160 lines
5.2 KiB
Python
160 lines
5.2 KiB
Python
"""
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SVG file format readers and writers
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"""
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from typing import Mapping
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import warnings
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import numpy
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from numpy.typing import ArrayLike
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import svgwrite # type: ignore
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from .utils import mangle_name
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from .. import Pattern
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def writefile(
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library: Mapping[str, Pattern],
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top: str,
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filename: str,
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custom_attributes: bool = False,
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) -> None:
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"""
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Write a Pattern to an SVG file, by first calling .polygonize() on it
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to change the shapes into polygons, and then writing patterns as SVG
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groups (<g>, inside <defs>), polygons as paths (<path>), and refs
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as <use> elements.
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Note that this function modifies the Pattern.
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If `custom_attributes` is `True`, a non-standard `pattern_layer` attribute
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is written to the relevant elements.
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It is often a good idea to run `pattern.dedup()` on pattern prior to
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calling this function, especially if calling `.polygonize()` will result in very
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many vertices.
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If you want pattern polygonized with non-default arguments, just call `pattern.polygonize()`
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prior to calling this function.
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Args:
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pattern: Pattern to write to file. Modified by this function.
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filename: Filename to write to.
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custom_attributes: Whether to write non-standard `pattern_layer` attribute to the
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SVG elements.
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"""
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pattern = library[top]
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# Polygonize pattern
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pattern.polygonize()
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bounds = pattern.get_bounds(library=library)
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if bounds is None:
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bounds_min, bounds_max = numpy.array([[-1, -1], [1, 1]])
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warnings.warn('Pattern had no bounds (empty?); setting arbitrary viewbox')
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else:
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bounds_min, bounds_max = bounds
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viewbox = numpy.hstack((bounds_min - 1, (bounds_max - bounds_min) + 2))
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viewbox_string = '{:g} {:g} {:g} {:g}'.format(*viewbox)
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# Create file
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svg = svgwrite.Drawing(filename, profile='full', viewBox=viewbox_string,
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debug=(not custom_attributes))
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# Now create a group for each pattern and add in any Boundary and Use elements
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for name, pat in library.items():
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svg_group = svg.g(id=mangle_name(name), fill='blue', stroke='red')
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for shape in pat.shapes:
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for polygon in shape.to_polygons():
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path_spec = poly2path(polygon.vertices + polygon.offset)
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path = svg.path(d=path_spec)
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if custom_attributes:
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path['pattern_layer'] = polygon.layer
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svg_group.add(path)
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for ref in pat.refs:
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if ref.target is None:
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continue
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transform = f'scale({ref.scale:g}) rotate({ref.rotation:g}) translate({ref.offset[0]:g},{ref.offset[1]:g})'
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use = svg.use(href='#' + mangle_name(ref.target), transform=transform)
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svg_group.add(use)
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svg.defs.add(svg_group)
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svg.add(svg.use(href='#' + mangle_name(top)))
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svg.save()
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def writefile_inverted(
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library: Mapping[str, Pattern],
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top: str,
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filename: str,
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) -> None:
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"""
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Write an inverted Pattern to an SVG file, by first calling `.polygonize()` and
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`.flatten()` on it to change the shapes into polygons, then drawing a bounding
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box and drawing the polygons with reverse vertex order inside it, all within
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one `<path>` element.
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Note that this function modifies the Pattern.
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If you want pattern polygonized with non-default arguments, just call `pattern.polygonize()`
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prior to calling this function.
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Args:
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pattern: Pattern to write to file. Modified by this function.
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filename: Filename to write to.
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"""
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pattern = library[top]
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# Polygonize and flatten pattern
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pattern.polygonize().flatten(library)
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bounds = pattern.get_bounds(library=library)
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if bounds is None:
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bounds_min, bounds_max = numpy.array([[-1, -1], [1, 1]])
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warnings.warn('Pattern had no bounds (empty?); setting arbitrary viewbox')
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else:
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bounds_min, bounds_max = bounds
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viewbox = numpy.hstack((bounds_min - 1, (bounds_max - bounds_min) + 2))
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viewbox_string = '{:g} {:g} {:g} {:g}'.format(*viewbox)
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# Create file
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svg = svgwrite.Drawing(filename, profile='full', viewBox=viewbox_string)
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# Draw bounding box
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slab_edge = [[bounds_min[0] - 1, bounds_max[1] + 1],
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[bounds_max[0] + 1, bounds_max[1] + 1],
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[bounds_max[0] + 1, bounds_min[1] - 1],
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[bounds_min[0] - 1, bounds_min[1] - 1]]
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path_spec = poly2path(slab_edge)
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# Draw polygons with reversed vertex order
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for shape in pattern.shapes:
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for polygon in shape.to_polygons():
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path_spec += poly2path(polygon.vertices[::-1] + polygon.offset)
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svg.add(svg.path(d=path_spec, fill='blue', stroke='red'))
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svg.save()
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def poly2path(vertices: ArrayLike) -> str:
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"""
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Create an SVG path string from an Nx2 list of vertices.
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Args:
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vertices: Nx2 array of vertices.
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Returns:
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SVG path-string.
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"""
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verts = numpy.array(vertices, copy=False)
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commands = 'M{:g},{:g} '.format(verts[0][0], verts[0][1])
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for vertex in verts[1:]:
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commands += 'L{:g},{:g}'.format(vertex[0], vertex[1])
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commands += ' Z '
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return commands
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