Inkscape module to generate SVG drawings with Python
As a new freelancer, I decided to create my own business cards using moo services. This website allow you to create collectors business cards. The principle is simple, you can upload one image per card so the Verso of the card will be different each time.
My problem : How to create a business card that match my website layout and make it uniq at the same time ?
This is when Python and Inkscape came to rescue me. Inkscape is a well know (GPL’ed) SVG graphic editor. If you have never tried it, consider doing it. It is amazing what this soft can produce within a couple of minutes. Beside Inkscape, the website commandlinfu.com is a (cool) website providing Unix Commands and explanations of what they do (be careful some commands may be dangerous or invalid though).
So I had an idea. Why not using the website commandlinefu, extract commands from the RSS feed and generate images for my Collector Business cards ?
How ?
Inkscape support plugins and offer a nice python module to help you to create SVG objects.
Let’s go !
Inkscape expect a couple of things from the module structure.
#!/usr/bin/env python
# These two lines are only needed if you don't put the script directly into
# the installation directory
import sys
from xml.dom import minidom
import urllib
import re
# This import is for MAc os X only. In GNU systems it should
# be somewhere in /usr/share/inkscape/extensions
sys.path.append('/Applications/Inkscape.app/Contents/Resources/extensions')
# We will use the inkex module with the predefined Effect base class.
import inkex
# The simplestyle module provides functions for style parsing.
from simplestyle import *
class BusinessCard(inkex.Effect)
"""
Example Inkscape effect extension. It reads an RSS feed and create objects according to the content.
"""
def __init__(self):
"""
Constructor.
Defines the "--what" option of a script.
"""
# Call the base class constructor.
inkex.Effect.__init__(self)
# Define string option "--what" with "-w" shortcut and default value "World".
self.OptionParser.add_option('-w', '--what', action = 'store',
type = 'integer', dest = 'cards_number', default = '10',
help = 'How many images do you want to create?')
The optionparser is required by Inkscape as it will pass some arguments to the script. We could, for example use this argument to know how many images we want to generate. In our case, the argument will be stored in the variable call cards_number. I let you have a closer look to this Wiki Page for any further explanation.
Now that we have the basis for creating an Inkscape plugin, we should define the main actions that this plugin is gonna do:
- Read the RSS feed
- Extract the usefull information (and filter)
- Create the SVG objects
- Add them to the SVG Layer
- Loop to 1
Let’s use Python wonderful XML parser to read our RSS feed
# Open the XML ressource and read it
socket = urllib.urlopen("http://feeds2.feedburner.com/Command-line-fu?format=xml");
# Create an object representing the XML structure
self.xmldoc = minidom.parse(socket).documentElement
socket.close();
Create the function that will do the loop
def effect(self):
"""
Effect behaviour.
Overrides base class' method and inserts "Hello World" text into SVG document.
"""
# Get script's "--what" option value.
cards_number = self.options.cards_number
# Get access to main SVG document element and get its dimensions.
svg = self.document.getroot()
# Create a new layer.
layer = inkex.etree.SubElement(svg, 'g')
layer.set(inkex.addNS('label', 'inkscape'), 'Hello %s Layer' % (what))
layer.set(inkex.addNS('groupmode', 'inkscape'), 'layer')
# Create text element from the RSS feed
itemlist = self.xmldoc.getElementsByTagName('item')
#we will loop so better initialize variables
item_x = 0
item_y = 0
# in the RSS feed, the iformation we want in contained in between
# the <code></code> markup. Let's use a regexp to get it.
regexp = re.compile('<code>.*</code>');
# Note that here, we should use the cards_number instead of reading
# the complete rss feed.
for node in itemlist:
title = node.getElementsByTagName('title')[0].firstChild.data
command = regexp.search(node.getElementsByTagName('description')[0].firstChild.data)
# Get ride of the markup
command = command.group()
command = command.replace("<code>", "");
command = command.replace("</code>", "");
# filter in case the comman is too long...
if len(command) > 40:
continue
Ok so now we have to start creating the objects. For this, Inkscape offer us a nice way to do it. Use the inkex extension. the function inkex.addNS is usefull to create everything you need in SVG.
#Design the background grey business card
background = inkex.etree.Element(inkex.addNS('rect', 'svg'))
background.set('x', str(item_x))
background.set('y', str(item_y))
background.set('width', str(520))
background.set('height', str(348))
background.set('fill', 'rgb(32, 32, 32)')
#Our lovely ornge square will fit here
square = inkex.etree.Element(inkex.addNS('rect', 'svg'))
square.set('x', str(item_x + 30))
square.set('y', str(item_y + 30))
square.set('width', str(84))
square.set('height', str(84))
square.set('rx', str(20))
square.set('ry', str(20))
square.set('fill', 'rgb(224, 121, 26)')
#Insert the "K" letter. K stands for Kolios
K_logo = inkex.etree.Element(inkex.addNS('text','svg'))
K_logo.text = ("K")
# Set text position to center of document.
K_logo.set('x', str(item_x + 61))
K_logo.set('y', str(item_y + 95))
K_logo.set('fill', "white")
# Center text horizontally with CSS style.
style = {'text-align' : 'left',
'font-family': 'MammaGamma',
'font-size': '56'
}
K_logo.set('style', formatStyle(style))
#Insert the Unix Tip
tip = inkex.etree.Element(inkex.addNS('text','svg'))
tip.text = (title)
# Set text position to center of document.
tip.set('x', str(item_x + 40))
tip.set('y', str(item_y + 200))
tip.set('fill', 'rgb(170, 170, 170)')
# Center text horizontally with CSS style.
style = {'text-align' : 'left',
'font-family': 'terminal',
'font-style': 'italic'
}
tip.set('style', formatStyle(style))
#Insert the Unix Command
unix = inkex.etree.Element(inkex.addNS('text','svg'))
unix.text = (command)
# Set text position to center of document.
unix.set('x', str(item_x + 30))
unix.set('y', str(item_y + 180))
unix.set('fill', 'rgb(224, 121, 26)')
# Center text horizontally with CSS style.
style = {'text-align' : 'left',
'font-family': 'Monaco',
'font-size': '20'
}
unix.set('style', formatStyle(style))
# Connect elements together.
layer.append(background)
layer.append(square)
layer.append(K_logo)
layer.append(kolios)
layer.append(slogan)
layer.append(unix)
layer.append(tip)
item_y = item_y + 360
# Create effect instance and apply it.
effect = BusinessCard()
effect.affect()
You can notice that we use css-style for the text. This is possible with the use of the module simplestyle.
Basically, you create an object and THEN add it to the layer. Pay attention that the order you add objects MATTERS for the rendering depth. In this case the background will be rendered first, then the square… and so on. All type of objects can be created and the entire list is available at the W3c webpage.
But how do I add my plugin to Inkscape ?
Well, last thing but not the least. You python script should be placed in .inkscape/extensions with a description file
<inkscape-extension>
<_name>Business Card</_name>
<id>org.ekips.filter.business_card</id>
<dependency type="executable" location="extensions">card.py</dependency>
<dependency type="executable" location="extensions">inkex.py</dependency>
<param name="what" type="integer" _gui-text="How many business cards ?">10</param>
<effect>
<object-type>all</object-type>
<effects-menu>
<submenu _name="Examples"/>
</effects-menu>
</effect>
<script>
<command reldir="extensions" interpreter="python">card.py</command>
</script>
</inkscape-extension>
The file should be named with a .inx extension. I won’t explain this as this is pretty obvious.
At last, you can take a llok at the final output. The first picture is NOT generated but … it gives a good example.
