Adding GravatarImageSource

[dansiegel]

Description of Change

Adds a new GravatarImageSource that can be easily added for any image source using a user's email address. This utilizes the image provided by gravatar.com and supports all of their default image results to handle when an email address has no associated Gravatar.

Issues

• closes [Spec] Gravatar Image Source #312

Platforms Supported

• Android
• iOS
• macOS
• UWP
• WPF
• Tizen

API Changes

Added:

public enum DefaultGravatar
{
	FileNotFound,
	MysteryPerson,
	Identicon,
	MonsterId,
	Wavatar,
	Retro,
	Robohash,
	Blank
}

public class GravatarImageSource : ImageSource
{
    public string Email { get; set; }
    public int Size { get; set; }
    public DefaultGravatar Default { get; set; }
    public boo CachingEnabled { get; set; }
    public TimeSpan CacheValidity { get; set; }
}

Note that by default Caching is enabled for 7 days. An additional XAML Extension has been provided to make it even easier to use.

Behavioral Changes

none

PR Checklist

• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Updated documentation

[pictos]

@dansiegel thanks for this amazing contribution. I didn't run the code yet to test. Do you mind adding some unit tests? If you can't do it don't worry I'll do it in the future (:

[AndreiMisiukevich]

I like it

[pictos]

@dansiegel we are getting there❣ Most of the comments are about code style.

[AndreiMisiukevich]

Needs others review

[jfversluis]

Build seems to fail

Views/GravatarImageSource/Android/GravatarImageSourceHandler.android.cs(20,13): error CS1996: Cannot await in the body of a lock statement

[dansiegel]

@jfversluis good catch... I'll update that shortly