SKVertices: CreateCopy is missing overload to pass vertices' and indexes' offset + count

[seclerp]

Description of Change

Add the ability to pass offsets and counts to the SKVertices struct for passing them to the DrawVertices call.

Features Resolved

• Resolves [FEATURE] Add overload for SKVertices.CreateCopy that accepts offset and count for vertices and indexes  #2431

API Changes

Added:

• SKVertices SKVertices.CreateCopy(SKVertexMode vmode, int vertexCount, SKPoint[] positions, SKPoint[] texs, SKColor[] colors, int indexCount, UInt16[] indices);
• SKVertices SKVertices.CreateCopy (SKVertexMode vmode, int vertexOffset, int vertexCount, SKPoint[] positions, SKPoint[] texs, SKColor[] colors, int indexOffset, int indexCount, UInt16[] indices)

Behavioral Changes

None.

PR Checklist

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

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Regarding tests - I can't find any tests related to SKVertices class usage at all.

The documentation PR is in progress.

[seclerp]

@dotnet-policy-service agree

[mattleibow]

Thanks for this PR. Not copying things to get a shorter array is a good thing.

For these types of things, maybe we can use ReadOnlySpan<T>?

Not only do we get performance benefits of not having to create arrays just to pass in, but we can make use of all the index/range features of spans.

An example of where I did this would is here:

SkiaSharp/binding/Binding/SKMask.cs

Lines 137 to 140 in a426c16

	public static SKMask Create (byte[] image, SKRectI bounds, UInt32 rowBytes, SKMaskFormat format) =>
	Create (image.AsSpan (), bounds, rowBytes, format);
	public static SKMask Create (ReadOnlySpan<byte> image, SKRectI bounds, UInt32 rowBytes, SKMaskFormat format)