Use color for color.

[waywardmonkeys]

This leaves peniko::Color for now, but begins the migration to using the new color crate.

[waywardmonkeys]

Some of these will be resolved in color and some here in this crate:

• Default for colors
• PartialEq
• PartialOrd (needed by ColorStop at least)
• Hash
• Add legacy_color feature (enabled by default for now) that feature gates the existing peniko::Color
• Do the work on Gradient
• Better solution for disabling some clippy lints for allow attributes
• serde support in color (Optionally support serde. color#61)
• Decide what type(s) to export
• Consider renaming mul_alpha to multiply_alpha in color (Rename mul_alpha to multiply_alpha color#65)
• Create a branch of Vello using this and see what the issues are (WIP: Converting to new peniko with color. vello#742)

[waywardmonkeys]

I've done more work here updating most of the gradient code, adding a feature to disable the legacy color code, and adding some more comments.

There are some FIXME(color) comments in the code to help point to things that need resolution in conjunction with the list in a comment above.

[tomcur]

Current Peniko defaults to transparent. Opaque black can be considered: it is visible, and has a natural representation in the color spaces we include in color. The other special color is white, though the physical color it represents depends on the color space.

[waywardmonkeys]

There was a previous PR with discussion about it: #31 and that links to more discussion in Xilem.

We'll also have to decide whether to solve it here in the Brush::default() only or also in color or both.

[waywardmonkeys]

Also, with linebender/color#63 in place, this would be shorter …

[waywardmonkeys]

I think I will remove the legacy code instead, and export a type alias Color that is the same as AlphaColor<Srgb> as that would simplify updating Vello.

[tomcur]

(Just a note: with color becoming 32-bit per channel, maybe peniko::Image::alpha should become f32.)

peniko/src/image.rs

Lines 37 to 50 in d825bdf

	pub struct Image {
	/// Blob containing the image data.
	pub data: Blob<u8>,
	/// Pixel format of the image.
	pub format: Format,
	/// Width of the image.
	pub width: u32,
	/// Height of the image.
	pub height: u32,
	/// Extend mode.
	pub extend: Extend,
	/// An additional alpha multiplier to use with the image.
	pub alpha: u8,
	}