Reputation: 2437
I am new to perl and cannot quite figure out how to solve this problem.
I have a variable which contains an SVG image in the form of an XML. I need to change the value of the tspan
tag in the SVG.
The code is as follows.
my $tempSvgImage =
qw~<?xml version="1.0" encoding="UTF-8" standalone="no" ?><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="3200" height="3200" xml:space="preserve">
<desc>Created with Fabric.js 1.4.0</desc>
<defs></defs>
<g transform="translate(482.36 1400) scale(8 8)">
<text font-family="Arial, Helvetica, sans-serif" font-size="50" font-style="normal" font-weight="normal" text-decoration="none" style="stroke: none; stroke-width: 1; stroke-dasharray: ; stroke-linecap: butt; stroke-linejoin: miter; stroke-miterlimit: 10; fill: #C9FA51; opacity: 1;" transform="translate(-40.3 49)">
<tspan x="0" y="-32.5" fill="#C9FA51">SampleCode</tspan>
</text>
</g>
</svg>~
In the above code I need to change the value of tspan
tag from Sample Code
to New value
. How am I supposed to do it?
Upvotes: 0
Views: 130
Reputation: 48619
From the XML::Simple docs:
The use of this module in new code is discouraged.
And in 2005, the author of a tutorial on XML::LibXML at perlmonks posted:
Also, XML::XPath is buggy and no-longer maintained so I don't recommend that.
Here it is with XML::LibXML:
use strict;
use warnings;
use 5.016;
use XML::LibXML;
my $dom = XML::LibXML->load_xml(string => <<'END_OF_XML');
<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="3200" height="3200" xml:space="preserve">
<desc>Created with Fabric.js 1.4.0</desc>
<defs></defs>
<g transform="translate(482.36 1400) scale(8 8)">
<text font-family="Arial, Helvetica, sans-serif" font-size="50" font-style="normal" font-weight="normal" text-decoration="none" style="stroke: none; stroke-width: 1; stroke-dasharray: ; stroke-linecap: butt; stroke-linejoin: miter; stroke-miterlimit: 10; fill: #C9FA51; opacity: 1;" transform="translate(-40.3 49)">
<tspan x="0" y="-32.5" fill="#C9FA51">SampleCode</tspan>
</text>
</g>
</svg>
END_OF_XML
#Deal with the namespace declared in the svg tag(explanation below):
my $xpc = XML::LibXML::XPathContext->new($dom);
$xpc->registerNs('ns', 'http://www.w3.org/2000/svg');
my ($tspan) = $xpc->findnodes('//ns:tspan');
#Change the tspan's text:
$tspan->removeChildNodes();
$tspan->appendTextNode("New data");
#Prove that the tspan's text changed:
say $tspan;
say $dom->toString;
All elements inside the svg tag have names of the form:
http://www.w3.org/2000/svg:tspan
|<----- namespace ------>|:tag name
...because of this directive:
<svg xmlns="http://www.w3.org/2000/svg"
That says that every tag name inside the <svg>
tag is prefixed by the namespace name:
http://www.w3.org/2000/svg
So the tspan's name is actually:
<http://www.w3.org/2000/svg:tspan ...>
Because names like that are too unwieldy to work with, you can alias the url:
$xpc->registerNs('ns', 'http://www.w3.org/2000/svg');
Then the name of the tspan tag in the perl code becomes:
ns:tspan
However, the XML::LibXML parser is intolerably slow--even for that short XML document(Edit: the DOCTYPE along with a slow connection is why it took my program ~5 seconds to complete. Removing the DOCTYPE solved that problem). So, here it is with XML::Twig:
use strict;
use warnings;
use 5.016;
use XML::Twig;
XML::Twig->new(
map_xmlns => {'http://www.w3.org/2000/svg' => "svg"},
twig_handlers => {
'svg:text/svg:tspan' => sub { $_->set_text('New Stuff') }
},
keep_original_prefix => 1,
pretty_print => 'indented',
)
->parse(<<'END_OF_XML')
<?xml version="1.0" encoding="UTF-8"?>
<my-root>
<text>
<tspan>Sample Code1</tspan>
</text>
<svg xmlns="http://www.w3.org/2000/svg" width="300px" height="200px">
<desc>Created with Fabric.js 1.4.0</desc>
<defs></defs>
<g transform="translate(482.36 1400) scale(8 8)">
<text font-family="Arial, Helvetica, sans-serif" font-size="50" font-style="normal" font-weight="normal" text-decoration="none" style="stroke: none; stroke-width: 1; stroke-dasharray: ; stroke-linecap: butt; stroke-linejoin: miter; stroke-miterlimit: 10; fill: #C9FA51; opacity: 1;" transform="translate(-40.3 49)">
<tspan x="0" y="-32.5" fill="#C9FA51">SampleCode2</tspan>
</text>
</g>
</svg>
</my-root>
END_OF_XML
->print;
Upvotes: 1