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LEDMatrix/src/plugin_system/vegas_elements.py
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ChuckandClaude Opus 5.5 56947298d6 a plugin API for content that changes while it scrolls (#696)
* perf(timing): say which render-thread work a late frame followed

The soak already says how often a moving frame reached the panel late, but
not what the render thread was doing just before it. Vegas does two kinds of
work there between frames -- building its strip (compose, extend) and, with
live elements, patching changed pixels into it -- and deciding whether either
is affordable needs their own numbers.

- FrameTimingRecorder.note_op(kind, nbytes) tags the next presented frame.
  Totals gain op_frames, late_op_frames, op_freezes and op_bytes per kind;
  aggregate() still takes frames without ops. The file schema is unchanged.
- Vegas tags compose and every strip extension (with the bytes it copied).
- frame_soak prints an "after work" table: frames, late %, freezes and MB
  moved per kind, only when something tagged its work.
- render_bench gains --strip-screens (Vegas-sized strips), --patch-bytes /
  --patch-every / --patch-where (in-place column writes, as a live element
  update does) and --extend-every-screens / --extend-width (append + trim on
  a fixed cadence that holds the strip's width).

No runtime behaviour changes: this is the measurement gate for live Vegas
elements.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* docs(changelog): note the frame-op attribution and bench modes

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* perf(scroll): build the strip's PIL image only when something reads it

Every Vegas strip extension rebuilt ScrollHelper.cached_image from
cached_array in full, twice (append, then trim), on the render thread:
Image.fromarray is 1.7ms for an 8,000px strip and 3.8ms for 20,000px on a
Pi 4 (measured on ledpi), about two thirds of an extension's render-thread
cost. Nothing on the frame path reads the image's pixels; every frame is cut
from the array.

cached_image is now a property. append_content and drop_scrolled_prefix
defer it; the first read builds it from the array it started with and keeps
it only if the strip has not changed meanwhile, so a sync push racing an
extension cannot leave a stale image cached. Assigning cached_image stores
exactly what was assigned, as before. has_strip() says whether there is a
strip without building its image; the helper's frame path, Vegas and the
adapter's scroll-cache invalidation use it. The strip is also no longer held
in memory twice.

In Vegas the image is now built only by a multi-display sync push.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* feat(vegas): live elements -- a plugin API for content that changes while it scrolls

Vegas bakes each plugin's pictures into one strip, so a card already on its
way across the panel keeps what it showed when it was drawn. This adds the
API and bookkeeping for content that can be updated in place; the worker
that redraws and swaps it follows separately. No shipped plugin implements
the hook yet, so nothing changes for users.

Plugin API (core 3.8.0), all no-ops by default:
- BasePlugin.get_vegas_elements() -> [VegasElement(key, image, version,
  live, refresh_hz)]: named, fixed-width pieces of Vegas content.
- BasePlugin.redraw_vegas_element(key, width, height, at): a lock-free
  redraw for content that changes with time.
- BasePlugin.notify_vegas_data_changed(): data that lands outside update().
- src/plugin_system/vegas_elements.py (VegasElement, re-exported from
  base_plugin).

Core:
- PluginAdapter asks a plugin that implements the hook for elements on the
  background fetch only (under its lock, on its own canvas); every other
  path keeps get_vegas_content(). Live elements are pinned (padded with
  content_padding, never trimmed), tagged with their key, digest and data
  epoch in Image.info so the existing cache and group plumbing carry them
  unchanged, and untagged if a width budget crops them.
- RenderPipeline records where each live element lands (ElementRecord), in
  absolute strip columns a trim does not move; the block-start arithmetic
  is shared with the STATIC markers.
- PluginManager update listeners (add/remove_update_listener,
  notify_data_changed): told the moment update() completes, not at the
  next ~4s Vegas poll. The coordinator uses one to move each plugin's data
  epoch on.
- vegas_scroll.live_refresh (kill switch), live_max_hz, live_min_interval,
  live_lead_screens; per-plugin core-owned vegas_live. Live elements are
  off under multi-display sync, in swap mode and with offscreen_prefetch off.
- scripts/check_plugin.py checks the element contract
  (src/plugin_system/testing/vegas.py); test/fixtures/plugins/vegas-live-stub
  is a working example.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
2026-09-30 20:59:16 -04:00

74 lines
3.5 KiB
Python

"""Live elements: Vegas content that can change while it is on screen.
A plugin's ``get_vegas_content()`` hands the Vegas ticker pictures, and the
ticker bakes them into its strip: a score drawn when the plugin's turn was
prefetched scrolls past with that score, however many goals are scored while
it crosses the panel. A plugin that returns **elements** instead gives each
picture a name and a fixed width. The ticker then keeps track of where each
one is in the strip, and when the plugin's data changes it asks for just the
changed elements and swaps their pixels in place -- on screen included,
between two frames, without anything next to them moving.
A plugin opts in by implementing ``BasePlugin.get_vegas_elements()``, and, for
content that changes with time rather than with data (an aircraft moving
between position reports), ``BasePlugin.redraw_vegas_element()``. See "Live
Vegas elements" in docs/PLUGIN_API_REFERENCE.md.
Added in LEDMatrix 3.8.0. Import it guarded, so the plugin still loads on an
older core (which never calls the hooks)::
try:
from src.plugin_system.vegas_elements import VegasElement
except ImportError: # core older than 3.8.0
VegasElement = None
def get_vegas_elements(self):
if VegasElement is None:
return None
return [VegasElement(key=f"game:{g['id']}", image=self._card(g),
version=self._fingerprint(g))
for g in self._games]
"""
from dataclasses import dataclass
from typing import Hashable, Optional
from PIL import Image
@dataclass(frozen=True, eq=False)
class VegasElement:
"""One named, fixed-width piece of a plugin's Vegas content.
Attributes:
key: Names the element across redraws, unique within one list the
plugin returns: ``"game:nfl:401547417"``, ``"sep:0:nfl"``,
``"map"``. The ticker matches a redraw to the pixels already in
its strip by this key, so it must stay the same for the same
logical thing and must not be reused for a different one.
image: The element as drawn now, at the display's height. For a
``live`` element its width is fixed for as long as the key is on
the strip: a redraw at a different width is never swapped in (it
appears the next time the plugin comes round instead), because
nothing on screen may move. Draw live elements at a width that
does not depend on the data -- a fixed card width, not the
width of the text.
version: Anything hashable that changes exactly when the pixels
would, such as the tuple of fields the element draws. The ticker
skips work for an unchanged version. ``None`` means "compare the
pixels", which is always correct and costs a checksum.
live: False places the element exactly as plain content is placed
(trimmed to its ink, never refreshed): separators, decoration.
refresh_hz: More than 0 asks for ``redraw_vegas_element()`` about
this often while the element is on or near the screen, for
content that changes with time rather than with data. The ticker
caps the rate (``vegas_scroll.live_max_hz``, 1 Hz on a display
without the rebuilt rgbmatrix binding) and slows it for an
element that is slow to draw.
"""
key: str
image: Image.Image
version: Optional[Hashable] = None
live: bool = True
refresh_hz: float = 0.0