Component Classes of the Charts Library

A chart object is an instance of the IlvChartGraphic class or one of its derived classes in the Charts Library. (See Chart Classes for more details.)

Each component object used by a chart object to convert data into a graphical display corresponds to a dedicated object in the Charts Library as well.

A chart data object is an instance of a subclass of the IlvAbstractChartData class. The data sets managed by the chart data object are instances of subclasses of the IlvChartDataSet class. (See Data Classes for more details.)

When you create a chart object, an IlvMemoryChartData object is created by default as the chart data object used to manage the data sets for the chart.

Displayer objects are instances of subclasses of the IlvAbstractChartDisplayer class. They are used to draw the graphical representations of the data.

No displayer objects are created by default when you create a chart object. You have to create the displayers that you want to use to display your data and set them on the created chart.

A displayer object stores:

A pointer to the coordinate information associated with the ordinate scale it considers to display the data.

Scale displayer objects are instances of subclasses of the IlvAbstractScaleDisplayer class. They are used to draw the scales of a chart. The computation of the steps and substeps of a scale is performed by means of a scale steps updater object that is set on the scale. This object is an instance of a subclass of the IlvScaleStepsUpdater class.

No scale displayer objects are created by default in an IlvChartGraphic object since the type of the scales depends on the type of the object used to project the data into screen coordinates.

However, when you create:

an IlvCartesianChart object, two IlvRectangularScaleDisplayer objects are created by default: one to display the rectangular abscissa scale and one to display the rectangular ordinate scale.

an IlvPolarChart object, an IlvCircularScaleDisplayer object is created by default to display the circular abscissa scale and an IlvRectangularScaleDisplayer object is created by default to display the rectangular ordinate scale.

When a scale displayer object is created, an automatic scale steps updater object (instance of the IlvAutoScaleStepsUpdater class) is created by default and set on the scale.

The layout object must be an instance of the IlvChartLayout class or one of its derived classes. The layout object handles the computation of the chart layout and the computation of the data display area within the bounding box of the chart.

When you create a chart object, an IlvChartLayout object is created by default to compute the layout.

A projector object is an instance of a subclass of the IlvAbstractProjector class. It is used to project the data into screen coordinates.

No projector object is created by default in an IlvChartGraphic object since the type of projector used to project the data depends on the type of the coordinate system in which the displayed data are expressed.

However, when you create:

an IlvCartesianChart object, an IlvCartesianProjector object that projects data expressed in a Cartesian system of coordinates is created by default.

an IlvPolarChart object, an IlvPolarProjector object that projects data expressed in a polar system of coordinates is created by default.

The coordinate information objects must be instances of the IlvCoordinateInfo class or one of its derived classes. They are used to store specific information for each coordinate of the data that is represented by a scale.

No coordinate information objects are created by default in an IlvChartGraphic object because the scale displayers are not created at that level and a coordinate information object must be created for each coordinate that is represented by a scale.

However, two IlvCoordinateInfo objects are created by default in the IlvCartesianChart and IlvPolarChart objects: one associated with the abscissa scale and one associated with the ordinate scale that are created by default.

A coordinate information object stores:

The minimum and maximum values considered for the coordinate with which the coordinate information object is associated. These values are used to select the data to display and to specify the minimum and maximum values for the scale that represents this coordinate.

Optionally, a transformer object that specifies the transformation that will be applied to the coordinate. The transformer object must be an instance of a subclass of the IlvCoordinateTransformer class.

A legend object must be an instance of the IlvChartLegend class or one of its derived classes. It is used to display the legend corresponding to the chart displayed.

No legend object is created by default when you create a chart object. You have to create the legend object you want to be used and to set it on the created chart. (For information on how to create and set a legend object, see Adding the Legend.)