ImageSharp/src/ImageSharp/Memory/Buffer2DExtensions.cs

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

using System;
using System.Runtime.CompilerServices;
using SixLabors.Primitives;

namespace SixLabors.Memory
{
    /// <summary>
    /// Defines extension methods for <see cref="Buffer2D{T}"/>.
    /// </summary>
    internal static class Buffer2DExtensions
    {
        /// <summary>
        /// Gets a <see cref="Span{T}"/> to the backing buffer of <paramref name="buffer"/>.
        /// </summary>
        internal static Span<T> GetSpan<T>(this Buffer2D<T> buffer)
            where T : struct
        {
            return buffer.MemorySource.GetSpan();
        }

        /// <summary>
        /// Gets a <see cref="Span{T}"/> to the row 'y' beginning from the pixel at 'x'.
        /// </summary>
        /// <param name="buffer">The buffer</param>
        /// <param name="x">The x coordinate (position in the row)</param>
        /// <param name="y">The y (row) coordinate</param>
        /// <typeparam name="T">The element type</typeparam>
        /// <returns>The <see cref="Span{T}"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Span<T> GetRowSpan<T>(this Buffer2D<T> buffer, int x, int y)
            where T : struct
        {
            return buffer.GetSpan().Slice((y * buffer.Width) + x, buffer.Width - x);
        }

        /// <summary>
        /// Gets a <see cref="Span{T}"/> to the row 'y' beginning from the pixel at the first pixel on that row.
        /// </summary>
        /// <param name="buffer">The buffer</param>
        /// <param name="y">The y (row) coordinate</param>
        /// <typeparam name="T">The element type</typeparam>
        /// <returns>The <see cref="Span{T}"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Span<T> GetRowSpan<T>(this Buffer2D<T> buffer, int y)
            where T : struct
        {
            return buffer.GetSpan().Slice(y * buffer.Width, buffer.Width);
        }

        /// <summary>
        /// Gets a <see cref="Memory{T}"/> to the row 'y' beginning from the pixel at the first pixel on that row.
        /// </summary>
        /// <param name="buffer">The buffer</param>
        /// <param name="y">The y (row) coordinate</param>
        /// <typeparam name="T">The element type</typeparam>
        /// <returns>The <see cref="Span{T}"/></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Memory<T> GetRowMemory<T>(this Buffer2D<T> buffer, int y)
            where T : struct
        {
            return buffer.MemorySource.Memory.Slice(y * buffer.Width, buffer.Width);
        }

        /// <summary>
        /// Returns the size of the buffer.
        /// </summary>
        /// <typeparam name="T">The element type</typeparam>
        /// <param name="buffer">The <see cref="Buffer2D{T}"/></param>
        /// <returns>The <see cref="Size{T}"/> of the buffer</returns>
        public static Size Size<T>(this Buffer2D<T> buffer)
            where T : struct
        {
            return new Size(buffer.Width, buffer.Height);
        }

        /// <summary>
        /// Returns a <see cref="Rectangle"/> representing the full area of the buffer.
        /// </summary>
        /// <typeparam name="T">The element type</typeparam>
        /// <param name="buffer">The <see cref="Buffer2D{T}"/></param>
        /// <returns>The <see cref="Rectangle"/></returns>
        public static Rectangle FullRectangle<T>(this Buffer2D<T> buffer)
            where T : struct
        {
            return new Rectangle(0, 0, buffer.Width, buffer.Height);
        }

        /// <summary>
        /// Return a <see cref="BufferArea{T}"/> to the subarea represented by 'rectangle'
        /// </summary>
        /// <typeparam name="T">The element type</typeparam>
        /// <param name="buffer">The <see cref="Buffer2D{T}"/></param>
        /// <param name="rectangle">The rectangle subarea</param>
        /// <returns>The <see cref="BufferArea{T}"/></returns>
        public static BufferArea<T> GetArea<T>(this Buffer2D<T> buffer, Rectangle rectangle)
            where T : struct => new BufferArea<T>(buffer, rectangle);

        public static BufferArea<T> GetArea<T>(this Buffer2D<T> buffer, int x, int y, int width, int height)
            where T : struct
        {
            var rectangle = new Rectangle(x, y, width, height);
            return new BufferArea<T>(buffer, rectangle);
        }

        /// <summary>
        /// Return a <see cref="BufferArea{T}"/> to the whole area of 'buffer'
        /// </summary>
        /// <typeparam name="T">The element type</typeparam>
        /// <param name="buffer">The <see cref="Buffer2D{T}"/></param>
        /// <returns>The <see cref="BufferArea{T}"/></returns>
        public static BufferArea<T> GetArea<T>(this Buffer2D<T> buffer)
            where T : struct => new BufferArea<T>(buffer);
    }
}