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Editing: gradients.py
#!/usr/bin/env python #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 """ delta = (sweep[1] - sweep[0]) / (len(colors) - 1) offset = sweep[0] 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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