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