CairoSVG

A work-in-progress fork of the vector graphics converter CairoSVG. It is intended to be a more modular version of the library, allowing its drawing functionality to be used directly from a script in addition to its original purpose of parsing and converting SVG files.

Other branches and related repositories:

• CairoSVG/master: for proposed changes to the original library
• Cairopath: my previous attempt at a vector graphics module

Features

• A class for each element, with methods for modifying attributes, adding child nodes and navigating the XML tree.
  • Currently supported elements: structures (svg, defs, g, use), shapes (circle, ellipse, line, path, polygon, polyline, rect), clipPath.
• Helper methods and classes for complex attributes like d (path data) and transform.
• Support for custom and redefined namespaces on the root element.
• Basic SVG file reading, output to SVG and formats supported by Cairo and OpenCV (PDF, PostScript, PNG, other image formats), and displaying the image in a popup window using OpenCV.

Todos

• A new name to avoid conflicts with the original library (suggestions are welcome!)
• Text nodes and elements, mask (included but not yet displaying correctly), gradients, markers, animation.
• CSS and style attributes.
• Custom shapes like regular polygons and stars, saved as a <path/> with custom namespace attributes (like e.g. Inkscape does).
• Not needing to have the whole tree in memory for files from disk.

Requirements

See requirements.txt for the necessary Python libraries. In addition, cairocffi needs a separate DLL file for Cairo itself, which must be named libcairo-2.dll and placed in a folder that is in the system's PATH.

Getting a working Cairo DLL can turn out to be a challenge, especially on Windows. The cairocffi documentation recommends installing GTK+, which includes Cairo. This worked for me when I first started working with it in 2018, but loading the DLL later failed in a new Anaconda environment on another device. I eventually found the cairo-windows repository, which has ZIP files with prebuilt 32- and 64-bit DLLs, and moved and renamed the DLL from the newest version (1.17.2) so cairocffi could find it.

Example

import math
from cairosvg import SVG

# Create an SVG object
svg = SVG(width=600, height=600)

# ...or load a file using
# svg = SVG.read('filename.svg')

# Add elements
svg.rect(width=600, height=600, fill='#fff')

g = svg.g()
g.transform.translate(300, 300)
g.circle(r=120, fill='#000')

# Draw a five-pointed star
path = g.path(fill='#fc0')
path.M(0, -100)
for i in range(1, 5):
	path.L(100*math.sin(i*4*math.pi/5), -100*math.cos(i*4*math.pi/5))
path.z()

# Display and save the image
svg.show()
svg.export('filename.svg')
svg.export('filename.png')