PixelResolutionUnitConverter

[TonyValenti]

It would be really nice if the following class were added.
It is based on https://github.com/SixLabors/ImageSharp/blob/1baba9e02d8b1ccc1078b125235b60b9b88f7f1f/src/ImageSharp/Common/Helpers/UnitConverter.cs

and adds a general Convert method.

namespace SixLabors.ImageSharp.Metadata;

/// <summary>
/// Contains methods for converting values between unit scales.
/// </summary>
public static class PixelResolutionUnitConverter {
    /// <summary>
    /// The number of centimeters in a meter.
    /// 1 cm is equal to exactly 0.01 meters.
    /// </summary>
    public const double CmsInMeter = 1 / 0.01D;

    /// <summary>
    /// The number of centimeters in an inch.
    /// 1 inch is equal to exactly 2.54 centimeters.
    /// </summary>
    public const double CmsInInch = 2.54D;

    /// <summary>
    /// The number of inches in a meter.
    /// 1 inch is equal to exactly 0.0254 meters.
    /// </summary>
    public const double InchesInMeter = 1 / 0.0254D;


    public static double CmToMeter(double x) => x * CmsInMeter;

    public static double MeterToCm(double x) => x / CmsInMeter;

    public static double MeterToInch(double x) => x / InchesInMeter;

    public static double InchToMeter(double x) => x * InchesInMeter;

    public static double CmToInch(double x) => x / CmsInInch;

    public static double InchToCm(double x) => x * CmsInInch;


    public static double Convert(double from, PixelResolutionUnit fromUnit, PixelResolutionUnit toUnit) {
        if (fromUnit == toUnit) {
            return from;
        } else {
            return (fromUnit, toUnit) switch {
                (PixelResolutionUnit.PixelsPerInch, PixelResolutionUnit.PixelsPerCentimeter) => InchToCm(from),
                (PixelResolutionUnit.PixelsPerInch, PixelResolutionUnit.PixelsPerMeter) => InchToMeter(from),
                (PixelResolutionUnit.PixelsPerCentimeter, PixelResolutionUnit.PixelsPerInch) => CmToInch(from),
                (PixelResolutionUnit.PixelsPerCentimeter, PixelResolutionUnit.PixelsPerMeter) => CmToMeter(from),
                (PixelResolutionUnit.PixelsPerMeter, PixelResolutionUnit.PixelsPerInch) => MeterToInch(from),
                (PixelResolutionUnit.PixelsPerMeter, PixelResolutionUnit.PixelsPerCentimeter) => MeterToCm(from),
                _ => throw new NotImplementedException($@"Conversions from {fromUnit} to {toUnit} are not allowed."),
            };

        }
    }

}

[JimBobSquarePants]

Yeah, I want to expose useful tooling like this in v4

[TonyValenti]

Also, I'm working with the code and I see that sometimes ImageSharp uses doubles (like here) and sometimes floats are used (like RectangleF). I'm not sure if standardizing on one is possible, but if so, that would be nice.