Support emscripten/pygbag in the meson buildconfig

Author: ankith26

.github/workflows/build-emsdk.yml

@@ -32,43 +32,45 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  build:
+  build-pygbag:
     runs-on: ubuntu-22.04
     env:
       # pin SDK version to the latest, update manually
-      SDK_VERSION: 3.1.32.0
-      SDK_ARCHIVE: python3.11-wasm-sdk-Ubuntu-22.04.tar.lz4
+      SDK_VERSION: 3.1.61.12bi
+      SDK_ARCHIVE: python3.13-wasm-sdk-Ubuntu-22.04.tar.lz4
       SDKROOT: /opt/python-wasm-sdk
+      PYBUILD: 3.13
 
     steps:
     - uses: actions/checkout@v5.0.0
 
-    - name: Regen with latest cython (using system python3)
-      run: |
-        pip3 install cython==3.0.10
-        python3 setup.py cython_only
-
     - name: Install python-wasm-sdk
       run: |
         sudo apt-get install lz4
-        echo https://github.com/pygame-web/python-wasm-sdk/releases/download/$SDK_VERSION/$SDK_ARCHIVE
         curl -sL --retry 5 https://github.com/pygame-web/python-wasm-sdk/releases/download/$SDK_VERSION/$SDK_ARCHIVE | tar xvP --use-compress-program=lz4
-        # do not let SDL1 interfere
-        rm -rf /opt/python-wasm-sdk/emsdk/upstream/emscripten/cache/sysroot/include/SDL
       working-directory: /opt
 
     - name: Build WASM with emsdk
-      run: |
-        ${SDKROOT}/python3-wasm setup.py build -j$(nproc)
-
-    - name: Generate libpygame.a static binaries archive
-      run: |
-        mkdir -p dist
-        SYS_PYTHON=python3 /opt/python-wasm-sdk/emsdk/upstream/emscripten/emar rcs dist/libpygame.a $(find build/temp.wasm32-*/ | grep o$)
+      run: ${SDKROOT}/python3-wasm dev.py build --wheel
 
     # Upload the generated files under github actions assets section
     - name: Upload dist
       uses: actions/upload-artifact@v4
       with:
         name: pygame-wasm-dist
         path: ./dist/*
+
+  build-pyodide:
+    name: Pyodide build
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v5.0.0
+
+    - uses: pypa/cibuildwheel@v3.1.4
+      env:
+        CIBW_PLATFORM: pyodide
+
+    - uses: actions/upload-artifact@v4
+      with:
+        name: pyodide-wheels
+        path: wheelhouse/*.whl

buildconfig/meson-cross-emscripten.ini

@@ -0,0 +1,12 @@
+[host_machine]
+system = 'emscripten'
+cpu_family = 'wasm32'
+cpu = 'wasm'
+endian = 'little'
+
+[binaries]
+c = 'emcc'
+cpp = 'em++'
+ar = 'emar'
+strip = 'emstrip'
+exe_wrapper = 'node'

dev.py

@@ -11,6 +11,7 @@
 import re
 import subprocess
 import sys
+import sysconfig
 from enum import Enum
 from pathlib import Path
 from typing import Any, Union
@@ -35,6 +36,19 @@
 # We assume this script works with any pip version above this.
 PIP_MIN_VERSION = "23.1"
 
+# we will assume dev.py wasm builds are made for pygbag.
+host_gnu_type = sysconfig.get_config_var("HOST_GNU_TYPE")
+if isinstance(host_gnu_type, str) and "wasm" in host_gnu_type:
+    wasm = "wasi" if "wasi" in host_gnu_type else "emscripten"
+else:
+    wasm = ""
+
+wasm_cross_file = (source_tree / "buildconfig" / f"meson-cross-{wasm}.ini").resolve()
+wasm_args = [
+    f"-Csetup-args=--cross-file={wasm_cross_file}",
+    "-Csetup-args=-Demscripten_type=pygbag",
+]
+
 
 class Colors(Enum):
     RESET = "\033[0m"
@@ -189,7 +203,11 @@ def check_module_in_constraint(mod: str, constraint: str):
 
 class Dev:
     def __init__(self) -> None:
-        self.py: Path = Path(sys.executable)
+        self.py: Path = (
+            Path(os.environ["SDKROOT"]) / "python3-wasm"
+            if wasm
+            else Path(sys.executable)
+        )
         self.args: dict[str, Any] = {}
 
         self.deps: dict[str, set[str]] = {
@@ -233,6 +251,14 @@ def cmd_build(self):
         ]
 
         if not wheel_dir:
+            if wasm:
+                pprint(
+                    "Editable builds are not supported on WASM as of now. "
+                    "Pass --wheel to do a regular build",
+                    Colors.RED,
+                )
+                sys.exit(1)
+
             # editable install
             if not quiet:
                 install_args.append("-Ceditable-verbose=true")
@@ -259,6 +285,9 @@ def cmd_build(self):
         if sanitize:
             install_args.append(f"-Csetup-args=-Db_sanitize={sanitize}")
 
+        if wasm:
+            install_args.extend(wasm_args)
+
         info_str = (
             f"with {debug=}, {lax=}, {sdl3=}, {stripped=}, {coverage=} and {sanitize=}"
         )
@@ -484,6 +513,12 @@ def prep_env(self):
         # set PATH to give high priority to executables in the python bin folder
         # this is where the binaries for meson/ninja/cython/sphinx/etc are installed
         os.environ["PATH"] = f"{self.py.parent}{os.pathsep}{os.environ.get('PATH', '')}"
+        if wasm:
+            for wasm_path in [
+                self.py.parent / "emsdk" / "upstream" / "emscripten",
+                self.py.parent / "devices" / "emsdk" / "usr" / "bin",
+            ]:
+                os.environ["PATH"] = f"{wasm_path}{os.pathsep}{os.environ['PATH']}"
 
         pprint("Checking pip version")
         pip_v = cmd_run([self.py, "-m", "pip", "-V"], capture_output=True)
@@ -497,6 +532,10 @@ def prep_env(self):
             pprint("pip version is too old or unknown, attempting pip upgrade")
             pip_install(self.py, ["-U", "pip"])
 
+        if wasm:
+            # dont try to install any deps on WASM
+            return
+
         deps = self.deps.get(self.args["command"], set())
         ignored_deps = self.args["ignore_dep"]
         deps_filtered = deps.copy()

meson.build

@@ -34,11 +34,7 @@ elif host_machine.system() == 'android'
         'However it may be added in the future',
     )
 elif host_machine.system() == 'emscripten'
-    plat = 'emscripten'
-    error(
-        'The meson buildconfig of pygame-ce does not support emscripten for now. ',
-        'However it may be added in the future',
-    )
+    plat = 'emscripten-@0@'.format(get_option('emscripten_type'))
 else
     # here it one of: cygwin, dragonfly, freebsd, gnu, haiku, netbsd, openbsd, sunos
     plat = 'unix'
@@ -90,6 +86,27 @@ endif
 
 pg_inc_dirs = []
 pg_lib_dirs = []
+
+if plat.startswith('emscripten')
+    sdl_dep = declare_dependency(
+        compile_args: ['-sUSE_SDL=2'],
+        link_args: ['-lSDL2'],
+    )
+    sdl_image_dep = declare_dependency(
+        link_args: ['-lSDL2_image'],
+    )
+    sdl_mixer_dep = declare_dependency(
+        link_args: ['-lSDL2_mixer'],
+    )
+    sdl_ttf_dep = declare_dependency(
+        link_args: ['-lSDL2_ttf'],
+    )
+    freetype_dep = declare_dependency(
+        compile_args: ['-sUSE_FREETYPE=1'],
+        link_args: ['-lfreetype', '-lharfbuzz']
+    )
+else
+
 if plat == 'win' and host_machine.cpu_family().startswith('x86')
     # yes, this is a bit ugly and hardcoded but it is what it is
     # TODO (middle-term goal) - Should migrate away from this
@@ -311,8 +328,10 @@ if not freetype_dep.found()
     )
 endif
 
+endif # emscripten
+
 portmidi_dep = dependency('portmidi', required: false)
-if not portmidi_dep.found()
+if not portmidi_dep.found() and not plat.startswith('emscripten')
     portmidi_dep = declare_dependency(
         include_directories: pg_inc_dirs,
         dependencies: cc.find_library(
@@ -436,7 +455,7 @@ endif
 subdir('src_c')
 subdir('src_py')
 
-if not get_option('stripped')
+if not get_option('stripped') and not plat.startswith('emscripten')
     # run make_docs and make docs
     if not fs.is_dir('docs/generated')
         make_docs = files('buildconfig/make_docs.py')

meson_options.txt

@@ -40,3 +40,6 @@ option('coverage', type: 'boolean', value: false)
 
 # Controls whether to use SDL3 instead of SDL2. The default is to use SDL2
 option('sdl_api', type: 'integer', min: 2, max: 3, value: 2)
+
+# Specify the type of emscripten build being done.
+option('emscripten_type', type: 'combo', choices: ['pygbag', 'generic'], value: 'generic')

pyproject.toml

@@ -97,6 +97,14 @@ setup-args = [
     "-Derror_docs_missing=true",
 ]
 
+[tool.cibuildwheel.pyodide]
+build = "cp313-*"  # build only for the latest python version.
+
+# taken from pyodide recipe at https://github.com/pyodide/pyodide-recipes/blob/main/packages/pygame-ce/meta.yaml
+before-build = "embuilder build sdl2 sdl2_ttf sdl2_image sdl2_mixer sdl2_gfx libjpeg libpng giflib harfbuzz vorbis mpg123 libmodplug freetype libhtml5 --pic"
+test-command = ""  # TODO: fix runtime issues and then figure out how to test
+
+
 [tool.ruff]
 exclude = [
   "buildconfig/*.py",

src_c/meson.build

@@ -1,3 +1,27 @@
+if plat == 'emscripten-pygbag'  # do a static build
+
+base_files = ['base.c', 'bitmask.c', 'SDL_gfx/SDL_gfxPrimitives.c']
+cython_files = [
+    'cython/pygame/_sdl2/audio.pyx',
+    'cython/pygame/_sdl2/mixer.pyx',
+    'cython/pygame/_sdl2/sdl2.pyx',
+    'cython/pygame/_sdl2/video.pyx',
+    'pgcompat.c'
+]
+
+# make one big static build on emscripten
+pygame = static_library(
+    'pygame',
+    base_files + cython_files,
+    # c_args: warnings_error,
+    dependencies: pg_base_deps + [sdl_image_dep, sdl_mixer_dep, sdl_ttf_dep, freetype_dep],
+    install: true,
+    install_dir: pg_dir,
+    install_tag: 'pg-tag'
+)
+
+else  # regular build
+
 # first the "required" modules
 
 base = py.extension_module(
@@ -327,6 +351,7 @@ subdir('_sdl2')
 endif
 
 # pygame._camera
+if not plat.startswith('emscripten')
 pg_camera_sources = ['_camera.c']
 pg_camera_link = []
 if plat == 'win'
@@ -357,6 +382,7 @@ _camera = py.extension_module(
     install: true,
     subdir: pg,
 )
+endif
 
 # pygame.scrap
 pg_scrap_link = [] # TODO: should this link logic be improved/made meson-ey?
@@ -452,3 +478,5 @@ if portmidi_dep.found()
         subdir: pg,
     )
 endif
+
+endif # emscripten

src_c/mixer.c

@@ -447,12 +447,18 @@ _init(int freq, int size, int channels, int chunk, char *devicename,
         if (!PG_InitSubSystem(SDL_INIT_AUDIO)) {
             return RAISE(pgExc_SDLError, SDL_GetError());
         }
-
+#if __EMSCRIPTEN__
+        if (Mix_OpenAudio(freq, fmt, channels, chunk) == -1) {
+            SDL_QuitSubSystem(SDL_INIT_AUDIO);
+            return RAISE(pgExc_SDLError, SDL_GetError());
+        }
+#else
         if (Mix_OpenAudioDevice(freq, fmt, channels, chunk, devicename,
                                 allowedchanges) == -1) {
             SDL_QuitSubSystem(SDL_INIT_AUDIO);
             return RAISE(pgExc_SDLError, SDL_GetError());
         }
+#endif
         Mix_ChannelFinished(endsound_callback);
         Mix_VolumeMusic(127);
     }

src_py/__init__.py

@@ -115,7 +115,7 @@ def warn(self):
     except ModuleNotFoundError:
         pygame_static = None
 
-    if pygame_static:
+    if pygame_static and hasattr(pygame_static, 'import_cython'):
         pygame = sys.modules[__name__]
 
         # cython modules use multiphase initialisation when not in builtin Inittab.