Sketching Slides: interactive creation and automatic solution of constrained document layout problems

The efficiency of desktop publishing is severely limited by the lack of sophisticated automatic document layout systems. State-of-the-art algorithms either require the input to be written in a description language such as HTML and LATEX, or to be a manually designed layout template. However, description languages are ill-suited to express layout problems with weak semantics and layout templates shift the burden from the end user to the template designer. This thesis defines a general layout problem with linear constraints in simple geometric terms. This problem definition encompasses many wellresearched layout problems, including table layout problems, yellow page layout problems, and many user interface layout problems. The first contribution of this thesis is an algorithm that solves this general class of layout problems by treating them as equitable resource allocation problems. The available document area is a resource that is distributed among inter-element gaps. The layout problem is transformed into a lexicographic min-ordering optimization problem that is solved using linear programming techniques in real-time. User-generated input problems are frequently overor under-constrained. If the layout problem is over-constrained, the quality of the solution layout degrades gracefully. The layout algorithm finds the solution layout with the most equitable distribution of constraint errors among the soft layout constraints, i.e., the solution closest to the user’s original intent. Conversely, the layout algorithm detects the underconstrained subproblems that adversely affect the solution layout. It adds the minimal number of constraints required to achieve the fully specified layout problem that is closest to the user’s input. The second contribution of this thesis is the creation of an intuitive direct manipulation user interface that lets users create the aforementioned class of general constrained layout problems. It hides the complexity of the constraint system and avoids the usability problems that have plagued constraint drawing applications. It eliminates the need of document description languages and manually-created layout templates. The layout algorithm and the user interface have been implemented in our ICBM system. In the evaluation, we show that the best state-of-the-art specialized table layout algorithms do not outperform the general ICBM layout algorithm by any significant margin.