Simple and portable (but not inflexible) GUI library in C that uses the native GUI technologies of each platform it supports.
C C++ Objective-C CMake Go
Latest commit 5fa7ba4 Dec 1, 2016 @andlabs committed on GitHub Merge pull request #240 from lailton/master
Update uipriv_darwin.h
Failed to load latest commit information.
_abort/windowevents And finished offing the movement window events. I think the others ca… Oct 22, 2016
_wip Added uiGrid on OS X. Now to fix build errors. Jun 12, 2016
common Started the process of splitting the table code into a separate branch. Nov 27, 2016
darwin Update uipriv_darwin.h Dec 1, 2016
doc More documentation stuff. Jun 16, 2016
examples Expanded the control gallery a bit further. Jun 17, 2016
test Started the process of splitting the table code into a separate branch. Nov 27, 2016
unix Oops, I forgot to remove the uiImage code from the GTK+ port when spl… Nov 30, 2016
windows Started the process of splitting the table code into a separate branch. Nov 27, 2016
.travis.yml Travis now installs the right version of cmake by default on OS X. No… Oct 17, 2016 Split old announcements and updates out. Jun 9, 2016
CMakeLists.txt More TODOs. Jun 18, 2016 Split old announcements and updates out. Jun 9, 2016 More future plans. Jun 12, 2016
LICENSE Split into a new repository and added a LICENSE. Apr 17, 2015 Started the process of splitting the table code into a separate branch. Nov 27, 2016 More TODOs. Nov 11, 2016
nowintable.diff Quick Windows fixes now localized. Oct 23, 2016
oldhaiku.tgz Discontinued the Haiku port for now. Apr 24, 2016
ui.h Started the process of splitting the table code into a separate branch. Nov 27, 2016
ui_darwin.h Added a facility to the OS X port to be notified when a child's visib… Jun 14, 2016
ui_unix.h Implemented uiGrid on GTK+. Jun 9, 2016
ui_windows.h Implemented visibility change detection on Windows. Now to refine the… Jun 14, 2016

libui: a portable GUI library for C

This README is being written.
Build Status


  • 27 November 2016

    • Decided to split the table stuff into its own branch. It will be developed independently of everything else, along with a few other features.
  • 2 November 2016

    • Added two new functions to replace the deleted uiWindowPosition() and friends: uiAreaBeginUserWindowMove() and uiAreaBeginUserWindowResize(). When used in a uiAreaHandler.Mouse() event handler, these let you initiate a user-driven mouse move or mouse resize of the window at any point in a uiArea.
  • 31 October 2016

    • @krakjoe noticed that I accidentally used thread-unsafe code in uiQueueMain() on Unix. Fixed.
  • 24 October 2016

    • uiWindowSetContentSize() on Unix no longer needs to call up the GTK+ main loop. As a result, bugs related to strange behavior using that function (and the now-deleted uiWindowSetPosition() and uiWindowCenter()) should go away. I'll need to go through the bugs to verify as much, though.
  • 22 October 2016

    • Due to being unable to guarantee they will work (especially as we move toward capability-driven window systems like Wayland), or being unable to work without hacking that breaks other things, the following functions have been removed: uiWindowPosition(), uiWindowSetPosition(), uiWindowCenter(), and uiWindowOnPositionChanged(). Centering may come back at some point in the future, albeit in a possibly restricted form. A function to initiate a user move when a part of a uiArea is clicked will be provided soon.
  • 21 October 2016

    • uiDrawTextWeightUltraBold is now spelled correctly. Thanks to @krakjoe.
  • 18 June 2016

  • 17 June 2016

    • CMake 3.1.0 is now required. This is due to CMake's rapid development pace in the past few years adding things libui needs to build on as many systems as possible. If your OS is supported by libui but its repositories ship with an older version of CMake, you will need to find an updated one somewhere.
    • Please help plan out a better menu API.
  • 5 June 2016

    • Alpha 3.1 is here. This was a much-needed update to Alpha 3 that changes a few things:
      • The build system is now cmake. cmake 2.8.11 or higher is needed.
      • Static linking is now fully possible.
      • MinGW linking is back, but static only.

Old announcements can be found in the file.


Note that today's entry (Eastern Time) may be updated later today.

  • <codedate

    • Added uiTable TODO
  • 17 June 2016

    • uiMainSteps() no longer takes any arguments and no longer needs to invoke a function to do the work. You still need to call it, but once you do, it will return immediately and you can then get right to your main loop.
    • CMake 3.1.0 is now required. This is due to CMake's rapid development pace in the past few years adding things libui needs to build on as many systems as possible. If your OS is supported by libui but its repositories ship with an older version of CMake, you will need to find an updated one somewhere.
    • Added uiNewVerticalSeparator() to complement uiNewHorizontalSeparator().
  • 16 June 2016

    • Added uiWindowContentSize(), uiWindowSetContentSize(), and uiWindowOnContentSizeChanged() methods for manipulating uiWindow content sizes. Note the use of "content size"; the size you work with does NOT include window decorations (titlebars, menus, etc.).
    • Added uiWindowFullscreen() and uiWindowSetFullscreen() to allow making fullscreen uiWindows, taking advantage of OS facilities for fullscreen and without changing the screen resolution (!).
    • Added uiWindowBorderless() and uiWindowSetBorderless() for allowing borderless uiWindows.
    • Added uiMainSteps(). You call this instead of uiMain() if you want to run the main loop yourself. You pass in a function that will be called; within that function, you call uiMainStep() repeatedly until it returns 0, doing whatever you need to do in the meantime. (This was needed because just having uiMainStep() by itself only worked on some systems.)
    • Added uiProgressBarValue() and allowed passing -1 to uiProgressBarSetValue() to make an indeterminate progress bar. Thanks to @emersion.
  • 15 June 2016

    • Added uiFormDelete(); thanks to @emersion.
    • Added uiWindowPosition(), uiWindowSetPosition(), uiWindowCenter(), and uiWindowOnPositionChanged(), methods for manipulating uiWindow position.
  • 14 June 2016

    • uiDarwinControl now has a ChildVisibilityChanged() method and a corresponding NotifyVisibilityChanged() function that is called by the default show/hide handlers. This is used to make visibility changes work on OS X; uiBox, uiForm, and uiGrid all respect these now.
    • The same has been done on the Windows side as well.
    • Hiding and showing controls and padding calculations are now correct on Windows at long last.
    • Hiding a control in a uiForm now hides its label on all platforms.
  • 13 June 2016

    • intmax_t and uintmax_t are no longer used for libui API functions; now we use int. This should make things much easier for bindings. int should be at least 32 bits wide; this should be sufficient for all but the most extreme cases.
  • 12 June 2016

    • Added uiGrid, a new container control that arranges controls in rows and columns, with stretchy ("expanding") rows, stretchy ("expanding") columns, cells that span rows and columns, and cells whose content is aligned in either direction rather than just filling. It's quite powerful, is it? =P
  • 8 June 2016

    • Added uiForm, a new container control that arranges controls vertically, with properly aligned labels on each. Have fun!
  • 6 June 2016

    • Added uiRadioButtonsSelected(), uiRadioButtonsSetSelected(), and uiRadioButtonsOnSelected() to control selection of a radio button and catch an event when such a thing happens.
  • 5 June 2016

    • Added uiNewPasswordEntry(), which creates a new uiEntry suitable for entering passwords.
    • Added uiNewSearchEntry(), which creates a new uiEntry suitable for searching. On some systems, the OnChanged() event will be slightly delayed and/or combined, to produce a more natural feel when searching.

Old updates can be found in the file.

Runtime Requirements

  • Windows: Windows Vista SP2 with Platform Update or newer
  • Unix: GTK+ 3.10 or newer
  • Mac OS X: OS X 10.8 or newer

Build Requirements

  • All platforms:
    • CMake 3.1.0 or newer
  • Windows: either
    • Microsoft Visual Studio 2013 or newer (2013 is needed for va_copy()) — you can build either a static or a shared library
    • MinGW-w64 (other flavors of MinGW may not work) — you can only build a static library; shared library support will be re-added once the following features come in:
      • Isolation awareness, which is how you get themed controls from a DLL without needing a manifest
  • Unix: nothing else specific
  • Mac OS X: nothing else specific, so long as you can build Cocoa programs


Out-of-tree builds typical of cmake are preferred:

$ # you must be in the top-level libui directory, otherwise this won't work
$ mkdir build
$ cd build
$ cmake ..

Pass -DBUILD_SHARED_LIBS=OFF to cmake to build a static library. The standard cmake build configurations are provided; if none is specified, Debug is used.

If you use a makefile generator with cmake, then

$ make
$ make tester         # for the test program
$ make examples       # for examples

and pass VERBOSE=1 to see build commands. Build targets will be in the build/out folder.

Project file generators should work, but are untested by me.

On Windows, I use the Unix Makefiles generator and GNU make (built using the build_w32.bat script included in the source and run in the Visual Studio command line). In this state, if MinGW-w64 (either 32-bit or 64-bit) is not in your %PATH%, cmake will use MSVC by default; otherwise, cmake will use with whatever MinGW-w64 is in your path. set PATH=%PATH%;c:\msys2\mingw(32/64)\bin should be enough to temporarily change to a MinGW-w64 build for the current command line session only if you installed MinGW-w64 through MSYS2; no need to change global environment variables constantly.


Arch Linux

Can be built from AUR:


Needs to be written. Consult ui.h and the examples for details for now.

Language Bindings

libui was originally written as part of my package ui for Go. Now that libui is separate, package ui has become a binding to libui. As such, package ui is the only official binding.

Other people have made bindings to other languages:

Language Bindings
C#/.net LibUI.Binding, SharpUI
CHICKEN Scheme wasamasa/libui
D DerelictLibui (flat API), libuid (object-oriented)
Euphoria libui-euphoria
Harbour HBUI
Haskell libui-haskell, beijaflor-io/haskell-libui (complete FFI bindings, extensions and higher-level API)
JavaScript libui.js (merged into libui-node?)
Julia Libui.jl
Lua libuilua, libui-lua
Nim ui
Node.js libui-node
PHP ui
Python pylibui
Ruby libui-ruby
Rust libui-rs
Swift libui-swift

Frequently Asked Questions

Why does my program start in the background on OS X if I run from the command line?

OS X normally does not start program executables directly; instead, it uses Launch Services to coordinate the launching of the program between the various parts of the system and the loading of info from an .app bundle. One of these coordination tasks is responsible for bringing a newly launched app into the foreground. This is called "activation".

When you run a binary directly from the Terminal, however, you are running it directly, not through Launch Services. Therefore, the program starts in the background, because no one told it to activate! Now, it turns out there is an API that we can use to force our app to be activated. But if we use it, then we'd be trampling over Launch Services, which already knows whether it should activate or not. Therefore, libui does not step over Launch Services, at the cost of requiring an extra user step if running directly from the command line.

See also this and this.


From examples/controlgallery: