TiffBitsPerSample.cs

// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

namespace SixLabors.ImageSharp.Formats.Tiff;

/// <summary>
/// The number of bits per component.
/// </summary>
public readonly struct TiffBitsPerSample : IEquatable<TiffBitsPerSample>
{
    /// <summary>
    /// Initializes a new instance of the <see cref="TiffBitsPerSample"/> struct.
    /// </summary>
    /// <param name="channel0">The bits for the channel 0.</param>
    /// <param name="channel1">The bits for the channel 1.</param>
    /// <param name="channel2">The bits for the channel 2.</param>
    /// <param name="channel3">The bits for the channel 3.</param>
    public TiffBitsPerSample(ushort channel0, ushort channel1, ushort channel2, ushort channel3 = 0)
    {
        this.Channel0 = (ushort)Numerics.Clamp(channel0, 0, 32);
        this.Channel1 = (ushort)Numerics.Clamp(channel1, 0, 32);
        this.Channel2 = (ushort)Numerics.Clamp(channel2, 0, 32);
        this.Channel3 = (ushort)Numerics.Clamp(channel3, 0, 32);

        this.Channels = 0;
        this.Channels += (byte)(this.Channel0 != 0 ? 1 : 0);
        this.Channels += (byte)(this.Channel1 != 0 ? 1 : 0);
        this.Channels += (byte)(this.Channel2 != 0 ? 1 : 0);
        this.Channels += (byte)(this.Channel3 != 0 ? 1 : 0);
    }

    /// <summary>
    /// Gets the bits for the channel 0.
    /// </summary>
    public readonly ushort Channel0 { get; }

    /// <summary>
    /// Gets the bits for the channel 1.
    /// </summary>
    public readonly ushort Channel1 { get; }

    /// <summary>
    /// Gets the bits for the channel 2.
    /// </summary>
    public readonly ushort Channel2 { get; }

    /// <summary>
    /// Gets the bits for the alpha channel.
    /// </summary>
    public readonly ushort Channel3 { get; }

    /// <summary>
    /// Gets the number of channels.
    /// </summary>
    public readonly byte Channels { get; }

    /// <summary>
    /// Checks whether two <see cref="TiffBitsPerSample"/> structures are equal.
    /// </summary>
    /// <param name="left">The left hand <see cref="TiffBitsPerSample"/> operand.</param>
    /// <param name="right">The right hand <see cref="TiffBitsPerSample"/> operand.</param>
    /// <returns>
    /// True if the <paramref name="left"/> parameter is equal to the <paramref name="right"/> parameter;
    /// otherwise, false.
    /// </returns>
    public static bool operator ==(TiffBitsPerSample left, TiffBitsPerSample right) => left.Equals(right);

    /// <summary>
    /// Checks whether two <see cref="TiffBitsPerSample"/> structures are not equal.
    /// </summary>
    /// <param name="left">The left hand <see cref="TiffBitsPerSample"/> operand.</param>
    /// <param name="right">The right hand <see cref="TiffBitsPerSample"/> operand.</param>
    /// <returns>
    /// True if the <paramref name="left"/> parameter is not equal to the <paramref name="right"/> parameter;
    /// otherwise, false.
    /// </returns>
    public static bool operator !=(TiffBitsPerSample left, TiffBitsPerSample right) => !(left == right);

    /// <summary>
    /// Tries to parse a ushort array and convert it into a TiffBitsPerSample struct.
    /// </summary>
    /// <param name="value">The value to parse.</param>
    /// <param name="sample">The tiff bits per sample.</param>
    /// <returns>True, if the value could be parsed.</returns>
    public static bool TryParse(ushort[]? value, out TiffBitsPerSample sample)
    {
        if (value is null || value.Length == 0)
        {
            sample = default;
            return false;
        }

        ushort c3 = 0;
        ushort c2;
        ushort c1;
        ushort c0;
        switch (value.Length)
        {
            case 4:
                c3 = value[3];
                c2 = value[2];
                c1 = value[1];
                c0 = value[0];
                break;

            case 3:
                c2 = value[2];
                c1 = value[1];
                c0 = value[0];
                break;
            case 2:
                c2 = 0;
                c1 = value[1];
                c0 = value[0];
                break;
            default:
                c2 = 0;
                c1 = 0;
                c0 = value[0];
                break;
        }

        sample = new TiffBitsPerSample(c0, c1, c2, c3);
        return true;
    }

    /// <inheritdoc/>
    public override bool Equals(object? obj)
        => obj is TiffBitsPerSample sample && this.Equals(sample);

    /// <inheritdoc/>
    public bool Equals(TiffBitsPerSample other)
        => this.Channel0 == other.Channel0
           && this.Channel1 == other.Channel1
           && this.Channel2 == other.Channel2
           && this.Channel3 == other.Channel3;

    /// <inheritdoc/>
    public override int GetHashCode()
        => HashCode.Combine(this.Channel0, this.Channel1, this.Channel2, this.Channel3);

    /// <summary>
    /// Converts the bits per sample struct to an ushort array.
    /// </summary>
    /// <returns>Bits per sample as ushort array.</returns>
    public ushort[] ToArray()
    {
        if (this.Channel1 == 0)
        {
            return new[] { this.Channel0 };
        }

        if (this.Channel2 == 0)
        {
            return new[] { this.Channel0, this.Channel1 };
        }

        if (this.Channel3 == 0)
        {
            return new[] { this.Channel0, this.Channel1, this.Channel2 };
        }

        return new[] { this.Channel0, this.Channel1, this.Channel2, this.Channel3 };
    }

    /// <summary>
    /// Gets the bits per pixel for the given bits per sample.
    /// </summary>
    /// <returns>Bits per pixel.</returns>
    public TiffBitsPerPixel BitsPerPixel()
    {
        int bitsPerPixel = this.Channel0 + this.Channel1 + this.Channel2 + this.Channel3;
        return (TiffBitsPerPixel)bitsPerPixel;
    }

    /// <inheritdoc/>
    public override string ToString()
        => this.Channel3 is 0 ?
            $"TiffBitsPerSample({this.Channel0}, {this.Channel1}, {this.Channel2})"
            : $"TiffBitsPerSample({this.Channel0}, {this.Channel1}, {this.Channel2}, {this.Channel3})";
}