reuk / pugl

A minimal portable API for embeddable GUIs

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 Vulkan, 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.

Documentation

Pugl is a C library that includes C++ bindings. Each API is documented separately:

• C Documentation (single page)
• C Documentation (paginated)
• C++ Documentation (single page)
• C++ Documentation (paginated)

The documentation will also be built from the source if the docs configuration option is enabled, and both Doxygen and Sphinx are available.

Testing

Some unit tests are included, but unfortunately manual testing is still required. The tests and example programs are built by default. You can run all the tests at once via ninja:

meson setup build
cd build
ninja test

The examples directory contains several programs 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_cpp_demo is a simple cube demo that uses the C++ API.

• pugl_vulkan_demo is a simple example of using Vulkan in C that simply clears the window.

• pugl_vulkan_cpp_demo is a more advanced Vulkan demo in C++ that draws many animated rectangles like pugl_shader_demo.

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.

-- David Robillard [e-mail]