LineChartModel: Plot Markers

By default, plot markers are disabled and an interpolated line that joins plot points is displayed. To display plot markers instead of an interpolation line, use the LineChartModel to

A LineChartModel can modify plot markers by

As an alternative to using these techniques for changing plot markers, a variable role in a LineChartTableDataModel can be used to control the markers according to the values of a data column in the graph's data source.

Assigning a MarkerStyle

To use the MarkerStyle class to set plot marker attributes (color, visibility, symbol, size),

  1. create a MarkerStyle array with the desired properties
  2. call the LineChartModel's getDataElementStyles() method to retrieve the DataElementStyles that encapsulate the visual properties of the plot markers
  3. call the DataElementStyles' setMarkerStyles() method to assign the defined MarkerStyle to the plot.

For example, the following code fragment specifies a filled square as the marker shape: 

 
LineChartModel graphModel=lineChart.getGraphModel();
MarkerStyle[] markerStyle=new MarkerStyle[] {
              new MarkerStyle(MarkerStyle.SYMBOL_SQUARE_FILLED)};
graphModel.getDataElementStyles().setMarkerStyles(markerStyle);

Example
Changing Markers in a Line Chart: Swing-based code, Servlet-based code

Hiding Plot Markers

To hide plot markers, call the LineChartModel's setMarkerEnabled() method with the argument value false.

LineChartModel: Display Properties

In addition to changing the markers, the LineChartModel can be used to change other general display properties, as shown in the following example: 


javax.swing.table.TableModel tableModel = <...>;  // some TableModel data
LineChartTableDataModel dataModel = new LineChartTableDataModel(tableModel);
GraphStyle graphStyle = new GraphStyle(GraphStyle.STYLE_SCIENCE);

// Get a LineChart
   LineChart lineChart = new LineChart(dataModel,graphStyle);

// Set a title
   lineChart.getTitle1().setText("Sample LineChart");

// Get the LineChart's graphModel
   LineChartModel lineChartModel = lineChart.getGraphModel();

// Change the bar outline color
   lineChartModel.getDataElementStyles().getOutlineLineStyle().setColor(Color.blue);

// Define a new set of solid fills for the bar elements to be 
// The colors of a rainbow:  red, orange, yellow, blue, green, indigo, violet
   StrokeLineStyle[] lineStyles = new StrokeLineStyle[] {
      new StrokeLineStyle(Color.red)
    , new StrokeLineStyle(Color.orange)
    , new StrokeLineStyle(Color.yellow)
    , new StrokeLineStyle(Color.blue)
    , new StrokeLineStyle(Color.green)
    , new StrokeLineStyle(new Color(75, 0, 130))
    , new StrokeLineStyle(new Color(238, 130, 238))
   };
// Set the fill styles to be used by the bar elements
   lineChartModel.getDataElementStyles().setLineStyles(lineStyles); 
   lineChartModel.getDataElementStyles().getOutlineLineStyle().setColor(Color.darkGray);

// set some response-axis text properties
   lineChartModel.getResponseAxisModel().getLabelTextStyle().setFont(new Font("TimesRoman",Font.BOLD,18));
   lineChartModel.getResponseAxisModel().getValueTextStyle().setFont(new Font("TimesRoman",Font.BOLD,14));
   lineChartModel.getResponseAxisModel().getValueTextStyle().setColor(Color.darkGray);

Rather than changing individual properties, it may be easier to use the LineChart to set a graph style, which makes it easier to manage multiple display properties.

LineChartModel: Interpolation Lines

By default for a LineChartModel, plot markers are displayed and plot points are connected with an interpolated line that uses the MarkerStyle.INTERPOLATION_STRAIGHT interpolation method. You can disable the interpolation so that the plot just displays plot markers, or you can change the interpolation method.

The sort order for connecting plot points with an interpolated line is always the sort order of values along the Category axis. Thus, the interpolation line for a single plot cannot change direction and cross over itself. A LineChartTableDataModel's CategorySortVariable role can be used to base the sorting order on the values of a variable in the data.

Disabling Interpolation

To disable interpolation, call the setInterpolationEnabled() method with the argument value false. Because plot markers are disabled by default, you must also display plot markers by calling the setMarkerEnabled() method with the argument value true: 

 
LineChartModel graphModel = lineChart.getGraphModel();
graphModel.setInterpolationEnabled(false);
graphModel.setMarkerEnabled(true);

Specifying an Interpolation Method

To set an interpolation method when interpolation is enabled, use the plot's DataElementStyles to get the array of MarkerStyles, and then use a MarkerStyle element to set an interpolation value on the setInterpolation() method. The following code fragment sets a step-right interpolation: 

 
LineChartModel graphModel=lineChart.getGraphModel();
DataElementStyles des=graphModel.getDataElementStyles();
MarkerStyle[] markerStyles=des.getMarkerStyles();
markerStyles[0].setInterpolation(MarkerStyle.INTERPOLATION_STEP_RIGHT);

Example
Change the Interpolation Method: Swing-based code, Servlet-based code

LineChartModel: Line Styles

A LineChartModel can be used to modify the line style (color, width, visibility, ...) of any of the various lines in a LineChart.

The following table shows the lines you can set and the method(s) to call to access and/or set the line attributes.

To change ... Call ...
marker outlines getDataElementStyles().setOutlineLineStyle(LineStyle)
plot line(s) getDataElementStyles().setLineStyles(StrokeLineStyle[] )
category axis lines
(axis, grid, tick, and reference lines) 		getCategoryAxisModel() and use the returned AxisModel to set axis line style, grid line styles, major tick styles, minor tick styles, and reference line models
response (left) axis lines
(axis, grid, tick, and reference lines) 		getResponseAxisModel() and use the returned AxisModel to set axis line style, grid line styles, major tick styles, minor tick styles, and reference line models
response2 (right) axis lines
(axis, grid, tick, and reference lines) 		getResponse2AxisModel() and use the returned AxisModel to set axis line style, grid line styles, major tick styles, minor tick styles, and reference line models
legend frame getLegendModel().setFrameLineStyle(LineStyle)
missing-values lines getDataElementStyles().setMissingLineStyle(StrokeLineStyle)
column axis lines
(available when ColumnVariable role is used)		 getColumnAxisModel().setFrameLineStyle(LineStyle)
row axis lines
(available when RowVariable role is used)		 getRowAxisModel().setFrameLineStyle(LineStyle)
frame lines around column/row cells
(available when ColumnVariable and/or RowVariable roles are used)		 setFrameLineStyle(LineStyle)

The following code fragment specifies a 3-point blue dashed line for a plot line: 


LineChartModel graphModel=lineChart.getGraphModel();

StrokeLineStyle[] lineStyles=new StrokeLineStyle[] {
                  new StrokeLineStyle(StrokeLineStyle.SASGRAPH_LINE03,
                  java.awt.Color.blue,
                  new com.sas.measures.BaseLength(3, "pt"),
                  com.sas.components.GraphConstants.TRUE) };

graphModel.getDataElementStyles().setLineStyles(lineStyles);

Example
Changing Line Style: Swing-based code
Changing the Axes: Swing-based code

LineChartModel: Filled Areas

When the specifications on the data model generate multiple plot lines, the areas between the lines can be filled by calling the LineChartModel's setFillAreaEnabled() method with the argument value true.

A unique FillStyle is used to fill the area under each plot. To change the fill styles, use the plot's DataElementStyles to set an alternative FillStyle array. The following code fragment creates transparent fills and then assigns them to the plot areas: 

 
LineChartModel graphModel=lineChart.getGraphModel();
graphModel.setFillAreaEnabled(true);

// Creates new FillStyles. The fourth argument on the
// java.awt.Color constructors is the transparency level
FillStyle[] transparencies=new FillStyle[] {
  new FillStyle(new Color(204,0,102,100) ),    // red transparency
  new FillStyle(new Color(102,153,102,100) ),  // green transparency
  new FillStyle(new Color(51,102,255,100) ) }; // blue transparency

// Assign the fills to the chart's areas (data elements)
graphModel.getDataElementStyles().setFillStyles(transparencies);

You can influence the order in which the filled areas are painted to the screen, depending on how the multiple plots are generated.

If changing the paint order does not provide a satisfactory display of the plot areas, try defining transparent fills for the areas, as shown by the code above.

Example
Filling Plot Areas: Swing-based code, Servlet-based code

LineChartModel: Behavior

LineChartModel properties are bound properties. Modifying a property triggers a PropertyChangeEvent. The LineChart asynchronously updates when a PropertyChangeEvent is received from the LineChartModel. Similarly, modifying a property in any of the LineChartModel's contained models triggers a PropertyChangeEvent. PropertyChangeEvent from contained models will bubble up to cause a PropertyChangeEvent to be fired from the LineChartModel.

For example, the following call 

 
lineChartModel.getColorLegendModel().getValueTextStyle().setColor(java.awt.Color.yellow);

would cause the legend's value text style model to fire a "color" PropertyChangeEvent, causing legend model to fire a "valueTextStyle" PropertyChangeEvent, causing the LineChartModel to fire a "colorLegendModel" PropertyChangeEvent. This bubbling up of events enables the graph or any other listener to manage updates at a higher level of containment.