To print a diagram: open the diagram you want to print, make sure it has the focus by pressing its editor tab, then press the Eclipse print button
on the toolbar. A print dialog, the exact format of which depends upon your operating system, will appear prompting you for information such as the number of copies to print, and which printer to send them to.
The diagram is split into pages, printed at a zoom matching the screen dimensions at 100% magnification. Pages are printed by-row; ie page 1 is at row 1 column 1, page 2 is at row 1 column 2 etc.

The Diagram Controls view offers additional controls for printing.

The scale factor of the print output can be selected directly, or automatically by selecting the number of pages.
Show Page Boundaries: selecting this option causes a grid of red lines corresponding to page boundaries to be drawn in the diagram editor, allowing the number of pages which will be required to be viewed before printing.