Issue #545: restore custom per-point tooltips for bubble charts

xchart-demo/src/main/java/org/knowm/xchart/demo/charts/bubble/BubbleChart02.java

@@ -0,0 +1,80 @@
+package org.knowm.xchart.demo.charts.bubble;
+
+import java.text.DecimalFormat;
+import org.knowm.xchart.BubbleChart;
+import org.knowm.xchart.BubbleChartBuilder;
+import org.knowm.xchart.BubbleSeries;
+import org.knowm.xchart.SwingWrapper;
+import org.knowm.xchart.XChartPanel;
+import org.knowm.xchart.demo.charts.ExampleChart;
+import org.knowm.xchart.style.Styler;
+
+/**
+ * Bubble Chart with Custom Tooltips
+ *
+ * <p>Demonstrates the following:
+ *
+ * <ul>
+ *   <li>Custom, per-data-point tooltip strings via {@link BubbleSeries#setToolTips(String[])}
+ *   <li>Tooltips always visible
+ */
+public class BubbleChart02 implements ExampleChart<BubbleChart> {
+
+  public static void main(String[] args) {
+
+    ExampleChart<BubbleChart> exampleChart = new BubbleChart02();
+    BubbleChart chart = exampleChart.getChart();
+    SwingWrapper<BubbleChart> wrapper = new SwingWrapper<>(chart);
+    wrapper.displayChart();
+    wrapper.getXChartPanel().setToolTipsEnabled(true);
+  }
+
+  @Override
+  public BubbleChart getChart() {
+
+    // Create Chart
+    BubbleChart chart =
+        new BubbleChartBuilder()
+            .width(800)
+            .height(600)
+            .title(getClass().getSimpleName())
+            .xAxisTitle("Volume")
+            .yAxisTitle("Rate")
+            .build();
+    chart.getStyler().setLegendPosition(Styler.LegendPosition.InsideSW);
+    chart.getStyler().setLegendLayout(Styler.LegendLayout.Horizontal);
+    chart.getStyler().setYAxisDecimalPattern("#%");
+    chart.getStyler().setToolTipsAlwaysVisible(true);
+
+    // Series: volume (x), rate (y), number of hits (bubble size)
+    double[] volume = new double[] {1298, 843, 2755, 1520};
+    double[] rate = new double[] {0.0215, 0.041, 0.017, 0.033};
+    double[] hits = new double[] {279, 346, 468, 502};
+
+    BubbleSeries series = chart.addSeries("conversion", volume, rate, hits);
+
+    // Build a custom tooltip string per data point combining all three values, e.g. "2% (279/1298)"
+    DecimalFormat percentFormat = new DecimalFormat("#%");
+    String[] toolTips = new String[volume.length];
+    for (int i = 0; i < volume.length; i++) {
+      toolTips[i] =
+          percentFormat.format(rate[i]) + " (" + (int) hits[i] + "/" + (int) volume[i] + ")";
+    }
+    series.setCustomToolTips(true);
+    series.setToolTips(toolTips);
+
+    return chart;
+  }
+
+  @Override
+  public void customizePanel(XChartPanel<BubbleChart> panel) {
+
+    panel.setToolTipsEnabled(true);
+  }
+
+  @Override
+  public String getExampleChartName() {
+
+    return getClass().getSimpleName() + " - Bubble Chart with Custom Tooltips";
+  }
+}

xchart-demo/src/main/java/org/knowm/xchart/standalone/issues/TestForIssue545.java

@@ -1,9 +1,12 @@
 package org.knowm.xchart.standalone.issues;
 
 import java.awt.Font;
+import java.text.DecimalFormat;
 import java.text.ParseException;
+
 import org.knowm.xchart.BubbleChart;
 import org.knowm.xchart.BubbleChartBuilder;
+import org.knowm.xchart.BubbleSeries;
 import org.knowm.xchart.SwingWrapper;
 import org.knowm.xchart.style.BubbleStyler;
 import org.knowm.xchart.style.Styler;
@@ -30,14 +33,18 @@ public static BubbleChart getBubbleChart() {
             .yAxisTitle("Rate")
             .build();
     setBubbleStyler(chart);
-    chart.addSeries(
-        "serieName", new double[] {data[0]}, new double[] {data[1]}, new double[] {data[2]});
-    //    bubbleSeries.setCustomToolTips(true);
-    //    String tooltip =
-    //        new DecimalFormat("#%").format(data[1]) + " (" + ((int) data[2]) + "/" + ((int)
-    // data[0]) + ")";
-    //
-    //    bubbleSeries.setToolTips(new String[] {tooltip});
+    BubbleSeries bubbleSeries =
+        chart.addSeries(
+            "seriesName", new double[] {data[0]}, new double[] {data[1]}, new double[] {data[2]});
+    String tooltip =
+        new DecimalFormat("#%").format(data[1])
+            + " ("
+            + ((int) data[2])
+            + "/"
+            + ((int) data[0])
+            + ")";
+    bubbleSeries.setCustomToolTips(true);
+    bubbleSeries.setToolTips(new String[] {tooltip});
 
     return chart;
   }

xchart/src/main/java/org/knowm/xchart/BubbleSeries.java

@@ -10,6 +10,12 @@ public class BubbleSeries extends NoMarkersSeries {
 
   private Optional<BubbleSeriesRenderStyle> bubbleSeriesRenderStyle = Optional.empty();
 
+  /** whether to use the custom, per-data-point tooltip strings instead of the x/y axis values */
+  private boolean customToolTips;
+
+  /** the custom tooltip strings, one per data point, indexed the same as the x/y/size data */
+  private String[] toolTips;
+
   /**
    * Constructor
    *
@@ -34,6 +40,44 @@ public BubbleSeries setBubbleSeriesRenderStyle(BubbleSeriesRenderStyle bubbleSer
     return this;
   }
 
+  public boolean isCustomToolTips() {
+
+    return customToolTips;
+  }
+
+  /**
+   * Set whether to show the custom, per-data-point tooltip strings set via {@link
+   * #setToolTips(String[])} instead of the default formatted x/y axis values. Requires tooltips to
+   * be enabled on the styler.
+   *
+   * @param customToolTips true to show the per-data-point strings from {@link
+   *     #setToolTips(String[])}; false to show the default formatted x/y axis values
+   */
+  public BubbleSeries setCustomToolTips(boolean customToolTips) {
+
+    this.customToolTips = customToolTips;
+    return this;
+  }
+
+  public String[] getToolTips() {
+
+    return toolTips;
+  }
+
+  /**
+   * Set the custom tooltip strings, one per data point, indexed the same as the x/y/bubble-size
+   * data. A null entry (or a null array) falls back to the default formatted x/y axis values for
+   * that data point. Also requires {@link #setCustomToolTips(boolean)} to be set to true.
+   *
+   * @param toolTips the tooltip strings, one per data point; a null entry (or a null array) falls
+   *     back to the default formatted x/y axis values for that data point
+   */
+  public BubbleSeries setToolTips(String[] toolTips) {
+
+    this.toolTips = toolTips;
+    return this;
+  }
+
   @Override
   public LegendRenderType getLegendRenderType() {
 

xchart/src/main/java/org/knowm/xchart/internal/chartpart/PlotContent_Bubble.java

@@ -134,13 +134,22 @@ public void doPaint(Graphics2D g) {
 
           // add tooltips
           if (interactionData != null) {
-            interactionData.addToolTip(
-                bubble,
-                xOffset,
-                yOffset,
-                0,
-                axesChart.getXAxisFormat().format(x),
-                axesChart.getYAxisFormat().format(yOrig));
+
+            String[] customToolTips = series.getToolTips();
+            if (series.isCustomToolTips()
+                && customToolTips != null
+                && i < customToolTips.length
+                && customToolTips[i] != null) {
+              interactionData.addToolTip(bubble, xOffset, yOffset, 0, customToolTips[i]);
+            } else {
+              interactionData.addToolTip(
+                  bubble,
+                  xOffset,
+                  yOffset,
+                  0,
+                  axesChart.getXAxisFormat().format(x),
+                  axesChart.getYAxisFormat().format(yOrig));
+            }
           }
         }
       }

xchart/src/test/java/org/knowm/xchart/BubbleChartTest.java

@@ -0,0 +1,73 @@
+package org.knowm.xchart;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+import java.awt.image.BufferedImage;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class BubbleChartTest {
+
+  private BubbleChart chart;
+
+  @BeforeEach
+  void setUp() {
+
+    chart = new BubbleChartBuilder().title("test").xAxisTitle("X").yAxisTitle("Y").build();
+  }
+
+  // https://github.com/knowm/XChart/issues/545
+  @Test
+  void customToolTipsDefaultOff() {
+
+    BubbleSeries series =
+        chart.addSeries("s", new double[] {1, 2}, new double[] {3, 4}, new double[] {5, 6});
+
+    assertThat(series.isCustomToolTips()).isFalse();
+    assertThat(series.getToolTips()).isNull();
+  }
+
+  // https://github.com/knowm/XChart/issues/545
+  @Test
+  void customToolTipsRoundTrip() {
+
+    BubbleSeries series =
+        chart.addSeries("s", new double[] {1, 2}, new double[] {3, 4}, new double[] {5, 6});
+
+    String[] toolTips = {"2% (279/1298)", "4% (346/843)"};
+    series.setCustomToolTips(true);
+    series.setToolTips(toolTips);
+
+    assertThat(series.isCustomToolTips()).isTrue();
+    assertThat(series.getToolTips()).containsExactly("2% (279/1298)", "4% (346/843)");
+  }
+
+  // https://github.com/knowm/XChart/issues/545
+  @Test
+  void renderWithCustomToolTipsDoesNotThrow() {
+
+    BubbleSeries series =
+        chart.addSeries("s", new double[] {1, 2}, new double[] {3, 4}, new double[] {5, 6});
+    series.setCustomToolTips(true);
+    series.setToolTips(new String[] {"2% (279/1298)", "4% (346/843)"});
+    chart.getStyler().setToolTipsAlwaysVisible(true);
+
+    BufferedImage image = assertDoesNotThrow(() -> BitmapEncoder.getBufferedImage(chart));
+    assertThat(image).isNotNull();
+  }
+
+  // https://github.com/knowm/XChart/issues/545
+  @Test
+  void renderWithPartialCustomToolTipsFallsBackWithoutThrowing() {
+
+    // fewer tooltip entries than data points, plus a null entry -> falls back to axis values
+    BubbleSeries series =
+        chart.addSeries("s", new double[] {1, 2, 3}, new double[] {3, 4, 5}, new double[] {5, 6, 7});
+    series.setCustomToolTips(true);
+    series.setToolTips(new String[] {null});
+    chart.getStyler().setToolTipsAlwaysVisible(true);
+
+    assertDoesNotThrow(() -> BitmapEncoder.getBufferedImage(chart));
+  }
+}