  Grid layouts are used by designers to spatially organise user interfaces when
sketching and wireframing. However, their design is largely time consuming
manual work. This is challenging due to combinatorial explosion and complex
objectives, such as alignment, balance, and expectations regarding positions.
This paper proposes a novel optimisation approach for the generation of diverse
grid-based layouts. Our mixed integer linear programming (MILP) model offers a
rigorous yet efficient method for grid generation that ensures packing,
alignment, grouping, and preferential positioning of elements. Further, we
present techniques for interactive diversification, enhancement, and completion
of grid layouts (Figure 1). These capabilities are demonstrated using GRIDS1, a
wireframing tool that provides designers with real-time layout suggestions. We
report findings from a ratings study (N = 13) and a design study (N = 16),
lending evidence for the benefit of computational grid generation during early
stages of design.
