107 lines
4.5 KiB
Python
107 lines
4.5 KiB
Python
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#!/usr/bin/env python3
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from __future__ import print_function
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import sys
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import math
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import inkex
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from inkex.paths import CubicSuperPath
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class ExponentialDistort(inkex.EffectExtension):
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def add_arguments(self, pars):
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#pars.add_argument('-a', '--axis', default='x', help='distortion axis. Valid values are "x", "y", or "xy". Default is "x"')
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pars.add_argument('-x', '--exponent', type=float, default=1.3, help='distortion factor. 1=no distortion, default 1.3')
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pars.add_argument('-p', '--padding_perc', type=float, default=0, help='pad at origin. Padding 100% runs the exponential curve through [0.5 .. 1.0] -- default 0% runs through [0.0 .. 1.0]')
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def x_exp(self, bbox, x):
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""" reference implementation ignoring padding. unused. """
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xmin = bbox[0] # maps to 0
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xmax = bbox[1] # maps to 1
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w = xmax-xmin # maps to 1
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# convert world to math coordinates
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xm = (x-xmin)/w
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# apply function with properties f(1.0) == 1.0 and f(0.0) == 0.0
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xm = xm**self.options.exponent # oh, parabola or logarithm?
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# convert back from math to world coordinates.
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return x*w + xmin
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def x_exp_p(self, bbox, x):
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""" parabola mapping with padding
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CAUTION: the properties f(1.0) == 1.0 and f(0.0) == 0.0
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do not really hold, as our x does not run the full range [0.0 .. 1.0]
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FIXME: if you expect some c**xm here, instead of xm**c, think about c==1 ...
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"""
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xmin = bbox[0] # maps to 0 when padding=0,
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xmax = bbox[1] # maps to 1
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xzero = xmin - (xmax-xmin)*self.options.padding_perc*0.01 # maps to 0, after applying padding
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w = xmax - xzero
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w = w * (1+self.options.padding_perc*0.01)
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# convert world to math coordinates
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xm = (x-xzero)/w
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# apply function with properties f(1.0) == 1.0 and f(0.0) == 0.0
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xm = xm**self.options.exponent # oh, parabola or logarithm?
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return xm
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def x_exp_p_inplace(self, bbox, xm):
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""" back from mat to world coordinates, retaining xmin and xmax
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Algorithm: (pre)compute a linear mapping function by explicitly
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running x_exp_p for the two points xmin and xmax.
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Then use the resulting linear function to map back any xm into world coordinates x.
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An obvious speedup by factor 3 is waiting for you here.
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"""
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xmin = bbox[0]
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xmax = bbox[1]
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## assert that xmin maps to xmin and xmax maps to xmax, whatever x_exp_p() does to us.
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f_xmin = self.x_exp_p(bbox, xmin)
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f_xmax = self.x_exp_p(bbox, xmax)
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f_x = self.x_exp_p(bbox, xm)
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x = (f_x - f_xmin) * (xmax-xmin) / (f_xmax-f_xmin) + xmin
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return x
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def computeBBox(self, pts):
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xmin = None
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xmax = None
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ymin = None
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ymax = None
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for p in pts:
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for pp in p:
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for ppp in pp:
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if xmin is None: xmin = ppp[0]
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if xmax is None: xmax = ppp[0]
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if ymin is None: ymin = ppp[1]
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if ymax is None: ymax = ppp[1]
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if xmin > ppp[0]: xmin = ppp[0]
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if xmax < ppp[0]: xmax = ppp[0]
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if ymin > ppp[1]: ymin = ppp[1]
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if ymax < ppp[1]: ymax = ppp[1]
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return (xmin, xmax, ymin, ymax)
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def effect(self):
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if len(self.svg.selected) == 0:
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inkex.errormsg("Please select an object to perform the " +
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"exponential-distort transformation on.")
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return
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for id, node in self.svg.selected.items():
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type = node.get("{http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd}type", "path")
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if node.tag != '{http://www.w3.org/2000/svg}path' or type != 'path':
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inkex.errormsg(node.tag + " is not a path. Type="+type+". Please use 'Path->Object to Path' first.")
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else:
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pts = CubicSuperPath(node.get('d'))
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bbox = self.computeBBox(pts)
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## bbox (60.0, 160.0, 77.0, 197.0)
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## pts [[[[60.0, 77.0], [60.0, 77.0], [60.0, 77.0]], [[60.0, 197.0], [60.0, 197.0], [60.0, 197.0]], [[70.0, 197.0], ...
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for p in pts:
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for pp in p:
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for ppp in pp:
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ppp[0] = self.x_exp_p_inplace(bbox, ppp[0])
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node.set('d', str(pts))
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if __name__ == '__main__':
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ExponentialDistort().run()
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