ImageSharp/src/SixLabors.Core/Primitives/Rectangle.cs

// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.

using System;
using System.ComponentModel;
using System.Numerics;
using System.Runtime.CompilerServices;

namespace SixLabors.Primitives
{
    /// <summary>
    /// Stores a set of four integers that represent the location and size of a rectangle.
    /// </summary>
    /// <remarks>
    /// This struct is fully mutable. This is done (against the guidelines) for the sake of performance,
    /// as it avoids the need to create new values for modification operations.
    /// </remarks>
    public struct Rectangle : IEquatable<Rectangle>
    {
        /// <summary>
        /// Represents a <see cref="Rectangle"/> that has X, Y, Width, and Height values set to zero.
        /// </summary>
        public static readonly Rectangle Empty = default(Rectangle);

        /// <summary>
        /// Initializes a new instance of the <see cref="Rectangle"/> struct.
        /// </summary>
        /// <param name="x">The horizontal position of the rectangle.</param>
        /// <param name="y">The vertical position of the rectangle.</param>
        /// <param name="width">The width of the rectangle.</param>
        /// <param name="height">The height of the rectangle.</param>
        public Rectangle(int x, int y, int width, int height)
        {
            this.X = x;
            this.Y = y;
            this.Width = width;
            this.Height = height;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="Rectangle"/> struct.
        /// </summary>
        /// <param name="point">
        /// The <see cref="Point"/> which specifies the rectangles point in a two-dimensional plane.
        /// </param>
        /// <param name="size">
        /// The <see cref="Size"/> which specifies the rectangles height and width.
        /// </param>
        public Rectangle(Point point, Size size)
        {
            this.X = point.X;
            this.Y = point.Y;
            this.Width = size.Width;
            this.Height = size.Height;
        }

        /// <summary>
        /// Gets or sets the x-coordinate of this <see cref="Rectangle"/>.
        /// </summary>
        public int X { get; set; }

        /// <summary>
        /// Gets or sets the y-coordinate of this <see cref="Rectangle"/>.
        /// </summary>
        public int Y { get; set; }

        /// <summary>
        /// Gets or sets the width of this <see cref="Rectangle"/>.
        /// </summary>
        public int Width { get; set; }

        /// <summary>
        /// Gets or sets the height of this <see cref="Rectangle"/>.
        /// </summary>
        public int Height { get; set; }

        /// <summary>
        /// Gets or sets the coordinates of the upper-left corner of the rectangular region represented by this <see cref="Rectangle"/>.
        /// </summary>
        [EditorBrowsable(EditorBrowsableState.Never)]
        public Point Location
        {
            [MethodImpl(MethodImplOptions.AggressiveInlining)]
            get => new Point(this.X, this.Y);

            [MethodImpl(MethodImplOptions.AggressiveInlining)]
            set
            {
                this.X = value.X;
                this.Y = value.Y;
            }
        }

        /// <summary>
        /// Gets or sets the size of this <see cref="Rectangle"/>.
        /// </summary>
        [EditorBrowsable(EditorBrowsableState.Never)]
        public Size Size
        {
            [MethodImpl(MethodImplOptions.AggressiveInlining)]
            get => new Size(this.Width, this.Height);

            [MethodImpl(MethodImplOptions.AggressiveInlining)]
            set
            {
                this.Width = value.Width;
                this.Height = value.Height;
            }
        }

        /// <summary>
        /// Gets a value indicating whether this <see cref="Rectangle"/> is empty.
        /// </summary>
        [EditorBrowsable(EditorBrowsableState.Never)]
        public bool IsEmpty => this.Equals(Empty);

        /// <summary>
        /// Gets the y-coordinate of the top edge of this <see cref="Rectangle"/>.
        /// </summary>
        public int Top => this.Y;

        /// <summary>
        /// Gets the x-coordinate of the right edge of this <see cref="Rectangle"/>.
        /// </summary>
        public int Right
        {
            [MethodImpl(MethodImplOptions.AggressiveInlining)]
            get => unchecked(this.X + this.Width);
        }

        /// <summary>
        /// Gets the y-coordinate of the bottom edge of this <see cref="Rectangle"/>.
        /// </summary>
        public int Bottom
        {
            [MethodImpl(MethodImplOptions.AggressiveInlining)]
            get => unchecked(this.Y + this.Height);

        }

        /// <summary>
        /// Gets the x-coordinate of the left edge of this <see cref="Rectangle"/>.
        /// </summary>
        public int Left => this.X;

        /// <summary>
        /// Creates a <see cref="RectangleF"/> with the coordinates of the specified <see cref="Rectangle"/>.
        /// </summary>
        /// <param name="rectangle">The rectangle</param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static implicit operator RectangleF(Rectangle rectangle) => new RectangleF(rectangle.X, rectangle.Y, rectangle.Width, rectangle.Height);

        /// <summary>
        /// Creates a <see cref="Vector4"/> with the coordinates of the specified <see cref="Rectangle"/>.
        /// </summary>
        /// <param name="rectangle">The rectangle</param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static implicit operator Vector4(Rectangle rectangle) => new Vector4(rectangle.X, rectangle.Y, rectangle.Width, rectangle.Height);

        /// <summary>
        /// Compares two <see cref="Rectangle"/> objects for equality.
        /// </summary>
        /// <param name="left">The <see cref="Rectangle"/> on the left side of the operand.</param>
        /// <param name="right">The <see cref="Rectangle"/> on the right side of the operand.</param>
        /// <returns>
        /// True if the current left is equal to the <paramref name="right"/> parameter; otherwise, false.
        /// </returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static bool operator ==(Rectangle left, Rectangle right) => left.Equals(right);

        /// <summary>
        /// Compares two <see cref="Rectangle"/> objects for inequality.
        /// </summary>
        /// <param name="left">The <see cref="Rectangle"/> on the left side of the operand.</param>
        /// <param name="right">The <see cref="Rectangle"/> on the right side of the operand.</param>
        /// <returns>
        /// True if the current left is unequal to the <paramref name="right"/> parameter; otherwise, false.
        /// </returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static bool operator !=(Rectangle left, Rectangle right) => !left.Equals(right);

        /// <summary>
        /// Creates a new <see cref="Rectangle"/> with the specified location and size. </summary>
        /// <param name="left">The left coordinate of the rectangle</param>
        /// <param name="top">The top coordinate of the rectangle</param>
        /// <param name="right">The right coordinate of the rectangle</param>
        /// <param name="bottom">The bottom coordinate of the rectangle</param>
        /// <returns>The <see cref="Rectangle"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]

        // ReSharper disable once InconsistentNaming
        public static Rectangle FromLTRB(int left, int top, int right, int bottom) => new Rectangle(left, top, unchecked(right - left), unchecked(bottom - top));

        /// <summary>
        /// Returns the center point of the given <see cref="Rectangle"/>
        /// </summary>
        /// <param name="rectangle">The rectangle</param>
        /// <returns>The <see cref="Point"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Point Center(Rectangle rectangle) => new Point(rectangle.Left + (rectangle.Width / 2), rectangle.Top + (rectangle.Height / 2));

        /// <summary>
        /// Creates a rectangle that represents the intersection between <paramref name="a"/> and
        /// <paramref name="b"/>. If there is no intersection, an empty rectangle is returned.
        /// </summary>
        /// <param name="a">The first rectangle</param>
        /// <param name="b">The second rectangle</param>
        /// <returns>The <see cref="Rectangle"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Rectangle Intersect(Rectangle a, Rectangle b)
        {
            int x1 = Math.Max(a.X, b.X);
            int x2 = Math.Min(a.Right, b.Right);
            int y1 = Math.Max(a.Y, b.Y);
            int y2 = Math.Min(a.Bottom, b.Bottom);

            if (x2 >= x1 && y2 >= y1)
            {
                return new Rectangle(x1, y1, x2 - x1, y2 - y1);
            }

            return Empty;
        }

        /// <summary>
        /// Creates a <see cref="Rectangle"/> that is inflated by the specified amount.
        /// </summary>
        /// <param name="rectangle">The rectangle</param>
        /// <param name="x">The amount to inflate the width by</param>
        /// <param name="y">The amount to inflate the height by</param>
        /// <returns>A new <see cref="Rectangle"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Rectangle Inflate(Rectangle rectangle, int x, int y)
        {
            Rectangle r = rectangle;
            r.Inflate(x, y);
            return r;
        }

        /// <summary>
        /// Converts a <see cref="RectangleF"/> to a <see cref="Rectangle"/> by performing a ceiling operation on all the coordinates.
        /// </summary>
        /// <param name="rectangle">The rectangle</param>
        /// <returns>The <see cref="Rectangle"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Rectangle Ceiling(RectangleF rectangle)
        {
            unchecked
            {
                return new Rectangle(
                    (int)MathF.Ceiling(rectangle.X),
                    (int)MathF.Ceiling(rectangle.Y),
                    (int)MathF.Ceiling(rectangle.Width),
                    (int)MathF.Ceiling(rectangle.Height));
            }
        }

        /// <summary>
        /// Transforms a rectangle by the given matrix.
        /// </summary>
        /// <param name="rectangle">The source rectangle.</param>
        /// <param name="matrix">The transformation matrix.</param>
        /// <returns>A transformed rectangle.</returns>
        public static RectangleF Transform(Rectangle rectangle, Matrix3x2 matrix)
        {
            PointF bottomRight = Point.Transform(new Point(rectangle.Right, rectangle.Bottom), matrix);
            PointF topLeft = Point.Transform(rectangle.Location, matrix);
            return new RectangleF(topLeft, new SizeF(bottomRight - topLeft));
        }

        /// <summary>
        /// Converts a <see cref="RectangleF"/> to a <see cref="Rectangle"/> by performing a truncate operation on all the coordinates.
        /// </summary>
        /// <param name="rectangle">The rectangle</param>
        /// <returns>The <see cref="Rectangle"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Rectangle Truncate(RectangleF rectangle)
        {
            unchecked
            {
                return new Rectangle(
                    (int)rectangle.X,
                    (int)rectangle.Y,
                    (int)rectangle.Width,
                    (int)rectangle.Height);
            }
        }

        /// <summary>
        /// Converts a <see cref="RectangleF"/> to a <see cref="Rectangle"/> by performing a round operation on all the coordinates.
        /// </summary>
        /// <param name="rectangle">The rectangle</param>
        /// <returns>The <see cref="Rectangle"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Rectangle Round(RectangleF rectangle)
        {
            unchecked
            {
                return new Rectangle(
                    (int)MathF.Round(rectangle.X),
                    (int)MathF.Round(rectangle.Y),
                    (int)MathF.Round(rectangle.Width),
                    (int)MathF.Round(rectangle.Height));
            }
        }

        /// <summary>
        /// Creates a rectangle that represents the union between <paramref name="a"/> and <paramref name="b"/>.
        /// </summary>
        /// <param name="a">The first rectangle</param>
        /// <param name="b">The second rectangle</param>
        /// <returns>The <see cref="Rectangle"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Rectangle Union(Rectangle a, Rectangle b)
        {
            int x1 = Math.Min(a.X, b.X);
            int x2 = Math.Max(a.Right, b.Right);
            int y1 = Math.Min(a.Y, b.Y);
            int y2 = Math.Max(a.Bottom, b.Bottom);

            return new Rectangle(x1, y1, x2 - x1, y2 - y1);
        }

        /// <summary>
        /// Creates a Rectangle that represents the intersection between this Rectangle and the <paramref name="rectangle"/>.
        /// </summary>
        /// <param name="rectangle">The rectangle</param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public void Intersect(Rectangle rectangle)
        {
            Rectangle result = Intersect(rectangle, this);

            this.X = result.X;
            this.Y = result.Y;
            this.Width = result.Width;
            this.Height = result.Height;
        }

        /// <summary>
        /// Inflates this <see cref="Rectangle"/> by the specified amount.
        /// </summary>
        /// <param name="width">The width</param>
        /// <param name="height">The height</param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public void Inflate(int width, int height)
        {
            unchecked
            {
                this.X -= width;
                this.Y -= height;

                this.Width += 2 * width;
                this.Height += 2 * height;
            }
        }

        /// <summary>
        /// Inflates this <see cref="Rectangle"/> by the specified amount.
        /// </summary>
        /// <param name="size">The size</param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public void Inflate(Size size) => this.Inflate(size.Width, size.Height);

        /// <summary>
        /// Determines if the specfied point is contained within the rectangular region defined by
        /// this <see cref="Rectangle"/>.
        /// </summary>
        /// <param name="x">The x-coordinate of the given point.</param>
        /// <param name="y">The y-coordinate of the given point.</param>
        /// <returns>The <see cref="bool"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool Contains(int x, int y) => this.X <= x && x < this.Right && this.Y <= y && y < this.Bottom;

        /// <summary>
        /// Determines if the specified point is contained within the rectangular region defined by this <see cref="Rectangle"/> .
        /// </summary>
        /// <param name="point">The point</param>
        /// <returns>The <see cref="bool"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool Contains(Point point) => this.Contains(point.X, point.Y);

        /// <summary>
        /// Determines if the rectangular region represented by <paramref name="rectangle"/> is entirely contained
        /// within the rectangular region represented by this <see cref="Rectangle"/> .
        /// </summary>
        /// <param name="rectangle">The rectangle</param>
        /// <returns>The <see cref="bool"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool Contains(Rectangle rectangle) =>
            (this.X <= rectangle.X) && (rectangle.Right <= this.Right) &&
            (this.Y <= rectangle.Y) && (rectangle.Bottom <= this.Bottom);

        /// <summary>
        /// Determines if the specfied <see cref="Rectangle"/> intersects the rectangular region defined by
        /// this <see cref="Rectangle"/>.
        /// </summary>
        /// <param name="rectangle">The other Rectange </param>
        /// <returns>The <see cref="bool"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool IntersectsWith(Rectangle rectangle) =>
            (rectangle.X < this.Right) && (this.X < rectangle.Right) &&
            (rectangle.Y < this.Bottom) && (this.Y < rectangle.Bottom);

        /// <summary>
        /// Adjusts the location of this rectangle by the specified amount.
        /// </summary>
        /// <param name="point">The point</param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public void Offset(Point point) => this.Offset(point.X, point.Y);

        /// <summary>
        /// Adjusts the location of this rectangle by the specified amount.
        /// </summary>
        /// <param name="dx">The amount to offset the x-coordinate.</param>
        /// <param name="dy">The amount to offset the y-coordinate.</param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public void Offset(int dx, int dy)
        {
            unchecked
            {
                this.X += dx;
                this.Y += dy;
            }
        }

        /// <inheritdoc/>
        public override int GetHashCode()
        {
            return HashHelpers.Combine(
               this.X.GetHashCode(),
               this.Y.GetHashCode(),
               this.Width.GetHashCode(),
               this.Height.GetHashCode());
        }

        /// <inheritdoc/>
        public override string ToString()
        {
            return $"Rectangle [ X={this.X}, Y={this.Y}, Width={this.Width}, Height={this.Height} ]";
        }

        /// <inheritdoc/>
        public override bool Equals(object obj) => obj is Rectangle other && this.Equals(other);

        /// <inheritdoc/>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool Equals(Rectangle other) => this.X == other.X && this.Y == other.Y && this.Width == other.Width && this.Height == other.Height;
    }
}