Grid Coordinate Mappers

Grid coordinate mappers are used in order to transform a grid layout of a graph into a real layout (which is represented by a layout interface). Each grid layout algorithm has a module option mapper, which determines the grid coordinate mapper used for the transformation of the grid layout.

AGD offers a collection of different grid coordinate mappers, each designed for specific purposes. The default is usually MaxAllMapper since it can be applied with all algorithms, i.e., it preserves angles, what is required by planar straight line algorithms. One disadvantage of MaxAllMapper is that it wastes a lot of space if the sizes of the nodes differ much from each other.

In this case, MaxEachMapper is the better choice. However, it does not preserve angles. It works best with orthogonal layout algorithms and MixedModelLayout.

The other two mappers, FixedGridMapper and FixedSizeMapper, are useful, when the actual size of rows and columns is given in advance, e.g., if you work in a graph editor with an enabled grid. The difference between both is that FixedGridMapper only enlarges nodes, whereas FixedSizeMapper can also make nodes smaller.