pythonnative/src/pythonnative/bridge/android.py at main · pythonnative/pythonnative · GitHub

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"""Android transport: the ``com.pythonnative.runtime.PNBridge`` class via Chaquopy.

``PNBridge`` is the only Java class Python touches. Its static methods

mirror the C entry points used on iOS (see ``docs/concepts/bridge.md``).

The reverse direction (native -> Python) is installed by the template's

``MainActivity``, which implements ``PythonHost`` by calling

[`pythonnative.bridge.native_callback`][pythonnative.bridge.native_callback]

through Chaquopy; this transport therefore has nothing to register.

"""

from __future__ import annotations

from typing import Any, Callable, Optional, Tuple

__all__ = ["AndroidTransport"]

BRIDGE_CLASS = "com.pythonnative.runtime.PNBridge"

class AndroidTransport:

"""Thin wrapper over the static ``PNBridge`` methods."""

name = "android"

asynchronous_commits = True

def __init__(self, bridge_class: Any = None) -> None:

if bridge_class is None:

from java import jclass

try:

bridge_class = jclass(BRIDGE_CLASS)

except Exception as exc:

raise RuntimeError(

f"{BRIDGE_CLASS} is not on the classpath. Rebuild the app with 'pn run android' or "

"'pn build android' so the pythonnative Gradle module is included."

) from exc

self._bridge = bridge_class

def protocol_version(self) -> int:

"""Return the protocol version compiled into the native library."""

return int(self._bridge.protocolVersion())

def apply(self, transaction_json: str) -> str:

"""Apply one serialized transaction (a JSON array of ops)."""

return str(self._bridge.apply(transaction_json))

def measure(self, tag: int, max_width: float, max_height: float) -> Tuple[float, float]:

"""Return the intrinsic ``(width, height)`` of the view ``tag`` under the constraints."""

packed = self._bridge.measure(int(tag), float(max_width), float(max_height))

if not packed:

return (0.0, 0.0)

text = str(packed)

w, _, h = text.partition(",")

try:

return (float(w), float(h))

except ValueError:

return (0.0, 0.0)

def command(self, tag: int, name: str, args_json: str) -> Optional[str]:

"""Run an imperative command on one view; returns its JSON result or ``None``."""

return _opt_str(self._bridge.command(int(tag), name, args_json))

def animate(self, tag: int, request_json: str) -> Optional[str]:

"""Handle an animation request (``set`` / ``start`` / ``cancel``) for one view."""

return _opt_str(self._bridge.animate(int(tag), request_json))

def call(self, module: str, method: str, args_json: str) -> Optional[str]:

"""Call a native module method with a ``{"call_id", "args"}`` envelope."""

return _opt_str(self._bridge.call(module, method, args_json))

def set_callback(self, callback: Callable[[str, int, str, str], Optional[str]]) -> None:

"""No-op: the Android template installs the host through ``PNBridge.setHost``."""

del callback

def _opt_str(value: Any) -> Optional[str]:

if value is None:

return None

return str(value)

pythonnative/src/pythonnative/bridge/android.py at main · pythonnative/pythonnative · GitHub

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