Proposal: Add Color.IsEmpty and Color.Empty

[robloo]

Proposal: Add Color.IsEmpty and Color.Empty

Summary

The Color struct in UWP/WinUI does not currently have an IsEmpty property or an Empty color field. This creates complications when trying to handle #00000000. Lack of support for this is likely also an issue with the WinUI ColorPicker (though I'm not addressing that here). This needs to be added just like it was in System.Drawing.Color from WPF.

API to add:

public static readonly Color Empty;
public bool IsEmpty { get; }

Rationale

Empty colors need to be fully supported without special code every time it's needed. Empty colors represent 'null' for no color has been selected or set. This is valid information that needs to be retained especially in pickers.

Scope

Capability	Priority
public static readonly Color Empty	Must
public bool IsEmpty	Must

Important Notes

• Color is missing several other properties that probably should be discussed as well IsKnownColor, IsNamedColor etc...

[mdtauk]

How is this different to Color.Transparent?

[robloo]

Color.Transparent is equal to #00FFFFFF. This was all designed like this on purpose. It allows you to just use the Color struct instead of having to have a 'null' value using a nullable Color.

[robloo]

This convention is also used in Size.IsEmpty, Rect.IsEmpty, etc... It allows 'no value' to be communicated without have to resort to 'null'. Representing 'no value' is required for logic all over the place and it's inefficient to use nullable structs for this.

[StephenLPeters]

@MikeHillberg I'm not sure that Windows.UI.Color is in our wheelhouse, is this one for project reunion?

[MikeHillberg]

It is, indeed, shipping first in WinUI3 (as Microsoft.UI.Color). We don't have support for members on structs in WinRT though, at least not yet, so we've been putting helpers like these on ColorHelper.