Python SVG converter creates empty file

Question

I have some code below that is supposed to convert a SVG image to a PNG. It runs without errors but creates a PNG file that is blank instead of one with the same image as the original SVG. I did find that it is not an error with cairo but more one relating to rsvg, which I got here.

import cairo
import rsvg

img = cairo.ImageSurface(cairo.FORMAT_ARGB32, 640,480)
ctx = cairo.Context(img)
handle= rsvghandler.Handle('example.svg')
handle.render_cairo(ctx)
img.write_to_png("svg.png")

I am using Python 3.6 on Windows 10.

I can't for the life of me figure out why it isn't displaying the correct picture. Any help would be hugely appreciated.

Lorianne

I tried to reproduce your issue, but I can't seem to install cairo. When running pip install cairo, I get Could not find a version that satisfies the requirement cairo (from versions: ). When running pip install pycairo, I get the error Package cairo was not found in the pkg-config search path.Perhaps you should add the directory containing 'cairo.pc' to the PKG_CONFIG_PATH environment variable. How did you get it? – Bondage

I installed cairo by downloading the Pycairo whl file at lfd.uci.edu/~gohlke/pythonlibs using pip install [wheelname] to install it. I don't remember which one worked for me, but I had to try a few before being able to install it correctly. – Lorianne

Answer 1

If your goal is to convert from SVG to PNG, I would recommend using Wand, as in the following script:

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=NAMEOFTHEFILE.read(), format="svg")
    png_image = image.make_blob("png32")

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

Farceuse

Thanks for the answer. The only issue is that I am using cairo so that I can convert the svg to a png and display the new image in a tkinter screen without saving it. Is there a way to do this with wand? – Lorianne

@Andoo I didn't see reference to that in your question. I would suggest that you maybe post a different question. But one way that you can do that is by using the file that you saved and open it in tkinter. Here you have an example of code to open in tkinter. – Pliers

I didn't realize that deleting the last two lines will prevent it from saving but still hold the PNG as a variable. I guess that is the answer to my other comment. Also, do you know any way of making my code work? (cairo is really fast) – Lorianne

How do I install ImageMagick? – Lorianne