Files
bambuddy/backend/app/services/stl_thumbnail.py
T
maziggy 53bd4fadb3 Fix safe security findings: hashlib, log injection, broad excepts
- Add usedforsecurity=False to MD5 (AMS fingerprint) and SHA1 (git blob
  hash) calls to silence Bandit B303 / CodeQL weak-crypto findings
- Convert ~996 f-string logging calls to parameterized %s-style across
  55 files to prevent log injection (Bandit G201 / CodeQL log-injection)
- Narrow ~199 broad except Exception blocks to specific types:
  OperationalError for DB migrations, OSError for network/file cleanup,
  (OSError, ftplib.error_reply) for FTP, and targeted tuples for
  ZIP/XML/JSON parsing — 36 intentionally left broad (mixed async,
  re-raise patterns)
2026-02-06 11:37:59 +01:00

141 lines
4.4 KiB
Python

"""STL Thumbnail Generation Service.
Generates thumbnail images from STL files using trimesh and matplotlib.
"""
import logging
import uuid
from pathlib import Path
logger = logging.getLogger(__name__)
# Bambu green color for rendering
BAMBU_GREEN = "#00AE42"
BACKGROUND_COLOR = "#1a1a1a"
# Maximum vertices before simplification
MAX_VERTICES = 100000
def generate_stl_thumbnail(
stl_path: Path,
thumbnails_dir: Path,
size: int = 256,
) -> str | None:
"""Generate a thumbnail image from an STL file.
Args:
stl_path: Path to the STL file
thumbnails_dir: Directory to save the thumbnail
size: Thumbnail size in pixels (default 256x256)
Returns:
Path to the generated thumbnail, or None on failure
"""
try:
import matplotlib
import trimesh
# Use Agg backend for headless rendering
matplotlib.use("Agg")
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D # noqa: F401
from mpl_toolkits.mplot3d.art3d import Poly3DCollection
# Load the STL file
mesh = trimesh.load(str(stl_path), force="mesh")
if mesh is None or not hasattr(mesh, "vertices") or len(mesh.vertices) == 0:
logger.warning("Failed to load STL or empty mesh: %s", stl_path)
return None
# Simplify large meshes for performance
if len(mesh.vertices) > MAX_VERTICES:
logger.info("Simplifying mesh from %s vertices", len(mesh.vertices))
try:
# Calculate reduction ratio (0-1 range)
# e.g., 124633 vertices -> 100000 means keep ~80%, so reduce by ~20%
keep_ratio = MAX_VERTICES / len(mesh.vertices)
target_reduction = 1.0 - keep_ratio
# Clamp to valid range (0.01 to 0.99)
target_reduction = max(0.01, min(0.99, target_reduction))
mesh = mesh.simplify_quadric_decimation(target_reduction)
logger.info("Simplified mesh to %s vertices", len(mesh.vertices))
except Exception as e:
logger.warning("Mesh simplification failed, using original: %s", e)
# Get mesh bounds and center it
vertices = mesh.vertices
bounds_min = vertices.min(axis=0)
bounds_max = vertices.max(axis=0)
center = (bounds_min + bounds_max) / 2
vertices_centered = vertices - center
# Scale to fit in view
max_extent = (bounds_max - bounds_min).max()
if max_extent > 0:
scale = 1.0 / max_extent
vertices_scaled = vertices_centered * scale
else:
vertices_scaled = vertices_centered
# Create figure with dark background
fig = plt.figure(figsize=(size / 100, size / 100), dpi=100)
fig.patch.set_facecolor(BACKGROUND_COLOR)
ax = fig.add_subplot(111, projection="3d")
ax.set_facecolor(BACKGROUND_COLOR)
# Create polygon collection from mesh faces
faces = mesh.faces
poly3d = [[vertices_scaled[vertex] for vertex in face] for face in faces]
collection = Poly3DCollection(
poly3d,
facecolors=BAMBU_GREEN,
edgecolors=BAMBU_GREEN,
linewidths=0.1,
alpha=0.9,
)
ax.add_collection3d(collection)
# Set axis limits
ax.set_xlim(-0.6, 0.6)
ax.set_ylim(-0.6, 0.6)
ax.set_zlim(-0.6, 0.6)
# Set view angle (isometric-ish)
ax.view_init(elev=25, azim=45)
# Remove axes and grid
ax.set_axis_off()
ax.grid(False)
# Remove margins
plt.subplots_adjust(left=0, right=1, top=1, bottom=0)
# Save thumbnail
thumb_filename = f"{uuid.uuid4().hex}.png"
thumb_path = thumbnails_dir / thumb_filename
fig.savefig(
thumb_path,
format="png",
facecolor=BACKGROUND_COLOR,
edgecolor="none",
bbox_inches="tight",
pad_inches=0.05,
dpi=100,
)
plt.close(fig)
logger.info("Generated STL thumbnail: %s", thumb_path)
return str(thumb_path)
except ImportError as e:
logger.warning("STL thumbnail generation unavailable (missing dependencies): %s", e)
return None
except Exception as e:
logger.warning("Failed to generate STL thumbnail for %s: %s", stl_path, e)
return None