[QUESTION] Is SKPixMap.GetPixelSpan supposed to be readonly?

[ziriax]

SKPixMap.GetPixelSpan returns a ReadOnlySpan<byte>, not a Span<byte>

So one can't use that for direct pixel manipulation.

Is this by design? I believe a pix-map is writable no?

Skia itself also has void* SKPixMap::writable_addr() .

It would also be useful to have a generic version, to avoid having to call MemoryMarshal methods

[mattleibow]

Technically yes... It uses the "readonly" version. But that pointer is also returned for the writeable. So there is actually no real difference.

I think it is good to add both the writeable version and the generic.

[mattleibow]

A "workaround" right now is to just create your own span:

var span = new Span<T> ((void*)pixmap.GetPixels (), pixmap.BytesSize);

That is almost exactly what I do under the hood. In fact, that is what this feature will be.

[ziriax]

Thanks, did that, and also added the unmanaged constraint.

I just discovered that .net core 3 now has native SIMD intristics...

C# is now exciting even for low level hackers ;-)

[mattleibow]

Thanks for the tip on the unmanaged constraint!

[mattleibow]

Just be aware that skia flips the bits depending on the CPU endian-ness.

[mattleibow]

Let me know what you think of #1242