libui: a portable GUI library for C

This README is being written.

Status

It has come to my attention that I have not been particularly clear about how usable or feature-complete libui is, and that this has fooled many people into expecting more from libui right this moment than I have explicitly promised to make available. I apologize for not doing this sooner.

libui is currently mid-alpha software. Much of what is currently present runs stabily enough for the examples and perhaps some small programs to work, but the stability is still a work-in-progress, much of what is already there is not feature-complete, some of it will be buggy on certain platforms, and there's a lot of stuff missing. In short, here's a list of features that I would like to add to libui, but that aren't in yet:

• tables and trees (the former is currently WIP and may land in preliminary form soon)
• clipboard support, including drag and drop
• more and better dialogs
• printing
• accessibility for uiArea and custom controls
• document-based programs
• tighter OS integration (especially for document-based programs), to allow programs to fully feel native, rather than merely look and act native
• better support for standard dialogs and features (search bars, etc.)
• OpenGL support (this was already being worked on by someone else, but I don't know what happened to them...)

In addition, here is a list of issues generalizing existing problems.

Furthermore, libui is not properly fully documented yet. This is mainly due to the fact that the API was initially unstable enough so as to result in rewriting documentation multiple times, in addition to me not being happy with really any existing C code documentation tool. That being said, I have started to pin down my ideal code documentation style in parts of ui.h, most notably in the uiAttributedString APIs. Over time, I plan on extending this to the rest of the headers. You can also use the documentation for libui's Go bindings as a reference, though it is somewhat stale and not optimally written.

But libui is not dead; I am working on it whenever I can, and I hope to get it to a point of real quality soon!

Announcements

• 16 May 2018

  • Thanks to @parro-it and @msink, libui now has better CI, including AppVeyor for Windows CI, and automated creation of binary releases when I make a tagged release.

• 13 May 2018

  • Added new functions to work with uiDateTimePickers: uiDateTimePickerTime(), uiDateTimePickerSetTime(), and uiDateTimePickerOnChanged(). These operate on standard <time.h> struct tms. Thanks @cody271!

• 2 May 2018

  • On Windows, you no longer need to carry around a libui.res file with static builds. You do need to link in the appropriate manifest file, such as the one in the windows/ folder (I still need to figure out exactly what is needed apart from the Common Controls v6 dependency, or at least to create a complete-ish template), or at least include it alongside your executables. This also means you should no longer see random cmake errors when building the static libraries.

• 18 April 2018

  • Introduced a new uiTimer() function for running code on a timer on the main thread. (Thanks to @cody271.)

• 18 March 2018

  • Introduced an all-new formatted text API that allows you to process formatted text in ways that the old API wouldn't allow. You can read on the whole API here. There is also a new examples for it: drawtext, which shows the whole API at a glance. It doesn't yet support measuring or manipulating text, nor does it currently support functions that would be necessary for things like text editors; all of this will be added back later.
  • libui also now uses my utf library for UTF-8 and UTF-16 processing, to allow consistent behavior across platforms. This usage is not completely propagated throughout libui, but the Windows port uses it in most places now, and eventually this will become what libui will use throughout.
  • Also introduced a formal set of contribution guidelines, see CONTRIBUTING.md for details. They are still WIP.

• 17 February 2018

  • The longstanding Enter+Escape crashes on Windows have finally been fixed (thanks to @lxn).
  • Alpha 3.5 is now here. This is a quickie release primiarly intended to deploy the above fix to package ui itself. It is a partial binary release; sorry! More new things will come in the next release, which will also introduce semver (so it will be called v0.4.0 instead).
  • Alpha 3.5 also includes a new control gallery example. The screenshots below have not been updated yet.

• 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

  • Help decide the design of tables and trees in libui; the implementation starts within the next few days, if not tomorrow!

• 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 ANNOUNCE.md file.

Updates

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

• 13 May 2018

  • Release builds on Windows with MSVC should be fixed now; thanks @l0calh05t, @slahn, @mischnic, and @zentner-kyle.

• 12 May 2018

  • GTK+ and OS X now have a cleaner build process for static libraries which no longer has intermediate files and differing configurations. As a result, certain issues should no longer be present. New naming rules for internal symbols of libui have also started being drafted; runtime symbols and edge cases still need to be handled (and the rules applied to Windows) before this can become a regular thing.

• 18 April 2018

  • Migrated all code in the common/ directory to use uipriv prefixes for everything that isn't static. This is the first step toward fixing static library oddities within libui, allowing libui to truly be safely used as either a static library or a shared library.

• 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 Changelog.md 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

Building

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.

Installation

Arch Linux

Can be built from AUR: https://aur.archlinux.org/packages/libui-git/

Documentation

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++	libui-cpp, cpp-libui-qtlike
C# / .NET Framework	LibUI.Binding
C# / .NET Core	DevZH.UI, SharpUI, LibUISharp
CHICKEN Scheme	wasamasa/libui
Common Lisp	jinwoo/cl-ui
Crystal	libui.cr, hedron
D	DerelictLibui (flat API), libuid (object-oriented)
Euphoria	libui-euphoria
Harbour	HBUI
Haskell	haskell-libui
JavaScript	libui.js (merged into libui-node?), proton-native
Julia	Libui.jl
Kotlin	kotlin-libui
Lua	libuilua, libui-lua, lui
Nim	ui
Node.js	libui-node
PHP	ui
Python	pylibui, pylibui-cffi
Ruby	libui-ruby
Rust	libui-rs, arcturu/libui-rs, LeoTindall/libui-rs
Scala	scalaui
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.

Contributing

See CONTRIBUTING.md.

Screenshots

From examples/controlgallery: