Files
LEDMatrix/plugin-repos/starlark-apps/pixlet_renderer.py
T

773 lines
30 KiB
Python

"""
Pixlet Renderer Module for Starlark Apps
Handles execution of Pixlet CLI to render .star files into WebP animations.
Supports bundled binaries and system-installed Pixlet.
"""
import json
import logging
import os
import platform
import re
import shutil
import subprocess
from pathlib import Path
from typing import Dict, Any, Optional, Tuple, List
logger = logging.getLogger(__name__)
class PixletRenderer:
"""
Wrapper for Pixlet CLI rendering.
Handles:
- Auto-detection of bundled or system Pixlet binary
- Rendering .star files with configuration
- Schema extraction from .star files
- Timeout and error handling
"""
def __init__(self, pixlet_path: Optional[str] = None, timeout: int = 30):
"""
Initialize the Pixlet renderer.
Args:
pixlet_path: Optional explicit path to Pixlet binary
timeout: Maximum seconds to wait for rendering
"""
self.timeout = timeout
self.pixlet_binary = self._find_pixlet_binary(pixlet_path)
if self.pixlet_binary:
logger.info(f"[Starlark Pixlet] Pixlet renderer initialized with binary: {self.pixlet_binary}")
else:
logger.warning("[Starlark Pixlet] Pixlet binary not found - rendering will fail")
def _find_pixlet_binary(self, explicit_path: Optional[str] = None) -> Optional[str]:
"""
Find Pixlet binary using the following priority:
1. Explicit path provided
2. Bundled binary for current architecture
3. System PATH
Args:
explicit_path: User-specified path to Pixlet
Returns:
Path to Pixlet binary, or None if not found
"""
# 1. Check explicit path
if explicit_path and os.path.isfile(explicit_path):
if os.access(explicit_path, os.X_OK):
logger.debug(f"Using explicit Pixlet path: {explicit_path}")
return explicit_path
else:
logger.warning(f"Explicit Pixlet path not executable: {explicit_path}")
# 2. Check bundled binary
try:
bundled_path = self._get_bundled_binary_path()
if bundled_path and os.path.isfile(bundled_path):
# Ensure executable
if not os.access(bundled_path, os.X_OK):
try:
os.chmod(bundled_path, 0o755)
logger.debug(f"Made bundled binary executable: {bundled_path}")
except OSError:
logger.exception(f"Could not make bundled binary executable: {bundled_path}")
if os.access(bundled_path, os.X_OK):
logger.debug(f"Using bundled Pixlet binary: {bundled_path}")
return bundled_path
except OSError:
logger.exception("Could not locate bundled binary")
# 3. Check system PATH
system_pixlet = shutil.which("pixlet")
if system_pixlet:
logger.debug(f"Using system Pixlet: {system_pixlet}")
return system_pixlet
logger.error("Pixlet binary not found in any location")
return None
def _get_bundled_binary_path(self) -> Optional[str]:
"""
Get path to bundled Pixlet binary for current architecture.
Returns:
Path to bundled binary, or None if not found
"""
try:
# Determine project root (parent of plugin-repos)
current_dir = Path(__file__).resolve().parent
project_root = current_dir.parent.parent
bin_dir = project_root / "bin" / "pixlet"
# Detect architecture
system = platform.system().lower()
machine = platform.machine().lower()
# Map architecture to binary name
if system == "linux":
if "aarch64" in machine or "arm64" in machine:
binary_name = "pixlet-linux-arm64"
elif "x86_64" in machine or "amd64" in machine:
binary_name = "pixlet-linux-amd64"
else:
logger.warning(f"Unsupported Linux architecture: {machine}")
return None
elif system == "darwin":
if "arm64" in machine:
binary_name = "pixlet-darwin-arm64"
else:
binary_name = "pixlet-darwin-amd64"
elif system == "windows":
binary_name = "pixlet-windows-amd64.exe"
else:
logger.warning(f"Unsupported system: {system}")
return None
binary_path = bin_dir / binary_name
if binary_path.exists():
return str(binary_path)
logger.debug(f"Bundled binary not found at: {binary_path}")
return None
except OSError:
logger.exception("Error finding bundled binary")
return None
def _get_safe_working_directory(self, star_file: str) -> Optional[str]:
"""
Get a safe working directory for subprocess execution.
Args:
star_file: Path to .star file
Returns:
Resolved parent directory, or None if empty or invalid
"""
try:
resolved_parent = os.path.dirname(os.path.abspath(star_file))
# Return None if empty string to avoid FileNotFoundError
if not resolved_parent:
logger.debug(f"Empty parent directory for star_file: {star_file}")
return None
return resolved_parent
except (OSError, ValueError):
logger.debug(f"Could not resolve working directory for: {star_file}")
return None
def is_available(self) -> bool:
"""
Check if Pixlet is available and functional.
Returns:
True if Pixlet can be executed
"""
if not self.pixlet_binary:
return False
try:
result = subprocess.run(
[self.pixlet_binary, "version"],
capture_output=True,
text=True,
timeout=5
)
return result.returncode == 0
except subprocess.TimeoutExpired:
logger.debug("Pixlet version check timed out")
return False
except (subprocess.SubprocessError, OSError):
logger.exception("Pixlet not available")
return False
def get_version(self) -> Optional[str]:
"""
Get Pixlet version string.
Returns:
Version string, or None if unavailable
"""
if not self.pixlet_binary:
return None
try:
result = subprocess.run(
[self.pixlet_binary, "version"],
capture_output=True,
text=True,
timeout=5
)
if result.returncode == 0:
return result.stdout.strip()
except subprocess.TimeoutExpired:
logger.debug("Pixlet version check timed out")
except (subprocess.SubprocessError, OSError):
logger.exception("Could not get Pixlet version")
return None
def render(
self,
star_file: str,
output_path: str,
config: Optional[Dict[str, Any]] = None,
magnify: int = 1,
width: Optional[int] = None,
height: Optional[int] = None
) -> Tuple[bool, Optional[str]]:
"""
Render a .star file to WebP output.
Args:
star_file: Path to .star file
output_path: Where to save WebP output
config: Configuration dictionary to pass to app
magnify: Magnification factor (default 1)
width: Optional native render width in pixels. Previously
there was no way to tell Pixlet to render at anything
other than its own default (64), relying entirely on
magnify to scale up afterward -- fine for apps designed
at that native size, but wrong for an app whose own
declared canvas size is genuinely different (confirmed
on real hardware, 2026-09-06, with an imported app
declaring width=128: rendering at the default 64 and
then magnifying silently clipped half the app's own
content before scaling ever happened, rather than
producing a correctly-sized image). Passed through as
Pixlet's own -w flag when provided; omitted (Pixlet's
default) otherwise, preserving existing behavior for
every other app.
height: Same as width, for Pixlet's -t flag.
Returns:
Tuple of (success: bool, error_message: Optional[str])
"""
if not self.pixlet_binary:
return False, "Pixlet binary not found"
if not os.path.isfile(star_file):
return False, f"Star file not found: {star_file}"
try:
# Build command - config params must be POSITIONAL between star_file and flags
# Format: pixlet render <file.star> [key=value]... [flags]
cmd = [
self.pixlet_binary,
"render",
star_file
]
# Add configuration parameters as positional arguments (BEFORE flags)
if config:
for key, value in config.items():
# Validate key format (alphanumeric + underscore only)
if not re.match(r'^[a-zA-Z_][a-zA-Z0-9_]*$', key):
logger.warning(f"Skipping invalid config key: {key}")
continue
# Convert value to string for CLI
if isinstance(value, bool):
value_str = "true" if value else "false"
elif isinstance(value, str) and (value.startswith('{') or value.startswith('[')):
# JSON string - keep as-is, will be properly quoted by subprocess
value_str = value
else:
value_str = str(value)
# Validate value doesn't contain dangerous shell metacharacters.
# Kept as defence in depth only: cmd is a list and there is no
# shell=True below, so nothing here is ever interpreted by a
# shell. That made the list worth trimming rather than growing
# -- "|" is a normal character inside a config value, and apps
# do use it as a separator (a PennDOT sign id is
# "I-476 North|175659"). Blocking it dropped the whole key
# silently, and the app then rendered its own "not configured"
# screen with nothing to say why.
# Block: backticks, $(), redirects, semicolons, ampersands, null bytes
# Allow: most printable chars including spaces, quotes, brackets, braces, pipes
if re.search(r'[`$<>&;\x00]|\$\(', value_str):
logger.warning(f"Skipping config value with unsafe shell characters for key {key}: {value_str}")
continue
# Add as positional argument (not -c flag)
cmd.append(f"{key}={value_str}")
# Add flags AFTER positional config arguments
cmd.extend([
"-o", output_path,
"-m", str(magnify)
])
if width is not None:
cmd.extend(["-w", str(width)])
if height is not None:
cmd.extend(["-t", str(height)])
# Build sanitized command for logging (redact sensitive values)
sanitized_cmd = [self.pixlet_binary, "render", star_file]
if config:
config_keys = list(config.keys())
sanitized_cmd.append(f"[{len(config_keys)} config entries: {', '.join(config_keys)}]")
sanitized_cmd.extend(["-o", output_path, "-m", str(magnify)])
if width is not None:
sanitized_cmd.extend(["-w", str(width)])
if height is not None:
sanitized_cmd.extend(["-t", str(height)])
logger.debug(f"Executing Pixlet: {' '.join(sanitized_cmd)}")
# Execute rendering
safe_cwd = self._get_safe_working_directory(star_file)
result = subprocess.run(
cmd,
capture_output=True,
text=True,
timeout=self.timeout,
cwd=safe_cwd # Run in .star file directory (or None if relative path)
)
if result.returncode == 0:
if not os.path.isfile(output_path):
error = "Rendering succeeded but output file not found"
logger.error(error)
return False, error
# Pixlet exits 0 and writes a 0-byte file when the app renders
# nothing -- an app whose config leaves it with no content to
# show does exactly that. Treating existence alone as success
# handed the caller a file with no frames in it, which reads
# downstream as a working app that draws a black panel.
if os.path.getsize(output_path) == 0:
error = "Rendering produced an empty (0-byte) file - the app rendered no content"
logger.error(error)
return False, error
logger.debug(f"Successfully rendered: {star_file} -> {output_path}")
return True, None
else:
error = f"Pixlet failed (exit {result.returncode}): {result.stderr}"
logger.error(error)
return False, error
except subprocess.TimeoutExpired:
error = f"Rendering timeout after {self.timeout}s"
logger.error(error)
return False, error
except (subprocess.SubprocessError, OSError):
logger.exception("Rendering exception")
return False, "Rendering failed - see logs for details"
#: Schema extraction runs an app's own get_schema(), which may make a
#: network call. Short enough that a hung app does not stall an upload,
#: long enough for a real API round trip on a slow connection.
SCHEMA_TIMEOUT = 20
def extract_schema_via_pixlet(self, star_file: str) -> Optional[Dict[str, Any]]:
"""Ask Pixlet itself for the app's schema, or None if it cannot say.
`pixlet schema` executes get_schema() instead of reading it, which is
the only way to see options an app computes at runtime -- a dropdown
whose choices come from a live API call has no option list anywhere in
the source for the regex parser below to find, so that parser reports
an empty dropdown and the config form offers nothing to pick.
Pixlet's own field keys are remapped to the ones the rest of this
plugin and the config UI already use ("typeOf"/"desc"), so the two
extractors return the same shape and callers cannot tell them apart.
"""
if not self.pixlet_binary:
return None
try:
result = subprocess.run(
[self.pixlet_binary, "schema", star_file],
capture_output=True, text=True, timeout=self.SCHEMA_TIMEOUT,
cwd=self._get_safe_working_directory(star_file),
)
except subprocess.TimeoutExpired:
logger.warning(
"pixlet schema timed out after %ss for %s - get_schema() may be "
"making a slow network call", self.SCHEMA_TIMEOUT, star_file)
return None
except (subprocess.SubprocessError, OSError) as e:
logger.warning(f"Could not run pixlet schema for {star_file}: {e}")
return None
if result.returncode != 0:
# Not an error worth failing on: older Pixlet builds have no
# `schema` subcommand at all, and the source parser still works.
logger.debug(
"pixlet schema exited %d for %s: %s",
result.returncode, star_file, (result.stderr or '').strip()[:300])
return None
try:
schema = json.loads(result.stdout)
except (json.JSONDecodeError, ValueError) as e:
logger.warning(f"pixlet schema returned unparseable output for {star_file}: {e}")
return None
if not isinstance(schema, dict) or not isinstance(schema.get("schema"), list):
logger.warning(f"pixlet schema returned an unexpected shape for {star_file}")
return None
for field in schema["schema"]:
if not isinstance(field, dict):
continue
if "type" in field and "typeOf" not in field:
field["typeOf"] = field.pop("type")
if "description" in field and "desc" not in field:
field["desc"] = field.pop("description")
return schema
def extract_schema(self, star_file: str) -> Tuple[bool, Optional[Dict[str, Any]], Optional[str]]:
"""
Extract configuration schema from a .star file.
Prefers `pixlet schema`, which runs the app and therefore sees options
it computes at runtime. Falls back to parsing the source when Pixlet is
unavailable, too old to have the subcommand, or the app fails to run --
that parser handles:
- Static field definitions (location, text, toggle, dropdown, color, datetime)
- Variable-referenced dropdown options
- Graceful degradation for unsupported field types
Args:
star_file: Path to .star file
Returns:
Tuple of (success: bool, schema: Optional[Dict], error: Optional[str])
"""
if not os.path.isfile(star_file):
return False, None, f"Star file not found: {star_file}"
schema = self.extract_schema_via_pixlet(star_file)
if schema is not None:
logger.debug(
"Extracted schema with %d field(s) from %s via pixlet schema",
len(schema.get('schema', [])), star_file)
return True, schema, None
try:
# Read .star file
with open(star_file, 'r', encoding='utf-8') as f:
content = f.read()
# Parse schema from source
schema = self._parse_schema_from_source(content, star_file)
if schema:
field_count = len(schema.get('schema', []))
logger.debug(f"Extracted schema with {field_count} field(s) from: {star_file}")
return True, schema, None
else:
# No schema found - not an error, app just doesn't have configuration
logger.debug(f"No schema found in: {star_file}")
return True, None, None
except UnicodeDecodeError as e:
error = f"File encoding error: {e}"
logger.warning(error)
return False, None, error
except Exception as e:
logger.exception(f"Schema extraction failed for {star_file}")
return False, None, f"Schema extraction error: {str(e)}"
def _parse_schema_from_source(self, content: str, file_path: str) -> Optional[Dict[str, Any]]:
"""
Parse get_schema() function from Starlark source code.
Args:
content: .star file content
file_path: Path to file (for logging)
Returns:
Schema dict with format {"version": "1", "schema": [...]}, or None
"""
# Extract variable definitions (for dropdown options)
var_table = self._extract_variable_definitions(content)
# Extract get_schema() function body
schema_body = self._extract_get_schema_body(content)
if not schema_body:
logger.debug(f"No get_schema() function found in {file_path}")
return None
# Extract version
version_match = re.search(r'version\s*=\s*"([^"]+)"', schema_body)
version = version_match.group(1) if version_match else "1"
# Extract fields array from schema.Schema(...) - handle nested brackets
fields_start_match = re.search(r'fields\s*=\s*\[', schema_body)
if not fields_start_match:
# Empty schema or no fields
return {"version": version, "schema": []}
# Find matching closing bracket
bracket_count = 1
i = fields_start_match.end()
while i < len(schema_body) and bracket_count > 0:
if schema_body[i] == '[':
bracket_count += 1
elif schema_body[i] == ']':
bracket_count -= 1
i += 1
if bracket_count != 0:
# Unmatched brackets
logger.warning(f"Unmatched brackets in schema fields for {file_path}")
return {"version": version, "schema": []}
fields_text = schema_body[fields_start_match.end():i-1]
# Parse individual fields
schema_fields = []
# Match schema.FieldType(...) patterns
field_pattern = r'schema\.(\w+)\s*\((.*?)\)'
# Find all field definitions (handle nested parentheses)
pos = 0
while pos < len(fields_text):
match = re.search(field_pattern, fields_text[pos:], re.DOTALL)
if not match:
break
field_type = match.group(1)
field_start = pos + match.start()
field_end = pos + match.end()
# Handle nested parentheses properly
paren_count = 1
i = pos + match.start() + len(f'schema.{field_type}(')
while i < len(fields_text) and paren_count > 0:
if fields_text[i] == '(':
paren_count += 1
elif fields_text[i] == ')':
paren_count -= 1
i += 1
field_params_text = fields_text[pos + match.start() + len(f'schema.{field_type}('):i-1]
# Parse field
field_dict = self._parse_schema_field(field_type, field_params_text, var_table)
if field_dict:
schema_fields.append(field_dict)
pos = i
return {
"version": version,
"schema": schema_fields
}
def _extract_variable_definitions(self, content: str) -> Dict[str, List[Dict]]:
"""
Extract top-level variable assignments (for dropdown options).
Args:
content: .star file content
Returns:
Dict mapping variable names to their option lists
"""
var_table = {}
# Find variable definitions like: variableName = [schema.Option(...), ...]
var_pattern = r'^(\w+)\s*=\s*\[(.*?schema\.Option.*?)\]'
matches = re.finditer(var_pattern, content, re.MULTILINE | re.DOTALL)
for match in matches:
var_name = match.group(1)
options_text = match.group(2)
# Parse schema.Option entries
options = self._parse_schema_options(options_text, {})
if options:
var_table[var_name] = options
return var_table
def _extract_get_schema_body(self, content: str) -> Optional[str]:
"""
Extract get_schema() function body using indentation-aware parsing.
Args:
content: .star file content
Returns:
Function body text, or None if not found
"""
# Find def get_schema(): line
pattern = r'^(\s*)def\s+get_schema\s*\(\s*\)\s*:'
match = re.search(pattern, content, re.MULTILINE)
if not match:
return None
# Get the indentation level of the function definition
func_indent = len(match.group(1))
func_start = match.end()
# Split content into lines starting after the function definition
lines_after = content[func_start:].split('\n')
body_lines = []
for line in lines_after:
# Skip empty lines
if not line.strip():
body_lines.append(line)
continue
# Calculate indentation of current line
stripped = line.lstrip()
line_indent = len(line) - len(stripped)
# If line has same or less indentation than function def, check if it's a top-level def
if line_indent <= func_indent:
# This is a line at the same or outer level - check if it's a function
if re.match(r'def\s+\w+', stripped):
# Found next top-level function, stop here
break
# Otherwise it might be a comment or other top-level code, stop anyway
break
# Line is indented more than function def, so it's part of the body
body_lines.append(line)
if body_lines:
return '\n'.join(body_lines)
return None
def _parse_schema_field(self, field_type: str, params_text: str, var_table: Dict) -> Optional[Dict[str, Any]]:
"""
Parse individual schema field definition.
Args:
field_type: Field type (Location, Text, Toggle, etc.)
params_text: Field parameters text
var_table: Variable lookup table
Returns:
Field dict, or None if parse fails
"""
# Map Pixlet field types to JSON typeOf
type_mapping = {
'Location': 'location',
'Text': 'text',
'Toggle': 'toggle',
'Dropdown': 'dropdown',
'Color': 'color',
'DateTime': 'datetime',
'OAuth2': 'oauth2',
'PhotoSelect': 'photo_select',
'LocationBased': 'location_based',
'Typeahead': 'typeahead',
'Generated': 'generated',
}
type_of = type_mapping.get(field_type, field_type.lower())
# Skip Generated fields (invisible meta-fields)
if type_of == 'generated':
return None
field_dict = {"typeOf": type_of}
# Extract common parameters
# id
id_match = re.search(r'id\s*=\s*"([^"]+)"', params_text)
if id_match:
field_dict['id'] = id_match.group(1)
else:
# id is required, skip field if missing
return None
# name
name_match = re.search(r'name\s*=\s*"([^"]+)"', params_text)
if name_match:
field_dict['name'] = name_match.group(1)
# desc
desc_match = re.search(r'desc\s*=\s*"([^"]+)"', params_text)
if desc_match:
field_dict['desc'] = desc_match.group(1)
# icon
icon_match = re.search(r'icon\s*=\s*"([^"]+)"', params_text)
if icon_match:
field_dict['icon'] = icon_match.group(1)
# default (can be string, bool, or variable reference)
# First try to match quoted strings (which may contain commas)
default_match = re.search(r'default\s*=\s*"([^"]*)"', params_text)
if not default_match:
# Try single quotes
default_match = re.search(r"default\s*=\s*'([^']*)'", params_text)
if not default_match:
# Fall back to unquoted value (stop at comma or closing paren)
default_match = re.search(r'default\s*=\s*([^,\)]+)', params_text)
if default_match:
default_value = default_match.group(1).strip()
# Handle boolean
if default_value in ('True', 'False'):
field_dict['default'] = default_value.lower()
# Handle string literal from first two patterns (already extracted without quotes)
elif re.search(r'default\s*=\s*["\']', params_text):
# This was a quoted string, use the captured content directly
field_dict['default'] = default_value
# Handle variable reference (can't resolve, use as-is)
else:
# Try to extract just the value if it's like options[0].value
if '.' in default_value or '[' in default_value:
# Complex expression, skip default
pass
else:
field_dict['default'] = default_value
# For dropdown, extract options
if type_of == 'dropdown':
options_match = re.search(r'options\s*=\s*([^,\)]+)', params_text)
if options_match:
options_ref = options_match.group(1).strip()
# Check if it's a variable reference
if options_ref in var_table:
field_dict['options'] = var_table[options_ref]
# Or inline options
elif options_ref.startswith('['):
# Find the full options array (handle nested brackets)
# This is tricky, for now try to extract inline options
inline_match = re.search(r'options\s*=\s*(\[.*?\])', params_text, re.DOTALL)
if inline_match:
options_text = inline_match.group(1)
field_dict['options'] = self._parse_schema_options(options_text, var_table)
return field_dict
def _parse_schema_options(self, options_text: str, var_table: Dict) -> List[Dict[str, str]]:
"""
Parse schema.Option list.
Args:
options_text: Text containing schema.Option(...) entries
var_table: Variable lookup table (not currently used)
Returns:
List of {"display": "...", "value": "..."} dicts
"""
options = []
# Match schema.Option(display = "...", value = "...")
option_pattern = r'schema\.Option\s*\(\s*display\s*=\s*"([^"]+)"\s*,\s*value\s*=\s*"([^"]+)"\s*\)'
matches = re.finditer(option_pattern, options_text)
for match in matches:
options.append({
"display": match.group(1),
"value": match.group(2)
})
return options