ttools: generalise ShapeForm to accommodate multiple positions

The ShapeMode/ShapeForm colouring machinery can now be used for
multi-point shapes such as links between groups of positions.

ttools/src/main/uk/ac/starlink/ttools/plot2/Plotter.java

@@ -54,7 +54,7 @@ public interface Plotter<S extends Style> {
      * Each of these is turned into a data space position by use of the
      * DataGeom presented at layer creation time.
      * 
-     * @return   number of positional coordinates
+     * @return   number of sets of positional coordinates
      */
     int getPositionCount();
 

ttools/src/main/uk/ac/starlink/ttools/plot2/layer/MarkForm.java

@@ -42,6 +42,10 @@ public class MarkForm implements ShapeForm {
 
     private static final Color DUMMY_COLOR = Color.GRAY;
 
+    public int getPositionCount() {
+        return 1;
+    }
+
     public String getFormName() {
         return "Mark";
     }

ttools/src/main/uk/ac/starlink/ttools/plot2/layer/MultiPointForm.java

@@ -33,9 +33,10 @@
 import uk.ac.starlink.ttools.plot2.paper.PaperType3D;
 
 /**
- * ShapeForm implementation that draws shapes based on the positions of
- * more than one data point.
- * The actual coordinates required (defining one or more non-central
+ * ShapeForm implementation that draws shapes based on a single main
+ * position, and a number of additional positions supplied as
+ * {@link ShapeForm#getExtraCoords extra} coordinates.
+ * The extra coordinates required (defining one or more non-central
  * data positions) are defined by a supplied {@link MultiPointCoordSet}
  * and those coordinates are then plotted by a corresponding
  * {@link uk.ac.starlink.ttools.plot.ErrorRenderer}.
@@ -78,6 +79,10 @@ public MultiPointForm( String name, Icon icon,
         rendererKey_ = rendererKey;
     }
 
+    public int getPositionCount() {
+        return 1;
+    }
+
     public String getFormName() {
         return name_;
     }

ttools/src/main/uk/ac/starlink/ttools/plot2/layer/Outliner.java

@@ -126,8 +126,8 @@ Object calculateBinPlan( Surface surface, DataGeom geom,
 
     /**
      * Interface to define the actual shape drawing.
-     * It contains a single method, {@link #paintPoint}, which is called
-     * once for each point.
+     * It contains a single method, {@link #paintPoint paintPoint},
+     * which is called once for each point.
      */
     interface ShapePainter {
 

ttools/src/main/uk/ac/starlink/ttools/plot2/layer/ShapeForm.java

@@ -10,14 +10,21 @@
 /**
  * Plotter Form sub-interface for use with ShapeMode.
  * This defines the shape of data points plotted, which may be influenced
- * by additional data than the actual point position
- * (for instance error bar sizes).
+ * by data other than the actual point position(s), for instance
+ * error bar sizes.
  *
  * @author   Mark Taylor
  * @since    18 Feb 2013
  */
 public interface ShapeForm extends ModePlotter.Form {
 
+    /**
+     * Returns the number of data positions per tuple used by this form.
+     *
+     * @return   number of sets of positional coordinates
+     */
+    int getPositionCount();
+
     /**
      * Returns data coordinates additional to the basic position which
      * are required to plot a point.

ttools/src/main/uk/ac/starlink/ttools/plot2/layer/ShapePlotter.java

@@ -40,7 +40,7 @@ public class ShapePlotter extends AbstractPlotter<ShapeStyle> {
      * @param   mode  colour determiner
      */
     public ShapePlotter( String name, ShapeForm form, ShapeMode mode ) {
-        super( name, form.getFormIcon(), 1,
+        super( name, form.getFormIcon(), form.getPositionCount(),
                PlotUtil.arrayConcat( form.getExtraCoords(),
                                      mode.getExtraCoords() ) );
         form_ = form;
@@ -76,7 +76,7 @@ public PlotLayer createLayer( DataGeom geom, DataSpec dataSpec,
      * @return  index of first mode-specific coordinate
      */
     public int getModeCoordsIndex( DataGeom geom ) {
-        return geom.getPosCoords().length
+        return geom.getPosCoords().length * form_.getPositionCount()
              + form_.getExtraCoords().length;
     }
 

ttools/src/main/uk/ac/starlink/ttools/plot2/layer/SizeForm.java

@@ -51,6 +51,10 @@ public class SizeForm implements ShapeForm {
                                          16, 2, 64, false );
     private static final AuxScale SIZE_SCALE = new AuxScale( "globalsize" );
 
+    public int getPositionCount() {
+        return 1;
+    }
+
     public String getFormName() {
         return "Size";
     }