Visualization customization

A non-transitory computer-readable storage medium having computer-executable instructions stored thereon that are executable by a processor device to perform or control performance of operations comprising:

• generating a semantic layout of a visualization based on a contract associated with a visualization type, the semantic layout specifying one or more of relative locations, arrangement, and relationships of a plurality of data objects to represent in the visualization, the plurality of data objects including at least some data of a data source;
• receiving input effective to alter a set of one or more graphical objects to display for each of some but not all of the plurality of data objects from a default set of one or more graphical objects to a custom set of one or more graphical objects, wherein the default set is different than the custom set;
• generating a concrete layout of the visualization that specifies the set of one or more graphical objects to display for each of the plurality of data objects, wherein the concrete layout specifies the default set for a first data object of the plurality of data objects and the custom set for a second data object of the plurality of data objects;
• and
• displaying the visualization of the at least some data of the data source based on the contract, the semantic layout, and the concrete layout, the visualization having the visualization type.