How to manipulate raw pixel data?

I was wondering how I can access the raw pixel byte array of an Image in Skija. After loading an Image via Image.makeFromEncoded I somehow could not find a good way to convert the Image to a Bitmap. And even if I would be able to create a Bitmap there seems no accessor for the raw byte[] of the image representing the pixels. I need to do some raw pixel manipulation (for diffing purposes).

On SkiaSharp you can create a SKBitmap either by using SKBitmap.Decode() or via SKBitmap.FromImage. The raw pixels are then accessible via skBitmap.Bytes.

Is this missing in Skija?

[tonsky]

Added everything except SKBitmap.Decode (will add later). Check out https://github.com/JetBrains/skija/blob/3fda7b5b74a42b2b015bebe2031fccff631fb409/examples/scenes/src/BitmapImageScene.java for examples. From your description, you should be able to do what you set up to do. Jar version 0.89.32

[Danielku15]

Thanks for the fast reply. Digging deeper I saw that there are quite some essentials missing. My use cases would be:

1. Converting Image to Bitmap for accessing the actual image contents. Related SkiaSharp methods: SKBitmap.Decode(SKData), SKBitmap.FromImage(SKImage)
2. Converting Bitmap to Image for saving the bitmap again to disk after manipulations. Related SkiaSharp method: SKImage.FromBitmap(SKBitmap)
3. Access the binary data of a Bitmap for raw pixel manipulations. I want to do diffing of images with anti-alias detection, basically a port of PixelMatch. Related SkiaSharp property: SKBitmap.Bytes
4. Converting a raw pixel byte array to a Bitmap/Image for further saving. The pixels which differ are written to a raw byte array. To save these “diff” pixels as PNG to disk I need to create an image out of it. Related SkiaSharp method: SKImage.FromPixels(SKImageInfo, SKData)

Hope this helps as input to cover my needs 😁 .