unshare_element_fonts re-instantiates a duplicate font face so two elements can be told apart by id(). It did so through bare ImageFont.truetype, which takes PIL's default layout engine rather than the one src/common/font_layout.py pins. Raqm and Basic disagree on fractional advances -- that disagreement is the reason the pin exists, having broken golden images across machines -- so a rebuilt face could measure differently from the shared face it replaced, on any host where Raqm is installed. These were the only two call sites in src/ bypassing the pin. The guard asserts that the rebuild goes through the pinned loader rather than comparing engine values: where Raqm is absent, bare truetype returns BASIC anyway, so an engine comparison passes whether or not the pin is honoured. The first draft of this test did exactly that and passed with the bug reintroduced. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Common Utilities
This directory contains reusable utilities and helpers for LEDMatrix plugins and core modules.
Adaptive Layout & Images (src/adaptive_layout.py, src/adaptive_images.py)
The recommended way to lay out plugins that render legibly on any panel
size (64x32 through 256x128+) without hand-tuned coordinates. Re-exported
from src.common for convenience; canonical import paths are
src.adaptive_layout / src.adaptive_images.
# Every BasePlugin already has self.layout and the draw helpers:
regs = scoreboard_regions(self.layout.bounds, ctx=self.layout)
self.draw_image(away_logo, regs.away_slot, mode="fill_height",
crop_to_ink=True, cache_key=f"logo:{abbr}")
self.draw_fit(score_text, regs.score_area) # largest crisp font that fits
self.draw_fit(status, regs.status_band)
Key pieces: Region (rect algebra: bands/columns/splits/offset),
font ladders (LADDER_GRID, LADDER_ARCADE — discrete crisp sizes, never
fractional scaling), LayoutContext (fit_text, fit_image, by_tier,
px), and composite carvers scoreboard_regions() / media_row().
Full guide: docs/ADAPTIVE_LAYOUT.md.
Error Handling (error_handler.py)
Common error handling patterns and utilities:
handle_file_operation()- Handle file I/O with consistent error handlinghandle_json_operation()- Handle JSON operations with error handlingsafe_execute()- Safely execute operations with error handlingretry_on_failure()- Decorator for retrying failed operationslog_and_continue()- Log non-critical errors and continuelog_and_raise()- Log errors and raise exceptions
Example Usage
from src.common.error_handler import handle_json_operation, safe_execute
# Handle JSON loading
config = handle_json_operation(
lambda: json.load(open('config.json')),
"Failed to load config",
logger,
default={}
)
# Safe execution with error handling
result = safe_execute(
lambda: risky_operation(),
"Operation failed",
logger,
default=None
)
API Helpers (api_helper.py)
Utilities for making HTTP requests and handling API responses.
Configuration Helpers (config_helper.py)
Utilities for loading, saving, and validating configuration files.
Display Helpers (display_helper.py)
Utilities for rendering content to the LED matrix display.
Game Helpers (game_helper.py)
Utilities for processing game data and team information.
Logo Helpers (logo_helper.py)
Utilities for loading and managing team logos.
Text Helpers (text_helper.py)
Utilities for text processing and formatting.
Scroll Helpers (scroll_helper.py)
Utilities for scrolling text on the display.
General Utilities (utils.py)
General-purpose utility functions:
- Team abbreviation normalization
- Time formatting
- Boolean parsing
- Logger creation (deprecated - use
src.logging_config.get_logger())
Permission Utilities (permission_utils.py)
Helpers for ensuring directory permissions and ownership are correct
when running as a service (used by CacheManager to set up its
persistent cache directory).
Best Practices
- Use centralized logging: Import from
src.logging_configinstead of creating loggers directly - Use error handlers: Use
error_handlerutilities for consistent error handling - Reuse utilities: Check existing utilities before creating new ones
- Document additions: Add documentation when adding new utilities