SVG rendering in a PyGame application

Question

In a pyGame application, I would like to render resolution-free GUI widgets described in SVG.

What tool and/or library can I use to reach this goal ?

(I like

Answer 1

You can use Cairo (with PyCairo), which has support for rendering SVGs. The PyGame webpage has a HOWTO for rendering into a buffer with a Cairo, and using that buffer directly with PyGame.

Answer 2

This is a complete example which combines hints by other people here. It should render a file called test.svg from the current directory. It was tested on Ubuntu 10.10, python-cairo 1.8.8, python-pygame 1.9.1, python-rsvg 2.30.0.

#!/usr/bin/python

import array
import math

import cairo
import pygame
import rsvg

WIDTH = 512
HEIGHT = 512

data = array.array('c', chr(0) * WIDTH * HEIGHT * 4)
surface = cairo.ImageSurface.create_for_data(
    data, cairo.FORMAT_ARGB32, WIDTH, HEIGHT, WIDTH * 4)

pygame.init()
window = pygame.display.set_mode((WIDTH, HEIGHT))
svg = rsvg.Handle(file="test.svg")
ctx = cairo.Context(surface)
svg.render_cairo(ctx)

screen = pygame.display.get_surface()
image = pygame.image.frombuffer(data.tostring(), (WIDTH, HEIGHT),"ARGB")
screen.blit(image, (0, 0)) 
pygame.display.flip() 

clock = pygame.time.Clock()
while True:
    clock.tick(15)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            raise SystemExit

Answer 3

Cairo cannot render SVG out of the box. It seems we have to use librsvg.

Just found those two pages:

• Rendering SVG with libRSVG,Python and c-types
• How to use librsvg from Python

Something like this should probably work (render test.svg to test.png):

import cairo
import rsvg

WIDTH, HEIGHT  = 256, 256
surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, WIDTH, HEIGHT)

ctx = cairo.Context (surface)

svg = rsvg.Handle(file="test.svg")
svg.render_cairo(ctx)

surface.write_to_png("test.png")

Answer 4

pynanosvg can be used to load and rasterize Vector Graphics (SVG) files. Install Cython and pynanosvg:

pip install Cython
pip install pynanosvg

The SVG file can be read, rasterized and loaded into a pygame.Surface object with the following function:

def load_svg(filename, scale=None, size=None, clip_from=None, fit_to=None, foramt='RGBA'):
    svg = Parser.parse_file(filename)
    scale = min((fit_to[0] / svg.width, fit_to[1] / svg.height)
                if fit_to else ([scale if scale else 1] * 2))
    width, height = size if size else (svg.width, svg.height)
    surf_size = round(width * scale), round(height * scale)
    buffer = Rasterizer().rasterize(svg, *surf_size, scale, *(clip_from if clip_from else 0, 0))
    return  pygame.image.frombuffer(buffer, surf_size, foramt)

See also svgsurf.py

---

Minimal example:

import pygame
from svg import Parser, Rasterizer

def load_svg(filename, scale=None, size=None, clip_from=None, fit_to=None, foramt='RGBA'):
    svg = Parser.parse_file(filename)
    scale = min((fit_to[0] / svg.width, fit_to[1] / svg.height)
                if fit_to else ([scale if scale else 1] * 2))
    width, height = size if size else (svg.width, svg.height)
    surf_size = round(width * scale), round(height * scale)
    buffer = Rasterizer().rasterize(svg, *surf_size, scale, *(clip_from if clip_from else 0, 0))
    return  pygame.image.frombuffer(buffer, surf_size, foramt)

pygame.init()
window = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()

pygameSurface = load_svg('Ice.svg', fit_to = (window.get_width()*3//4, window.get_height()))

run = True
while run:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False

    window.fill((127, 127, 127))
    window.blit(pygameSurface, pygameSurface.get_rect(center = window.get_rect().center))
    pygame.display.flip()

pygame.quit()
exit()

Answer 5

I realise this doesn't exactly answer your question, but there's a library called Squirtle that will render SVG files using either Pyglet or PyOpenGL.

Answer 6

Based on other answers, here's a function to read a SVG file into a pygame image - including correcting color channel order and scaling:

def pygame_svg( svg_file, scale=1 ):
    svg = rsvg.Handle(file=svg_file)
    width, height= map(svg.get_property, ("width", "height"))
    width*=scale; height*=scale
    data = array.array('c', chr(0) * width * height * 4)
    surface = cairo.ImageSurface.create_for_data( data, cairo.FORMAT_ARGB32, width, height, width*4)
    ctx = cairo.Context(surface)
    ctx.scale(scale, scale)
    svg.render_cairo(ctx)

    #seemingly, cairo and pygame expect channels in a different order...
    #if colors/alpha are funny, mess with the next lines
    import numpy
    data= numpy.fromstring(data, dtype='uint8')
    data.shape= (height, width, 4)
    c= data.copy()
    data[::,::,0]=c[::,::,1]
    data[::,::,1]=c[::,::,0]
    data[::,::,2]=c[::,::,3]
    data[::,::,3]=c[::,::,2]

    image = pygame.image.frombuffer(data.tostring(), (width, height),"ARGB")
    return image