Jacked Atlas

a tool for clipping regions of interest based on a bitmap mask, which is commonly referred to as an atlas.
under the hood, I'm simply utilizing an OffscreenCanvas with ctx.globalCompositeOperation = "source-in" to clip
there are several ways of going about extracting masked regions of interest from an image.
but in general, you need 3 sets of information/data:

• source image
  • can be anything accepted by ctx.drawImage (aka CanvasImageSource)
• bitmap of mask
  • can be anything accepted by ctx.drawImage (aka CanvasImageSource)
  • can be either a boolean Array or Uint8Array of y-major stream of pixel data (px_data = [x0y0, x1y0, x2y0, ..., x0y1, x1y1, ...])
  • can be scanline drawing instructions (TODO)
• offset position of mask
  • [x, y, width, height] = [185, 184, 172, 258]

although clipping regions of interest is the fundamental functionality of this library, it is just a small portion of the codebase
much of the library provides an interface for managing clips asynchronously, converting from various input atlas formats to different various output atlas formats, and previewing clips on canvas asynchronously.

the source is written in Typescript and the documentation is generated using TypeDoc.

Example

description	data
input source image
input juice bitmask
input mask rect coordinates	let rect = { x: 185, y: 184, width: 172, height: 258 }
output extracted image

TODO

• improve name consistency, especially the loadImage function of JAtlasManager and JAtlasManager.source
• make more Promise<void> functions return their important value rather than just signallying undefined
• make an interactive HScroller
• design uncaching/deleting of ClipMask.data_blob
• turn ClipMask or JAtlas into a recursive/nested JAtlasManager, with the clipped parent image always being the source of the child/nested JAtlas clip
• for web supported MIME image formats, don't put the MIME-text inside of JAtlas.kind, but rather keep it prepended to JAtlas.data, and introduce JAtlas.kind = "mime" | "native" | "uri" | "data_uri" | "base64" | etc... for natively supported web browser images
• use idat_codec_ts to encode 1bit png clipmasks into JAtlas.data, because browsers are too stupid to realize the compressibility of bit-data. although webp might already do that, but the native webp encoding is not lossless, nor can you set an option for it to become lossless. But I have yet to see an artifacact from the lossy compression of webp, unlike jpg, where it was immediately clear at 75% quality encoding