Added support for labels in pie and doughnut charts

org.eclipse.swtchart.examples/src/org/eclipse/swtchart/examples/MultiLevelDoughnutChart.java

@@ -19,6 +19,7 @@
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.swtchart.Chart;
 import org.eclipse.swtchart.ICircularSeries;
+import org.eclipse.swtchart.ICircularSeriesLabel;
 import org.eclipse.swtchart.ISeries.SeriesType;
 
 /**
@@ -77,6 +78,8 @@ static public Chart createChart(Composite parent) {
 		ICircularSeries<?> multiLevelDoughnut = (ICircularSeries<?>)chart.getSeriesSet().createSeries(SeriesType.DOUGHNUT, "countries");
 		// sets the series.
 		multiLevelDoughnut.setSeries(continentLabels, continentValues);
+		multiLevelDoughnut.getLabel().setVisible(true);
+		multiLevelDoughnut.getLabel().setPosition(ICircularSeriesLabel.Position.Inside);
 		// adding Asian countries. These go in as second level
 		multiLevelDoughnut.getNodeById("Asia").addChildren(AsianCountriesLabels, AsianCountriesValues);
 		//

org.eclipse.swtchart.examples/src/org/eclipse/swtchart/examples/SingleLevelDoughnutChartExample.java

@@ -20,6 +20,7 @@
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.swtchart.Chart;
 import org.eclipse.swtchart.ICircularSeries;
+import org.eclipse.swtchart.ICircularSeriesLabel;
 import org.eclipse.swtchart.ISeries.SeriesType;
 
 /**
@@ -73,6 +74,11 @@ static public Chart createChart(Composite parent) {
 		// change color of India to DARK_RED
 		Color color = Display.getDefault().getSystemColor(SWT.COLOR_DARK_RED);
 		circularSeries.setColor("India", color);
+
+		circularSeries.getLabel().setVisible(true);
+		circularSeries.getLabel().setPosition(ICircularSeriesLabel.Position.Inside);
+		circularSeries.getLabel().setForeground(Display.getDefault().getSystemColor(SWT.COLOR_DARK_RED));
+		circularSeries.getLabel().setLabelProvider(node -> String.format("%s (%.1f%%)", node.getId(), node.getValue() / node.getParent().getValue() * 100));
 		//
 		return chart;
 	}

org.eclipse.swtchart/src/org/eclipse/swtchart/ICircularSeries.java

@@ -24,6 +24,9 @@
  */
 public interface ICircularSeries<T> extends ISeries<T> {
 
+	@Override
+	ICircularSeriesLabel getLabel();
+
 	/**
 	 * gets the label series
 	 * 

org.eclipse.swtchart/src/org/eclipse/swtchart/ICircularSeriesLabel.java

@@ -0,0 +1,18 @@
+package org.eclipse.swtchart;
+
+import java.util.function.Function;
+
+import org.eclipse.swtchart.model.Node;
+
+public interface ICircularSeriesLabel extends ISeriesLabel {
+
+	public enum Position {
+		Inside, Outside
+	}
+
+	void setPosition(Position position);
+
+	Position getPosition();
+
+	void setLabelProvider(Function<Node, String> labelProvider);
+}

org.eclipse.swtchart/src/org/eclipse/swtchart/internal/series/CircularSeries.java

@@ -21,6 +21,7 @@
 import org.eclipse.swtchart.Chart;
 import org.eclipse.swtchart.IAxis;
 import org.eclipse.swtchart.ICircularSeries;
+import org.eclipse.swtchart.ICircularSeriesLabel;
 import org.eclipse.swtchart.internal.axis.Axis;
 import org.eclipse.swtchart.internal.compress.Compress;
 import org.eclipse.swtchart.internal.compress.CompressCircularSeries;
@@ -47,6 +48,7 @@ public CircularSeries(Chart chart, String id) {
 
 		super(chart, id);
 		this.chart = chart;
+		this.seriesLabel = new CircularSeriesLabel();
 		initialise();
 		model = new IdNodeDataModel(id);
 		rootNode = model.getRootNode();
@@ -58,6 +60,12 @@ public CircularSeries(Chart chart, String id) {
 		borderStyle = SWT.LINE_SOLID;
 	}
 
+	@Override
+	public ICircularSeriesLabel getLabel() {
+
+		return (ICircularSeriesLabel)super.getLabel();
+	}
+
 	@Override
 	public Color getBorderColor() {
 
@@ -106,6 +114,7 @@ public Compress getCompressor() {
 		return (Compress)compressor;
 	}
 
+	@Override
 	public Node getRootNode() {
 
 		return rootNode;

org.eclipse.swtchart/src/org/eclipse/swtchart/internal/series/CircularSeriesLabel.java

@@ -0,0 +1,127 @@
+package org.eclipse.swtchart.internal.series;
+
+import java.util.function.Function;
+
+import org.eclipse.swt.graphics.Font;
+import org.eclipse.swt.graphics.GC;
+import org.eclipse.swt.graphics.Point;
+import org.eclipse.swt.graphics.Rectangle;
+import org.eclipse.swt.graphics.Transform;
+import org.eclipse.swtchart.IAxis;
+import org.eclipse.swtchart.ICircularSeriesLabel;
+import org.eclipse.swtchart.internal.axis.Axis;
+import org.eclipse.swtchart.model.Node;
+
+public class CircularSeriesLabel extends SeriesLabel implements ICircularSeriesLabel {
+
+	private Position position = Position.Inside;
+	private Function<Node, String> labelProvider = Node::getId;
+
+	public CircularSeriesLabel() {
+
+	}
+
+	@Override
+	public void setPosition(Position position) {
+
+		this.position = position;
+	}
+
+	@Override
+	public Position getPosition() {
+
+		return position;
+	}
+
+	@Override
+	public void setLabelProvider(Function<Node, String> labelProvider) {
+
+		this.labelProvider = labelProvider;
+	}
+
+	/* package */ void draw(GC gc, Node node, int level, Axis xAxis, Axis yAxis) {
+
+		if(!isVisible())
+			return;
+		switch(position) {
+			case Inside:
+				drawInside(gc, node, level, xAxis, yAxis);
+				break;
+			case Outside:
+				drawOutside(gc, node, level, xAxis, yAxis);
+				break;
+			default:
+				throw new IllegalArgumentException();
+		}
+	}
+
+	private void drawInside(GC gc, Node node, int level, Axis xAxis, Axis yAxis) {
+
+		String label = labelProvider.apply(node);
+		if(label == null)
+			return;
+
+		Point angleBounds = node.getAngleBounds();
+		// check if pie chart (inner bound) is big enough to draw label
+		gc.setFont(getFont());
+		Point textSize = gc.textExtent(label);
+		Point start = getPixelCoordinate(xAxis, yAxis, (level - 1), angleBounds.x);
+		Point end = getPixelCoordinate(xAxis, yAxis, (level - 1), angleBounds.x + angleBounds.y);
+		int size = (int)Math.sqrt(Math.pow((end.x - start.x), 2) + Math.pow((end.y - start.y), 2));
+		if(size < textSize.y - 4)
+			return;
+		// calculate text angle
+		int angle = angleBounds.x + angleBounds.y / 2;
+		Point innerBound = getPixelCoordinate(xAxis, yAxis, (level - 1), angle);
+		Point outerBound = getPixelCoordinate(xAxis, yAxis, level, angle);
+		Transform t = new Transform(gc.getDevice());
+		Point textPosition;
+		if(angle >= 90 && angle <= 270) {
+			textPosition = outerBound;
+			t.translate(textPosition.x, textPosition.y);
+			t.rotate((-angle + 180));
+		} else {
+			textPosition = innerBound;
+			t.translate(textPosition.x, textPosition.y);
+			t.rotate(-angle);
+		}
+		gc.setTransform(t);
+		gc.setForeground(getForeground());
+		int length = (int)Math.sqrt(Math.pow((outerBound.x - innerBound.x), 2) + Math.pow((outerBound.y - innerBound.y), 2));
+		gc.setClipping(0, 0 - (textSize.y / 2), length - 3, textSize.y);
+		gc.drawString(label, 2, 0 - (textSize.y / 2), true);
+		gc.setClipping((Rectangle)null);
+		gc.setTransform(null);
+	}
+
+	private void drawOutside(GC gc, Node node, int level, Axis xAxis, Axis yAxis) {
+
+		String label = labelProvider.apply(node);
+		if(label == null)
+			return;
+
+		Point angleBounds = node.getAngleBounds();
+		int angle = angleBounds.x + angleBounds.y / 2;
+		Point textSize = gc.textExtent(label);
+		// some heuristic to check if there is enough space to render a
+		// label
+		Point start = getPixelCoordinate(xAxis, yAxis, (level - 1), angleBounds.x);
+		Point end = getPixelCoordinate(xAxis, yAxis, (level - 1), angleBounds.x + angleBounds.y);
+		if(Math.abs(start.y - end.y) < 4)
+			return;
+		Point point = getPixelCoordinate(xAxis, yAxis, level * 1.03, angle);
+		int x = angle >= 90 && angle <= 270 ? point.x - textSize.x : point.x;
+		Font oldFont = gc.getFont();
+		gc.setForeground(getForeground());
+		gc.setFont(getFont());
+		gc.drawString(label, x, point.y - (textSize.y / 2), true);
+		gc.setFont(oldFont);
+	}
+
+	protected final Point getPixelCoordinate(IAxis xAxis, IAxis yAxis, double pieLevel, int angle) {
+
+		double xCoordinate = pieLevel * Math.cos(Math.toRadians(angle));
+		double yCoordinate = pieLevel * Math.sin(Math.toRadians(angle));
+		return new Point(xAxis.getPixelCoordinate(xCoordinate), yAxis.getPixelCoordinate(yCoordinate));
+	}
+}

org.eclipse.swtchart/src/org/eclipse/swtchart/internal/series/Doughnut.java

@@ -37,6 +37,7 @@ protected Doughnut(Chart chart, String id) {
 	 * @param xAxis
 	 * @param yAxis
 	 */
+	@Override
 	protected void drawNode(Node node, GC gc, Axis xAxis, Axis yAxis) {
 
 		// children drawn first as parent overrides it's section of drawing
@@ -45,7 +46,7 @@ protected void drawNode(Node node, GC gc, Axis xAxis, Axis yAxis) {
 				drawNode(nodes, gc, xAxis, yAxis);
 			}
 		}
-		if(node.isVisible() == false)
+		if(!node.isVisible())
 			return;
 		int level = node.getLevel() - getRootPointer().getLevel() + 1;
 		/*
@@ -85,6 +86,7 @@ protected void drawNode(Node node, GC gc, Axis xAxis, Axis yAxis) {
 		//
 		if(node != getRootPointer())
 			gc.drawLine(xZero, yZero, xEndPixelCoordinate, yEndPixelCoordinate);
+		((CircularSeriesLabel)seriesLabel).draw(gc, node, level, xAxis, yAxis);
 	}
 
 	/**

org.eclipse.swtchart/src/org/eclipse/swtchart/internal/series/Pie.java

@@ -37,6 +37,7 @@ protected Pie(Chart chart, String id) {
 	 * @param xAxis
 	 * @param yAxis
 	 */
+	@Override
 	protected void drawNode(Node node, GC gc, Axis xAxis, Axis yAxis) {
 
 		// children drawn first as parent overrides it's section of drawing
@@ -45,7 +46,7 @@ protected void drawNode(Node node, GC gc, Axis xAxis, Axis yAxis) {
 				drawNode(nodes, gc, xAxis, yAxis);
 			}
 		}
-		if(node.isVisible() == false)
+		if(!node.isVisible())
 			return;
 		int level = node.getLevel() - getRootPointer().getLevel();
 		/*
@@ -83,6 +84,7 @@ protected void drawNode(Node node, GC gc, Axis xAxis, Axis yAxis) {
 		int yEndPixelCoordinate = yAxis.getPixelCoordinate(yEndCoordinate);
 		//
 		gc.drawLine(xZero, yZero, xEndPixelCoordinate, yEndPixelCoordinate);
+		((CircularSeriesLabel)seriesLabel).draw(gc, node, level, xAxis, yAxis);
 	}
 
 	/**