Pugl

Pugl (PlUgin Graphics Library) is a minimal portable API for GUIs which is suitable for use in plugins. It works on X11, MacOS, and Windows, and optionally supports OpenGL and Cairo graphics contexts.

Pugl is vaguely similar to libraries like GLUT and GLFW, but with some distinguishing features:

Minimal in scope, providing only a thin interface to isolate platform-specific details from applications.
Zero dependencies, aside from standard system libraries.
Support for embedding in native windows, for example as a plugin or component within a larger application that is not based on Pugl.
Simple and extensible event-based API that makes dispatching in application or toolkit code easy with minimal boilerplate.
Suitable not only for continuously rendering applications like games, but also event-driven applications that only draw when necessary.
Explicit context and no static data whatsoever, so that several instances can be used within a single program at once.
Small, liberally licensed Free Software implementation that is suitable for vendoring and/or static linking. Pugl can be installed as a library, or used by simply copying the headers into a project.

Stability

Pugl is currently being developed towards a long-term stable API. For the time being, however, the API may break occasionally. Please report any relevant feedback, or file feature requests, so that we can ensure that the released API is stable for as long as possible.

Distribution

Pugl is designed for flexible distribution. It can be used by simply including the source code, or installed and linked against as a static or shared library. Static linking or direct inclusion is a good idea for plugins that will be distributed as binaries to avoid dependency problems.

If you are including the code, please use a submodule so that suitable changes can be merged upstream to keep fragmentation to a minimum.

When installed, Pugl is split into different libraries to keep dependencies minimal. The core implementation is separate from graphics backends:

The core implementation for a particular platform is in one library: pugl_x11, pugl_mac, or pugl_win. This does not depend on backends or their dependencies.
Backends for platforms are in separate libraries, which depend on the core: pugl_x11_cairo, pugl_x11_gl, pugl_mac_cairo, and so on.

Applications must link against the core and at least one backend. Normally, this can be achieved by simply depending on the package pugl-gl-0 or pugl-cairo-0. Though it is possible to compile everything into a monolithic library, distributions should retain this separation so that GL applications don't depend on Cairo and its dependencies, or vice-versa.

Distributions are encouraged to include static libraries if possible so that developers can build portable plugin binaries.

Testing

There are a few unit tests included, but unfortunately manual testing is still required. The tests and example programs will be built if you pass the --test option when configuring:

./waf configure --test

Then, after building, the unit tests can be run:

./waf
./waf test --gui-tests

Several example programs are included that serve as both manual tests and demonstrations:

pugl_embed_demo shows a view embedded in another, and also tests requesting attention (which happens after 5 seconds), keyboard focus (switched by pressing tab), view moving (with the arrow keys), and view resizing (with the arrow keys while shift is held). This program uses only very old OpenGL and should work on any system.
pugl_window_demo demonstrates multiple top-level windows.
pugl_shader_demo demonstrates using more modern OpenGL (version 3 or 4) where dynamic loading and shaders are required. It can also be used to test performance by passing the number of rectangles to draw on the command line.
pugl_cairo_demo demonstrates using Cairo on top of the native windowing system (without OpenGL), and partial redrawing.
pugl_print_events is a utility that prints all received events to the console in a human readable format.
pugl_cxx_demo is a simple cube demo that uses the C++ API.

All example programs support several command line options to control various behaviours, see the output of --help for details. Please file an issue if any of these programs do not work as expected on your system.

Documentation

The API reference for the latest master is available online, and can also be built from the source code by configuring with --docs.

-- David Robillard d@drobilla.net