drawSvg

A Python 3 library for programmatically generating SVG images (vector drawings) and rendering them or displaying them in a Jupyter notebook.

Most common SVG tags are supported and others can easily be added by writing a small subclass of

DrawableBasicElement

DrawableParentElement

An interactive Jupyter notebook widget,

drawSvg.widgets.DrawingWidget

Install

drawSvg is available on PyPI:

$ pip3 install drawSvg

Prerequisites

Cairo needs to be installed separately. When Cairo is installed, drawSvg can output PNG or other image formats in addition to SVG. See platform-specific instructions for Linux, Windows, and macOS from Cairo. Below are some examples for installing Cairo on Linux distributions and macOS.

Ubuntu

$ sudo apt-get install libcairo2

macOS

Using homebrew:

$ brew install cairo

Examples

Basic drawing elements

import drawSvg as draw

d = draw.Drawing(200, 100, origin='center', displayInline=False)
Draw an irregular polygon
d.append(draw.Lines(-80, -45,
                    70, -49,
                    95, 49,
                    -90, 40,
                    close=False,
            fill='#eeee00',
            stroke='black'))
Draw a rectangle
r = draw.Rectangle(-80,0,40,50, fill='#1248ff')
r.appendTitle("Our first rectangle")  # Add a tooltip
d.append(r)
Draw a circle
d.append(draw.Circle(-40, -10, 30,
            fill='red', stroke_width=2, stroke='black'))
Draw an arbitrary path (a triangle in this case)
p = draw.Path(stroke_width=2, stroke='lime',
              fill='black', fill_opacity=0.2)
p.M(-10, 20)  # Start path at point (-10, 20)
p.C(30, -10, 30, 50, 70, 20)  # Draw a curve to (70, 20)
d.append(p)
Draw text
d.append(draw.Text('Basic text', 8, -10, 35, fill='blue'))  # Text with font size 8
d.append(draw.Text('Path text', 8, path=p, text_anchor='start', valign='middle'))
d.append(draw.Text(['Multi-line', 'text'], 8, path=p, text_anchor='end'))
Draw multiple circular arcs
d.append(draw.ArcLine(60,-20,20,60,270,
            stroke='red', stroke_width=5, fill='red', fill_opacity=0.2))
d.append(draw.Arc(60,-20,20,60,270,cw=False,
            stroke='green', stroke_width=3, fill='none'))
d.append(draw.Arc(60,-20,20,270,60,cw=True,
            stroke='blue', stroke_width=1, fill='black', fill_opacity=0.3))
Draw arrows
arrow = draw.Marker(-0.1, -0.5, 0.9, 0.5, scale=4, orient='auto')
arrow.append(draw.Lines(-0.1, -0.5, -0.1, 0.5, 0.9, 0, fill='red', close=True))
p = draw.Path(stroke='red', stroke_width=2, fill='none',
              marker_end=arrow)  # Add an arrow to the end of a path
p.M(20, -40).L(20, -27).L(0, -20)  # Chain multiple path operations
d.append(p)
d.append(draw.Line(30, -20, 0, -10,
            stroke='red', stroke_width=2, fill='none',
            marker_end=arrow))  # Add an arrow to the end of a line
d.setPixelScale(2)  # Set number of pixels per geometry unit
#d.setRenderSize(400,200)  # Alternative to setPixelScale
d.saveSvg('example.svg')
d.savePng('example.png')
Display in Jupyter notebook
d.rasterize()  # Display as PNG
d  # Display as SVG

Gradients

import drawSvg as draw

d = draw.Drawing(1.5, 0.8, origin='center')
d.draw(draw.Rectangle(-0.75,-0.5,1.5,1, fill='#ddd'))
Create gradient
gradient = draw.RadialGradient(0,-0.35,0.7*10)
gradient.addStop(0.5/0.7/10, 'green', 1)
gradient.addStop(1/10, 'red', 0)
Draw a shape to fill with the gradient
p = draw.Path(fill=gradient, stroke='black', stroke_width=0.002)
p.arc(0,-0.35,0.7,30,120)
p.arc(0,-0.35,0.5,120,30,cw=True, includeL=True)
p.Z()
d.append(p)
Draw another shape to fill with the same gradient
p = draw.Path(fill=gradient, stroke='red', stroke_width=0.002)
p.arc(0,-0.35,0.75,130,160)
p.arc(0,-0.35,0,160,130,cw=True, includeL=True)
p.Z()
d.append(p)
Another gradient
gradient2 = draw.LinearGradient(0.1,-0.35,0.1+0.6,-0.35+0.2)
gradient2.addStop(0, 'green', 1)
gradient2.addStop(1, 'red', 0)
d.append(draw.Rectangle(0.1,-0.35,0.6,0.2,
                        stroke='black', stroke_width=0.002,
                        fill=gradient2))
Display
d.setRenderSize(w=600)
d

Duplicate geometry and clip paths

import drawSvg as draw

d = draw.Drawing(1.4, 1.4, origin='center')
Define clip path
clip = draw.ClipPath()
clip.append(draw.Rectangle(-.25,.25-1,1,1))
Draw a cropped circle
c = draw.Circle(0,0,0.5, stroke_width='0.01', stroke='black',
                         fill_opacity=0.3, clip_path=clip,
                         id='circle')
d.append(c)
Make a transparent copy, cropped again
g = draw.Group(opacity=0.5, clip_path=clip)
g.append(draw.Use('circle', 0.25,0.1))
d.append(g)
Display
d.setRenderSize(400)
d.rasterize()

Implementing other SVG tags

import drawSvg as draw

Subclass DrawingBasicElement if it cannot have child nodes
Subclass DrawingParentElement otherwise
Subclass DrawingDef if it must go between  tags in an SVG
class Hyperlink(draw.DrawingParentElement):
    TAG_NAME = 'a'
    def init(self, href, target=None, **kwargs):
        # Other init logic...
        # Keyword arguments to super().init() correspond to SVG node
        # arguments: stroke_width=5 -> stroke-width="5"
        super().init(href=href, target=target, **kwargs)
d = draw.Drawing(1, 1.2, origin='center')
Create hyperlink
hlink = Hyperlink('https://www.python.org', target='_blank',
                  transform='skewY(-30)')
Add child elements
hlink.append(draw.Circle(0,0,0.5, fill='green'))
hlink.append(draw.Text('Hyperlink',0.2, 0,0, center=0.6, fill='white'))
Draw and display
d.append(hlink)
d.setRenderSize(200)
d

Animation with the SVG Animate Tag

import drawSvg as draw

d = draw.Drawing(200, 200, origin='center')
Animate the position and color of circle
c = draw.Circle(0, 0, 20, fill='red')
See for supported attributes:
https://developer.mozilla.org/en-US/docs/Web/SVG/Element/animate
c.appendAnim(draw.Animate('cy', '6s', '-80;80;-80',
                          repeatCount='indefinite'))
c.appendAnim(draw.Animate('cx', '6s', '0;80;0;-80;0',
                          repeatCount='indefinite'))
c.appendAnim(draw.Animate('fill', '6s', 'red;green;blue;yellow',
                          calcMode='discrete',
                          repeatCount='indefinite'))
d.append(c)
Animate a black circle around an ellipse
ellipse = draw.Path()
ellipse.M(-90, 0)
ellipse.A(90, 40, 360, True, True, 90, 0)  # Ellipse path
ellipse.A(90, 40, 360, True, True, -90, 0)
ellipse.Z()
c2 = draw.Circle(0, 0, 10)
See for supported attributes:
https://developer.mozilla.org/en-US/docs/Web/SVG/Element/animateMotion
c2.appendAnim(draw.AnimateMotion(ellipse, '3s',
                                 repeatCount='indefinite'))
See for supported attributes:
https://developer.mozilla.org/en-US/docs/Web/SVG/Element/animateTransform
c2.appendAnim(draw.AnimateTransform('scale', '3s', '1,2;2,1;1,2;2,1;1,2',
                                    repeatCount='indefinite'))
d.append(c2)
d.saveSvg('animated.svg')  # Save to file
d  # Display in Jupyter notebook

Interactive Widget

import drawSvg as draw
from drawSvg.widgets import DrawingWidget
import hyperbolic.poincare.shapes as hyper  # pip3 install hyperbolic

Create drawing
d = draw.Drawing(2, 2, origin='center')
d.setRenderSize(500)
d.append(draw.Circle(0, 0, 1, fill='orange'))
group = draw.Group()
d.append(group)
Update the drawing based on user input
click_list = []
def redraw(points):
    group.children.clear()
    for x1, y1 in points:
        for x2, y2 in points:
            if (x1, y1) == (x2, y2): continue
            p1 = hyper.Point.fromEuclid(x1, y1)
            p2 = hyper.Point.fromEuclid(x2, y2)
            if p1.distanceTo(p2) <= 2:
                line = hyper.Line.fromPoints(*p1, *p2, segment=True)
                group.draw(line, hwidth=0.2, fill='white')
    for x, y in points:
        p = hyper.Point.fromEuclid(x, y)
        group.draw(hyper.Circle.fromCenterRadius(p, 0.1),
                   fill='green')
redraw(click_list)
Create interactive widget and register mouse events
widget = DrawingWidget(d)
@widget.mousedown
def mousedown(widget, x, y, info):
    if (x2 + y2) ** 0.5 + 1e-5 < 1:
        click_list.append((x, y))
    redraw(click_list)
    widget.refresh()
@widget.mousemove
def mousemove(widget, x, y, info):
    if (x2 + y2) ** 0.5 + 1e-5 < 1:
        redraw(click_list + [(x, y)])
    widget.refresh()
widget

Animation with Python

import drawSvg as draw

Draw a frame of the animation
def draw_frame(t):
    d = draw.Drawing(2, 6.05, origin=(-1,-1.05))
    d.setRenderSize(h=300)
    d.append(draw.Rectangle(-2, -2, 4, 8, fill='white'))
    d.append(draw.Rectangle(-1, -1.05, 2, 0.05, fill='brown'))
    t = (t + 1) % 2 - 1
    y = 4 - t**2 * 4
    d.append(draw.Circle(0, y, 1, fill='lime'))
    return d
with draw.animate_jupyter(draw_frame, delay=0.05) as anim:
Or:
#with draw.animate_video('example6.gif', draw_frame, duration=0.05
) as anim:
# Add each frame to the animation
for i in range(20):
    anim.draw_frame(i/10)
for i in range(20):
    anim.draw_frame(i/10)
for i in range(20):
    anim.draw_frame(i/10)

Asynchronous Animation in Jupyter

# Jupyter cell 1:
import drawSvg as draw
from drawSvg.widgets import AsyncAnimation
widget = AsyncAnimation(fps=10)
widget
# [Animation is displayed here (click to pause)]

Jupyter cell 2:
global_variable = 'a'
@widget.set_draw_frame  # Animation above is automatically updated
def draw_frame(secs=0):
    # Draw something...
    d = draw.Drawing(100, 40)
    d.append(draw.Text(global_variable, 20, 0, 10))
    d.append(draw.Text('{:0.1f}'.format(secs), 20, 30, 10))
    return d
Jupyter cell 3:
global_variable = 'b'  # Animation above now displays 'b'