com.unity.uiwidgets/com.unity.uiwidgets/Runtime/painting/alignment.cs

using System;
using Unity.UIWidgets.foundation;
using Unity.UIWidgets.ui;

namespace Unity.UIWidgets.painting {
    public abstract class AlignmentGeometry {
        public AlignmentGeometry() {
        }

        protected float _x { get; }

        protected float _start { get; }

        protected float _y { get; }

        // public static AlignmentGeometry add(AlignmentGeometry other) {
        //   return new _MixedAlignment(
        //     _x + other._x,
        //     _start + other._start,
        //     _y + other._y,
        //   );
        // }

        // public abstract AlignmentGeometry operator -();
        //
        // public abstract AlignmentGeometry operator *(double other);
        //
        // public abstract AlignmentGeometry operator /(double other);
        //
        // public abstract AlignmentGeometry operator ~/(double other);
        //
        // public abstract AlignmentGeometry operator %(double other);

        // static AlignmentGeometry lerp(AlignmentGeometry a, AlignmentGeometry b, float t) {
        //   D.assert(t != null);
        //   if (a == null && b == null)
        //     return null;
        //   if (a == null)
        //     return b * t;
        //   if (b == null)
        //     return a * (1.0 - t);
        //   if (a is Alignment && b is Alignment)
        //     return Alignment.lerp(a, b, t);
        //   if (a is AlignmentDirectional && b is AlignmentDirectional)
        //     return AlignmentDirectional.lerp(a, b, t);
        //   return _MixedAlignment(
        //     ui.lerpDouble(a._x, b._x, t),
        //     ui.lerpDouble(a._start, b._start, t),
        //     ui.lerpDouble(a._y, b._y, t),
        //   );
        // }
        //
        public abstract Alignment resolve(TextDirection? direction);
        //
        // @override
        // String toString() {
        //   if (_start == 0.0)
        //     return Alignment._stringify(_x, _y);
        //   if (_x == 0.0)
        //     return AlignmentDirectional._stringify(_start, _y);
        //   return Alignment._stringify(_x, _y) + ' + ' + AlignmentDirectional._stringify(_start, 0.0);
        // }
        //
        // @override
        // bool operator ==(Object other) {
        //   return other is AlignmentGeometry
        //       && other._x == _x
        //       && other._start == _start
        //       && other._y == _y;
        // }
        //
        // @override
        // int get hashCode => hashValues(_x, _start, _y);
    }

    public class Alignment : AlignmentGeometry, IEquatable<Alignment> {
        public Alignment(float x, float y) {
            this.x = x;
            this.y = y;
        }

        public readonly float x;

        public readonly float y;

        public static readonly Alignment topLeft = new Alignment(-1.0f, -1.0f);
        public static readonly Alignment topCenter = new Alignment(0, -1.0f);
        public static readonly Alignment topRight = new Alignment(1.0f, -1.0f);
        public static readonly Alignment centerLeft = new Alignment(-1.0f, 0.0f);
        public static readonly Alignment center = new Alignment(0.0f, 0.0f);
        public static readonly Alignment centerRight = new Alignment(1.0f, 0.0f);
        public static readonly Alignment bottomLeft = new Alignment(-1.0f, 1.0f);
        public static readonly Alignment bottomCenter = new Alignment(0.0f, 1.0f);
        public static readonly Alignment bottomRight = new Alignment(1.0f, 1.0f);

        public static Alignment operator -(Alignment a, Alignment b) {
            return new Alignment(a.x - b.x, a.y - b.y);
        }

        public static Alignment operator +(Alignment a, Alignment b) {
            return new Alignment(a.x + b.x, a.y + b.y);
        }

        public static Alignment operator -(Alignment a) {
            return new Alignment(-a.x, -a.y);
        }

        public static Alignment operator *(Alignment a, float b) {
            return new Alignment(a.x * b, a.y * b);
        }

        public static Alignment operator /(Alignment a, float b) {
            return new Alignment(a.x / b, a.y / b);
        }

        public static Alignment operator %(Alignment a, float b) {
            return new Alignment(a.x % b, a.y % b);
        }

        public Offset alongOffset(Offset other) {
            float centerX = other.dx / 2.0f;
            float centerY = other.dy / 2.0f;
            return new Offset(centerX + x * centerX, centerY + y * centerY);
        }

        public Offset alongSize(Size other) {
            float centerX = other.width / 2.0f;
            float centerY = other.height / 2.0f;
            return new Offset(centerX + x * centerX, centerY + y * centerY);
        }

        public Offset withinRect(Rect rect) {
            float halfWidth = rect.width / 2.0f;
            float halfHeight = rect.height / 2.0f;
            return new Offset(
                rect.left + halfWidth + x * halfWidth,
                rect.top + halfHeight + y * halfHeight
            );
        }

        public Rect inscribe(Size size, Rect rect) {
            float halfWidthDelta = (rect.width - size.width) / 2.0f;
            float halfHeightDelta = (rect.height - size.height) / 2.0f;
            return Rect.fromLTWH(
                rect.left + halfWidthDelta + x * halfWidthDelta,
                rect.top + halfHeightDelta + y * halfHeightDelta,
                size.width,
                size.height
            );
        }

        public static Alignment lerp(Alignment a, Alignment b, float t) {
            if (a == null && b == null) {
                return null;
            }

            if (a == null) {
                return new Alignment(MathUtils.lerpFloat(0.0f, b.x, t), MathUtils.lerpFloat(0.0f, b.y, t));
            }

            if (b == null) {
                return new Alignment(MathUtils.lerpFloat(a.x, 0.0f, t), MathUtils.lerpFloat(a.y, 0.0f, t));
            }

            return new Alignment(MathUtils.lerpFloat(a.x, b.x, t), MathUtils.lerpFloat(a.y, b.y, t));
        }

        public bool Equals(Alignment other) {
            if (ReferenceEquals(null, other)) {
                return false;
            }

            if (ReferenceEquals(this, other)) {
                return true;
            }

            return x.Equals(other.x) && y.Equals(other.y);
        }

        public override bool Equals(object obj) {
            if (ReferenceEquals(null, obj)) {
                return false;
            }

            if (ReferenceEquals(this, obj)) {
                return true;
            }

            if (obj.GetType() != GetType()) {
                return false;
            }

            return Equals((Alignment) obj);
        }

        public override int GetHashCode() {
            unchecked {
                return (x.GetHashCode() * 397) ^ y.GetHashCode();
            }
        }

        public static bool operator ==(Alignment a, Alignment b) {
            return Equals(a, b);
        }

        public static bool operator !=(Alignment a, Alignment b) {
            return !(a == b);
        }

        public override string ToString() {
            if (x == -1.0f && y == -1.0f) {
                return "topLeft";
            }

            if (x == 0.0f && y == -1.0f) {
                return "topCenter";
            }

            if (x == 1.0f && y == -1.0f) {
                return "topRight";
            }

            if (x == -1.0f && y == 0.0f) {
                return "centerLeft";
            }

            if (x == 0.0f && y == 0.0f) {
                return "center";
            }

            if (x == 1.0f && y == 0.0f) {
                return "centerRight";
            }

            if (x == -1.0f && y == 1.0f) {
                return "bottomLeft";
            }

            if (x == 0.0f && y == 1.0f) {
                return "bottomCenter";
            }

            if (x == 1.0f && y == 1.0f) {
                return "bottomRight";
            }

            return $"Alignment({x:F1}, {y:F1})";
        }

        public override Alignment resolve(TextDirection? direction) {
            D.assert(direction != null);
            switch (direction) {
                case TextDirection.rtl:
                    return new Alignment(_x - _start, _y);
                case TextDirection.ltr:
                    return new Alignment(_x + _start, _y);
            }
            return null;
        }
    }
}