path: root/gn2/utility/svg.py

# Copyright (C) University of Tennessee Health Science Center, Memphis, TN.
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License
# as published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the GNU Affero General Public License for more details.
#
# This program is available from Source Forge: at GeneNetwork Project
# (sourceforge.net/projects/genenetwork/).
#
# Contact Drs. Robert W. Williams and Xiaodong Zhou (2010)
# at rwilliams@uthsc.edu and xzhou15@uthsc.edu
#
#
#
# This module is used by GeneNetwork project (www.genenetwork.org)
#
# Created by GeneNetwork Core Team 2010/08/10
#
# Last updated by GeneNetwork Core Team 2010/10/20

#!/usr/bin/env python
# Copyright (c) 2002, Fedor Baart & Hans de Wit (Stichting Farmaceutische Kengetallen)
# All rights reserved.
##
# Redistribution and use in source and binary forms, with or without modification,
# are permitted provided that the following conditions are met:
##
# Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
##
# Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation and/or
# other materials provided with the distribution.
##
# Neither the name of the Stichting Farmaceutische Kengetallen nor the names of
# its contributors may be used to endorse or promote products derived from this
# software without specific prior written permission.
##
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# Thanks to Gerald Rosennfellner for his help and useful comments.

import sys
import exceptions
__doc__ = """Use SVGdraw to generate your SVGdrawings.

SVGdraw uses an object model drawing and a method toXML to create SVG graphics
by using easy to use classes and methods usualy you start by creating a drawing eg

    d=drawing()
    # then you create a SVG root element
    s=svg()
    # then you add some elements eg a circle and add it to the svg root element
    c=circle()
    # you can supply attributes by using named arguments.
    c=circle(fill='red',stroke='blue')
    # or by updating the attributes attribute:
    c.attributes['stroke-width']=1
    s.addElement(c)
    # then you add the svg root element to the drawing
    d.setSVG(s)
    # and finaly you xmlify the drawing
    d.toXml()


this results in the svg source of the drawing, which consists of a circle
on a white background. Its as easy as that;)
This module was created using the SVG specification of www.w3c.org and the
O'Reilly (www.oreilly.com) python books as information sources. A svg viewer
is available from www.adobe.com"""

__version__ = "1.0"

# there are two possibilities to generate svg:
# via a dom implementation and directly using <element>text</element> strings
# the latter is way faster (and shorter in coding)
# the former is only used in debugging svg programs
# maybe it will be removed alltogether after a while
# with the following variable you indicate whether to use the dom implementation
# Note that PyXML is required for using the dom implementation.
# It is also possible to use the standard minidom. But I didn't try that one.
# Anyway the text based approach is about 60 times faster than using the full dom implementation.
use_dom_implementation = 0


if use_dom_implementation != 0:
    try:
        from xml.dom import implementation
        from xml.dom.ext import PrettyPrint
    except:
        raise exceptions.ImportError(
            "PyXML is required for using the dom implementation")
# The implementation is used for the creating the XML document.
# The prettyprint module is used for converting the xml document object to a xml file

sys.setrecursionlimit = 50
# The recursion limit is set conservative so mistakes like s=svg() s.addElement(s)
# won't eat up too much processor time.

# the following code is pasted form xml.sax.saxutils
# it makes it possible to run the code without the xml sax package installed
# To make it possible to have <rubbish> in your text elements, it is necessary to escape the texts


def _escape(data, entities={}):
    """Escape &, <, and > in a string of data.

    You can escape other strings of data by passing a dictionary as
    the optional entities parameter.  The keys and values must all be
    strings; each key will be replaced with its corresponding value.
    """
    # data = data.replace("&", "&amp;")
    data = data.replace("<", "&lt;")
    data = data.replace(">", "&gt;")
    for chars, entity in list(entities.items()):
        data = data.replace(chars, entity)
    return data


def _quoteattr(data, entities={}):
    """Escape and quote an attribute value.

    Escape &, <, and > in a string of data, then quote it for use as
    an attribute value.  The \" character will be escaped as well, if
    necessary.

    You can escape other strings of data by passing a dictionary as
    the optional entities parameter.  The keys and values must all be
    strings; each key will be replaced with its corresponding value.
    """
    data = _escape(data, entities)
    if '"' in data:
        if "'" in data:
            data = '"%s"' % data.replace('"', "&quot;")
        else:
            data = "'%s'" % data
    else:
        data = '"%s"' % data
    return data


def _xypointlist(a):
    """formats a list of xy pairs"""
    s = ''
    for e in a:  # this could be done more elegant
        s += str(e)[1:-1] + '  '
    return s


def _viewboxlist(a):
    """formats a tuple"""
    s = ''
    for e in a:
        s += str(e) + ' '
    return s


def _pointlist(a):
    """formats a list of numbers"""
    return str(a)[1:-1]


class pathdata:
    """class used to create a pathdata object which can be used for a path.
    although most methods are pretty straightforward it might be useful to look at the SVG specification."""
    # I didn't test the methods below.

    def __init__(self, x=None, y=None):
        self.path = []
        if x is not None and y is not None:
            self.path.append('M ' + str(x) + ' ' + str(y))

    def closepath(self):
        """ends the path"""
        self.path.append('z')

    def move(self, x, y):
        """move to absolute"""
        self.path.append('M ' + str(x) + ' ' + str(y))

    def relmove(self, x, y):
        """move to relative"""
        self.path.append('m ' + str(x) + ' ' + str(y))

    def line(self, x, y):
        """line to absolute"""
        self.path.append('L ' + str(x) + ' ' + str(y))

    def relline(self, x, y):
        """line to relative"""
        self.path.append('l ' + str(x) + ' ' + str(y))

    def hline(self, x):
        """horizontal line to absolute"""
        self.path.append('H' + str(x))

    def relhline(self, x):
        """horizontal line to relative"""
        self.path.append('h' + str(x))

    def vline(self, y):
        """verical line to absolute"""
        self.path.append('V' + str(y))

    def relvline(self, y):
        """vertical line to relative"""
        self.path.append('v' + str(y))

    def bezier(self, x1, y1, x2, y2, x, y):
        """bezier with xy1 and xy2 to xy absolut"""
        self.path.append('C' + str(x1) + ',' + str(y1) + ' ' + str(x2)
                         + ',' + str(y2) + ' ' + str(x) + ',' + str(y))

    def relbezier(self, x1, y1, x2, y2, x, y):
        """bezier with xy1 and xy2 to xy relative"""
        self.path.append('c' + str(x1) + ',' + str(y1) + ' ' + str(x2)
                         + ',' + str(y2) + ' ' + str(x) + ',' + str(y))

    def smbezier(self, x2, y2, x, y):
        """smooth bezier with xy2 to xy absolut"""
        self.path.append('S' + str(x2) + ',' + str(y2) + \
                         ' ' + str(x) + ',' + str(y))

    def relsmbezier(self, x2, y2, x, y):
        """smooth bezier with xy2 to xy relative"""
        self.path.append('s' + str(x2) + ',' + str(y2) + \
                         ' ' + str(x) + ',' + str(y))

    def qbezier(self, x1, y1, x, y):
        """quadratic bezier with xy1 to xy absolut"""
        self.path.append('Q' + str(x1) + ',' + str(y1) + \
                         ' ' + str(x) + ',' + str(y))

    def relqbezier(self, x1, y1, x, y):
        """quadratic bezier with xy1 to xy relative"""
        self.path.append('q' + str(x1) + ',' + str(y1) + \
                         ' ' + str(x) + ',' + str(y))

    def smqbezier(self, x, y):
        """smooth quadratic bezier to xy absolut"""
        self.path.append('T' + str(x) + ',' + str(y))

    def relsmqbezier(self, x, y):
        """smooth quadratic bezier to xy relative"""
        self.path.append('t' + str(x) + ',' + str(y))

    def ellarc(self, rx, ry, xrot, laf, sf, x, y):
        """elliptival arc with rx and ry rotating with xrot using large-arc-flag and sweep-flag  to xy absolut"""
        self.path.append('A' + str(rx) + ',' + str(ry) + ' ' + str(xrot)
                         + ' ' + str(laf) + ' ' + str(sf) + ' ' + str(x) + ' ' + str(y))

    def relellarc(self, rx, ry, xrot, laf, sf, x, y):
        """elliptival arc with rx and ry rotating with xrot using large-arc-flag and sweep-flag  to xy relative"""
        self.path.append('a' + str(rx) + ',' + str(ry) + ' ' + str(xrot)
                         + ' ' + str(laf) + ' ' + str(sf) + ' ' + str(x) + ' ' + str(y))

    def __repr__(self):
        return ' '.join(self.path)


class SVGelement:
    """SVGelement(type,attributes,elements,text,namespace,**args)
    Creates a arbitrary svg element and is intended to be subclassed not used on its own.
    This element is the base of every svg element it defines a class which resembles
    a xml-element. The main advantage of this kind of implementation is that you don't
    have to create a toXML method for every different graph object. Every element
    consists of a type, attribute, optional subelements, optional text and an optional
    namespace. Note the elements==None, if elements = None:self.elements=[] construction.
    This is done because if you default to elements=[] every object has a reference
    to the same empty list."""

    def __init__(self, type='', attributes=None, elements=None, text='', namespace='', cdata=None, **args):
        self.type = type
        if attributes == None:
            self.attributes = {}
        else:
            self.attributes = attributes
        if elements == None:
            self.elements = []
        else:
            self.elements = elements
        self.text = text
        self.namespace = namespace
        self.cdata = cdata
        for arg in list(args.keys()):
            arg2 = arg.replace("__", ":")
            arg2 = arg2.replace("_", "-")
            self.attributes[arg2] = args[arg]

    def addElement(self, SVGelement):
        """adds an element to a SVGelement

        SVGelement.addElement(SVGelement)
        """
        self.elements.append(SVGelement)

    def toXml(self, level, f):
        f.write('\t' * level)
        f.write('<' + self.type)
        for attkey in list(self.attributes.keys()):
            f.write(' ' + _escape(str(attkey)) + '='
                    + _quoteattr(str(self.attributes[attkey])))
        if self.namespace:
            f.write(' xmlns="' + _escape(str(self.namespace))
                    + '" xmlns:xlink="http://www.w3.org/1999/xlink"')
        if self.elements or self.text or self.cdata:
            f.write('>')
        if self.elements:
            f.write('\n')
        for element in self.elements:
            element.toXml(level + 1, f)
        if self.cdata:
            f.write('\n' + '\t' * (level + 1) + '<![CDATA[')
            for line in self.cdata.splitlines():
                f.write('\n' + '\t' * (level + 2) + line)
            f.write('\n' + '\t' * (level + 1) + ']]>\n')
        if self.text:
            if isinstance(self.text, type('')):  # If the text is only text
                f.write(_escape(str(self.text)))
            else:  # If the text is a spannedtext class
                f.write(str(self.text))
        if self.elements:
            f.write('\t' * level + '</' + self.type + '>\n')
        elif self.text:
            f.write('</' + self.type + '>\n')
        elif self.cdata:
            f.write('\t' * level + '</' + self.type + '>\n')
        else:
            f.write('/>\n')


class tspan(SVGelement):
    """ts=tspan(text='',**args)

    a tspan element can be used for applying formatting to a textsection
    usage:
    ts=tspan('this text is bold')
    ts.attributes['font-weight']='bold'
    st=spannedtext()
    st.addtspan(ts)
    t=text(3,5,st)
    """

    def __init__(self, text=None, **args):
        SVGelement.__init__(self, 'tspan', **args)
        if self.text != None:
            self.text = text

    def __repr__(self):
        s = "<tspan"
        for key, value in list(self.attributes.items()):
            s += ' %s="%s"' % (key, value)
        s += '>'
        s += self.text
        s += '</tspan>'
        return s


class tref(SVGelement):
    """tr=tref(link='',**args)

    a tref element can be used for referencing text by a link to its id.
    usage:
    tr=tref('#linktotext')
    st=spannedtext()
    st.addtref(tr)
    t=text(3,5,st)
    """

    def __init__(self, link, **args):
        SVGelement.__init__(self, 'tref', {'xlink:href': link}, **args)

    def __repr__(self):
        s = "<tref"

        for key, value in list(self.attributes.items()):
            s += ' %s="%s"' % (key, value)
        s += '/>'
        return s


class spannedtext:
    """st=spannedtext(textlist=[])

    a spannedtext can be used for text which consists of text, tspan's and tref's
    You can use it to add to a text element or path element. Don't add it directly
    to a svg or a group element.
    usage:

    ts=tspan('this text is bold')
    ts.attributes['font-weight']='bold'
    tr=tref('#linktotext')
    tr.attributes['fill']='red'
    st=spannedtext()
    st.addtspan(ts)
    st.addtref(tr)
    st.addtext('This text is not bold')
    t=text(3,5,st)
    """

    def __init__(self, textlist=None):
        if textlist == None:
            self.textlist = []
        else:
            self.textlist = textlist

    def addtext(self, text=''):
        self.textlist.append(text)

    def addtspan(self, tspan):
        self.textlist.append(tspan)

    def addtref(self, tref):
        self.textlist.append(tref)

    def __repr__(self):
        s = ""
        for element in self.textlist:
            s += str(element)
        return s


class rect(SVGelement):
    """r=rect(width,height,x,y,fill,stroke,stroke_width,**args)

    a rectangle is defined by a width and height and a xy pair
    """

    def __init__(self, x=None, y=None, width=None, height=None, fill=None, stroke=None, stroke_width=None, **args):
        if width == None or height == None:
            raise ValueError('both height and width are required')

        SVGelement.__init__(
            self, 'rect', {'width': width, 'height': height}, **args)
        if x != None:
            self.attributes['x'] = x
        if y != None:
            self.attributes['y'] = y
        if fill != None:
            self.attributes['fill'] = fill
        if stroke != None:
            self.attributes['stroke'] = stroke
        if stroke_width != None:
            self.attributes['stroke-width'] = stroke_width


class ellipse(SVGelement):
    """e=ellipse(rx,ry,x,y,fill,stroke,stroke_width,**args)

    an ellipse is defined as a center and a x and y radius.
    """

    def __init__(self, cx=None, cy=None, rx=None, ry=None, fill=None, stroke=None, stroke_width=None, **args):
        if rx == None or ry == None:
            raise ValueError('both rx and ry are required')

        SVGelement.__init__(self, 'ellipse', {'rx': rx, 'ry': ry}, **args)
        if cx != None:
            self.attributes['cx'] = cx
        if cy != None:
            self.attributes['cy'] = cy
        if fill != None:
            self.attributes['fill'] = fill
        if stroke != None:
            self.attributes['stroke'] = stroke
        if stroke_width != None:
            self.attributes['stroke-width'] = stroke_width


class circle(SVGelement):
    """c=circle(x,y,radius,fill,stroke,stroke_width,**args)

    The circle creates an element using a x, y and radius values eg
    """

    def __init__(self, cx=None, cy=None, r=None, fill=None, stroke=None, stroke_width=None, **args):
        if r == None:
            raise ValueError('r is required')
        SVGelement.__init__(self, 'circle', {'r': r}, **args)
        if cx != None:
            self.attributes['cx'] = cx
        if cy != None:
            self.attributes['cy'] = cy
        if fill != None:
            self.attributes['fill'] = fill
        if stroke != None:
            self.attributes['stroke'] = stroke
        if stroke_width != None:
            self.attributes['stroke-width'] = stroke_width


class point(circle):
    """p=point(x,y,color)

    A point is defined as a circle with a size 1 radius. It may be more efficient to use a
    very small rectangle if you use many points because a circle is difficult to render.
    """

    def __init__(self, x, y, fill='black', **args):
        circle.__init__(self, x, y, 1, fill, **args)


class line(SVGelement):
    """l=line(x1,y1,x2,y2,stroke,stroke_width,**args)

    A line is defined by a begin x,y pair and an end x,y pair
    """

    def __init__(self, x1=None, y1=None, x2=None, y2=None, stroke=None, stroke_width=None, **args):
        SVGelement.__init__(self, 'line', **args)
        if x1 != None:
            self.attributes['x1'] = x1
        if y1 != None:
            self.attributes['y1'] = y1
        if x2 != None:
            self.attributes['x2'] = x2
        if y2 != None:
            self.attributes['y2'] = y2
        if stroke_width != None:
            self.attributes['stroke-width'] = stroke_width
        if stroke != None:
            self.attributes['stroke'] = stroke


class polyline(SVGelement):
    """pl=polyline([[x1,y1],[x2,y2],...],fill,stroke,stroke_width,**args)

    a polyline is defined by a list of xy pairs
    """

    def __init__(self, points, fill=None, stroke=None, stroke_width=None, **args):
        SVGelement.__init__(self, 'polyline', {
                            'points': _xypointlist(points)}, **args)
        if fill != None:
            self.attributes['fill'] = fill
        if stroke_width != None:
            self.attributes['stroke-width'] = stroke_width
        if stroke != None:
            self.attributes['stroke'] = stroke


class polygon(SVGelement):
    """pl=polyline([[x1,y1],[x2,y2],...],fill,stroke,stroke_width,**args)

    a polygon is defined by a list of xy pairs
    """

    def __init__(self, points, fill=None, stroke=None, stroke_width=None, **args):
        SVGelement.__init__(
            self, 'polygon', {'points': _xypointlist(points)}, **args)
        if fill != None:
            self.attributes['fill'] = fill
        if stroke_width != None:
            self.attributes['stroke-width'] = stroke_width
        if stroke != None:
            self.attributes['stroke'] = stroke


class path(SVGelement):
    """p=path(path,fill,stroke,stroke_width,**args)

    a path is defined by a path object and optional width, stroke and fillcolor
    """

    def __init__(self, pathdata, fill=None, stroke=None, stroke_width=None, id=None, **args):
        SVGelement.__init__(self, 'path', {'d': str(pathdata)}, **args)
        if stroke != None:
            self.attributes['stroke'] = stroke
        if fill != None:
            self.attributes['fill'] = fill
        if stroke_width != None:
            self.attributes['stroke-width'] = stroke_width
        if id != None:
            self.attributes['id'] = id


class text(SVGelement):
    """t=text(x,y,text,font_size,font_family,**args)

    a text element can bge used for displaying text on the screen
    """

    def __init__(self, x=None, y=None, text=None, font_size=None, font_family=None, text_anchor=None, **args):
        SVGelement.__init__(self, 'text', **args)
        if x != None:
            self.attributes['x'] = x
        if y != None:
            self.attributes['y'] = y
        if font_size != None:
            self.attributes['font-size'] = font_size
        if font_family != None:
            self.attributes['font-family'] = font_family
        if text != None:
            self.text = text
        if text_anchor != None:
            self.attributes['text-anchor'] = text_anchor


class textpath(SVGelement):
    """tp=textpath(text,link,**args)

    a textpath places a text on a path which is referenced by a link.
    """

    def __init__(self, link, text=None, **args):
        SVGelement.__init__(self, 'textPath', {'xlink:href': link}, **args)
        if text != None:
            self.text = text


class pattern(SVGelement):
    """p=pattern(x,y,width,height,patternUnits,**args)

    A pattern is used to fill or stroke an object using a pre-defined
    graphic object which can be replicated ("tiled") at fixed intervals
    in x and y to cover the areas to be painted.
    """

    def __init__(self, x=None, y=None, width=None, height=None, patternUnits=None, **args):
        SVGelement.__init__(self, 'pattern', **args)
        if x != None:
            self.attributes['x'] = x
        if y != None:
            self.attributes['y'] = y
        if width != None:
            self.attributes['width'] = width
        if height != None:
            self.attributes['height'] = height
        if patternUnits != None:
            self.attributes['patternUnits'] = patternUnits


class title(SVGelement):
    """t=title(text,**args)

    a title is a text element. The text is displayed in the title bar
    add at least one to the root svg element
    """

    def __init__(self, text=None, **args):
        SVGelement.__init__(self, 'title', **args)
        if text != None:
            self.text = text


class description(SVGelement):
    """d=description(text,**args)

    a description can be added to any element and is used for a tooltip
    Add this element before adding other elements.
    """

    def __init__(self, text=None, **args):
        SVGelement.__init__(self, 'desc', **args)
        if text != None:
            self.text = text


class lineargradient(SVGelement):
    """lg=lineargradient(x1,y1,x2,y2,id,**args)

    defines a lineargradient using two xy pairs.
    stop elements van be added to define the gradient colors.
    """

    def __init__(self, x1=None, y1=None, x2=None, y2=None, id=None, **args):
        SVGelement.__init__(self, 'linearGradient', **args)
        if x1 != None:
            self.attributes['x1'] = x1
        if y1 != None:
            self.attributes['y1'] = y1
        if x2 != None:
            self.attributes['x2'] = x2
        if y2 != None:
            self.attributes['y2'] = y2
        if id != None:
            self.attributes['id'] = id


class radialgradient(SVGelement):
    """rg=radialgradient(cx,cy,r,fx,fy,id,**args)

    defines a radial gradient using a outer circle which are defined by a cx,cy and r and by using a focalpoint.
    stop elements van be added to define the gradient colors.
    """

    def __init__(self, cx=None, cy=None, r=None, fx=None, fy=None, id=None, **args):
        SVGelement.__init__(self, 'radialGradient', **args)
        if cx != None:
            self.attributes['cx'] = cx
        if cy != None:
            self.attributes['cy'] = cy
        if r != None:
            self.attributes['r'] = r
        if fx != None:
            self.attributes['fx'] = fx
        if fy != None:
            self.attributes['fy'] = fy
        if id != None:
            self.attributes['id'] = id


class stop(SVGelement):
    """st=stop(offset,stop_color,**args)

    Puts a stop color at the specified radius
    """

    def __init__(self, offset, stop_color=None, **args):
        SVGelement.__init__(self, 'stop', {'offset': offset}, **args)
        if stop_color != None:
            self.attributes['stop-color'] = stop_color


class style(SVGelement):
    """st=style(type,cdata=None,**args)

    Add a CDATA element to this element for defing in line stylesheets etc..
    """

    def __init__(self, type, cdata=None, **args):
        SVGelement.__init__(self, 'style', {'type': type}, cdata=cdata, **args)


class image(SVGelement):
    """im=image(url,width,height,x,y,**args)

    adds an image to the drawing. Supported formats are .png, .jpg and .svg.
    """

    def __init__(self, url, x=None, y=None, width=None, height=None, **args):
        if width == None or height == None:
            raise ValueError('both height and width are required')
        SVGelement.__init__(
            self, 'image', {'xlink:href': url, 'width': width, 'height': height}, **args)
        if x != None:
            self.attributes['x'] = x
        if y != None:
            self.attributes['y'] = y


class cursor(SVGelement):
    """c=cursor(url,**args)

    defines a custom cursor for a element or a drawing
    """

    def __init__(self, url, **args):
        SVGelement.__init__(self, 'cursor', {'xlink:href': url}, **args)


class marker(SVGelement):
    """m=marker(id,viewbox,refX,refY,markerWidth,markerHeight,**args)

    defines a marker which can be used as an endpoint for a line or other pathtypes
    add an element to it which should be used as a marker.
    """

    def __init__(self, id=None, viewBox=None, refx=None, refy=None, markerWidth=None, markerHeight=None, **args):
        SVGelement.__init__(self, 'marker', **args)
        if id != None:
            self.attributes['id'] = id
        if viewBox != None:
            self.attributes['viewBox'] = _viewboxlist(viewBox)
        if refx != None:
            self.attributes['refX'] = refx
        if refy != None:
            self.attributes['refY'] = refy
        if markerWidth != None:
            self.attributes['markerWidth'] = markerWidth
        if markerHeight != None:
            self.attributes['markerHeight'] = markerHeight


class group(SVGelement):
    """g=group(id,**args)

    a group is defined by an id and is used to contain elements
    g.addElement(SVGelement)
    """

    def __init__(self, id=None, **args):
        SVGelement.__init__(self, 'g', **args)
        if id != None:
            self.attributes['id'] = id


class symbol(SVGelement):
    """sy=symbol(id,viewbox,**args)

    defines a symbol which can be used on different places in your graph using
    the use element. A symbol is not rendered but you can use 'use' elements to
    display it by referencing its id.
    sy.addElement(SVGelement)
    """

    def __init__(self, id=None, viewBox=None, **args):
        SVGelement.__init__(self, 'symbol', **args)
        if id != None:
            self.attributes['id'] = id
        if viewBox != None:
            self.attributes['viewBox'] = _viewboxlist(viewBox)


class defs(SVGelement):
    """d=defs(**args)

    container for defining elements
    """

    def __init__(self, **args):
        SVGelement.__init__(self, 'defs', **args)


class switch(SVGelement):
    """sw=switch(**args)

    Elements added to a switch element which are "switched" by the attributes
    requiredFeatures, requiredExtensions and systemLanguage.
    Refer to the SVG specification for details.
    """

    def __init__(self, **args):
        SVGelement.__init__(self, 'switch', **args)


class use(SVGelement):
    """u=use(link,x,y,width,height,**args)

    references a symbol by linking to its id and its position, height and width
    """

    def __init__(self, link, x=None, y=None, width=None, height=None, **args):
        SVGelement.__init__(self, 'use', {'xlink:href': link}, **args)
        if x != None:
            self.attributes['x'] = x
        if y != None:
            self.attributes['y'] = y

        if width != None:
            self.attributes['width'] = width
        if height != None:
            self.attributes['height'] = height


class link(SVGelement):
    """a=link(url,**args)

    a link  is defined by a hyperlink. add elements which have to be linked
    a.addElement(SVGelement)
    """

    def __init__(self, link='', **args):
        SVGelement.__init__(self, 'a', {'xlink:href': link}, **args)


class view(SVGelement):
    """v=view(id,**args)

    a view can be used to create a view with different attributes"""

    def __init__(self, id=None, **args):
        SVGelement.__init__(self, 'view', **args)
        if id != None:
            self.attributes['id'] = id


class script(SVGelement):
    """sc=script(type,type,cdata,**args)

    adds a script element which contains CDATA to the SVG drawing

    """

    def __init__(self, type, cdata=None, **args):
        SVGelement.__init__(
            self, 'script', {'type': type}, cdata=cdata, **args)


class animate(SVGelement):
    """an=animate(attribute,from,to,during,**args)

    animates an attribute.
    """

    def __init__(self, attribute, fr=None, to=None, dur=None, **args):
        SVGelement.__init__(
            self, 'animate', {'attributeName': attribute}, **args)
        if fr != None:
            self.attributes['from'] = fr
        if to != None:
            self.attributes['to'] = to
        if dur != None:
            self.attributes['dur'] = dur


class animateMotion(SVGelement):
    """an=animateMotion(pathdata,dur,**args)

    animates a SVGelement over the given path in dur seconds
    """

    def __init__(self, pathdata, dur, **args):
        SVGelement.__init__(self, 'animateMotion', **args)
        if pathdata != None:
            self.attributes['path'] = str(pathdata)
        if dur != None:
            self.attributes['dur'] = dur


class animateTransform(SVGelement):
    """antr=animateTransform(type,from,to,dur,**args)

    transform an element from and to a value.
    """

    def __init__(self, type=None, fr=None, to=None, dur=None, **args):
        SVGelement.__init__(self, 'animateTransform', {
                            'attributeName': 'transform'}, **args)
        # As far as I know the attributeName is always transform
        if type != None:
            self.attributes['type'] = type
        if fr != None:
            self.attributes['from'] = fr
        if to != None:
            self.attributes['to'] = to
        if dur != None:
            self.attributes['dur'] = dur


class animateColor(SVGelement):
    """ac=animateColor(attribute,type,from,to,dur,**args)

    Animates the color of a element
    """

    def __init__(self, attribute, type=None, fr=None, to=None, dur=None, **args):
        SVGelement.__init__(self, 'animateColor', {
                            'attributeName': attribute}, **args)
        if type != None:
            self.attributes['type'] = type
        if fr != None:
            self.attributes['from'] = fr
        if to != None:
            self.attributes['to'] = to
        if dur != None:
            self.attributes['dur'] = dur


class set(SVGelement):
    """st=set(attribute,to,during,**args)

    sets an attribute to a value for a
    """

    def __init__(self, attribute, to=None, dur=None, **args):
        SVGelement.__init__(self, 'set', {'attributeName': attribute}, **args)
        if to != None:
            self.attributes['to'] = to
        if dur != None:
            self.attributes['dur'] = dur


class svg(SVGelement):
    """s=svg(viewbox,width,height,**args)

    a svg or element is the root of a drawing add all elements to a svg element.
    You can have different svg elements in one svg file
    s.addElement(SVGelement)

    eg
    d=drawing()
    s=svg((0,0,100,100),'100%','100%')
    c=circle(50,50,20)
    s.addElement(c)
    d.setSVG(s)
    d.toXml()
    """

    def __init__(self, viewBox=None, width=None, height=None, **args):
        SVGelement.__init__(self, 'svg', **args)
        if viewBox != None:
            self.attributes['viewBox'] = _viewboxlist(viewBox)
        if width != None:
            self.attributes['width'] = width
        if height != None:
            self.attributes['height'] = height
        self.namespace = "http://www.w3.org/2000/svg"


class drawing:
    """d=drawing()

    this is the actual SVG document. It needs a svg element as a root.
    Use the addSVG method to set the svg to the root. Use the toXml method to write the SVG
    source to the screen or to a file
    d=drawing()
    d.addSVG(svg)
    d.toXml(optionalfilename)
    """

    def __init__(self, entity={}):
        self.svg = None
        self.entity = entity

    def setSVG(self, svg):
        self.svg = svg
        # Voeg een element toe aan de grafiek toe.
    if use_dom_implementation == 0:
        def toXml(self, filename='', compress=False):
            import io
            xml = io.StringIO()
            xml.write("<?xml version='1.0' encoding='UTF-8'?>\n")
            xml.write(
                "<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.0//EN\" \"http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd\"")
            if self.entity:
                xml.write(" [\n")
                for item in list(self.entity.keys()):
                    xml.write("<!ENTITY %s \"%s\">\n" %
                              (item, self.entity[item]))
                xml.write("]")
            xml.write(">\n")
            self.svg.toXml(0, xml)
            if not filename:
                if compress:
                    import gzip
                    f = io.StringIO()
                    zf = gzip.GzipFile(fileobj=f, mode='wb')
                    zf.write(xml.getvalue())
                    zf.close()
                    f.seek(0)
                    return f.read()
                else:
                    return xml.getvalue()
            else:
                if filename[-4:] == 'svgz':
                    import gzip
                    f = gzip.GzipFile(filename=filename,
                                      mode="wb", compresslevel=9)
                    f.write(xml.getvalue())
                    f.close()
                else:
                    f = file(filename, 'w')
                    f.write(xml.getvalue())
                    f.close()

    else:
        def toXml(self, filename='', compress=False):
            """drawing.toXml()        ---->to the screen
            drawing.toXml(filename)---->to the file
            writes a svg drawing to the screen or to a file
            compresses if filename ends with svgz or if compress is true
            """
            doctype = implementation.createDocumentType(
                'svg', "-//W3C//DTD SVG 1.0//EN""", 'http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd ')

            global root
            # root is defined global so it can be used by the appender. Its also possible to use it as an arugument but
            # that is a bit messy.
            root = implementation.createDocument(None, None, doctype)
            # Create the xml document.
            global appender

            def appender(element, elementroot):
                """This recursive function appends elements to an element and sets the attributes
                and type. It stops when alle elements have been appended"""
                if element.namespace:
                    e = root.createElementNS(element.namespace, element.type)
                else:
                    e = root.createElement(element.type)
                if element.text:
                    textnode = root.createTextNode(element.text)
                    e.appendChild(textnode)
                # in element.attributes is supported from python 2.2
                for attribute in list(element.attributes.keys()):
                    e.setAttribute(attribute, str(
                        element.attributes[attribute]))
                if element.elements:
                    for el in element.elements:
                        e = appender(el, e)
                elementroot.appendChild(e)
                return elementroot
            root = appender(self.svg, root)
            if not filename:
                import io
                xml = io.StringIO()
                PrettyPrint(root, xml)
                if compress:
                    import gzip
                    f = io.StringIO()
                    zf = gzip.GzipFile(fileobj=f, mode='wb')
                    zf.write(xml.getvalue())
                    zf.close()
                    f.seek(0)
                    return f.read()
                else:
                    return xml.getvalue()
            else:
                try:
                    if filename[-4:] == 'svgz':
                        import gzip
                        import io
                        xml = io.StringIO()
                        PrettyPrint(root, xml)
                        f = gzip.GzipFile(filename=filename,
                                          mode='wb', compresslevel=9)
                        f.write(xml.getvalue())
                        f.close()
                    else:
                        f = open(filename, 'w')
                        PrettyPrint(root, f)
                        f.close()
                except:
                    print(("Cannot write SVG file: " + filename))

    def validate(self):
        try:
            import xml.parsers.xmlproc.xmlval
        except:
            raise exceptions.ImportError(
                'PyXml is required for validating SVG')
        svg = self.toXml()
        xv = xml.parsers.xmlproc.xmlval.XMLValidator()
        try:
            xv.feed(svg)
        except:
            raise Exception("SVG is not well formed, see messages above")
        else:
            print("SVG well formed")


if __name__ == '__main__':

    d = drawing()
    s = svg((0, 0, 100, 100))
    r = rect(-100, -100, 300, 300, 'cyan')
    s.addElement(r)

    t = title('SVGdraw Demo')
    s.addElement(t)
    g = group('animations')
    e = ellipse(0, 0, 5, 2)
    g.addElement(e)
    c = circle(0, 0, 1, 'red')
    g.addElement(c)
    pd = pathdata(0, -10)
    for i in range(6):
        pd.relsmbezier(10, 5, 0, 10)
        pd.relsmbezier(-10, 5, 0, 10)
    an = animateMotion(pd, 10)
    an.attributes['rotate'] = 'auto-reverse'
    an.attributes['repeatCount'] = "indefinite"
    g.addElement(an)
    s.addElement(g)
    for i in range(20, 120, 20):
        u = use('#animations', i, 0)
        s.addElement(u)
    for i in range(0, 120, 20):
        for j in range(5, 105, 10):
            c = circle(i, j, 1, 'red', 'black', .5)
            s.addElement(c)
    d.setSVG(s)

    print((d.toXml()))