Convert SVG to PNG in Python

Question

How do I convert an svg to png, in Python? I am storing the svg in an instance of StringIO. Should I use the pyCairo library? How do I write that code?

Answer 1

Here is what I did using cairosvg:

from cairosvg import svg2png

svg_code = """
    <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#000" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
        <circle cx="12" cy="12" r="10"/>
        <line x1="12" y1="8" x2="12" y2="12"/>
        <line x1="12" y1="16" x2="12" y2="16"/>
    </svg>
"""

svg2png(bytestring=svg_code,write_to='output.png')

And it works like a charm!

See more: cairosvg document

Answer 2

The answer is "pyrsvg" - a Python binding for librsvg.

There is an Ubuntu python-rsvg package providing it. Searching Google for its name is poor because its source code seems to be contained inside the "gnome-python-desktop" Gnome project GIT repository.

I made a minimalist "hello world" that renders SVG to a cairo surface and writes it to disk:

import cairo
import rsvg

img = cairo.ImageSurface(cairo.FORMAT_ARGB32, 640,480)

ctx = cairo.Context(img)

## handle = rsvg.Handle(<svg filename>)
# or, for in memory SVG data:
handle= rsvg.Handle(None, str(<svg data>))

handle.render_cairo(ctx)

img.write_to_png("svg.png")

Update: as of 2014 the needed package for Fedora Linux distribution is: gnome-python2-rsvg. The above snippet listing still works as-is.

Answer 3

Install Inkscape and call it as command line:

${INKSCAPE_PATH} -z -f ${source_svg} -w ${width} -j -e ${dest_png}

You can also snap specific rectangular area only using parameter -j, e.g. co-ordinate "0:125:451:217"

${INKSCAPE_PATH} -z -f ${source_svg} -w ${width} -j -a ${coordinates} -e ${dest_png}

If you want to show only one object in the SVG file, you can specify the parameter -i with the object id that you have setup in the SVG. It hides everything else.

${INKSCAPE_PATH} -z -f ${source_svg} -w ${width} -i ${object} -j -a ${coordinates} -e ${dest_png}

Answer 4

I'm using Wand-py (an implementation of the Wand wrapper around ImageMagick) to import some pretty advanced SVGs and so far have seen great results! This is all the code it takes:

    with wand.image.Image( blob=svg_file.read(), format="svg" ) as image:
        png_image = image.make_blob("png")

I just discovered this today, and felt like it was worth sharing for anyone else who might straggle across this answer as it's been a while since most of these questions were answered.

NOTE: Technically in testing I discovered you don't even actually have to pass in the format parameter for ImageMagick, so with wand.image.Image( blob=svg_file.read() ) as image: was all that was really needed.

EDIT: From an attempted edit by qris, here's some helpful code that lets you use ImageMagick with an SVG that has a transparent background:

from wand.api import library
import wand.color
import wand.image

with wand.image.Image() as image:
    with wand.color.Color('transparent') as background_color:
        library.MagickSetBackgroundColor(image.wand, 
                                         background_color.resource) 
    image.read(blob=svg_file.read(), format="svg")
    png_image = image.make_blob("png32")

with open(output_filename, "wb") as out:
    out.write(png_image)

Answer 5

I did not find any of the answers satisfactory. All the mentioned libraries have some problem or the other like Cairo dropping support for python 3.6 (they dropped Python 2 support some 3 years ago!). Also, installing the mentioned libraries on the Mac was a pain.

Finally, I found the best solution was svglib + reportlab. Both installed without a hitch using pip and first call to convert from svg to png worked beautifully! Very happy with the solution.

Just 2 commands do the trick:

from svglib.svglib import svg2rlg
from reportlab.graphics import renderPM
drawing = svg2rlg("my.svg")
renderPM.drawToFile(drawing, "my.png", fmt="PNG")

Are there any limitations with these I should be aware of?

Answer 6

Try this: http://cairosvg.org/

The site says:

CairoSVG is written in pure python and only depends on Pycairo. It is known to work on Python 2.6 and 2.7.

Update November 25, 2016:

2.0.0 is a new major version, its changelog includes:

• Drop Python 2 support

Answer 7

Another solution I've just found here How to render a scaled SVG to a QImage?

from PySide.QtSvg import *
from PySide.QtGui import *


def convertSvgToPng(svgFilepath,pngFilepath,width):
    r=QSvgRenderer(svgFilepath)
    height=r.defaultSize().height()*width/r.defaultSize().width()
    i=QImage(width,height,QImage.Format_ARGB32)
    p=QPainter(i)
    r.render(p)
    i.save(pngFilepath)
    p.end()

PySide is easily installed from a binary package in Windows (and I use it for other things so is easy for me).

However, I noticed a few problems when converting country flags from Wikimedia, so perhaps not the most robust svg parser/renderer.

Answer 8

A little extension on the answer of jsbueno:

#!/usr/bin/env python

import cairo
import rsvg
from xml.dom import minidom


def convert_svg_to_png(svg_file, output_file):
    # Get the svg files content
    with open(svg_file) as f:
        svg_data = f.read()

    # Get the width / height inside of the SVG
    doc = minidom.parse(svg_file)
    width = int([path.getAttribute('width') for path
                 in doc.getElementsByTagName('svg')][0])
    height = int([path.getAttribute('height') for path
                  in doc.getElementsByTagName('svg')][0])
    doc.unlink()

    # create the png
    img = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
    ctx = cairo.Context(img)
    handler = rsvg.Handle(None, str(svg_data))
    handler.render_cairo(ctx)
    img.write_to_png(output_file)

if __name__ == '__main__':
    from argparse import ArgumentParser

    parser = ArgumentParser()

    parser.add_argument("-f", "--file", dest="svg_file",
                        help="SVG input file", metavar="FILE")
    parser.add_argument("-o", "--output", dest="output", default="svg.png",
                        help="PNG output file", metavar="FILE")
    args = parser.parse_args()

    convert_svg_to_png(args.svg_file, args.output)

Answer 9

Here is a another solution without using rsvg(which is currently not available for windows).Only install cairosvg using pip install CairoSVG

svg2png.py

from cairosvg import svg2png
svg_code = open("input.svg", 'rt').read()
svg2png(bytestring=svg_code,write_to='output.png')

Answer 10

Here is an approach where Inkscape is called by Python.

Note that it suppresses certain crufty output that Inkscape writes to the console (specifically, stderr and stdout) during normal error-free operation. The output is captured in two string variables, out and err.

import subprocess               # May want to use subprocess32 instead

cmd_list = [ '/full/path/to/inkscape', '-z', 
             '--export-png', '/path/to/output.png',
             '--export-width', 100,
             '--export-height', 100,
             '/path/to/input.svg' ]

# Invoke the command.  Divert output that normally goes to stdout or stderr.
p = subprocess.Popen( cmd_list, stdout=subprocess.PIPE, stderr=subprocess.PIPE )

# Below, < out > and < err > are strings or < None >, derived from stdout and stderr.
out, err = p.communicate()      # Waits for process to terminate

# Maybe do something with stdout output that is in < out >
# Maybe do something with stderr output that is in < err >

if p.returncode:
    raise Exception( 'Inkscape error: ' + (err or '?')  )

For example, when running a particular job on my Mac OS system, out ended up being:

Background RRGGBBAA: ffffff00
Area 0:0:339:339 exported to 100 x 100 pixels (72.4584 dpi)
Bitmap saved as: /path/to/output.png

(The input svg file had a size of 339 by 339 pixels.)

Answer 11

SVG scaling and PNG rendering

Using pycairo and librsvg I was able to achieve SVG scaling and rendering to a bitmap. Assuming your SVG is not exactly 256x256 pixels, the desired output, you can read in the SVG to a Cairo context using rsvg and then scale it and write to a PNG.

main.py

import cairo
import rsvg

width = 256
height = 256

svg = rsvg.Handle('cool.svg')
unscaled_width = svg.props.width
unscaled_height = svg.props.height

svg_surface = cairo.SVGSurface(None, width, height)
svg_context = cairo.Context(svg_surface)
svg_context.save()
svg_context.scale(width/unscaled_width, height/unscaled_height)
svg.render_cairo(svg_context)
svg_context.restore()

svg_surface.write_to_png('cool.png')

RSVG C binding

From the Cario website with some minor modification. Also a good example of how to call a C-library from Python

from ctypes import CDLL, POINTER, Structure, byref, util
from ctypes import c_bool, c_byte, c_void_p, c_int, c_double, c_uint32, c_char_p


class _PycairoContext(Structure):
    _fields_ = [("PyObject_HEAD", c_byte * object.__basicsize__),
                ("ctx", c_void_p),
                ("base", c_void_p)]


class _RsvgProps(Structure):
    _fields_ = [("width", c_int), ("height", c_int),
                ("em", c_double), ("ex", c_double)]


class _GError(Structure):
    _fields_ = [("domain", c_uint32), ("code", c_int), ("message", c_char_p)]


def _load_rsvg(rsvg_lib_path=None, gobject_lib_path=None):
    if rsvg_lib_path is None:
        rsvg_lib_path = util.find_library('rsvg-2')
    if gobject_lib_path is None:
        gobject_lib_path = util.find_library('gobject-2.0')
    l = CDLL(rsvg_lib_path)
    g = CDLL(gobject_lib_path)
    g.g_type_init()

    l.rsvg_handle_new_from_file.argtypes = [c_char_p, POINTER(POINTER(_GError))]
    l.rsvg_handle_new_from_file.restype = c_void_p
    l.rsvg_handle_render_cairo.argtypes = [c_void_p, c_void_p]
    l.rsvg_handle_render_cairo.restype = c_bool
    l.rsvg_handle_get_dimensions.argtypes = [c_void_p, POINTER(_RsvgProps)]

    return l


_librsvg = _load_rsvg()


class Handle(object):
    def __init__(self, path):
        lib = _librsvg
        err = POINTER(_GError)()
        self.handle = lib.rsvg_handle_new_from_file(path.encode(), byref(err))
        if self.handle is None:
            gerr = err.contents
            raise Exception(gerr.message)
        self.props = _RsvgProps()
        lib.rsvg_handle_get_dimensions(self.handle, byref(self.props))

    def get_dimension_data(self):
        svgDim = self.RsvgDimensionData()
        _librsvg.rsvg_handle_get_dimensions(self.handle, byref(svgDim))
        return (svgDim.width, svgDim.height)

    def render_cairo(self, ctx):
        """Returns True is drawing succeeded."""
        z = _PycairoContext.from_address(id(ctx))
        return _librsvg.rsvg_handle_render_cairo(self.handle, z.ctx)

Answer 12

Try this python script:

Don't forget to install cairosvg: pip3 install cairosvg

#!/usr/bin/env python3
import os
import cairosvg

for file in os.listdir('.'):
    if os.path.isfile(file) and file.endswith(".svg"):
        name = file.split('.svg')[0]
        cairosvg.svg2png(url=name+'.svg',write_to=name+'.png')

Answer 13

Try using Gtk.Image and Gdk.Pixbuf

import gi
gi.require_version('Gtk', '3.0')
gi.require_version('Gdk', '3.0')

from gi.repository import Gdk, Gtk
from PIL import Image

image = Gtk.Image()
image.set_from_file("path/to/image.svg")
pb = image.get_pixbuf()
pb.savev("path/to/convented/image.jpeg","jpeg",[],[])
im = Image.open("path/to/convented/image.jpeg")
pix = im.load()
print(pix[1,1])

Answer 14

Actually, I did not want to be dependent of anything else but Python (Cairo, Ink.., etc.) My requirements were to be as simple as possible, at most, a simple pip install "savior" would suffice, that's why any of those above didn't suit for me.

I came through this (going further than Stackoverflow on the research). https://www.tutorialexample.com/best-practice-to-python-convert-svg-to-png-with-svglib-python-tutorial/

Looks good, so far. So I share it in case anyone in the same situation.