Wrapping GLFW

This will be a walkthrough of using wrapdevtools to wrap glfw. And a demonstration of what will hopefully be an ergonomic wrapping workflow.

First things first, install the tools with pip3 install --user -e . from the wrapdevtools repo.

Create The Wrap file

First make a new directory to work in:

mkdir glfw-wrapping
cd glfw-wrapping

Now find the upstream source tarball. I know glfw is at http://www.glfw.org. And I’ve found that the link to the latest version (3.2.1 as of writing) is https://github.com/glfw/glfw/releases/download/3.2.1/glfw-3.2.1.zip.

To start off I run:

wrapdev-newwrap https://github.com/glfw/glfw/releases/download/3.2.1/glfw-3.2.1.zip glfw

This will create a subprojects directory (within the current working directory), download the referenced file to the packagecache, extract it, and then generate a subprojects/glfw.wrap for it. This wrap file will become the contents of upstream.wrap on wrapdb

Writing the meson build files

Next I go through and read the native build files to find what goes into the targets I want, usually it’s a list of sources + some config dependent sources. In the case of glfw the list of sources is quite small, so I’ll just write them out myself. However for a larger library I could use wrapdev-listsrc to help generate parts of my meson build file

When I’m done I get the following meson.build file

project('glfw', 'c', version: '3.2.1')

cc = meson.get_compiler('c')


glfw_core_src = files(
    'src/context.c',
    'src/init.c',
    'src/input.c',
    'src/monitor.c',
    'src/vulkan.c',
    'src/window.c'
)
glfw_platform_src = []
glfw_deps = []
glfw_deps += cc.find_library('m', required: false)
glfw_deps += cc.find_library('dl', required: false)
glfw_deps += dependency('threads')
if get_option('windowing_backend') == 'x11'
    x11_dep = dependency('x11')
    xrandr_dep = dependency('xrandr')
    xinerama_dep = dependency('xinerama')
    xkb_dep = dependency('xkbcommon')
    xcursor_dep = dependency('xcursor')
    glfw_deps += [x11_dep, xrandr_dep, xinerama_dep, xkb_dep, xcursor_dep]
    glfw_platform_src += files(
        'src/x11_init.c',
        'src/x11_monitor.c',
        'src/x11_window.c',
        'src/xkb_unicode.c',
        'src/linux_joystick.c',
        'src/posix_time.c',
        'src/posix_tls.c',
        'src/glx_context.c',
        'src/egl_context.c'
    )

else
   error('backend not supported')
endif

conf_data = configuration_data()
if get_option('windowing_backend') == 'x11'
    conf_data.set('_GLFW_X11', 1)
endif
conf_file = configure_file(configuration: conf_data, output: 'glfw_config.h')


glfw_lib = library('glfw', glfw_core_src + glfw_platform_src,
                include_directories: include_directories('src'),
                dependencies: glfw_deps,
                c_args: ['-D_GLFW_USE_CONFIG_H'])

glfw_dep = declare_dependency(
    include_directories: include_directories('src'),
    link_with: glfw_lib)

and the following meson_options.txt file

option('windowing_backend', type: 'combo',
    choices: ['x11', 'wayland', 'win32', 'cocoa'],
    description: 'windowing backend to use',
    value: 'x11')

Testing the wrap

To test the wrap I add a simple meson.build file to the root of my project tree (the one with subprojects in it), that looks like this:

project('test')
subproject('glfw')

I then test this file with meson.

Exporting the wrap

Next I use wrapdev-extractpatch to copy my build files over to a directory sutable for the wrapdb. This tool does the following:

1. Extracts the upstream tarball to a temporary directory.
2. Compares the extracted directory with the directory referenced by the wrap file
3. Copies any files that only exist in the second directory to the output directory
4. Copies the wrapfile to <output directory>/upstream.wrap

for GLFW I would use

wrapdev-extractpatch subprojects/glfw.wrap --output glfw-patch

I get a patch filetree in the glfw-patch directory