The Graph Component Hierarchy
The components that make up a graph in Gnumeric are arranged in a hierarchy with all the configurable options of the graph assigned as properties to one of the components in the hierarchy.
The hierarchy of graph component elements and the associated properties. In this case, the element 'X-Axis2' is selected.
In Gnumeric, Graphs are the top level element containing all the other components. Graphs have two properties related to the style of the background rectangular panel, its fill and its outline. Graphs can hold one or more titles and one or more charts.
Titles have the same properties related to their background rectangular panel, the fill and outline, have properties related to the text, the font type, style, and size, and have the text data that will be the title itself.
Charts have the same properties related to the background rectangular panel and can contain a number of other components including their own titles, a legend, plot accessories and plots.
Legends have the same properties related to their background rectangular panel and also have the properties related to the font in which the name of each series will be added to the legend, the font type, style, and size.
Certain plot types require accessory components such as the elements related to the creation of a Cartesian coordinate system. Charts which include one or more plots of this kind will have a Grid and may have X (horizontal) and Y (vertical) axes.
Grids are the background of Cartesian plots and have the properties determining the fill of this area and the line pattern displayed behind the plotted series.
Axes have properties related to the outer bounds of the axis, the style of the line drawn for the axis, the font style of the markers along the axis, detail properties of the tics and other markers on the axis, and the number format of the axis markers.
Axis labels share the same properties related to the style of their background rectangular panel, including the fill and outline properties, have properties related to the style of the font used for the text, including the font type, style and size, and the data contents of the text used to label the axis.
The properties of each type of plot, and of the data series they contain, vary depending on the actual type of the plot. For instance, the values of a data series which are plotted as a pie plot will not have any associated error values, whereas values plotted as columns could be associated to Y-error values and values plotted as an XY scatterplot could be associated with error values in both the X and the Y direction. Obviously, these different plot types will require different options. The options associated with each specific plot type will be discussed below, in Section 10.4 ― Configuring Graph Element Properties.