gbui

A UI toolkit for C++20. Flexbox layout, themeable components, and a painter interface a backend implements — with no web engine and nothing to fetch: the toolkit is the standard library and nothing else, and the two public-domain headers it vendors sit in the platform layer, where the machine already is.

gitgusilva.github.io/gbui

Live demos · Guide · Your first window · Reference · Contributing

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Each stage reads only the one before it, which is why layout is arithmetic you can assert without a window and painting is a list of commands you can inspect without a GPU. Over sixty components sit on top — from a button to a table, a tree view, a rich-text editor and nine kinds of chart — all stateless functions, themed by token rather than by colour.

Every one of them says what it is. A role, a name, whatever state and value apply, and the relations that attach a caption to its field — read into a pruned accessibility tree that is diffed each frame, so a screen reader is told what changed rather than everything. It is a rule rather than a milestone: two checks in CI fail the build for a control with nothing to announce, one over the library and one over the applications built on it.

It was written for GitBox as a path off Electron, and reads the same theme.json the gitbox-themes registry publishes.

Seven full application screens — a revenue dashboard, a weather desk, a plant supervisory HMI, a production line monitor, a grid control desk, a logistics control tower and a trading desk — run in the browser on the demos page, compiled to WebAssembly and rasterised on the CPU. Their source is in demos/, and it is ordinary consumer code: public headers, one link line, no private access.

Build

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build
ctest --test-dir build --output-on-failure

./build/demos/gbui_demo --list                 # seven application screens
./build/demos/gbui_demo --component treeView   # one component's live example

C++20 and CMake 3.20. SDL2 is optional — without it everything still builds and every test still passes, and only Window::create changes.

add_subdirectory(gbui)
target_link_libraries(your_app PRIVATE gbui::gbui)

Or don't build it: every release carries a shared library, the headers and the CMake package files for Linux, Windows and both kinds of Mac — download. Those have no SDL2 and so no window, because a prebuilt library that links SDL2 needs the same SDL2 on the machine that loads it; everything else in them is the same code.

Then read Your first window.

Licence

LGPL-3.0-or-later — see LICENSE and GPL-3.0.txt. Icons are Lucide (ISC); third_party/stb_truetype.h is public domain.