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When rasterizing svg file, I would like to be able to set width and height for the resulting png file. With the following code, only the canvas is set to the desired width and height, the actual image content with the original svg file dimension is rendered in the top left corner on the (500, 600) canvas.

import cairo
import rsvg
WIDTH, HEIGHT  = 500, 600
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")
What should I do to make the image content same size with cairo canvas? I tried
svg.set_property('width', 500)
svg.set_property('height', 500)
but got
TypeError: property 'width' is not writable
Also documents for librsvg python binding seem to be extremely rare, only some random code snippets on cairo site.
There is a resize function in librsvg, but it is deprecated.
Set up a scale matrix in Cairo to change the size of your drawing:
setup a scale transformation matrix on your cairo context
draw your SVG with the .render_cairo() method
write your surface to PNG
                Will rescaling the already rasterized image result in data loss of the original vector image?
– btw0
                Jul 27, 2009 at 11:19
                The cairo transformation matrix operates on vector data drawed after setting it. You don't scale the rasterized image but the commands issued by librsvg that produce it.
– Luper Rouch
                Jul 27, 2009 at 12:07
                Care to post a code snippet? Documentation you linked is for C, the Python equivalent syntax is not obvious, specially when dealing with matrices and transforms. Also, scaling seems to be always by a factor, not directly to (x, y) dimension rescale
– MestreLion
                Aug 15, 2014 at 8:15
# Scale whatever is written into this context
# in this case 2x both x and y directions
ctx.scale(2, 2)
svg.render_cairo(ctx)
# Write out into a PNG file
png_io = StringIO.StringIO()
img.write_to_png(png_io)    
with open('sample.png', 'wb') as fout:
    fout.write(png_io.getvalue())
Resizing svg files programmatically is not obvious.  The solution provided here by other answers may be outdated/difficult to implement. I'm using another library svgutils.
The following should work.
import svgutils.transform as sg
import sys
fig = sg.fromfile('myimage.svg')
fig.set_size(('200','200'))
fig.save('myimage2.svg')
You can install svgutils with usual -
pip install svgutils
Once you have properly resized svg file, you can use ffmpeg or any other image converter to save it into png.
        
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