Mobile eBook readers are now commonplace in today's society, but their document layout algorithms remain basic, largely due to constraints imposed by short battery life. At present, with any eBook file format not based on PDF, the layout of the document, as it appears to the end user, is at the mercy of hidden reformatting and reflow algorithms interacting with the screen parameters of the device on which the document is rendered. Very little control is provided to the publisher or author, beyond some basic formatting options.This paper describes a method of producing well-typeset, scalable, document layouts by embedding several pre-rendered versions of a document within one file, thus enabling many computationally expensive steps (e.g. hyphenation and line-breaking) to be carried out at document compilation time, rather than at 'view time'. This system has the advantage that end users are not constrained to a single, arbitrarily chosen view of the document, nor are they subjected to reading a poorly typeset version rendered on the fly. Instead, the device can choose a layout appropriate to its screen size and the end user's choice of zoom level, and the author and publisher can have fine-grained control over all layouts.

Implementations of eBooks have existed in one form or another for at least the past 20 years, but it is only in the past 5 years that dedicated eBook hardware has become a mass-market item.New screen technologies, such as e-paper, provide a reading experience similar to those of physical books, and even backlit LCD and OLED displays are beginning to have high enough pixel densities to render text crisply at small point sizes. Despite this, the major element of the physical book that has not yet made the transition to the eBook is high-quality typesetting.The great advantage of eBooks is that the presentation of the page can adapt, at rendering time, to the physical screen size and to the reading preferences of the user. Until now, simple first-fit linebreaking algorithms have had to be used in order to give acceptable rendering speed whilst conserving battery life. This paper describes a system for producing well-typeset, scalable document layouts for eBook readers, without the computational overhead normally associated with better-quality typesetting. We precompute many of the complex parts of the typesetting process, and perform the majority of the 'heavy lifting' at document compile-time, rather than at rendering time. Support is provided for floats (such as figures in an academic paper, or illustrations in a novel), for arbitrary screen sizes, and also for arbitrary point-size changes within the text.