131 lines
4.5 KiB
Python
131 lines
4.5 KiB
Python
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#!/usr/bin/env python
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#coding:utf-8
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# Author: mozman --<mozman@gmx.at>
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# Purpose: gradients module
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# Created: 26.10.2010
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# Copyright (C) 2010, Manfred Moitzi
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# License: MIT License
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"""
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Gradients consist of continuously smooth color transitions along a vector
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from one color to another, possibly followed by additional transitions along
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the same vector to other colors. SVG provides for two types of gradients:
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linear gradients and radial gradients.
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"""
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from svgwrite.base import BaseElement
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from svgwrite.mixins import Transform, XLink
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from svgwrite.utils import is_string
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class _GradientStop(BaseElement):
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elementname = 'stop'
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def __init__(self, offset=None, color=None, opacity=None, **extra):
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super(_GradientStop, self).__init__(**extra)
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if offset is not None:
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self['offset'] = offset
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if color is not None:
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self['stop-color'] = color
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if opacity is not None:
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self['stop-opacity'] = opacity
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class _AbstractGradient(BaseElement, Transform, XLink):
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transformname = 'gradientTransform'
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def __init__(self, inherit=None, **extra):
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super(_AbstractGradient, self).__init__(**extra)
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if inherit is not None:
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if is_string(inherit):
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self.set_href(inherit)
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else:
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self.set_href(inherit.get_iri())
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def get_paint_server(self, default='none'):
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""" Returns the <FuncIRI> of the gradient. """
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return "%s %s" % (self.get_funciri(), default)
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def add_stop_color(self, offset=None, color=None, opacity=None):
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""" Adds a stop-color to the gradient.
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:param offset: is either a <number> (usually ranging from 0 to 1) or
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a `<percentage>` (usually ranging from 0% to 100%) which indicates where
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the gradient stop is placed. Represents a location along the gradient
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vector. For radial gradients, it represents a percentage distance from
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(fx,fy) to the edge of the outermost/largest circle.
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:param color: indicates what color to use at that gradient stop
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:param opacity: defines the opacity of a given gradient stop
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"""
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self.add(_GradientStop(offset, color, opacity, factory=self))
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return self
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def add_colors(self, colors, sweep=(0., 1.), opacity=None):
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""" Add stop-colors from colors with linear offset distributuion
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from sweep[0] to sweep[1].
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i.e. colors=['white', 'red', 'blue']
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'white': offset = 0.0
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'red': offset = 0.5
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'blue': offset = 1.0
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"""
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start = float(sweep[0])
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end = float(sweep[1])
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delta = (end-start) / float(len(colors) - 1)
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offset = start
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for color in colors:
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self.add_stop_color(round(offset, 3), color, opacity)
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offset += delta
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return self
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def get_xml(self):
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if hasattr(self, 'href'):
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self.update_id()
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return super(_AbstractGradient, self).get_xml()
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class LinearGradient(_AbstractGradient):
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""" Linear gradients are defined by a SVG <linearGradient> element.
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"""
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elementname = 'linearGradient'
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def __init__(self, start=None, end=None, inherit=None, **extra):
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"""
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:param 2-tuple start: start point of the gradient (**x1**, **y1**)
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:param 2-tuple end: end point of the gradient (**x2**, **y2**)
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:param inherit: gradient inherits properties from `inherit` see: **xlink:href**
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"""
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super(LinearGradient, self).__init__(inherit=inherit, **extra)
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if start is not None:
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self['x1'] = start[0]
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self['y1'] = start[1]
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if end is not None:
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self['x2'] = end[0]
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self['y2'] = end[1]
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class RadialGradient(_AbstractGradient):
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""" Radial gradients are defined by a SVG <radialGradient> element.
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"""
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elementname = 'radialGradient'
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def __init__(self, center=None, r=None, focal=None, inherit=None, **extra):
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"""
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:param 2-tuple center: center point for the gradient (**cx**, **cy**)
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:param r: radius for the gradient
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:param 2-tuple focal: focal point for the radial gradient (**fx**, **fy**)
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:param inherit: gradient inherits properties from `inherit` see: **xlink:href**
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"""
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super(RadialGradient, self).__init__(inherit=inherit, **extra)
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if center is not None:
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self['cx'] = center[0]
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self['cy'] = center[1]
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if r is not None:
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self['r'] = r
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if focal is not None:
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self['fx'] = focal[0]
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self['fy'] = focal[1]
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