EFx — Rust 🦀 XML Template Engine for egui-based frameworks: eframe, bevy_egui, egui-winit, egui-miniquad. efx! is a proc-macro for writing tiny XML-like UI snippets in eframe/egui. It converts short tags into egui calls.

You can embed arbitrary Rust expressions inside braces ({...}).

Requires egui (the project currently uses egui 0.32). Add to Cargo.toml:

[dependencies]
efx = "0.5"
egui = "0.32" # or egui-based framework

Inside this repo just import the macro:

use efx::efx; // the macro

You can see on web page https://docs.rs/efx/latest/efx/ or in files:

• Introduction
• Tags
• Guide

Inside tag content you can insert any Rust expression that implements Display:

let a = 2;
let b = 3;
efx!(ui, r#"<Label>Sum: {a + b}</Label>"#);

To print { or }, use double braces (same as format!):

efx!(ui, r#"<Label>Literals: {{ and }}</Label>"#);

At compile time the macro parses your snippet; at runtime it shows readable diagnostics via ui.Label(...) when input is invalid:

• Unknown tag Output: Unknown tag: <TagName>

• Mismatched open/close tags Output: Mismatched tags: <open> and </close>

• Interpolation count mismatch Happens if the parser found e.g. two {expr} parts but after processing the text there’s a different number of {} placeholders. Make the counts match.

• Case-sensitive tag names.
• Interpolated expressions must implement Display.

TL;DR. EFx is a minimalist XML DSL on top of egui that compiles to plain ui.* calls. The next three releases focus on expressiveness and first-class examples across popular egui runtimes:

• 0.5 — Attributes & core tags: type-checked attributes, Heading, Hyperlink, Image, TextField, Grid, plus Window/CentralPanel/SidePanel. Diagnostics & examples.
• 0.6 — Components & events: reusable components/slots, event sugar (onClick, etc.), classes/presets, Bevy examples.
• 0.7 — Themes & layouts: lightweight style sheets, extended containers (Tabs/Table behind extras), perf & polish.

This plan is incremental and non-breaking; new features are opt-in. Priorities may change based on community feedback.

👉 Full RFC: EFX-0001 — Roadmap 0.5–0.7

👉 RFC index: RFC/README.md

EFx renders into any runtime that provides &mut egui::Ui. We officially build examples for the following targets:

Tier-1

• eframe (native + wasm)
• bevy_egui (native)
• raw winit+wgpu (via egui-winit + egui-wgpu). Wgpu - a cross-platform, safe, pure-rust graphics API. It runs natively on Vulkan, Metal, D3D12, and OpenGL; and on top of WebGL2 and WebGPU on wasm. Follows WebGPU specification. With async/await API.

Tier-2 (compatible today; examples later / community support)

• egui-miniquad (for macroquad/miniquad overlays) - Relatively minimalistic API well suited for small to medium graphics projects. Supports multiple backends, including browser target.
• egui_sdl2_* backends
• egui_glow / tao (lower-level backends)

A) eframe

# Cargo.toml
[dependencies]
efx    = "0.5"
eframe = "0.32"

use eframe::egui;
use efx::efx;

egui::CentralPanel::default().show(ctx, |ui| {
    efx!(ui, r#"<Column><Label>Hello, EFx</Label><Separator/></Column>"#);
});

B) Bevy + bevy_egui

# Cargo.toml
[dependencies]
efx       = "0.5"
bevy      = "0.16"
bevy_egui = "0.36"  # re-exports `egui`

use bevy_egui::{EguiPlugin, EguiContexts};
use efx::efx;

bevy_egui::egui::Window::new("EFx").show(egui_ctx.ctx_mut(), |ui| {
    efx!(ui, r#"<Row><Label>It works</Label></Row>"#);
});

Tip: import egui via use bevy_egui::egui as egui; to avoid version mismatches.

C) Raw winit + wgpu

# Cargo.toml
[dependencies]
efx        = "0.5"
egui       = "0.32"
egui-winit = "0.32"
egui-wgpu  = "0.32"
winit      = "0.30"
wgpu       = "26.0"

Use the example in examples/winit_wgpu_min.rs as a starting point.

• Start with the roadmap RFC: EFX-0001.
• You can write me with your ideas on [email protected].
• Open issues are grouped by milestones 0.5 / 0.6 / 0.7.
• PRs that change behavior should reference the relevant RFC section.
• Looking for help with: Bevy example(s), raw winit+wgpu example, attribute codegen & compile-fail tests, TextField docs.

See in file Changelog.md

The MIT License. Please see License File for more information.