border_radius.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/foundation.dart';

import 'basic_types.dart';

/// Base class for [BorderRadius] that allows for text-direction aware resolution.
///
/// A property or argument of this type accepts classes created either with [new
/// BorderRadius.only] and its variants, or [new BorderRadiusDirectional.only]
/// and its variants.
///
/// To convert a [BorderRadiusGeometry] object of indeterminate type into a
/// [BorderRadius] object, call the [resolve] method.
@immutable
abstract class BorderRadiusGeometry {
  /// Abstract const constructor. This constructor enables subclasses to provide
  /// const constructors so that they can be used in const expressions.
  const BorderRadiusGeometry();

  Radius get _topLeft;
  Radius get _topRight;
  Radius get _bottomLeft;
  Radius get _bottomRight;
  Radius get _topStart;
  Radius get _topEnd;
  Radius get _bottomStart;
  Radius get _bottomEnd;

  /// Returns the difference between two [BorderRadiusGeometry] objects.
  ///
  /// If you know you are applying this to two [BorderRadius] or two
  /// [BorderRadiusDirectional] objects, consider using the binary infix `-`
  /// operator instead, which always returns an object of the same type as the
  /// operands, and is typed accordingly.
  ///
  /// If [subtract] is applied to two objects of the same type ([BorderRadius] or
  /// [BorderRadiusDirectional]), an object of that type will be returned (though
  /// this is not reflected in the type system). Otherwise, an object
  /// representing a combination of both is returned. That object can be turned
  /// into a concrete [BorderRadius] using [resolve].
  ///
  /// This method returns the same result as [add] applied to the result of
  /// negating the argument (using the prefix unary `-` operator or multiplying
  /// the argument by -1.0 using the `*` operator).
  BorderRadiusGeometry subtract(BorderRadiusGeometry other) {
    return _MixedBorderRadius(
      _topLeft - other._topLeft,
      _topRight - other._topRight,
      _bottomLeft - other._bottomLeft,
      _bottomRight - other._bottomRight,
      _topStart - other._topStart,
      _topEnd - other._topEnd,
      _bottomStart - other._bottomStart,
      _bottomEnd - other._bottomEnd,
    );
  }

  /// Returns the sum of two [BorderRadiusGeometry] objects.
  ///
  /// If you know you are adding two [BorderRadius] or two [BorderRadiusDirectional]
  /// objects, consider using the `+` operator instead, which always returns an
  /// object of the same type as the operands, and is typed accordingly.
  ///
  /// If [add] is applied to two objects of the same type ([BorderRadius] or
  /// [BorderRadiusDirectional]), an object of that type will be returned (though
  /// this is not reflected in the type system). Otherwise, an object
  /// representing a combination of both is returned. That object can be turned
  /// into a concrete [BorderRadius] using [resolve].
  BorderRadiusGeometry add(BorderRadiusGeometry other) {
    return _MixedBorderRadius(
      _topLeft + other._topLeft,
      _topRight + other._topRight,
      _bottomLeft + other._bottomLeft,
      _bottomRight + other._bottomRight,
      _topStart + other._topStart,
      _topEnd + other._topEnd,
      _bottomStart + other._bottomStart,
      _bottomEnd + other._bottomEnd,
    );
  }

  /// Returns the [BorderRadiusGeometry] object with each corner radius negated.
  ///
  /// This is the same as multiplying the object by -1.0.
  ///
  /// This operator returns an object of the same type as the operand.
  BorderRadiusGeometry operator -();

  /// Scales the [BorderRadiusGeometry] object's corners by the given factor.
  ///
  /// This operator returns an object of the same type as the operand.
  BorderRadiusGeometry operator *(double other);

  /// Divides the [BorderRadiusGeometry] object's corners by the given factor.
  ///
  /// This operator returns an object of the same type as the operand.
  BorderRadiusGeometry operator /(double other);

  /// Integer divides the [BorderRadiusGeometry] object's corners by the given factor.
  ///
  /// This operator returns an object of the same type as the operand.
  ///
  /// This operator may have unexpected results when applied to a mixture of
  /// [BorderRadius] and [BorderRadiusDirectional] objects.
  BorderRadiusGeometry operator ~/(double other);

  /// Computes the remainder of each corner by the given factor.
  ///
  /// This operator returns an object of the same type as the operand.
  ///
  /// This operator may have unexpected results when applied to a mixture of
  /// [BorderRadius] and [BorderRadiusDirectional] objects.
  BorderRadiusGeometry operator %(double other);

  /// Linearly interpolate between two [BorderRadiusGeometry] objects.
  ///
  /// If either is null, this function interpolates from [BorderRadius.zero],
  /// and the result is an object of the same type as the non-null argument. (If
  /// both are null, this returns null.)
  ///
  /// If [lerp] is applied to two objects of the same type ([BorderRadius] or
  /// [BorderRadiusDirectional]), an object of that type will be returned (though
  /// this is not reflected in the type system). Otherwise, an object
  /// representing a combination of both is returned. That object can be turned
  /// into a concrete [BorderRadius] using [resolve].
  ///
  /// {@macro dart.ui.shadow.lerp}
  static BorderRadiusGeometry lerp(BorderRadiusGeometry a, BorderRadiusGeometry b, double t) {
    assert(t != null);
    if (a == null && b == null)
      return null;
    a ??= BorderRadius.zero;
    b ??= BorderRadius.zero;
    return a.add((b.subtract(a)) * t);
  }

  /// Convert this instance into a [BorderRadius], so that the radii are
  /// expressed for specific physical corners (top-left, top-right, etc) rather
  /// than in a direction-dependent manner.
  ///
  /// See also:
  ///
  ///  * [BorderRadius], for which this is a no-op (returns itself).
  ///  * [BorderRadiusDirectional], which flips the horizontal direction
  ///    based on the `direction` argument.
  BorderRadius resolve(TextDirection direction);

  @override
  String toString() {
    String visual, logical;
    if (_topLeft == _topRight &&
        _topRight == _bottomLeft &&
        _bottomLeft == _bottomRight) {
      if (_topLeft != Radius.zero) {
        if (_topLeft.x == _topLeft.y) {
          visual = 'BorderRadius.circular(${_topLeft.x.toStringAsFixed(1)})';
        } else {
          visual = 'BorderRadius.all($_topLeft)';
        }
      }
    } else {
      // visuals aren't the same and at least one isn't zero
      final StringBuffer result = StringBuffer();
      result.write('BorderRadius.only(');
      bool comma = false;
      if (_topLeft != Radius.zero) {
        result.write('topLeft: $_topLeft');
        comma = true;
      }
      if (_topRight != Radius.zero) {
        if (comma)
          result.write(', ');
        result.write('topRight: $_topRight');
        comma = true;
      }
      if (_bottomLeft != Radius.zero) {
        if (comma)
          result.write(', ');
        result.write('bottomLeft: $_bottomLeft');
        comma = true;
      }
      if (_bottomRight != Radius.zero) {
        if (comma)
          result.write(', ');
        result.write('bottomRight: $_bottomRight');
      }
      result.write(')');
      visual = result.toString();
    }
    if (_topStart == _topEnd &&
        _topEnd == _bottomEnd &&
        _bottomEnd == _bottomStart) {
      if (_topStart != Radius.zero) {
        if (_topStart.x == _topStart.y) {
          logical = 'BorderRadiusDirectional.circular(${_topStart.x.toStringAsFixed(1)})';
        } else {
          logical = 'BorderRadiusDirectional.all($_topStart)';
        }
      }
    } else {
      // logicals aren't the same and at least one isn't zero
      final StringBuffer result = StringBuffer();
      result.write('BorderRadiusDirectional.only(');
      bool comma = false;
      if (_topStart != Radius.zero) {
        result.write('topStart: $_topStart');
        comma = true;
      }
      if (_topEnd != Radius.zero) {
        if (comma)
          result.write(', ');
        result.write('topEnd: $_topEnd');
        comma = true;
      }
      if (_bottomStart != Radius.zero) {
        if (comma)
          result.write(', ');
        result.write('bottomStart: $_bottomStart');
        comma = true;
      }
      if (_bottomEnd != Radius.zero) {
        if (comma)
          result.write(', ');
        result.write('bottomEnd: $_bottomEnd');
      }
      result.write(')');
      logical = result.toString();
    }
    if (visual != null && logical != null)
      return '$visual + $logical';
    if (visual != null)
      return visual;
    if (logical != null)
      return logical;
    return 'BorderRadius.zero';
  }

  @override
  bool operator ==(Object other) {
    if (identical(this, other))
      return true;
    if (other.runtimeType != runtimeType)
      return false;
    return other is BorderRadiusGeometry
        && other._topLeft == _topLeft
        && other._topRight == _topRight
        && other._bottomLeft == _bottomLeft
        && other._bottomRight == _bottomRight
        && other._topStart == _topStart
        && other._topEnd == _topEnd
        && other._bottomStart == _bottomStart
        && other._bottomEnd == _bottomEnd;
  }

  @override
  int get hashCode {
    return hashValues(
      _topLeft,
      _topRight,
      _bottomLeft,
      _bottomRight,
      _topStart,
      _topEnd,
      _bottomStart,
      _bottomEnd,
    );
  }
}

/// An immutable set of radii for each corner of a rectangle.
///
/// Used by [BoxDecoration] when the shape is a [BoxShape.rectangle].
///
/// The [BorderRadius] class specifies offsets in terms of visual corners, e.g.
/// [topLeft]. These values are not affected by the [TextDirection]. To support
/// both left-to-right and right-to-left layouts, consider using
/// [BorderRadiusDirectional], which is expressed in terms that are relative to
/// a [TextDirection] (typically obtained from the ambient [Directionality]).
class BorderRadius extends BorderRadiusGeometry {
  /// Creates a border radius where all radii are [radius].
  const BorderRadius.all(Radius radius) : this.only(
    topLeft: radius,
    topRight: radius,
    bottomLeft: radius,
    bottomRight: radius,
  );

  /// Creates a border radius where all radii are [Radius.circular(radius)].
  BorderRadius.circular(double radius) : this.all(
    Radius.circular(radius),
  );

  /// Creates a vertically symmetric border radius where the top and bottom
  /// sides of the rectangle have the same radii.
  const BorderRadius.vertical({
    Radius top = Radius.zero,
    Radius bottom = Radius.zero,
  }) : this.only(
    topLeft: top,
    topRight: top,
    bottomLeft: bottom,
    bottomRight: bottom,
  );

  /// Creates a horizontally symmetrical border radius where the left and right
  /// sides of the rectangle have the same radii.
  const BorderRadius.horizontal({
    Radius left = Radius.zero,
    Radius right = Radius.zero,
  }) : this.only(
    topLeft: left,
    topRight: right,
    bottomLeft: left,
    bottomRight: right,
  );

  /// Creates a border radius with only the given non-zero values. The other
  /// corners will be right angles.
  const BorderRadius.only({
    this.topLeft = Radius.zero,
    this.topRight = Radius.zero,
    this.bottomLeft = Radius.zero,
    this.bottomRight = Radius.zero,
  });

  /// A border radius with all zero radii.
  static const BorderRadius zero = BorderRadius.all(Radius.zero);

  /// The top-left [Radius].
  final Radius topLeft;

  @override
  Radius get _topLeft => topLeft;

  /// The top-right [Radius].
  final Radius topRight;

  @override
  Radius get _topRight => topRight;

  /// The bottom-left [Radius].
  final Radius bottomLeft;

  @override
  Radius get _bottomLeft => bottomLeft;

  /// The bottom-right [Radius].
  final Radius bottomRight;

  @override
  Radius get _bottomRight => bottomRight;

  @override
  Radius get _topStart => Radius.zero;

  @override
  Radius get _topEnd => Radius.zero;

  @override
  Radius get _bottomStart => Radius.zero;

  @override
  Radius get _bottomEnd => Radius.zero;

  /// Creates an [RRect] from the current border radius and a [Rect].
  RRect toRRect(Rect rect) {
    return RRect.fromRectAndCorners(
      rect,
      topLeft: topLeft,
      topRight: topRight,
      bottomLeft: bottomLeft,
      bottomRight: bottomRight,
    );
  }

  @override
  BorderRadiusGeometry subtract(BorderRadiusGeometry other) {
    if (other is BorderRadius)
      return this - other;
    return super.subtract(other);
  }

  @override
  BorderRadiusGeometry add(BorderRadiusGeometry other) {
    if (other is BorderRadius)
      return this + other;
    return super.add(other);
  }

  /// Returns the difference between two [BorderRadius] objects.
  BorderRadius operator -(BorderRadius other) {
    return BorderRadius.only(
      topLeft: topLeft - other.topLeft,
      topRight: topRight - other.topRight,
      bottomLeft: bottomLeft - other.bottomLeft,
      bottomRight: bottomRight - other.bottomRight,
    );
  }

  /// Returns the sum of two [BorderRadius] objects.
  BorderRadius operator +(BorderRadius other) {
    return BorderRadius.only(
      topLeft: topLeft + other.topLeft,
      topRight: topRight + other.topRight,
      bottomLeft: bottomLeft + other.bottomLeft,
      bottomRight: bottomRight + other.bottomRight,
    );
  }

  /// Returns the [BorderRadius] object with each corner negated.
  ///
  /// This is the same as multiplying the object by -1.0.
  @override
  BorderRadius operator -() {
    return BorderRadius.only(
      topLeft: -topLeft,
      topRight: -topRight,
      bottomLeft: -bottomLeft,
      bottomRight: -bottomRight,
    );
  }

  /// Scales each corner of the [BorderRadius] by the given factor.
  @override
  BorderRadius operator *(double other) {
    return BorderRadius.only(
      topLeft: topLeft * other,
      topRight: topRight * other,
      bottomLeft: bottomLeft * other,
      bottomRight: bottomRight * other,
    );
  }

  /// Divides each corner of the [BorderRadius] by the given factor.
  @override
  BorderRadius operator /(double other) {
    return BorderRadius.only(
      topLeft: topLeft / other,
      topRight: topRight / other,
      bottomLeft: bottomLeft / other,
      bottomRight: bottomRight / other,
    );
  }

  /// Integer divides each corner of the [BorderRadius] by the given factor.
  @override
  BorderRadius operator ~/(double other) {
    return BorderRadius.only(
      topLeft: topLeft ~/ other,
      topRight: topRight ~/ other,
      bottomLeft: bottomLeft ~/ other,
      bottomRight: bottomRight ~/ other,
    );
  }

  /// Computes the remainder of each corner by the given factor.
  @override
  BorderRadius operator %(double other) {
    return BorderRadius.only(
      topLeft: topLeft % other,
      topRight: topRight % other,
      bottomLeft: bottomLeft % other,
      bottomRight: bottomRight % other,
    );
  }

  /// Linearly interpolate between two [BorderRadius] objects.
  ///
  /// If either is null, this function interpolates from [BorderRadius.zero].
  ///
  /// {@macro dart.ui.shadow.lerp}
  static BorderRadius lerp(BorderRadius a, BorderRadius b, double t) {
    assert(t != null);
    if (a == null && b == null)
      return null;
    if (a == null)
      return b * t;
    if (b == null)
      return a * (1.0 - t);
    return BorderRadius.only(
      topLeft: Radius.lerp(a.topLeft, b.topLeft, t),
      topRight: Radius.lerp(a.topRight, b.topRight, t),
      bottomLeft: Radius.lerp(a.bottomLeft, b.bottomLeft, t),
      bottomRight: Radius.lerp(a.bottomRight, b.bottomRight, t),
    );
  }

  @override
  BorderRadius resolve(TextDirection direction) => this;
}

/// An immutable set of radii for each corner of a rectangle, but with the
/// corners specified in a manner dependent on the writing direction.
///
/// This can be used to specify a corner radius on the leading or trailing edge
/// of a box, so that it flips to the other side when the text alignment flips
/// (e.g. being on the top right in English text but the top left in Arabic
/// text).
///
/// See also:
///
///  * [BorderRadius], a variant that uses physical labels (`topLeft` and
///    `topRight` instead of `topStart` and `topEnd`).
class BorderRadiusDirectional extends BorderRadiusGeometry {
  /// Creates a border radius where all radii are [radius].
  const BorderRadiusDirectional.all(Radius radius) : this.only(
    topStart: radius,
    topEnd: radius,
    bottomStart: radius,
    bottomEnd: radius,
  );

  /// Creates a border radius where all radii are [Radius.circular(radius)].
  BorderRadiusDirectional.circular(double radius) : this.all(
    Radius.circular(radius),
  );

  /// Creates a vertically symmetric border radius where the top and bottom
  /// sides of the rectangle have the same radii.
  const BorderRadiusDirectional.vertical({
    Radius top = Radius.zero,
    Radius bottom = Radius.zero,
  }) : this.only(
    topStart: top,
    topEnd: top,
    bottomStart: bottom,
    bottomEnd: bottom,
  );

  /// Creates a horizontally symmetrical border radius where the start and end
  /// sides of the rectangle have the same radii.
  const BorderRadiusDirectional.horizontal({
    Radius start = Radius.zero,
    Radius end = Radius.zero,
  }) : this.only(
    topStart: start,
    topEnd: end,
    bottomStart: start,
    bottomEnd: end,
  );

  /// Creates a border radius with only the given non-zero values. The other
  /// corners will be right angles.
  const BorderRadiusDirectional.only({
    this.topStart = Radius.zero,
    this.topEnd = Radius.zero,
    this.bottomStart = Radius.zero,
    this.bottomEnd = Radius.zero,
  });

  /// A border radius with all zero radii.
  ///
  /// Consider using [EdgeInsets.zero] instead, since that object has the same
  /// effect, but will be cheaper to [resolve].
  static const BorderRadiusDirectional zero = BorderRadiusDirectional.all(Radius.zero);

  /// The top-start [Radius].
  final Radius topStart;

  @override
  Radius get _topStart => topStart;

  /// The top-end [Radius].
  final Radius topEnd;

  @override
  Radius get _topEnd => topEnd;

  /// The bottom-start [Radius].
  final Radius bottomStart;

  @override
  Radius get _bottomStart => bottomStart;

  /// The bottom-end [Radius].
  final Radius bottomEnd;

  @override
  Radius get _bottomEnd => bottomEnd;

  @override
  Radius get _topLeft => Radius.zero;

  @override
  Radius get _topRight => Radius.zero;

  @override
  Radius get _bottomLeft => Radius.zero;

  @override
  Radius get _bottomRight => Radius.zero;

  @override
  BorderRadiusGeometry subtract(BorderRadiusGeometry other) {
    if (other is BorderRadiusDirectional)
      return this - other;
    return super.subtract(other);
  }

  @override
  BorderRadiusGeometry add(BorderRadiusGeometry other) {
    if (other is BorderRadiusDirectional)
      return this + other;
    return super.add(other);
  }

  /// Returns the difference between two [BorderRadiusDirectional] objects.
  BorderRadiusDirectional operator -(BorderRadiusDirectional other) {
    return BorderRadiusDirectional.only(
      topStart: topStart - other.topStart,
      topEnd: topEnd - other.topEnd,
      bottomStart: bottomStart - other.bottomStart,
      bottomEnd: bottomEnd - other.bottomEnd,
    );
  }

  /// Returns the sum of two [BorderRadiusDirectional] objects.
  BorderRadiusDirectional operator +(BorderRadiusDirectional other) {
    return BorderRadiusDirectional.only(
      topStart: topStart + other.topStart,
      topEnd: topEnd + other.topEnd,
      bottomStart: bottomStart + other.bottomStart,
      bottomEnd: bottomEnd + other.bottomEnd,
    );
  }

  /// Returns the [BorderRadiusDirectional] object with each corner negated.
  ///
  /// This is the same as multiplying the object by -1.0.
  @override
  BorderRadiusDirectional operator -() {
    return BorderRadiusDirectional.only(
      topStart: -topStart,
      topEnd: -topEnd,
      bottomStart: -bottomStart,
      bottomEnd: -bottomEnd,
    );
  }

  /// Scales each corner of the [BorderRadiusDirectional] by the given factor.
  @override
  BorderRadiusDirectional operator *(double other) {
    return BorderRadiusDirectional.only(
      topStart: topStart * other,
      topEnd: topEnd * other,
      bottomStart: bottomStart * other,
      bottomEnd: bottomEnd * other,
    );
  }

  /// Divides each corner of the [BorderRadiusDirectional] by the given factor.
  @override
  BorderRadiusDirectional operator /(double other) {
    return BorderRadiusDirectional.only(
      topStart: topStart / other,
      topEnd: topEnd / other,
      bottomStart: bottomStart / other,
      bottomEnd: bottomEnd / other,
    );
  }

  /// Integer divides each corner of the [BorderRadiusDirectional] by the given factor.
  @override
  BorderRadiusDirectional operator ~/(double other) {
    return BorderRadiusDirectional.only(
      topStart: topStart ~/ other,
      topEnd: topEnd ~/ other,
      bottomStart: bottomStart ~/ other,
      bottomEnd: bottomEnd ~/ other,
    );
  }

  /// Computes the remainder of each corner by the given factor.
  @override
  BorderRadiusDirectional operator %(double other) {
    return BorderRadiusDirectional.only(
      topStart: topStart % other,
      topEnd: topEnd % other,
      bottomStart: bottomStart % other,
      bottomEnd: bottomEnd % other,
    );
  }

  /// Linearly interpolate between two [BorderRadiusDirectional] objects.
  ///
  /// If either is null, this function interpolates from [BorderRadiusDirectional.zero].
  ///
  /// {@macro dart.ui.shadow.lerp}
  static BorderRadiusDirectional lerp(BorderRadiusDirectional a, BorderRadiusDirectional b, double t) {
    assert(t != null);
    if (a == null && b == null)
      return null;
    if (a == null)
      return b * t;
    if (b == null)
      return a * (1.0 - t);
    return BorderRadiusDirectional.only(
      topStart: Radius.lerp(a.topStart, b.topStart, t),
      topEnd: Radius.lerp(a.topEnd, b.topEnd, t),
      bottomStart: Radius.lerp(a.bottomStart, b.bottomStart, t),
      bottomEnd: Radius.lerp(a.bottomEnd, b.bottomEnd, t),
    );
  }

  @override
  BorderRadius resolve(TextDirection direction) {
    assert(direction != null);
    switch (direction) {
      case TextDirection.rtl:
        return BorderRadius.only(
          topLeft: topEnd,
          topRight: topStart,
          bottomLeft: bottomEnd,
          bottomRight: bottomStart,
        );
      case TextDirection.ltr:
        return BorderRadius.only(
          topLeft: topStart,
          topRight: topEnd,
          bottomLeft: bottomStart,
          bottomRight: bottomEnd,
        );
    }
    return null;
  }
}

class _MixedBorderRadius extends BorderRadiusGeometry {
  const _MixedBorderRadius(
    this._topLeft,
    this._topRight,
    this._bottomLeft,
    this._bottomRight,
    this._topStart,
    this._topEnd,
    this._bottomStart,
    this._bottomEnd,
  );

  @override
  final Radius _topLeft;

  @override
  final Radius _topRight;

  @override
  final Radius _bottomLeft;

  @override
  final Radius _bottomRight;

  @override
  final Radius _topStart;

  @override
  final Radius _topEnd;

  @override
  final Radius _bottomStart;

  @override
  final Radius _bottomEnd;

  @override
  _MixedBorderRadius operator -() {
    return _MixedBorderRadius(
      -_topLeft,
      -_topRight,
      -_bottomLeft,
      -_bottomRight,
      -_topStart,
      -_topEnd,
      -_bottomStart,
      -_bottomEnd,
    );
  }

  /// Scales each corner of the [_MixedBorderRadius] by the given factor.
  @override
  _MixedBorderRadius operator *(double other) {
    return _MixedBorderRadius(
      _topLeft * other,
      _topRight * other,
      _bottomLeft * other,
      _bottomRight * other,
      _topStart * other,
      _topEnd * other,
      _bottomStart * other,
      _bottomEnd * other,
    );
  }

  @override
  _MixedBorderRadius operator /(double other) {
    return _MixedBorderRadius(
      _topLeft / other,
      _topRight / other,
      _bottomLeft / other,
      _bottomRight / other,
      _topStart / other,
      _topEnd / other,
      _bottomStart / other,
      _bottomEnd / other,
    );
  }

  @override
  _MixedBorderRadius operator ~/(double other) {
    return _MixedBorderRadius(
      _topLeft ~/ other,
      _topRight ~/ other,
      _bottomLeft ~/ other,
      _bottomRight ~/ other,
      _topStart ~/ other,
      _topEnd ~/ other,
      _bottomStart ~/ other,
      _bottomEnd ~/ other,
    );
  }

  @override
  _MixedBorderRadius operator %(double other) {
    return _MixedBorderRadius(
      _topLeft % other,
      _topRight % other,
      _bottomLeft % other,
      _bottomRight % other,
      _topStart % other,
      _topEnd % other,
      _bottomStart % other,
      _bottomEnd % other,
    );
  }

  @override
  BorderRadius resolve(TextDirection direction) {
    assert(direction != null);
    switch (direction) {
      case TextDirection.rtl:
        return BorderRadius.only(
          topLeft: _topLeft + _topEnd,
          topRight: _topRight + _topStart,
          bottomLeft: _bottomLeft + _bottomEnd,
          bottomRight: _bottomRight + _bottomStart,
        );
      case TextDirection.ltr:
        return BorderRadius.only(
          topLeft: _topLeft + _topStart,
          topRight: _topRight + _topEnd,
          bottomLeft: _bottomLeft + _bottomStart,
          bottomRight: _bottomRight + _bottomEnd,
        );
    }
    return null;
  }
}