10. A method comprising: analyzing drawing commands that describe a presentation of content for a two-dimensional document, the presentation of content having a fixed, graphical layout in a rendering of the two-dimensional document; identifying graphical content portions from the drawing commands, each graphical content portion having graphical dimensions and a two-dimensional graphical location in the rendering of the two-dimensional document; sorting the graphical content portions to generate a sort order by comparing relative graphical locations and graphical dimensions of each graphical content portion with graphical locations and graphical dimensions of at least one other graphical content portion; and generating an ordered tree structure of the graphical content portions based on the sort order, the ordered tree structure comprising a plurality of nodes, each node identifying one of the graphical content portions, the plurality of nodes arranged in the ordered tree structure such that an in-order traversal of each node of the ordered tree structure maintains the presentation order between the graphical content portions, that enables rendering of the graphical content portions in a non-fixed graphical layout in accordance with the presentation order based on the in-order traversal of each node of the ordered tree structure.
10. A method comprising: analyzing drawing commands that describe a presentation of content for a two-dimensional document, the presentation of content having a fixed, graphical layout in a rendering of the two-dimensional document; identifying graphical content portions from the drawing commands, each graphical content portion having graphical dimensions and a two-dimensional graphical location in the rendering of the two-dimensional document; sorting the graphical content portions to generate a sort order by comparing relative graphical locations and graphical dimensions of each graphical content portion with graphical locations and graphical dimensions of at least one other graphical content portion; and generating an ordered tree structure of the graphical content portions based on the sort order, the ordered tree structure comprising a plurality of nodes, each node identifying one of the graphical content portions, the plurality of nodes arranged in the ordered tree structure such that an in-order traversal of each node of the ordered tree structure maintains the presentation order between the graphical content portions, that enables rendering of the graphical content portions in a non-fixed graphical layout in accordance with the presentation order based on the in-order traversal of each node of the ordered tree structure. 11. The method of claim 10 , wherein generating the ordered tree structure of the graphical content portions includes: adding structural data to the graphical content portions.