think-cell technical report TC2003/01 A GUI-based Interaction ...

4.1 A New Approach to Slide Layout INTERACTION CONCEPT
Another user request that was revealed by the field study (Chap. 2) cannot easily
be integrated into the smart grid concept: So-called stickers are visual elements
that appear on a couple of slides throughout a presentation, always in the same
size, position and style. In Solo [Axo] there is a feature called named objects that
explicitly supports this concept. It will be up to future work to represent the sticker
concept with the smart grid approach.
4.1.3 Implementing Esthetics by Rules
The argument for a substantial performance gain by computer supported layout
says, first, that it is easier and faster for the user to specify abstract layout intentions
as opposed to concrete pixel positions. Second, the argument assumes that the
translation from an abstract specification to a concrete layout can be done by an
automated process and third, that on a recent personal computer this process runs
fast enough to support the user interactively.
An abstract layout specification allows for a much faster input, because it carries
much less information than an exact, pixel-based specification. As a consequence,
an abstract specification typically is an underspecification of the desired outcome.
Just as in inter-human communication, the pure user input leaves room for am-
biguities that must be resolved. In inter-human communication, ambiguities are
resolved by supplementary input from other media, namely gestures and tone, and
by conventions. Conventions go a long way to resolve ambiguities in the literal infor-
mation, because by convention we have certain preconceptions about the meaning
of a piece of information depending on the situation, the relationship between the
speaker and the listener, and so forth.
Similarly, in computer supported layout conventions help to resolve ambiguities
in the user input. More technically speaking, the constraints implicitly given by
the smart grid and the constraints explicitly specified by the user are supplemented
with a collection of generic constraints that comprise conventions – or rules – about
esthetic layout and corporate design (see knowledge base in Fig. 11). Those generic
constraints bridge the gap between the abstract and underspecifying user input and
a concrete layout.
The actual definition of generic constraints must come from expert knowledge
as well as from studying a substantial set of sample slides. The constraints must
be weighted and the formulation of the constraints as well as their weights must be
carefully tuned to the constraint solving algorithm. Those details are beyond the
scope of my thesis, but to fortify the feasibility of the smart grid approach and to
give an impression of what conventions in computer supported layout may look like,
I propose some rules for this purpose. This listing of rules is certainly incomplete,
inaccurate and open to discussion.
• A slide consists of static objects such as headline and page number, and a set
of dynamic objects, the body.
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