Each MathML element can be viewed as a box that will be placed on the final SVG document. A box is represented by a minimum of six attributes that give information about its position and its size.
Attributes of a box
X, Y
Represent the two dimension coordinates of the upper left corner of the box.
WIDTH, HEIGHT
Represent the size of the box.
BASELINE
Represents the line on which the character will be aligned. Analogies can be made with the light guide lines on a lined sheet.
FONTSIZE
Determines the font size used in this box.
pMML2SVG works with the XML tree and transforms MathML to SVG in two passes. The first
pass, called formatting mode, anotates each node of the MathML tree with information about position
and size in order to compute a box. These annotations are placed as attributes on the node and belong to a temporary namespace named
t. A namespace is a family of XML tags and attributes defined in an XML schemas. The second
pass, named drawing mode, interprets annotations in order to draw the boxes on the SVG result canevas.
Some boxes need additionnal information to render correctly. For example, for the fraction, coordinates have to be added to place the fraction bar. Each element will describe which information is added to the tree and how it is handled.
An XSLT template is written for each MathML element and for each pass. It means that to implement a
MathML element, two templates have to be written. One for the formatting mode and one for the
drawing mode.
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