Faster image copy to other buffers

[lovettchris]

Description

I need to interoperate between ImageSharp and other libraries like UAP or WPF WriteableBitmap for reasons outside my control and so I would love a fast memcpy solution for whole image frame contiguous buffer copies. Seems to me you could just expose the ImageFrame.PixelBuffer and then expose GetSingleMemory, so System.Memory can do the CopyTo and we're good.

Steps to Reproduce

Try create the quickest way to copy Image to WriteableBitmap, currently have to iterate 1 row at a time?

System Configuration

• ImageSharp version: 1.0.1
• Other ImageSharp packages and versions: n/a
• Environment (Operating system, version and so on): Windows 10
• .NET Framework version: .net core 3.1 and soon 5.0...
• Additional information:

[JimBobSquarePants]

If the backing buffer is contiguous (which is often the case unless dealing with multi-megapixel images) we've got Image<TPixel>.TryGetSinglePixelSpan(out Span<TPixel>)

See #1375 (comment)

[antonfirsov]

@lovettchris note that - in order to access the backing buffers - you need the generic Image<TPixel> and not the non-generic Image base type.

You can also create an "image" copy-free with Image.WrapMemory<TPixel>. See the usage sample in #1419, would be nice to hear your thoughts on that proposal.

[lovettchris]

Thanks for the quick response, Image.TryGetSinglePixelSpan(out Span) works great.