Forma

A cross-platform UI library and toolkit in Rust.

Forma draws beautiful, fully themeable, pixel-identical interfaces on Linux, macOS, Windows, Android, iOS, and the web — staying as close to the OS as possible while depending on as little third-party code as possible.

It builds on the pure-Rust oxideav media stack for all 2D content rendering (scene graph, CPU rasterizer, font shaping, image decode, SVG) and adds everything around it: native windowing and input per OS, presenting the rendered buffer, and a declarative, reactive UI toolkit.

use forma::prelude::*;

struct Counter { n: i64 }

fn view(state: &Counter) -> impl View {
    Column((
        Text(format!("{}", state.n)).font_size(48.0),
        Row((
            Button("−").on_tap(|s: &mut Counter| s.n -= 1),
            Button("+").on_tap(|s: &mut Counter| s.n += 1),
        )).gap(8.0),
    ))
    .padding(24.0)
}

fn main() {
    forma::App::new(Counter { n: 0 }, view)
        .title("Counter")
        .run();
}

Status: pre-alpha. The architecture and phased plan live in ROADMAP.md. APIs are unstable.

The same app, rendered by Forma's native backends and screenshotted in CI (the Visual workflow) — Linux X11 (under Xvfb) and Wayland (under headless sway), Win32, and Cocoa, each from-scratch with no windowing crates:

Linux / X11	Linux / Wayland	Windows / Win32	macOS / Cocoa

Web / wasm + canvas	GPU / GLES (offscreen)

Input is verified too: CI synthesizes real events and screenshots the result — X11 via xdotool (clicking a counter; caret-aware editing — type "Forma", arrow-left twice, insert "XY" → "ForXYma" with a mid-string caret), macOS via cliclick, and Wayland via wtype (whose virtual keyboard exercises the wl_seat keyboard + xkb-keymap decode path — Tab to focus, then type "forma wl"):

X11 click	X11 edit (mid-string caret)	macOS click	Wayland type

Themeable by design

Every widget reads its colors and metrics from a [Theme] — a semantic Palette (roles, interaction states, status colors, overlays), a Typography scale, a Spacing scale, and a corner radius. Customizing is a one-liner: Theme::dark().with_accent(color).with_radius(14.0) recolors the accent, derives its hover/active tints, and picks a readable on-color automatically; high_contrast() maximizes text/border contrast. The same card below is rendered under four themes (light, dark, a violet-accent dark, high-contrast), montaged in CI:

Design at a glance

• Software-first rendering behind a GPU-ready Surface seam (raw Metal/Vulkan/D3D12/WebGPU later — never wgpu).
• Reactive / declarative API: UI is a function of state.
• Self-drawn widgets — one theme engine, identical on every platform.
• No winit / wgpu / taffy / lyon / GTK / Qt. OS interfaces are hand-written per platform in forma-platform.

Workspace layout

Crate	Role
forma-geometry	Logical-pixel math (Point, Size, Rect, Affine)
forma-render	Scene → oxideav VectorFrame → raster → Surface
forma-platform	Per-OS windowing, input, IME, clipboard, vsync
forma-layout	Flex/box layout solver
forma-core	Reactive runtime: View, reconcile, state, events
forma-anim	Frame clock, easing, springs, transitions
forma-style	Design tokens and themes
forma-widgets	Standard widget library
forma	Umbrella crate: App, prelude, re-exports

Examples

cargo run -p window       # a settings panel in a native window
cargo run -p clickdemo    # a click-counting button
cargo run -p textinput    # an editable text field (Tab to focus, then type)
cargo run -p themegallery # one card rendered under four themes (writes .raw files)

Each opens a real native window (X11/Win32/Cocoa) via App::run, or falls back to a one-shot headless render where no display is available. The web target lives in crates/forma-web (built for wasm32; see the Visual workflow).

Status & MSRV

Pre-alpha. The whole workspace builds on Rust 1.88 (edition 2024).

Working today: the full reactive toolkit (render, layout, state, tap/keyboard/ focus/drag, text, 12 widgets, theming) and four rendering targets — native X11, Win32, and Cocoa (window + input + resize) plus web (wasm + canvas) — each verified by a CI screenshot on its platform.

Next milestones (see ROADMAP.md): Wayland, mobile (Android/iOS), and GPU backends; web font + canvas input.

License

MIT