186 lines
8.5 KiB
Python
186 lines
8.5 KiB
Python
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#!/usr/bin/env python3
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'''
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---DESTRUCTIVE Clip---
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An Inkscape Extension which works like Object|Clip|Set except that the paths clipped are actually *modified*
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Thus the clipping is included when exported, for example as a DXF file.
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Select two or more *paths* then choose Extensions|Modify path|Destructive clip. The topmost path will be used to clip the others.
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Notes:-
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* Curves in paths are not supported (use Flatten Beziers).
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* Non-path objects in the selection will be ignored. Use Object|Ungroup.
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* Paths entirely outside the clipping path will remain untouched (rather than modifying them to an empty path)
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* Complex paths may take a while (there seems to be no way too show progress)
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* Yes, using MBR's to do gross clipping might make it faster
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* No, Python is not my first language (C/C++ is)
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Mark Wilson Feb 2016
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----
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Edits by Windell H. Oskay, www.evilmadscientit.com, August 2020
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Update calls to Inkscape 1.0 extension API to avoid deprecation warnings
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Minimal standardization of python whitespace
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Handle some errors more gracefully
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'''
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import inkex
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import sys
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class DestructiveClip(inkex.Effect):
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def __init__(self):
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self.tolerance = 0.0001 # arbitrary fudge factor
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inkex.Effect.__init__(self)
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self.error_messages = []
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self.curve_error = 'Unable to parse path.\nConsider removing curves '
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self.curve_error += 'with Extensions > Modify Path > Flatten Beziers...'
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def approxEqual(self, a, b):
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# compare with tiny tolerance
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return abs(a-b) <= self.tolerance
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def midPoint(self, line):
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# midPoint of line
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return [(line[0][0] + line[1][0])/2, (line[0][1] + line[1][1])/2]
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def maxX(self, lineSegments):
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# return max X coord of lineSegments
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maxx = 0.0
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for line in lineSegments:
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maxx = max(maxx, line[0][0])
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maxx = max(maxx, line[1][0])
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return maxx
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def simplepathToLineSegments(self, path):
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# takes a simplepath and converts to line *segments*, for simplicity.
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# Thus [MoveTo P0, LineTo P1, LineTo P2] becomes [[P0-P1],[P1,P2]]
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# only handles, Move, Line and Close.
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# The simplepath library has already simplified things, normalized relative commands, etc
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lineSegments = first = prev = this = []
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errors = set([]) # Similar errors will be stored only once
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for cmd in path:
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this = cmd[1]
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if cmd[0] == 'M': # moveto
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if first == []:
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first = this
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elif cmd[0] == 'L': # lineto
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lineSegments.append([prev, this])
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elif cmd[0] == 'Z': # close
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lineSegments.append([prev, first])
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first = []
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elif cmd[0] == 'C':
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# https://developer.mozilla.org/en/docs/Web/SVG/Tutorial/Paths
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lineSegments.append([prev, [this[4], this[5]]])
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errors.add("Curve node detected (svg type C), this node will be handled as a regular node")
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else:
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errors.add("Invalid node type detected: {}. This script only handle type M, L, Z".format(cmd[0]))
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prev = this
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return (lineSegments, errors)
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def linesgmentsToSimplePath(self, lineSegments):
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# reverses simplepathToLines - converts line segments to Move/Line-to's
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path = []
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end = None
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for line in lineSegments:
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start = line[0]
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if end is None:
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path.append(['M', start]) # start with a move
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elif not (self.approxEqual(end[0], start[0]) and self.approxEqual(end[1], start[1])):
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path.append(['M', start]) # only move if previous end not within tolerance of this start
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end = line[1]
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path.append(['L', end])
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return path
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def lineIntersection(self, L1From, L1To, L2From, L2To):
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# returns as [x, y] the intersection of the line L1From-L1To and L2From-L2To, or None
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# http://stackoverflow.com/questions/563198/how-do-you-detect-where-two-line-segments-intersect
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try:
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dL1 = [L1To[0] - L1From[0], L1To[1] - L1From[1]]
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dL2 = [L2To[0] - L2From[0], L2To[1] - L2From[1]]
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except IndexError:
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inkex.errormsg(self.curve_error)
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sys.exit()
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denominator = -dL2[0]*dL1[1] + dL1[0]*dL2[1]
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if not self.approxEqual(denominator, 0.0):
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s = (-dL1[1]*(L1From[0] - L2From[0]) + dL1[0]*(L1From[1] - L2From[1]))/denominator
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t = (+dL2[0]*(L1From[1] - L2From[1]) - dL2[1]*(L1From[0] - L2From[0]))/denominator
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if s >= 0.0 and s <= 1.0 and t >= 0.0 and t <= 1.0:
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return [L1From[0] + (t * dL1[0]), L1From[1] + (t * dL1[1])]
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else:
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return None
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def insideRegion(self, point, lineSegments, lineSegmentsMaxX):
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# returns true if point is inside the region defined by lineSegments. lineSegmentsMaxX is the maximum X extent
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ray = [point, [lineSegmentsMaxX*2.0, point[1]]] # hz line to right of point, extending well outside MBR
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crossings = 0
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for line in lineSegments:
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if not self.lineIntersection(line[0], line[1], ray[0], ray[1]) is None:
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crossings += 1
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return (crossings % 2) == 1 # odd number of crossings means inside
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def cullSegmentedLine(self, segmentedLine, lineSegments, lineSegmentsMaxX):
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# returns just the segments in segmentedLine which are inside lineSegments
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culled = []
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for segment in segmentedLine:
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if self.insideRegion(self.midPoint(segment), lineSegments, lineSegmentsMaxX):
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culled.append(segment)
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return culled
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def clipLine(self, line, lineSegments):
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# returns line split where-ever lines in lineSegments cross it
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linesWrite = [line]
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for segment in lineSegments:
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linesRead = linesWrite
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linesWrite = []
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for line in linesRead:
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intersect = self.lineIntersection(line[0], line[1], segment[0], segment[1])
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if intersect is None:
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linesWrite.append(line)
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else: # split
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linesWrite.append([line[0], intersect])
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linesWrite.append([intersect, line[1]])
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return linesWrite
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def clipLineSegments(self, lineSegmentsToClip, clippingLineSegments):
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# return the lines in lineSegmentsToClip clipped by the lines in clippingLineSegments
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clippedLines = []
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for lineToClip in lineSegmentsToClip:
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clippedLines.extend(self.cullSegmentedLine(self.clipLine(lineToClip, clippingLineSegments), clippingLineSegments, self.maxX(clippingLineSegments)))
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return clippedLines
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def effect(self):
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clippingLineSegments = None
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pathTag = inkex.addNS('path', 'svg')
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groupTag = inkex.addNS('g', 'svg')
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self.error_messages = []
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for id in self.options.ids: # the selection, top-down
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node = self.svg.selected[id]
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if node.tag == pathTag:
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if clippingLineSegments is None: # first path is the clipper
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(clippingLineSegments, errors) = self.simplepathToLineSegments(node.path.to_arrays())
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self.error_messages.extend(['{}: {}'.format(id, err) for err in errors])
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else:
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# do all the work!
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segmentsToClip, errors = self.simplepathToLineSegments(node.path.to_arrays())
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self.error_messages.extend(['{}: {}'.format(id, err) for err in errors])
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clippedSegments = self.clipLineSegments(segmentsToClip, clippingLineSegments)
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if len(clippedSegments) != 0:
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path = str(inkex.Path(self.linesgmentsToSimplePath(clippedSegments)))
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node.set('d', path)
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else:
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# don't put back an empty path(?) could perhaps put move, move?
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inkex.errormsg('Object {} clipped to nothing, will not be updated.'.format(node.get('id')))
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elif node.tag == groupTag: # we don't look inside groups for paths
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inkex.errormsg('Group object {} will be ignored. Please ungroup before running the script.'.format(id))
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else: # something else
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inkex.errormsg('Object {} is not of type path ({}), and will be ignored. Current type "{}".'.format(id, pathTag, node.tag))
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for error in self.error_messages:
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inkex.errormsg(error)
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if __name__ == '__main__':
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DestructiveClip().run()
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