fix(scripts): scroll_speeds.py opens the panel with the service's options

--measure and --demo built RGBMatrixOptions from a private copy of the
display service's builder that had drifted: gpio_slowdown came from
display.hardware (default 2) instead of display.runtime (default 3), and
rp1_rio, panel_type, disable_hardware_pulsing, inverse_colors,
pixel_mapper_config and orientation were skipped, with different defaults
(hardware_mapping "regular", pwm_bits 11). A panel needing a high slowdown
was measured -- or garbled -- in a setup the service never drives.

The option filling in DisplayManager._setup_matrix moves, unchanged, into
DisplayManager.apply_matrix_options(options, config), which _setup_matrix
calls and the script reuses (overriding only limit_refresh_rate_hz for
--measure). The script now loads the whole config rather than the hardware
block. Tests pin the script's options to the service's attribute for
attribute.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/scroll_speeds.py

@@ -47,52 +47,47 @@ from src.common import scroll_config  # noqa: E402
 CONFIG = Path(__file__).resolve().parent.parent / "config" / "config.json"
 
 
-def load_hardware():
+def load_config():
+    """The whole config.json, or {} when it is missing or unreadable."""
     try:
         with open(CONFIG, encoding="utf-8") as handle:
-            return (json.load(handle).get("display") or {}).get("hardware") or {}
+            config = json.load(handle)
     except (OSError, ValueError):
         return {}
+    return config if isinstance(config, dict) else {}
 
 
-def build_options(hardware, refresh_override=None):
+def hardware_of(config):
-    from rgbmatrix import RGBMatrixOptions
+    return (config.get("display") or {}).get("hardware") or {}
-
-    o = RGBMatrixOptions()
-    from src.display_geometry import (
-        DEFAULT_CHAIN_LENGTH, DEFAULT_COLS, DEFAULT_PARALLEL, DEFAULT_ROWS,
-    )
-    o.rows = int(hardware.get("rows", DEFAULT_ROWS))
-    o.cols = int(hardware.get("cols", DEFAULT_COLS))
-    o.chain_length = int(hardware.get("chain_length", DEFAULT_CHAIN_LENGTH))
-    o.parallel = int(hardware.get("parallel", DEFAULT_PARALLEL))
-    o.brightness = int(hardware.get("brightness", 80))
-    o.hardware_mapping = hardware.get("hardware_mapping", "regular")
-    o.pwm_bits = int(hardware.get("pwm_bits", 11))
-    o.pwm_dither_bits = int(hardware.get("pwm_dither_bits", 0))
-    o.pwm_lsb_nanoseconds = int(hardware.get("pwm_lsb_nanoseconds", 130))
-    o.led_rgb_sequence = hardware.get("led_rgb_sequence", "RGB")
-    o.scan_mode = int(hardware.get("scan_mode", 0))
-    o.row_address_type = int(hardware.get("row_address_type", 0))
-    o.multiplexing = int(hardware.get("multiplexing", 0))
-    o.gpio_slowdown = int(hardware.get("gpio_slowdown", 2))
-    o.limit_refresh_rate_hz = (
-        int(refresh_override) if refresh_override is not None
-        else int(hardware.get("limit_refresh_rate_hz", 0))
-    )
-    return o
 
 
-def open_matrix(hardware, refresh_override=None):
+def build_options(config, refresh_override=None):
+    """The matrix options the display service would use for this config.
+
+    Built by DisplayManager.apply_matrix_options, not a copy of it, so the
+    measurement and the demo drive the panel exactly as the service does
+    (runtime gpio_slowdown, rp1_rio, panel_type, orientation, defaults).
+    ``refresh_override`` replaces limit_refresh_rate_hz; 0 means uncapped.
+    """
+    from src.display_manager import DisplayManager, RGBMatrixOptions
+
+    options = DisplayManager.apply_matrix_options(RGBMatrixOptions(), config)
+    if refresh_override is not None:
+        options.limit_refresh_rate_hz = int(refresh_override)
+    return options
+
+
+def open_matrix(config, refresh_override=None):
     """Construct the matrix, or explain why it will not open."""
     if os.geteuid() != 0:
         sys.exit("this needs root for GPIO access - rerun with sudo")
     try:
-        from rgbmatrix import RGBMatrix
+        from src.display_manager import RGBMatrix
-    except ImportError:
+    except ImportError as exc:
-        sys.exit("rgbmatrix is not installed on this machine")
+        sys.exit("could not load the display stack ({}); is rgbmatrix "
+                 "installed on this machine?".format(exc))
     try:
-        return RGBMatrix(options=build_options(hardware, refresh_override))
+        return RGBMatrix(options=build_options(config, refresh_override))
     except Exception as exc:  # pragma: no cover - hardware dependent
         sys.exit(
             "could not open the panel ({}).\n"
@@ -101,7 +96,7 @@ def open_matrix(hardware, refresh_override=None):
         )
 
 
-def measure_refresh(hardware, seconds=6.0):
+def measure_refresh(config, seconds=6.0):
     """Actual refresh rate, by running uncapped and timing the swaps.
 
     SwapOnVSync blocks until the panel's next refresh, so an unthrottled loop
@@ -109,7 +104,7 @@ def measure_refresh(hardware, seconds=6.0):
     chain will really give you, as opposed to whatever limit_refresh_rate_hz
     optimistically asks for.
     """
-    matrix = open_matrix(hardware, refresh_override=0)
+    matrix = open_matrix(config, refresh_override=0)
     canvas = matrix.CreateFrameCanvas()
     canvas = matrix.SwapOnVSync(canvas)  # discard the first, it includes setup
     frames = 0
@@ -122,17 +117,17 @@ def measure_refresh(hardware, seconds=6.0):
     return measured
 
 
-def demo(hardware, target, seconds):
+def demo(config, target, seconds):
     """Scroll text at the crisp speed nearest `target`."""
     from PIL import Image, ImageDraw, ImageFont
 
     from src.common.font_layout import load_truetype
 
-    hz = float(hardware.get("limit_refresh_rate_hz") or scroll_config.DEFAULT_REFRESH_HZ)
+    hz = scroll_config.refresh_hz_from_config(config)
     choice = scroll_config.solve_crisp(target, hz)
     print("asked for {:.0f} px/s -> {}".format(target, choice.describe()))
 
-    matrix = open_matrix(hardware)
+    matrix = open_matrix(config)
     canvas = matrix.CreateFrameCanvas()
     W, H = canvas.width, canvas.height
 
@@ -214,15 +209,15 @@ def main():
                     help="highlight the entry nearest this speed")
     args = ap.parse_args()
 
-    hardware = load_hardware()
+    config = load_config()
-    configured = float(hardware.get("limit_refresh_rate_hz") or 0)
+    configured = float(hardware_of(config).get("limit_refresh_rate_hz") or 0)
 
     if args.demo is not None:
-        demo(hardware, args.demo, args.seconds)
+        demo(config, args.demo, args.seconds)
         return
 
     if args.measure:
-        measured = measure_refresh(hardware)
+        measured = measure_refresh(config)
         print("measured panel refresh: {:.1f}Hz".format(measured))
         if configured:
             print("configured limit_refresh_rate_hz: {:.0f}".format(configured))

src/display_manager.py

@@ -279,50 +279,9 @@ class DisplayManager:
             hardware_config = self.config.get('display', {}).get('hardware', {})
             runtime_config = self.config.get('display', {}).get('runtime', {})
             
-            # Basic hardware settings
+            # Every option comes from display.hardware / display.runtime, in
-            options.rows = hardware_config.get('rows', DEFAULT_ROWS)
+            # one place that scripts/scroll_speeds.py shares.
-            options.cols = hardware_config.get('cols', DEFAULT_COLS)
+            self.apply_matrix_options(options, self.config)
-            options.chain_length = hardware_config.get('chain_length', DEFAULT_CHAIN_LENGTH)
-            options.parallel = hardware_config.get('parallel', DEFAULT_PARALLEL)
-            options.hardware_mapping = hardware_config.get('hardware_mapping', 'adafruit-hat-pwm')
-            
-            # Performance and stability settings
-            options.brightness = hardware_config.get('brightness', 90)
-            options.pwm_bits = hardware_config.get('pwm_bits', 10)
-            options.pwm_lsb_nanoseconds = hardware_config.get('pwm_lsb_nanoseconds', 150)
-            options.led_rgb_sequence = hardware_config.get('led_rgb_sequence', 'RGB')
-            options.pixel_mapper_config = self._build_pixel_mapper_config(hardware_config)
-            options.row_address_type = hardware_config.get('row_address_type', 0)
-            options.multiplexing = hardware_config.get('multiplexing', 0)
-            options.panel_type = hardware_config.get('panel_type', '')
-            options.disable_hardware_pulsing = hardware_config.get('disable_hardware_pulsing', False)
-            options.show_refresh_rate = hardware_config.get('show_refresh_rate', False)
-            options.limit_refresh_rate_hz = hardware_config.get('limit_refresh_rate_hz', 90)
-            options.gpio_slowdown = runtime_config.get('gpio_slowdown', 3)
-            
-            # Disable internal privilege dropping - we manage this via systemd or remain root
-            # This prevents the library from dropping to 'daemon' user which breaks file permissions
-            options.drop_privileges = False
-            
-            # Additional settings from config
-            if 'scan_mode' in hardware_config:
-                options.scan_mode = hardware_config.get('scan_mode')
-            if 'pwm_dither_bits' in hardware_config:
-                options.pwm_dither_bits = hardware_config.get('pwm_dither_bits')
-            if 'inverse_colors' in hardware_config:
-                options.inverse_colors = hardware_config.get('inverse_colors')
-            # Pi 5 only: 0=PIO/RP1 coprocessor (default, less CPU),
-            # 1=RIO/Registered IO (faster; gpio_slowdown effect is inverted in this mode)
-            if 'rp1_rio' in runtime_config:
-                if hasattr(options, 'rp1_rio'):
-                    options.rp1_rio = runtime_config.get('rp1_rio')
-                else:
-                    logger.warning(
-                        "rp1_rio is set in config but the installed rgbmatrix library does "
-                        "not support it — the library was likely built without Pi 5 RP1 "
-                        "support (mmap to 0x3f000000 instead of RP1 chip). "
-                        "Fix: sudo RPI_RGB_FORCE_REBUILD=1 ./first_time_install.sh"
-                    )
             
             logger.info(f"Initializing RGB Matrix with settings: rows={options.rows}, cols={options.cols}, chain_length={options.chain_length}, parallel={options.parallel}, hardware_mapping={options.hardware_mapping}")
             
@@ -1370,6 +1329,68 @@ class DisplayManager:
         
         return dt.strftime(f"%b %-d{suffix}") 
 
+    @classmethod
+    def apply_matrix_options(cls, options, config: Dict[str, Any]):
+        """Fill ``options`` (an ``RGBMatrixOptions``) from the LEDMatrix config.
+
+        This is exactly what the display service drives the panel with, so a
+        tool that opens the matrix itself (``scripts/scroll_speeds.py``) gets
+        the same panel -- same runtime ``gpio_slowdown``, ``rp1_rio``,
+        ``panel_type``, orientation and defaults -- rather than a private copy
+        that drifts. Does not open the matrix. Returns ``options``.
+        """
+        display = config.get('display', {}) if isinstance(config, dict) else {}
+        hardware_config = display.get('hardware', {})
+        runtime_config = display.get('runtime', {})
+
+        # Basic hardware settings
+        options.rows = hardware_config.get('rows', DEFAULT_ROWS)
+        options.cols = hardware_config.get('cols', DEFAULT_COLS)
+        options.chain_length = hardware_config.get('chain_length', DEFAULT_CHAIN_LENGTH)
+        options.parallel = hardware_config.get('parallel', DEFAULT_PARALLEL)
+        options.hardware_mapping = hardware_config.get('hardware_mapping', 'adafruit-hat-pwm')
+
+        # Performance and stability settings
+        options.brightness = hardware_config.get('brightness', 90)
+        options.pwm_bits = hardware_config.get('pwm_bits', 10)
+        options.pwm_lsb_nanoseconds = hardware_config.get('pwm_lsb_nanoseconds', 150)
+        options.led_rgb_sequence = hardware_config.get('led_rgb_sequence', 'RGB')
+        # _build_pixel_mapper_config reads only class attributes, so the class
+        # stands in for an instance here.
+        options.pixel_mapper_config = cls._build_pixel_mapper_config(cls, hardware_config)
+        options.row_address_type = hardware_config.get('row_address_type', 0)
+        options.multiplexing = hardware_config.get('multiplexing', 0)
+        options.panel_type = hardware_config.get('panel_type', '')
+        options.disable_hardware_pulsing = hardware_config.get('disable_hardware_pulsing', False)
+        options.show_refresh_rate = hardware_config.get('show_refresh_rate', False)
+        options.limit_refresh_rate_hz = hardware_config.get('limit_refresh_rate_hz', 90)
+        options.gpio_slowdown = runtime_config.get('gpio_slowdown', 3)
+
+        # Disable internal privilege dropping - we manage this via systemd or remain root
+        # This prevents the library from dropping to 'daemon' user which breaks file permissions
+        options.drop_privileges = False
+
+        # Additional settings from config
+        if 'scan_mode' in hardware_config:
+            options.scan_mode = hardware_config.get('scan_mode')
+        if 'pwm_dither_bits' in hardware_config:
+            options.pwm_dither_bits = hardware_config.get('pwm_dither_bits')
+        if 'inverse_colors' in hardware_config:
+            options.inverse_colors = hardware_config.get('inverse_colors')
+        # Pi 5 only: 0=PIO/RP1 coprocessor (default, less CPU),
+        # 1=RIO/Registered IO (faster; gpio_slowdown effect is inverted in this mode)
+        if 'rp1_rio' in runtime_config:
+            if hasattr(options, 'rp1_rio'):
+                options.rp1_rio = runtime_config.get('rp1_rio')
+            else:
+                logger.warning(
+                    "rp1_rio is set in config but the installed rgbmatrix library does "
+                    "not support it — the library was likely built without Pi 5 RP1 "
+                    "support (mmap to 0x3f000000 instead of RP1 chip). "
+                    "Fix: sudo RPI_RGB_FORCE_REBUILD=1 ./first_time_install.sh"
+                )
+        return options
+
     @property
     def refresh_hz(self) -> float:
         """The panel's refresh rate in Hz, from the hardware config.

test/test_scroll_speeds_script.py

@@ -0,0 +1,98 @@
+"""scripts/scroll_speeds.py must drive the panel the way the service does.
+
+--measure and --demo open the matrix themselves. They used to build the
+options from a private copy of DisplayManager's builder that had drifted: it
+read gpio_slowdown from display.hardware (the service reads display.runtime),
+and skipped rp1_rio, panel_type, orientation and more. On a panel that needs a
+high slowdown that measured -- or garbled -- a panel the service never drives.
+"""
+import importlib.util
+import os
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+
+os.environ.setdefault("EMULATOR", "true")
+
+import src.display_manager as display_manager  # noqa: E402
+from src.display_manager import DisplayManager  # noqa: E402
+
+SCRIPT = Path(__file__).resolve().parents[1] / "scripts" / "scroll_speeds.py"
+
+
+@pytest.fixture(scope="module")
+def script():
+    spec = importlib.util.spec_from_file_location("scroll_speeds_script", SCRIPT)
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+class _Options:
+    """Records what is set; declares rp1_rio like a Pi 5-capable binding."""
+
+    rp1_rio = None
+
+
+CONFIG = {
+    "display": {
+        "hardware": {
+            "rows": 64, "cols": 64, "chain_length": 2, "parallel": 1,
+            "hardware_mapping": "adafruit-hat-pwm",
+            "brightness": 70, "pwm_bits": 9, "pwm_lsb_nanoseconds": 130,
+            "row_address_type": 5, "panel_type": "FM6126A",
+            "limit_refresh_rate_hz": 120, "orientation": "180",
+            "pixel_mapper_config": "U-mapper",
+            "gpio_slowdown": 2,  # a stale key in the wrong block
+        },
+        "runtime": {"gpio_slowdown": 7, "rp1_rio": 1},
+    }
+}
+
+
+def _script_options(script, config, **kwargs):
+    with patch.object(display_manager, "RGBMatrixOptions", _Options):
+        return script.build_options(config, **kwargs)
+
+
+def test_runtime_settings_are_used(script):
+    options = _script_options(script, CONFIG)
+    assert options.gpio_slowdown == 7
+    assert options.rp1_rio == 1
+    assert options.panel_type == "FM6126A"
+    assert options.row_address_type == 5
+    assert options.pixel_mapper_config == "U-mapper;Rotate:180"
+    assert options.limit_refresh_rate_hz == 120
+
+
+def test_the_options_match_the_display_service(script):
+    """Same config in, same options out, attribute for attribute."""
+    service = DisplayManager.apply_matrix_options(_Options(), CONFIG)
+    assert vars(_script_options(script, CONFIG)) == vars(service)
+
+
+def test_measure_runs_uncapped(script):
+    assert _script_options(script, CONFIG, refresh_override=0).limit_refresh_rate_hz == 0
+
+
+def test_an_empty_config_gets_the_service_defaults(script):
+    options = _script_options(script, {})
+    assert vars(options) == vars(DisplayManager.apply_matrix_options(_Options(), {}))
+    assert options.gpio_slowdown == 3
+
+
+def test_the_service_uses_the_shared_builder(test_config):
+    """DisplayManager._setup_matrix fills its options through the same call."""
+    with patch.object(display_manager, "RGBMatrix"), \
+            patch.object(display_manager, "RGBMatrixOptions", _Options), \
+            patch.object(display_manager, "freetype"), \
+            patch.object(DisplayManager, "apply_matrix_options",
+                         wraps=DisplayManager.apply_matrix_options) as shared, \
+            patch.dict(os.environ, {"EMULATOR": "false"}):
+        DisplayManager._instance = None
+        try:
+            DisplayManager(test_config)
+        finally:
+            DisplayManager._instance = None
+    shared.assert_called_once()