svglue

svglue is a small library that takes a template in form of a specially prepared SVG document and fills in text and images to create an output SVG file. Style information like opacity, size, and ordering is kept.

It's mainly intended to be used to set up a nice workflow creating templates for PDF generation:

1. Create your template in Inkscape, a placeholder text-element where you want to fill in text later, or a rectangle for filling in images.
2. Add a custom attribute template-id to every <tspan> or <rect> element that you want to replace. Each template-id must be a unique identifier.
3. Using svglue, you can programmatically replace every text or rect using its template-id with either a raster image, another SVG graphic or replacement text.
4. Finally, use something like rsvg, CairoSVG or another SVG-renderer to create a PDF document.

Example code:

Step 3:

#!/usr/bin/env python

import svglue


# load the template from a file
tpl = svglue.load(file='sample-tpl.svg')

# replace some text
tpl.set_text('sample-text', u'This was replaced.')

# replace the pink box with 'hello.png'. if you do not specify the mimetype,
# the image will get linked instead of embedded
tpl.set_image('pink-box', file='hello.png', mimetype='image/png')

# svgs are merged into the svg document (i.e. always embedded)
tpl.set_svg('yellow-box', file='Ghostscript_Tiger.svg')

# to render the template, cast it to a string. this also allows passing it
# as a parameter to set_svg() of another template
src = str(tpl)

# write out the result as an SVG image and render it to pdf using cairosvg
import cairosvg
with open('output.pdf', 'w') as out, open('output.svg', 'w') as svgout:
    svgout.write(src)
    cairosvg.svg2pdf(bytestring=src, write_to=out)

It's important to note that versions <= 0.5 of cairosvg have a bug that renders the tiger scaled incorrectly. For now, you can use a different renderer for better results until that bug is fixed.

Installation

svglue is available via PyPI, so a simple pip install svglue should suffice to install.

API reference

Note that the main target for this library is Python3. The later versions of cairosvg do not compile on Python2 anymore for me.

If you need Python2 support, restrict the version of svglue to <=0.2.1.

svglue.load(src=None, file=None)

Loads a template, returning a Template-object. The src/file load pattern is used through the library - src is a string containing the source of the SVG file, or file can either be a file-like object (with a read() method) or a filename for the source file. Only one of src/file may be specified.

Template.set_text(tid, text)

Replaces the text inside the element <tspan id="tid"> (whose id is the actual tid) with the specified text.

Template.set_image(tid, src=None, file=None, mimetype=None)

Replaces a rectangle whose id is tid (<rect id="tid">) with an <image> tag to link/embed the specified image. If mimetype is None, the image is linked (so file should be the path/URI of thte image).

If mimetype is given (should be either image/png or image/jpeg), the supplied image is stored inline in the resulting SVG document.

Template.set_svg(tid, src=None, file=None)

Conceptually similiar to Template.set_image(), this replaces a rectangle with an SVG-image. However, no linking is supported, the SVG is copied into the resulting SVG-documents <defs>-section and a <use>-Element replaces the rectangle.

Since Template.__str__() (see below) is used to render templates, this allows nesting templates by simply passing them as the second argument to set_svg().

Template.__str__()

Renders the template. Returns the template with all supplied info filled in.