2007/10/30, Boris.Gaertner Boris.Gaertner@gmx.net:
I ran into a problem when I tried to process the svg example files that come with the SVG specification from W3C
The following is valid xml and even a valid SVG (Scalable Vector Graphics) file.
<?xml version="1.0" standalone="no"?>
<svg width="10cm" height="3cm" viewBox="0 0 1000 300" xmlns="http://www.w3.org/2000/svg">
<text x="200" y="150" fill="blue" font-family="Verdana" font-size="45"> Text with <tspan fill="red" >read</tspan> and <tspan fill="green">green</tspan> text spans </text></svg>
(This code draws one line of blue text, the words 'red' and 'green' are displayed in red and in green. The tspan elements are used to encode text adornment. Try a newer release of Mozilla Firefox to render this svg file. Note also that some xml readers expect a DOCTYPE specification. A suitable DOCTYPE specification for svg is
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20010904//EN" "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
)
The text element is a mixed contents element (in XML terminology, see section 3.2.2 of the XML reference from Oct 2000), it contains three #PCDATA items and two child elementrs (The tspan elements).
When we parse this piece of xml with XMLDOMParser, the text element is translated into an instance of XMLElement with the following values of its more important instance variables:
name = 'text' element an OrderedCollection with two XMLElements, one for each tspan item contents an OrderedCollection with the three instances of XMLStringNode for the strings 'Text with ', 'and', 'text spans'. attributes a Dictionary with 5 elements.
The problem here is that this XMLElement does not contain information about the sequence of the strings and the text spans. This is however a very important information when you want to render a svg text element. I really think that it is an error to put #PCDATA and child elements into separate collections.
For now, I changed XMLDOMParser>>characters from
characters: aString | newElement | newElement _ XMLStringNode string: aString. self top addContent: newElement.
to
characters: aString | newElement | newElement _ XMLStringNode string: aString. self top addElement: newElement.
With that change, I put all substructures into the 'elements' collection; the 'contents' collection becomes obsolete.
This solves my problem with decorated svg text but my change will certainly break a lot of other applications that use the XMLDOMParser.
My questions:
- what is your experience with xml elements that have mixed contents?
They're broken Yaxo. The other Yaxo bug I know of is: http://bugs.squeak.org/view.php?id=3082
Cheers Philippe
- what do you think should be done with svg text like the one of my example?
Any comments are welcome.
Greetings Boris