flutter_corner_shape 0.1.5

CSS corner-shape for Flutter. Round, scoop, bevel, notch, squircle, and superellipse corners — per-corner control, smooth animations, and a drop-in ShapeBorder + Clipper.

flutter_corner_shape

CSS corner-shape for Flutter. Round, scoop, bevel, notch, squircle, and superellipse corners — with per-corner control, smooth animations, and drop-in ShapeBorder + Clipper widgets.

Examples

Why?

Flutter gives you RoundedRectangleBorder (round), BeveledRectangleBorder (bevel), and the new RoundedSuperellipseBorder (squircle). But there's no scoop (concave), no notch (inward square cut), no superellipse(K) fine-tuning, and no way to mix different shapes per corner.

CSS solved this with the corner-shape property. This package brings that full API to Flutter.

Features

• 6 keyword shapes: round, squircle, bevel, scoop, notch, square
• superellipse(K) for continuous fine-tuning from K = -∞ to +∞
• Per-corner control: different shape on each corner
• Smooth animation between any two shapes via CornerShapeSpecTween
• CornerShapeBorder: drop-in ShapeBorder for ShapeDecoration, Material, Card, etc.
• ClipCornerShape: clip widget, like ClipRRect but with corner shapes
• CornerShapeDecoration: convenience Decoration with color, gradient, shadows
• Lerp to/from RoundedRectangleBorder for seamless transition with existing Flutter code

Quick Start

import 'package:flutter_corner_shape/flutter_corner_shape.dart';

Scoop (ticket/coupon shape)

Container(
  width: 300,
  height: 100,
  decoration: ShapeDecoration(
    color: Colors.orange,
    shape: CornerShapeBorder(
      borderRadius: BorderRadius.circular(50),
      cornerShape: CornerShapeSpec.scoop,
    ),
  ),
)

Bevel (diagonal cut)

Container(
  decoration: ShapeDecoration(
    color: Colors.blue,
    shape: CornerShapeBorder(
      borderRadius: BorderRadius.circular(20),
      cornerShape: CornerShapeSpec.bevel,
    ),
  ),
)

Notch (inward square cut)

CornerShapeBorder(
  borderRadius: BorderRadius.circular(20),
  cornerShape: CornerShapeSpec.notch,
)

Fine-tuned superellipse

CornerShapeBorder(
  borderRadius: BorderRadius.circular(24),
  cornerShape: CornerShapeSpec.all(
    CornerShapeValue.superellipse(-1.5), // between scoop and notch
  ),
)

Per-corner shapes

CornerShapeBorder(
  borderRadius: BorderRadius.circular(24),
  cornerShape: CornerShapeSpec.only(
    topLeft: CornerShapeValue.round,
    topRight: CornerShapeValue.scoop,
    bottomRight: CornerShapeValue.bevel,
    bottomLeft: CornerShapeValue.notch,
  ),
)

Clip an image

ClipCornerShape(
  borderRadius: BorderRadius.circular(30),
  cornerShape: CornerShapeSpec.scoop,
  child: Image.network('https://example.com/photo.jpg'),
)

Animated morph

TweenAnimationBuilder<CornerShapeSpec>(
  tween: CornerShapeSpecTween(
    begin: CornerShapeSpec.all(CornerShapeValue.superellipse(3)),
    end: CornerShapeSpec.all(CornerShapeValue.superellipse(-3)),
  ),
  duration: const Duration(seconds: 2),
  builder: (context, spec, child) {
    return Container(
      width: 120,
      height: 120,
      decoration: ShapeDecoration(
        color: Colors.orange,
        shape: CornerShapeBorder(
          borderRadius: BorderRadius.circular(60),
          cornerShape: spec,
        ),
      ),
    );
  },
)

Decoration with shadows

Container(
  decoration: CornerShapeDecoration(
    color: Colors.deepPurple,
    borderRadius: BorderRadius.circular(24),
    cornerShape: CornerShapeSpec.scoop,
    side: BorderSide(color: Colors.white, width: 2),
    shadows: [
      BoxShadow(
        color: Colors.black26,
        blurRadius: 16,
        offset: Offset(0, 6),
      ),
    ],
  ),
)

CSS ↔ Dart Mapping

CSS	Dart
corner-shape: round	CornerShapeSpec.round
corner-shape: squircle	CornerShapeSpec.squircle
corner-shape: bevel	CornerShapeSpec.bevel
corner-shape: scoop	CornerShapeSpec.scoop
corner-shape: notch	CornerShapeSpec.notch
corner-shape: square	CornerShapeSpec.square
corner-shape: superellipse(-1.5)	CornerShapeSpec.all(CornerShapeValue.superellipse(-1.5))
corner-shape: round scoop bevel notch	CornerShapeSpec.only(topLeft: .round, topRight: .scoop, ...)
border-radius: 30px	BorderRadius.circular(30)

Superellipse Value Spectrum

K Value	Keyword	Visual Effect
+∞	square	Sharp 90° corner
3	—	Very subtle rounding
2	squircle	iOS-style smooth curve
1	round	Standard circular arc
0.5	—	Extra-rounded outward
0	bevel	Straight diagonal line
-0.5	—	Slight inward curve
-1	scoop	Concave circular arc
-∞	notch	90° inward square cut

API Overview

Class	Purpose
CornerShapeValue	Single corner's shape (keyword or superellipse(K))
CornerShapeSpec	All 4 corners' shapes (like CSS shorthand)
CornerShapeBorder	ShapeBorder — use with ShapeDecoration, Material
ClipCornerShape	Clip widget — like ClipRRect with corner shapes
CornerShapeDecoration	Convenience Decoration (color + shape + shadows)
CornerShapeSpecTween	Tween for animating between shapes
CornerShapeType	Enum of keyword values

How It Works

The package uses cubic Bézier curves to approximate superellipse corners:

• Convex (K > 0): Control points placed between edge start/end and corner, with handle length derived from K
• Bevel (K = 0): Straight line between edges
• Concave (K < 0): Control points pulled inward past the diagonal, creating the scoop effect
• Square (K = +∞): Two straight lines through the corner point
• Notch (K = -∞): Two straight lines to an inward-reflected point

For K = 1 (standard round), the Bézier handle factor is the classic (4/3)(√2 - 1) ≈ 0.5523, matching a perfect circular arc.

License

MIT