Let a line chart's axis title and readout units be bound

yAxisTitle and the cursor readout's scale, decimals and suffix read their
bindings, so a chart can follow a units setting (feet or metres).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01F3B1XCZZ7QGvZLUGgSG5H4

Author: claude

lib/src/transformers/node_transformers/passive_line_chart_transformer.dart

@@ -260,7 +260,7 @@ class LineChartSpec {
               color: LineChartGeometry.parseColor(t['color']),
             ),
       ],
-      yAxisTitle: props.yAxisTitle,
+      yAxisTitle: text(bound('yAxisTitle')) ?? props.yAxisTitle,
       areaBands: [
         for (final Map b in maps('areaBands'))
           if ((x(b['from']), x(b['to']), n(b['below']), c(b)) case (
@@ -341,9 +341,11 @@ class LineChartSpec {
         props.tooltipValueStyle,
       ),
       tooltipXFormat: props.tooltipXFormat,
-      tooltipYScale: props.tooltipYScale,
-      tooltipYDecimals: props.tooltipYDecimals,
-      tooltipYSuffix: props.tooltipYSuffix,
+      // The readout's units can follow a setting (feet or metres).
+      tooltipYScale: n(bound('tooltipYScale')) ?? props.tooltipYScale,
+      tooltipYDecimals:
+          n(bound('tooltipYDecimals'))?.round() ?? props.tooltipYDecimals,
+      tooltipYSuffix: text(bound('tooltipYSuffix')) ?? props.tooltipYSuffix,
       tooltipTrend: props.tooltipTrend,
     );
   }

test/line_chart_test.dart

@@ -373,4 +373,25 @@ void main() {
       expect(find.byType(PassiveLineChartWidget), findsOneWidget);
     });
   });
+
+  testWidgets('the axis title and readout units can be bound', (
+    tester,
+  ) async {
+    await pumpChart(
+      tester,
+      chart(
+        variables: {
+          'yAxisTitle': r"${= 1 > 0 ? 'M' : 'FT'}",
+          'tooltipYScale': r'${= 0.3048}',
+          'tooltipYDecimals': r'${= 2}',
+          'tooltipYSuffix': r"${= ' m'}",
+        },
+      ),
+    );
+    final spec = painterOf(tester).spec;
+    expect(spec.yAxisTitle, 'M');
+    expect(spec.tooltipYScale, 0.3048);
+    expect(spec.tooltipYDecimals, 2);
+    expect(spec.tooltipYSuffix, ' m');
+  });
 }