fix(charts): a bar's value label gets the halo the style asks for

CHANGELOG.md

@@ -164,6 +164,16 @@ follow semantic versioning; release dates are ISO 8601.
 
 ### Fixed
 
+- **A bar chart's value labels get the halo the style asks for.** The halo chip exists
+  so a grid line stops running through the digits. `BarChartLayout` resolved the colour
+  from the style and then passed `null` for every value label except a stacked total —
+  a hardcoded argument forty lines from a sibling call that passed the real one. The
+  result read as a feature that does nothing: the style accepted a halo, the layout
+  computed it, and the label was drawn without it. Line charts and donuts had it all
+  along, which is why the gap survived since 1.8.0 — where the release notes already
+  promised the chip for a label sitting at a "marker **or bar top**". Two arguments, and
+  the six committed previews that carry a bar chart with outside labels are re-rendered
+  with their grid lines cleanly interrupted.
 - **The example catalogue renders the weights it declares.** The same defect the donut
   KPI had, 138 times over in the examples: a font *face* constant named with no
   decoration, which the library rewrites to its base family before the lookup. The PPTX

core/src/main/java/com/demcha/compose/document/chart/BarChartLayout.java

@@ -141,7 +141,7 @@ private static List<ChartPrimitive> resolveVertical(ChartSpec.Bar bar, ChartStyl
                         double labelBottomY = v >= baseValue
                                 ? yBottom + h + labelGap
                                 : yBottom - labelGap - f.valueLineH();
-                        emitChipLabel(out, "value_c" + c + "_s" + s, text, valueStyle, null,
+                        emitChipLabel(out, "value_c" + c + "_s" + s, text, valueStyle, halo,
                                 bx + innerBarW / 2.0, labelBottomY,
                                 labelW, f.valueLineH());
                     }
@@ -338,7 +338,7 @@ private static List<ChartPrimitive> resolveHorizontal(ChartSpec.Bar bar, ChartSt
                         double centerX = v >= baseValue
                                 ? xLeft + w + labelGap + labelW / 2.0
                                 : xLeft - labelGap - labelW / 2.0;
-                        emitChipLabel(out, "value_c" + c + "_s" + s, text, valueStyle, null,
+                        emitChipLabel(out, "value_c" + c + "_s" + s, text, valueStyle, halo,
                                 centerX, barTop - innerBarH / 2.0 - valueInk, labelW, valueLineH);
                     }
                 }

core/src/main/java/com/demcha/compose/document/chart/ChartDefaults.java

@@ -81,8 +81,8 @@ public final class ChartDefaults {
             .build();
 
     /**
-     * Default value-label halo — a white chip behind line-chart value labels so
-     * digits stay legible where line strokes cross them. Charts rendered on a
+     * Default value-label halo — a white chip behind chart value labels so the
+     * digits stay legible where a grid line or a stroke crosses them. Charts on a
      * non-white surface should override it with the surface colour via
      * {@code ChartStyle.valueLabelHalo(...)}.
      */

core/src/main/java/com/demcha/compose/document/chart/ChartStyle.java

@@ -45,9 +45,10 @@
  * @param axisTextStyle        tick / category label style
  * @param legendTextStyle      legend label style
  * @param valueLabelTextStyle  value-label style
- * @param valueLabelHalo       halo chip painted behind line-chart value labels so the
- *                             digits stay legible where line strokes cross them; match
- *                             it to the chart's surface colour on non-white backgrounds
+ * @param valueLabelHalo       halo chip painted behind chart value labels so the digits
+ *                             stay legible where a grid line or a stroke crosses them;
+ *                             match it to the chart's surface colour on non-white
+ *                             backgrounds
  * @param areaOpacity          opacity of the area fill under {@code ChartSpec.line().area(true)}
  *                             series, in (0..1], or {@code null} for the default (0.35)
  * @param sliceStroke          pie/donut slice separator stroke, or {@code null} for the
@@ -357,8 +358,9 @@ public Builder valueLabelTextStyle(DocumentTextStyle s) {
         }
 
         /**
-         * Sets the halo chip painted behind line-chart value labels. Match it to
-         * the chart's surface colour on non-white backgrounds.
+         * Sets the halo chip painted behind chart value labels — bar, line and
+         * pie alike. Match it to the chart's surface colour on non-white
+         * backgrounds.
          *
          * @param halo halo paint
          * @return this builder

core/src/main/java/com/demcha/compose/document/chart/ChartTheme.java

@@ -20,7 +20,7 @@
  * @param axisTextStyle       default tick / category label style
  * @param legendTextStyle     default legend label style
  * @param valueLabelTextStyle default value-label style
- * @param valueLabelHalo      default halo chip painted behind line-chart value labels
+ * @param valueLabelHalo      default halo chip painted behind chart value labels
  *                            so digits stay legible where line strokes cross them
  * @author Artem Demchyshyn
  * @since 1.8.0

core/src/test/java/com/demcha/compose/document/chart/ChartLayoutResolverTest.java

@@ -3,6 +3,7 @@
 import com.demcha.compose.document.node.LineNode;
 import com.demcha.compose.document.node.ParagraphNode;
 import com.demcha.compose.document.node.ShapeNode;
+import com.demcha.compose.document.style.DocumentColor;
 import com.demcha.compose.document.style.DocumentPaint;
 import com.demcha.compose.document.style.DocumentTextStyle;
 import org.junit.jupiter.api.Test;
@@ -134,15 +135,80 @@ void minimalChartHidesGridAxesButKeepsBarsAndValueLabels() {
         assertThat(count(out, LineNode.class)).isZero();
         assertThat(out.stream().anyMatch(p -> p.node().name().startsWith("tick_"))).isFalse();
         assertThat(out.stream().anyMatch(p -> p.node().name().startsWith("cat_"))).isFalse();
-        // Only the bars and their value labels remain.
-        assertThat(count(out, ShapeNode.class)).isEqualTo(2);
-        assertThat(out.stream().filter(p -> p.node().name().startsWith("value_")).count())
+        // Only the bars and their value labels remain — each label carrying the
+        // halo chip the theme defines, which is a ShapeNode of its own.
+        assertThat(count(out, ShapeNode.class)).isEqualTo(4);
+        assertThat(out.stream().filter(p -> p.node().name().startsWith("value_")
+                && !p.node().name().endsWith("_halo")).count())
                 .isEqualTo(2);
         // With no tick labels the value axis reserves no left gutter: bars start at x≈0.
         ChartPrimitive barA = byName(out, "bar_c0_s0");
         assertThat(barA.x()).isLessThan(20.0);
     }
 
+    /**
+     * A bar's value label sits on the grid line as readily as a line chart's does,
+     * and the halo exists to punch the line out from behind the digits. The bar
+     * layout resolved the colour and then passed {@code null} for every label
+     * except a stacked total, so the chip the style asked for was dropped on the
+     * floor for the commonest chart in the library.
+     */
+    @Test
+    void barValueLabelsCarryTheHaloTheStyleAsksFor() {
+        DocumentColor haloColour = DocumentColor.rgb(20, 27, 51);
+        ChartData data = ChartData.builder()
+                .categories("A", "B")
+                .series("S", 10.0, 20.0)
+                .build();
+        ChartSpec.Bar bar = ChartSpec.bar()
+                .data(data)
+                .valueLabels(ValueLabelMode.OUTSIDE)
+                .build();
+        ChartStyle style = baseStyle().mergedUnder(ChartStyle.builder()
+                .valueLabelHalo(DocumentPaint.solid(haloColour))
+                .build());
+
+        List<ChartPrimitive> out = ChartLayoutResolver.resolve(
+                bar, style, ChartDefaults.DEFAULT_THEME, 200.0, 100.0, METRICS);
+
+        // One chip per label, each filled with the colour the style named — not the
+        // theme's, which is what a dropped argument would silently fall back to.
+        List<ChartPrimitive> halos = out.stream()
+                .filter(p -> p.node().name().endsWith("_halo"))
+                .toList();
+        assertThat(halos).hasSize(2);
+        assertThat(halos).allSatisfy(halo ->
+                assertThat(((ShapeNode) halo.node()).fillColor()).isEqualTo(haloColour));
+
+        // The chip is painted before its label, or it would cover the digits.
+        int chip = indexOfName(out, "value_c0_s0_halo");
+        int label = indexOfName(out, "value_c0_s0");
+        assertThat(chip).isLessThan(label);
+
+        // And it is wider than the text box it backs, so the digits sit inside it.
+        assertThat(out.get(chip).width()).isGreaterThan(out.get(label).width());
+    }
+
+    /**
+     * The horizontal branch dropped the same argument, so it is pinned separately —
+     * a fix applied to one orientation would otherwise look complete.
+     */
+    @Test
+    void horizontalBarValueLabelsCarryTheHaloToo() {
+        ChartData data = ChartData.builder().categories("A").series("S", 10.0).build();
+        ChartSpec.Bar bar = ChartSpec.bar()
+                .data(data)
+                .horizontal(true)
+                .valueLabels(ValueLabelMode.OUTSIDE)
+                .build();
+
+        List<ChartPrimitive> out = ChartLayoutResolver.resolve(
+                bar, baseStyle(), ChartDefaults.DEFAULT_THEME, 200.0, 100.0, METRICS);
+
+        assertThat(out.stream().filter(p -> p.node().name().endsWith("_halo")).count())
+                .isEqualTo(1);
+    }
+
     @Test
     void valueLabelsNoneEmitsNoValueText() {
         ChartData data = ChartData.builder().categories("A").series("S", 5.0).build();
@@ -942,4 +1008,14 @@ private static long count(List<ChartPrimitive> out, Class<?> type) {
     private static ChartPrimitive byName(List<ChartPrimitive> out, String name) {
         return out.stream().filter(p -> p.node().name().equals(name)).findFirst().orElseThrow();
     }
+
+    /** Emission order matters for anything painted behind something else. */
+    private static int indexOfName(List<ChartPrimitive> out, String name) {
+        for (int i = 0; i < out.size(); i++) {
+            if (out.get(i).node().name().equals(name)) {
+                return i;
+            }
+        }
+        throw new AssertionError("no primitive named " + name);
+    }
 }

examples/src/main/java/com/demcha/examples/flagships/LinkedInCarouselExample.java

@@ -503,6 +503,10 @@ private static ChartStyle latencyStyle() {
                 .barWidthRatio(0.5)
                 .axisTextStyle(mono(22, ON_DARK_MUTED))
                 .valueLabelTextStyle(mono(25, ON_DARK))
+                // The labels sit over the gridlines, which on this surface read as
+                // strikethroughs across the digits. The halo punches a chip of the
+                // card's own fill out from under each one.
+                .valueLabelHalo(DocumentPaint.solid(SURFACE))
                 .build();
     }