112 lines
3.1 KiB
Python
112 lines
3.1 KiB
Python
"""
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raster.py
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------------
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Turn 2D vector paths into raster images using `pillow`
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"""
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import numpy as np
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try:
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# keep pillow as a soft dependency
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from PIL import (Image,
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ImageDraw,
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ImageChops)
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except BaseException as E:
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from .. import exceptions
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# re-raise the useful exception when called
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closure = exceptions.closure(E)
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Image = closure
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ImageDraw = closure
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ImageChops = closure
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def rasterize(path,
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pitch,
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origin,
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resolution=None,
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fill=True,
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width=None):
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"""
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Rasterize a Path2D object into a boolean image ("mode 1").
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Parameters
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------------
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path : Path2D
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Original geometry
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pitch : float
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Length in model space of a pixel edge
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origin : (2,) float
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Origin position in model space
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resolution : (2,) int
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Resolution in pixel space
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fill : bool
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If True will return closed regions as filled
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width : int
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If not None will draw outline this wide in pixels
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Returns
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------------
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raster : PIL.Image object mode 1
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Rasterized version of input
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"""
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# check inputs
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pitch = float(pitch)
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origin = np.asanyarray(origin, dtype=np.float64)
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# if resolution is None make it larger than path
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if resolution is None:
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span = np.vstack((path.bounds,
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origin)).ptp(
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axis=0)
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resolution = np.ceil(span / pitch) + 2
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resolution = np.asanyarray(resolution,
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dtype=np.int64)
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resolution = tuple(resolution.tolist())
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# convert all discrete paths to pixel space
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discrete = [((i - origin) / pitch).astype(np.int)
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for i in path.discrete]
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# the path indexes that are exteriors
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# needed to know what to fill/empty but expensive
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roots = path.root
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# draw the exteriors
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exteriors = Image.new(mode='1', size=resolution)
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edraw = ImageDraw.Draw(exteriors)
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# if a width is specified draw the outline
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if width is not None:
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width = int(width)
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for coords in discrete:
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edraw.line(coords.flatten().tolist(),
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fill=1,
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width=width)
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# if we are not filling the polygon exit
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if not fill:
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del edraw
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return exteriors
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# draw the interiors
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interiors = Image.new(mode='1', size=resolution)
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idraw = ImageDraw.Draw(interiors)
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for i, points in enumerate(discrete):
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# draw the polygon on either the exterior or
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# interior image buffer
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if i in roots:
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edraw.polygon(points.flatten().tolist(),
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fill=1)
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else:
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idraw.polygon(points.flatten().tolist(),
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fill=1)
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# clean up the draw objects
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# this is in the PIL examples and I have
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# no idea if it this is actually necessary
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del edraw
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del idraw
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# the final result is the exteriors minus the interiors
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raster = ImageChops.subtract(exteriors, interiors)
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return raster
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