Official plugins

SF Symbols

Apple's SF Symbols for native UI on macOS, drawn by the system.

The sfsymbols plugin draws Apple's SF Symbols for native UI on macOS. The symbols are read from the running system: AppKit draws each with its own design and weight, and the plugin copies the pixels into an image. Nothing of Apple's artwork is in your app or its build. It is all Go: no JavaScript package, and nothing to mygo.Use.

Show one as SwiftUI's Image(systemName:) does:

import "github.com/egoist/mygo/plugins/sfsymbols"

sfsymbols.Symbol(c, "gearshape")
sfsymbols.Symbol(c, "trash").Size(20).Color(t.Accent).Weight(sfsymbols.Semibold).Fill()
sfsymbols.Symbol(c, "sparkles").Fallback(sparklesSVG) // where the system has none

Symbol

Symbol(c, name) makes an element that shows the symbol at the theme's font size, in its text color, drawn at the display's scale so it stays sharp, and named name for assistive technology. Its modifiers chain, as SwiftUI's:

sfsymbols	SwiftUI
`.Size(24)`	`.font(.system(size: 24))`
`.Color(col)`	`.foregroundStyle(col)`
`.Weight(sfsymbols.Bold)`	`.fontWeight(.bold)`
`.Fill()`	`.symbolVariant(.fill)`: `trash.fill` for `trash`, the symbol itself where it has no filled variant
`.Natural()`	the size a symbol has beside others of one point size, rather than filling its box
`.Fallback(svg)`	an SVG, in the symbol's color, where the system has no such symbol

A SymbolElement is a ui.Element too: Margin, Tooltip and the rest work on it. Where the system has no symbol of the name (on another OS, or an older macOS) it draws its fallback, or nothing, at the same size.

What it doesn't do, unlike SwiftUI: follow the text color of the element it is in (it takes the theme's, or Color), sit on the baseline of text beside it, or draw multicolor and hierarchical symbols in more than one color.

Names

Names() returns the names of every SF Symbol the running macOS has, in the order the SF Symbols app shows them (thousands, localized variants such as .ar and .ja among them), for a symbol picker or a search. It reads the system's own catalog, so nothing of Apple's is in your app. The catalog is not public API: a macOS that moves it gives nil, while Symbol and Image still draw the symbols they name. Every other OS gives nil.

Image

For drawing with a ui.Painter, Image(name, px, col, opts) returns the symbol named name (as "gearshape"), drawn px pixels square in the color col, as a ui.ImageSource. It returns false where the system has no such symbol: on another OS, or on a macOS that lacks it. Available reports whether the system draws SF Symbols at all.

opts holds Natural and Weight, as Symbol's modifiers.
px is limited to 8 through 512; a Symbol larger than that in pixels is scaled up from 512. Draw at two or three times the size in DIPs, so that the symbol stays sharp on any display.
By default the symbol's ink fills its box, centered with a small inset. Options{Natural: true} draws every symbol at one scale instead, the size it has beside others of the same point size: a cross stays smaller than a wide rectangle, as SF Symbols balance them.
Results are cached by name, size, color and options, and the names the system has no symbol for too, the least recently used dropped past a limit, so an animated color or size doesn't grow memory without end. Image is safe to call from any goroutine.

Every other OS has no SF Symbols: Image returns false there, so keep an icon of your own to fall back on, and use ui.Image or Painter.Image (with ui.Contain) for what it returns.

Apps that don't import the plugin don't pay for it.

See examples/sf-symbols, which shows every symbol with a search: go run ./examples/sf-symbols.