feat: add final.png export

polylan_submitter/place/export.py

@@ -0,0 +1,31 @@
+"""Exports one event's final board as a PNG.
+
+Reads the live Redis canvas rather than replaying the history like gif.py -
+once placement is over the canvas endpoint serves a wiped board, but Redis
+still holds the real final one (see tasks.py).
+"""
+
+from io import BytesIO
+
+from events.models import Event
+
+from .canvas import read_canvas
+from .gif import _render_frame
+from .models import PlaceSettings
+
+
+def build_final_png(event: Event) -> bytes:
+    """Renders `event`'s current board as a PNG, upscaled like gif.py.
+
+    Redis only pads up to the last written pixel, so a short canvas is
+    padded with white (and a longer one, e.g. from before a shrink, cut)
+    to the current grid dimensions."""
+    place_settings = PlaceSettings.current(event)
+    width, height = place_settings.width, place_settings.height
+    size = width * height
+
+    canvas = read_canvas(event.path, width, height)[:size].ljust(size, b"\0")
+
+    buffer = BytesIO()
+    _render_frame(bytearray(canvas), width, height).save(buffer, format="PNG")
+    return buffer.getvalue()