Support emscripten/pygbag in the meson buildconfig

Author: ankith26

.github/workflows/build-emsdk.yml

@@ -36,35 +36,22 @@ jobs:
     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

buildconfig/meson-cross-emscripten.ini

@@ -0,0 +1,13 @@
+[host_machine]
+system = 'emscripten'
+cpu_family = 'wasm64'
+cpu = 'wasm'
+endian = 'little'
+
+[binaries]
+c = '/opt/python-wasm-sdk/emsdk/upstream/emscripten/emcc'
+cpp = '/opt/python-wasm-sdk/emsdk/upstream/emscripten/em++'
+ar = '/opt/python-wasm-sdk/emsdk/upstream/bin/llvm-ar'
+strip = '/opt/python-wasm-sdk/emsdk/upstream/bin/llvm-strip'
+exe_wrapper = 'node'
+pkgconfig_path = '/opt/python-wasm-sdk/devices/x86_64/usr/bin/pkgconfig'

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 / "devices" / "emsdk" / "usr" / "bin",
+                self.py.parent / "emsdk" / "upstream" / "emscripten",
+            ]:
+                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'
@@ -80,7 +76,7 @@ pg_dir = py.get_install_dir() / pg
 
 sdl_api = get_option('sdl_api')
 sdl = 'SDL@0@'.format(sdl_api)
-sdl_mixer = '@0@_mixer'.format(sdl)
+sdl_mixer = (plat == 'emscripten-pygbag') ? '@0@_mixer_ogg'.format(sdl) : '@0@_mixer'.format(sdl)
 sdl_ttf = '@0@_ttf'.format(sdl)
 sdl_image = '@0@_image'.format(sdl)
 
@@ -229,7 +225,20 @@ if plat == 'win' and host_machine.cpu_family().startswith('x86')
     install_data(dlls, install_dir: pg_dir, install_tag: 'pg-tag')
 
 else
-    bases = ['/usr/local', '/usr', '/opt/homebrew', '/opt/local']
+    if plat == 'emscripten-pygbag'
+        bases = [
+            '/opt/python-wasm-sdk/emsdk/upstream/emscripten/cache/sysroot',
+            '/opt/python-wasm-sdk/devices/emsdk/usr'
+        ]
+        add_global_arguments(['-DBUILD_STATIC'], language: 'c')
+    elif plat == 'emscripten-generic'
+        # TODO: check if these bases are valid in pyodide
+        bases = ['/usr/local', '/usr', '/opt/local']
+        add_global_arguments(['-DBUILD_STATIC'], language: 'c')
+    else
+        bases = ['/usr/local', '/usr', '/opt/homebrew', '/opt/local']
+    endif
+
     foreach inc_dir : bases
         foreach sub_inc : [
             '',
@@ -244,7 +253,7 @@ else
     endforeach
 
     foreach lib_dir : bases
-        foreach sub_lib : ['lib', 'lib64']
+        foreach sub_lib : ['lib', 'lib64', 'lib/wasm32-emscripten/pic', 'lib/wasm32-emscripten']
             full_lib = lib_dir / sub_lib
             if fs.exists(full_lib)
                 pg_lib_dirs += full_lib
@@ -312,7 +321,7 @@ if not freetype_dep.found()
 endif
 
 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 +445,7 @@ 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 +40,7 @@ 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.
+# TODO: add a 'pyodide' option here if it requires specialised code
+option('emscripten_type', type: 'combo', choices: ['pygbag', 'generic'], value: 'generic')

src_c/meson.build

@@ -1,3 +1,27 @@
+if plat.startswith('emscripten')   # emscripten 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(
@@ -452,3 +476,5 @@ if portmidi_dep.found()
         subdir: pg,
     )
 endif
+
+endif # emscripten