Add Electron app bridge for anyplotlib figures

Author: CSSFrancis

anyplotlib/_electron.py

@@ -0,0 +1,74 @@
+"""
+_electron.py
+============
+Electron app bridge for anyplotlib figures.
+
+Registers figures so their trait changes are forwarded to the Electron
+renderer via stdout, and provides dispatch_event() so the renderer can
+send interaction events back to Python.
+"""
+from __future__ import annotations
+
+import json
+import sys
+import uuid
+
+_figures: dict[str, object] = {}   # fig_id -> Figure
+
+
+def register(fig) -> str:
+    """Register *fig* for bidirectional state sync and return its fig_id."""
+    fig_id = uuid.uuid4().hex[:8]
+    _figures[fig_id] = fig
+
+    def _on_change(change):
+        name = change["name"]
+        value = change["new"]
+        if isinstance(value, (bytes, bytearray)):
+            import base64
+            value = {"buffer": base64.b64encode(value).decode()}
+        emit({"type": "state_update", "fig_id": fig_id, "key": name, "value": value})
+
+    for name in fig.traits(sync=True):
+        if not name.startswith("_"):
+            try:
+                fig.observe(_on_change, names=[name])
+            except Exception:
+                pass
+
+    return fig_id
+
+
+def resize_figure(fig_id: str, width: int, height: int) -> None:
+    """Update fig_width / fig_height and push new layout to the iframe."""
+    fig = _figures.get(fig_id)
+    if fig is None:
+        return
+    try:
+        # Batch both trait changes so _on_resize fires only once each.
+        with fig.hold_trait_notifications():
+            fig.fig_width  = int(width)
+            fig.fig_height = int(height)
+    except Exception:
+        pass
+
+
+def dispatch_event(fig_id: str, event_json: str) -> None:
+    """Apply a frontend interaction event to the registered figure."""
+    fig = _figures.get(fig_id)
+    if fig is None:
+        return
+    try:
+        # Figure.show() registers Figure objects which use _dispatch_event(raw_json_str).
+        # Standalone widgets use _update_from_js(dict, event_type).
+        if hasattr(fig, "_dispatch_event"):
+            fig._dispatch_event(event_json)
+        elif hasattr(fig, "_update_from_js"):
+            fig._update_from_js(json.loads(event_json))
+    except Exception:
+        pass
+
+
+def emit(obj: dict) -> None:
+    sys.stdout.write(f"PLOTAPP:{json.dumps(obj, default=str)}\n")
+    sys.stdout.flush()