Electron and Chrome patcher to force OpenGL rendering

electron_patcher.py

"""
electron_patcher.py: Enforce 'use-angle@1' in Chrome and Electron applications

Version 1.0.0 (2024-08-11)
"""

import enum
import json

from pathlib import Path


class ChromiumSettingsPatcher:

    class AngleVariant(enum.Enum):
        Default = "0"
        OpenGL = "1"
        Metal = "2"

    def __init__(self, state_file: str) -> None:
        self._local_state_file = Path(state_file).expanduser()


    def patch(self) -> None:
        """
        Ensure 'use-angle@1' is set in Chrome's experimental settings
        """
        _desired_key   = "use-angle"
        _desired_value = self.AngleVariant.OpenGL.value

        if not self._local_state_file.exists():
            print("  Local State missing, creating...")
            self._local_state_file.parent.mkdir(parents=True, exist_ok=True)
            state_data = {}
        else:
            print("  Parsing Local State file")
            state_data = json.loads(self._local_state_file.read_bytes())


        if "browser" not in state_data:
            state_data["browser"] = {}
        if "enabled_labs_experiments" not in state_data["browser"]:
            state_data["browser"]["enabled_labs_experiments"] = []

        for key in state_data["browser"]["enabled_labs_experiments"]:
            if "@" not in key:
                continue

            key_pair = key.split("@")
            if len(key_pair) < 2:
                continue
            if key_pair[0] != _desired_key:
                continue
            if key_pair[1] == _desired_value:
                print(f"  {_desired_key}@{_desired_value} is already set")
                break

            index = state_data["browser"]["enabled_labs_experiments"].index(key)
            state_data["browser"]["enabled_labs_experiments"][index] = f"{_desired_key}@{_desired_value}"
            print(f"  Updated {_desired_key}@{_desired_value}")

        if f"{_desired_key}@{_desired_value}" not in state_data["browser"]["enabled_labs_experiments"]:
            state_data["browser"]["enabled_labs_experiments"].append(f"{_desired_key}@{_desired_value}")
            print(f"  Added {_desired_key}@{_desired_value}")

        print("  Writing to Local State file")
        self._local_state_file.write_text(json.dumps(state_data, indent=4))


def main():
    # Patch all Electron applications
    for directory in Path("~/Library/Application Support").expanduser().iterdir():
        if not directory.is_dir():
            continue

        state_file = directory / "Local State"
        if not state_file.exists():
            continue

        print(f"Patching {directory.name}")
        patcher = ChromiumSettingsPatcher(state_file)
        patcher.patch()

    # Patch all Chrome variants
    if Path("~/Library/Application Support/Google").expanduser().exists():
        for directory in Path("~/Library/Application Support/Google").expanduser().iterdir():
            if not directory.is_dir():
                continue

            state_file = directory / "Local State"
            if not state_file.exists():
                continue

            print(f"Patching {directory.name}")
            patcher = ChromiumSettingsPatcher(state_file)
            patcher.patch()


if __name__ == "__main__":
    main()

For the Signals app, the file in line 76 would typically not exist, and the rest of the magic then skipped. Also manually creating the file with the right content wouldn't work.

open /Applications/Signal.app --args --use-angle=gl

however works.