
• Independent source, inner, and outer corners. AnyPoint.shape defines the source; outerCorners and per-corner outer* box settings allow explicit outer boundaries alongside the existing inner overrides.
• AnyShapeBase.shapeBorder selects the source path for backgrounds, clipping, and shadows.
• Const .multi(borders: ..., primaryBorderIndex: ...) constructors on AnyDecoration, AnyBoxDecoration, and AnyTabDecoration. Borders paint in order with independent settings; the primary border supplies effect paths.
• buildContours returns all border layers. Layer-aware interpolation supports independent ratios and added or removed borders.
• Public AnyCornerGeometry providers for custom corner construction, with built-in RoundedCornerGeometry, BevelCornerGeometry, and InverseRoundedCornerGeometry implementations.
• AnyResolvedCorner and AnyCornerSegment expose resolved line/cubic geometry, contacts, points, tangents, and subdivision.
• Optional AnyCornerGeometry.prepareTransition and AnyCornerTransition contracts let custom providers specialize interpolation.

Changed

• AnyBorder.corners and unprefixed box corner fields now describe the source shape instead of the outer boundary. Direct AnyPoint construction requires shape.
• Background, clipping, and shadow selectors now default to AnyShapeBase.shapeBorder. zeroBorder remains available explicitly.
• AnyCorner.geometry is required. Custom construction belongs in a geometry provider, accessed through corner.geometry.
• Resolved geometry and named signed boundary distances replace descriptor-level path methods and positional conversion calls.
• buildPoints receives a border index and the combined path offset. Point helpers accept a border index; AnyDecorationCache.get/put exchange ordered contour lists instead of a single contour.
• Removed unused corner and utility conveniences; ratio fitting, contour bookkeeping, and resolved interpolation helpers are internal.

Migration

1. Separate source settings from boundary overrides

In 1.x, corners and topLeft/topRight/bottomRight/bottomLeft described outer corners. In 2.0 they describe the source shape, independently of border widths, alignment, and boundary overrides.

Role	Default setting	Box override example	AnyPoint field
Source shape	corners	topLeft	required shape
Outer boundary	outerCorners	outerTopLeft	optional outer
Inner boundary	innerCorners	innerTopLeft	optional inner

Move authored outer settings to outerCorners or the corresponding outer* field and choose source settings separately. If exact boundary dimensions are required, specify both inner and outer overrides.

const AnyBoxBorder(
  corners: RoundedCorner(radius: 20),
  sides: AnySide(width: 4, align: AnySide.alignOutside),
  outerTopLeft: BevelCorner(radius: 26),
)

Direct point construction must supply shape:

const AnyPoint(
  point: Offset(0, 0),
  shape: RoundedCorner(radius: 20),
  side: AnySide(width: 4),
)

2. Choose effect paths explicitly where needed

AnyBackground.shapeBase, AnyDecoration.clipBase, and AnyDecoration.shadowBase now default to AnyShapeBase.shapeBorder. Select zeroBorder explicitly for an outer-derived return path, or outerBorder / innerBorder for the corresponding boundary.

const AnyBoxDecoration(
  border: AnyBoxBorder(outerCorners: RoundedCorner(radius: 24)),
  background: AnyBackground(
    color: Color(0xFF85AEA8),
    shapeBase: AnyShapeBase.zeroBorder,
  ),
  clipBase: AnyShapeBase.zeroBorder,
  shadowBase: AnyShapeBase.zeroBorder,
)

3. Update custom point builders and cache access

Add the third positional borderIndex and fourth positional double offset to buildPoints. Pass the index to every point(...) call. The offset already contains decoration.offset + border.offset; apply it once to outline points, not as a corner boundary distance. Custom constructors can expose super.offset. If a custom shape does not support offsets, reject a nonzero value explicitly:

@override
List<AnyPoint> buildPoints(
    Rect bounds, TextDirection? textDirection, int borderIndex,
    double offset) {
  if (offset != 0) {
    throw UnsupportedError('This decoration does not support path offsets.');
  }
  return [
    point(bounds.topCenter, borderIndex: borderIndex),
    point(bounds.centerRight, borderIndex: borderIndex),
    point(bounds.bottomCenter, borderIndex: borderIndex),
    point(bounds.centerLeft, borderIndex: borderIndex),
  ];
}

• Read borders[borderIndex] for per-layer settings; the border getter selects the primary border.
• Use points(bounds, direction, borderIndex: i) to select a layer's points. Omitting the index selects the primary layer.
• Use buildContours(size, direction) for all contours in paint order; buildContour(size, direction) returns the primary contour.
• Update direct AnyDecorationCache.get/put calls to use List<AnyContour>. Stored lists are read-only.
• Preserve custom settings in copying, interpolation, equality, and hashCode.

See Custom decorations for the full contract.

4. Account for independent layers and interpolation

Single-border constructors remain available. For .multi, supply a nonempty, immutable border list and a valid primaryBorderIndex. Use a zero-width border for a background-only decoration.

Layers overlap in paint order. Backgrounds, clipping, and shadows use the primary layer; changing the primary index does not reorder borders or combine their outlines.

Tweens pair borders by index, so reordering the list changes interpolation pairing. Added or removed borders animate their widths from or to zero. Ratios interpolate per layer; primary selection switches at the midpoint.

5. Replace descriptor-level geometry calls

Earlier operation	Current API
Resolve a corner descriptor	corner.geometry.resolve(corner, frame)
Convert with positional distances	corner.geometry.resolveBoundary(source, previousDistance: ..., nextDistance: ...)
Evaluate a descriptor's curve	AnyResolvedCorner.pointAt / tangentAt
Append a descriptor arc	AnyResolvedCorner.appendTo with parameter range
Create a path for one resolved corner	Create a Path, then call corner.appendTo(path, moveTo: true)
Read consumed edge lengths	previousExtent / nextExtent on the resolved corner
Read a contour's corner collections	shapeCorners / outerCorners / innerCorners / zeroCorners contain AnyResolvedCorner
Assemble the final filled boundary	contour.pathFor(base)

Boundary distances are positive inward, unlike public path offsets, which are positive outward. See Geometry inspection for resolved-geometry usage.

AnyCorner.isCircular and the public any_utils.dart library are removed. Use the concrete corner's contract when interpreting its dimensions. Internal ratio fitting, contour indexing, and interpolation helpers are not extension points; use the decoration, contour, and provider APIs above.

6. Move custom construction into providers

Every custom AnyCorner must return an AnyCornerGeometry from geometry:

1. Move descriptor resolve logic into MyCornerGeometry.resolve(corner, frame).
2. Move boundary construction into the provider's protected buildBoundary hook.
3. Remove descriptor resolution overrides and call the provider directly: corner.geometry.resolve(corner, frame) and corner.geometry.resolveBoundary(source, ...).
4. Implement the provider's sizing contract. Preserve custom descriptor fields during copying, scaling, interpolation, and equality comparisons.
5. If boundary continuation needs custom state, use immutable geometryState and implement resolveZeroBoundary. Keep eligibility traits conservative unless the custom geometry meets their guarantees.

Built-in constructors and the main package entrypoints remain valid. See Custom corners for provider responsibilities and extension guidance.

• Added offsetOutward to AnyTabDecoration to choose between outward and inward tab offsets.

• Added AnyTabDecoration extras decoration.
• Added skipped contour points so decorations can keep stable point lists while avoiding collapsed zero-length sides.

• Migrated AnyDecoration to use a single AnyBorder.
• Migrated AnyBoxDecoration to configure sides, corners, ratio, and shape through AnyBoxBorder.
• Refactored cache

• Updated README.md

• Initial release