Adds CSS support for shadows and a simpler way of defining shadows in XAML

[sthewissen]

Description of Change

Added support for a new -maui-shadow CSS property which can be used to initialize a Shadow on a VisualElement. This also introduces a new ShadowTypeConverter that allows for 3 different ways to initialize a Shadow. These have been kept in line as much as possible with the existing guidelines on box-shadows in CSS.

-maui-shadow: #000000 4 4; // color, offset X, offset Y
-maui-shadow: 4 4 16 #000000;  // offset X, offset Y, radius, color
-maui-shadow: 4 4 16 #000000 0.5;  // offset X, offset Y, radius, color, opacity

Or in XAML:

<VerticalStackLayout BackgroundColor="#fff" Shadow="4 4 16 #000000" />

Issues Fixed

This currently contains a basic implementation for #27157.

[MartyIX]

Could this be

Suggested change

	#nullable disable
	#nullable enable

?

[sthewissen]

Added support for the various solid color implementations;

#000000 4 4
rgb(6, 201, 198) 4 4
rgba(6, 201, 188, 0.2) 4 8
hsl(6, 20%, 45%) 1 5
hsla(6, 20%, 45%,0.75) 6 3
rgb(100%, 32%, 64%) 8 5
rgba(100%, 32%, 64%,0.27) 16 5

EDIT: I still want to improve this a bit to also allow X11 named colors and HSV/HSVA.

fuchsia 4 4
hsv(6, 20%, 45%) 1 5
hsva(6, 20%, 45%,0.75) 6 3

[sthewissen]

Updated color parsing for more color support.

Type	Format	Remark
HEX	#rgb, #argb, #rrggbb, #aarrggbb
RGB	rgb(255,0,0), rgb(100%,0%,0%)	values in range 0-255 or 0%-100%
RGBA	rgba(255, 0, 0, 0.8), rgba(100%, 0%, 0%, 0.8)	opacity is 0.0-1.0
HSL	hsl(120, 100%, 50%)
HSLA	hsla(120, 100%, 50%, .8)	opacity is 0.0-1.0
HSV	hsv(120, 100%, 50%)	h is 0-360, s and v are 0%-100%
HSVA	hsva(120, 100%, 50%, .8)	opacity is 0.0-1.0
Predefined color	fuchsia, AquaMarine, limegreen	case insensitive

[sthewissen]

While I'd love to get individual property support through CSS in there, it might be a bit of a big change to pull off in the short term. Therefore I'm setting this as ready for review to get the basic support rolling. We can then improve upon it in the future after giving the best solution some more thought.

[jfversluis]

/azp run

[jsuarezruiz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[mattleibow]

#27157 (comment)

[jsuarezruiz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[mattleibow]

Should this be targeting .NET 10 since it is a new thing? If we are to target .NET 9/main, then the converter will have to be internal. We can always merge the converter as internal, and then open an issue to make it public in net 10 once main is merged up to net10.

[sthewissen]

Should this be targeting .NET 10 since it is a new thing? If we are to target .NET 9/main, then the converter will have to be internal. We can always merge the converter as internal, and then open an issue to make it public in net 10 once main is merged up to net10.

If making it internal gets it in faster I'm all for it @mattleibow :)

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[mattleibow]

Make ShadowTypeConverter public and enabled nullable references #nullable enable