Architecture

Why a foundation

2D graphics in most languages means binding a C engine — Skia, Cairo, Pixman. Across the Go fleet, several libraries had each grown their own copy of the same primitives:

• an image processor resampling pixels,
• a widget toolkit rasterizing vector paths,
• a web engine decoding image codecs,
• a desktop stack rendering icons and thumbnails.

That is duplicated, separately-tested, separately-buggy code. go-gfx extracts the shared substrate into one pure-Go, cgo-free module so colour blending, resampling, codecs and path rasterization are written and tested once.

It follows the classic layering — Skia / Cairo / image/draw: a foundation below, many renderers on top.

                 ┌───────────────┐ ┌────────────────────┐ ┌──────────────┐
   consumers →   │   go-images   │ │ go-widgets/painter │ │ go-webengine │  …
                 └───────┬───────┘ └─────────┬──────────┘ └──────┬───────┘
                         │                   │                   │
                 ┌───────┴───────────────────┴───────────────────┴───────┐
   foundation →  │                      go-gfx/gfx                        │
                 │  geometry · color · raster · resample · codec · vector │
                 └───────────────────────────────────────────────────────┘
                                          │
                              ┌───────────┴───────────┐
   optional SIMD →            │  go-asmgen (gen-time)  │
                              └───────────────────────┘

Boundaries

go-gfx deliberately draws its edges:

• Not image processing. Filters, edges, morphology, feature detection — that is go-images, the scikit-image analogue, which is built on raster / color / resample.
• Not a widget toolkit. Widgets, layout and event handling are go-widgets; its painter backend is built on vector / raster / color.
• Not text shaping. The text stack (fonts, shaping, glyph rasterization) is go-opentype; it stays separate and is composed alongside go-gfx, not inside it.
• Not 3D. The bespoke rasterizers in the game/virtio ports are deliberate C ports or 3D pipelines and are out of scope.

Dependencies

go-gfx depends on nothing fleet-side at runtime. Its only optional dependency is go-asmgen, pulled in at code generation time to emit SIMD assembly for hot kernels; the committed library keeps a zero-dependency go.mod. The whole module cross-compiles to a static binary on all six of Go's 64-bit targets.

Consumers

Consumer	Builds on	Uses it for
go-images	raster, color, resample	filters, edges, morphology, geometry
go-widgets/painter	vector, raster, color	path fills, strokes, gradients
go-webengine	resample, codec, vector	painting HTML/CSS layout to an image
go-widgets/desktop	codec, resample	icon & thumbnail rendering