xpui-fui

An xpui backend that draws through FreeInkUI.

FreeInkUI is a header-only C++ component library for e-ink firmware. It already knows what a list row, a dialog and a slider look like — so a screen written against xpui and one written in C++ against FreeInkUI come out as the same pixels. That is the whole reason to sit on it rather than beside it. Two halves: src/ is the Rust Host implementation over a C ABI, and cpp/ is that ABI implemented against FreeInkUI.

Using it

TOML

[dependencies]
xpui-fui = { git = "https://github.com/XPUI-Framework/xpui-backends", branch = "main" }

Rust

// Once, with the panel's framebuffer.
unsafe { xpui_fui::attach(framebuffer.as_mut_ptr(), 480, 800) };

static PLATFORM: MyPlatform = MyPlatform;
static BACKEND: Backend<MyPlatform> = Backend::new(&PLATFORM);
unsafe { xpui::host::install(&BACKEND) };

A firmware compiles two sources, cpp/xpui_fui.cpp and FreeInkUI's own src/FreeInkUI.cpp, with FreeInkUI's include directory on the path — docs/firmware.md has the lines for PlatformIO and for CMake. Platform is the one thing this crate cannot supply: whatever drives the panel already knows whether a button was pressed, so it implements those five methods and the backend forwards to it.

Requirements

The C++ half needs the FreeInkUI headers, <freeink-sdk>/libs/ui/FreeInkUI/include, and a C++17 compiler. The Rust half needs nothing; its tests run against doubles, with no firmware to link.

Checking it

The gate is the repository's; run ./build-and-test.sh from the root. The shim's compile stage takes the FreeInkUI headers from FREEINK_SDK_INCLUDE, or else from an unpinned sibling checkout, and skips with a note only when it finds neither — never on CI, where that is a failure; docs/contributing.md says where it looks.

Where next

docs/reference.md	every public item: the backend and its platform, the screen lifecycle, and the C ABI
docs/design.md	why this backend has the shape it does, the boundary's four places, input, and the distinctions that break things quietly
docs/coverage.md	which FreeInkUI components the shim uses, which it draws itself, and which it leaves alone
docs/firmware.md	adding the shim to a firmware: sources, includes, wiring, what the build does not ship
cpp/	the C++ half, and its own README