89 lines
2.5 KiB
Python
89 lines
2.5 KiB
Python
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"""
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Vektorisierung: PNG → Pfade via potrace.
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Zerlegt das Bitmap in Konturen, die dann als SVG-Pfade manipuliert werden können.
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"""
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from __future__ import annotations
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import numpy as np
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try:
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import potracer
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HAS_POTRACER = True
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except ImportError:
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HAS_POTRACER = False
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from svgpathtools import Path as SvgPath, CubicBezier, Line
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from core.logo_model import GlyphGroup
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def _rgba_to_bitmap(pixels: np.ndarray, threshold: int = 128) -> np.ndarray:
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"""Konvertiert RGBA in ein Schwarz/Weiß-Bitmap für potrace."""
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gray = np.mean(pixels[:, :, :3], axis=2)
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alpha = pixels[:, :, 3] / 255.0
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effective = gray * alpha + 255 * (1 - alpha)
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return (effective < threshold).astype(np.uint8)
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def _curve_to_svg_segment(segment):
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"""Konvertiert ein potrace-Kurvensegment in ein svgpathtools-Segment."""
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tag = segment.tag
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c = segment.c
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end = segment.end_point
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if tag == potracer.CORNER:
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return [
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Line(complex(c[0][0], c[0][1]), complex(c[1][0], c[1][1])),
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Line(complex(c[1][0], c[1][1]), complex(end[0], end[1])),
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]
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else:
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start_pt = complex(c[0][0], c[0][1])
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cp1 = complex(c[0][0], c[0][1])
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cp2 = complex(c[1][0], c[1][1])
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end_pt = complex(end[0], end[1])
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return [CubicBezier(start_pt, cp1, cp2, end_pt)]
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def trace_to_paths(
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pixels: np.ndarray,
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threshold: int = 128,
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turd_size: int = 2,
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alpha_max: float = 1.0,
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) -> list[GlyphGroup]:
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"""
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Hauptfunktion: Konvertiert ein RGBA-Bild in eine Liste von GlyphGroups.
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Jede zusammenhängende Kontur wird eine eigene Gruppe.
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"""
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if not HAS_POTRACER:
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raise ImportError(
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"potracer ist nicht installiert. "
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"Bitte 'pip install potracer' ausführen."
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)
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bitmap = _rgba_to_bitmap(pixels, threshold)
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bmp = potracer.Bitmap(bitmap)
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path_result = bmp.trace(
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turdsize=turd_size,
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alphamax=alpha_max,
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)
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groups: list[GlyphGroup] = []
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for i, curve in enumerate(path_result):
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svg_segments = []
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for segment in curve.segments:
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svg_segments.extend(_curve_to_svg_segment(segment))
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if not svg_segments:
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continue
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svg_path = SvgPath(*svg_segments)
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bbox = svg_path.bbox() # xmin, xmax, ymin, ymax
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group = GlyphGroup(
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label=f"Pfad_{i}",
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paths=[svg_path],
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bbox=(bbox[0], bbox[2], bbox[1] - bbox[0], bbox[3] - bbox[2]),
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)
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groups.append(group)
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return groups
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