Update amount chart y labels

lib/src/components/painter/amount_chart/amount_y_label_painter.dart

@@ -13,19 +13,27 @@ class AmountYLabelPainter extends YLabelPainter {
 
   @override
   void drawYLabels(Canvas canvas, Size size) {
-    final hourSuffix = translations.shortHour;
-    final double interval =
+    final String hourSuffix = translations.shortHour;
+    final double labelInterval =
         (size.height - kXLabelHeight) / (topHour - bottomHour);
+    final int hourDuration = topHour - bottomHour;
+    final int timeStep;
+    if (hourDuration >= 12) {
+      timeStep = 4;
+    } else if (hourDuration >= 8) {
+      timeStep = 2;
+    } else {
+      timeStep = 1;
+    }
     double posY = 0;
 
-    for (int time = topHour; time >= bottomHour; --time) {
-      drawYText(canvas, size,
-          time == bottomHour ? '0 $hourSuffix' : '$time $hourSuffix', posY);
+    for (int time = topHour; time >= bottomHour; time = time - timeStep) {
+      drawYText(canvas, size, '$time $hourSuffix', posY);
       if (topHour > time && time > bottomHour) {
         drawHorizontalLine(canvas, size, posY);
       }
 
-      posY += interval;
+      posY += labelInterval * timeStep;
     }
   }
 }

lib/src/components/utils/time_data_processor.dart

@@ -323,11 +323,9 @@ mixin TimeDataProcessor {
   }
 
   void _calcAmountPivotHeights(List<DateTimeRange> dataList) {
-    const double infinity = 10000.0;
     final int len = dataList.length;
 
     double maxResult = 0.0;
-    double minResult = infinity;
     double sum = 0.0;
 
     for (int i = 0; i < len; ++i) {
@@ -338,15 +336,13 @@ mixin TimeDataProcessor {
           dataList[i].end.dateWithoutTime() !=
               dataList[i + 1].end.dateWithoutTime()) {
         maxResult = max(maxResult, sum);
-        if (sum > 0.0) {
-          minResult = min(minResult, sum);
-        }
         sum = 0.0;
       }
     }
 
-    _topHour = maxResult.ceil();
-    _bottomHour = minResult == infinity ? 0 : max(0, minResult.floor() - 1);
+    // `_topHour`는 4의 배수가 되도록 한다.
+    _topHour = ((maxResult.ceil()) / 4).ceil() * 4;
+    _bottomHour = 0;
   }
 
   /// [b]에서 [a]로 흐른 시간을 구한다. 예를 들어 5시에서 3시로 흐른 시간은 22시간이고,

test/amount_chart_test/amount_chart_test.dart

@@ -0,0 +1,73 @@
+import 'dart:io';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:time_chart/src/chart.dart';
+import 'package:time_chart/time_chart.dart';
+
+void main() {
+  group('AmountChart y labels', () {
+    testWidgets('have 4 hours intervals if max amount is over 8 hours',
+        (tester) async {
+      await tester.pumpWidget(MaterialApp(
+        home: TimeChart(
+          chartType: ChartType.amount,
+          data: [
+            DateTimeRange(
+              start: DateTime(2022, 5, 27, 0, 0),
+              end: DateTime(2022, 5, 27, 8, 1),
+            ),
+          ],
+        ),
+      ));
+
+      await expectLater(
+        find.byType(Chart),
+        matchesGoldenFile('golden/y_label_golden1.png'),
+        skip: !Platform.isMacOS,
+      );
+    });
+
+    testWidgets('have 2 hours intervals if max amount is in range (4, 8] hours',
+        (tester) async {
+      await tester.pumpWidget(MaterialApp(
+        home: TimeChart(
+          chartType: ChartType.amount,
+          data: [
+            DateTimeRange(
+              start: DateTime(2022, 5, 27, 0, 0),
+              end: DateTime(2022, 5, 27, 5, 0),
+            ),
+          ],
+        ),
+      ));
+
+      await expectLater(
+        find.byType(Chart),
+        matchesGoldenFile('golden/y_label_golden2.png'),
+        skip: !Platform.isMacOS,
+      );
+    });
+
+    testWidgets('have 1 hour interval if max amount is below 4 hours',
+        (tester) async {
+      await tester.pumpWidget(MaterialApp(
+        home: TimeChart(
+          chartType: ChartType.amount,
+          data: [
+            DateTimeRange(
+              start: DateTime(2022, 5, 27, 0, 0),
+              end: DateTime(2022, 5, 27, 4, 0),
+            ),
+          ],
+        ),
+      ));
+
+      await expectLater(
+        find.byType(Chart),
+        matchesGoldenFile('golden/y_label_golden3.png'),
+        skip: !Platform.isMacOS,
+      );
+    });
+  });
+}

test/time_data_processor_test.dart

@@ -48,7 +48,7 @@ Chart _getChart(
 }
 
 void main() {
-  group('Time chart data processor test', () {
+  group('TimeChart data processor', () {
     testWidgets('merge if has overlapping time', (tester) async {
       final _MockTimeDataProcessor processor = _MockTimeDataProcessor();
       final data = [
@@ -235,9 +235,11 @@ void main() {
         reason: 'default pivot hour is used as `topHour` if there is no data',
       );
     });
+  });
 
+  group('AmountChart data processor', () {
     testWidgets(
-        'show empty graph if there is no data when chart type is amount',
+        'shows empty graph if there is no data when chart type is amount',
         (tester) async {
       final _MockTimeDataProcessor processor = _MockTimeDataProcessor();
       final List<DateTimeRange> data = [];
@@ -305,5 +307,43 @@ void main() {
 
       expect(processor.dayCount!, equals(18));
     });
+
+    testWidgets('always sets bottomHour to 0', (tester) async {
+      final _MockTimeDataProcessor processor = _MockTimeDataProcessor();
+      final data = [
+        DateTimeRange(
+          start: DateTime(2021, 12, 1, 0, 12),
+          end: DateTime(2021, 12, 1, 17, 12),
+        ),
+      ];
+
+      processor.process(
+        data,
+        chartType: ChartType.amount,
+      );
+
+      expect(processor.bottomHour!, equals(0));
+    });
+
+    testWidgets('sets topHour to 20 if max amount is 17 hours', (tester) async {
+      final _MockTimeDataProcessor processor = _MockTimeDataProcessor();
+      final data = [
+        DateTimeRange(
+          start: DateTime(2021, 12, 2, 22, 10),
+          end: DateTime(2021, 12, 2, 23, 20),
+        ),
+        DateTimeRange(
+          start: DateTime(2021, 12, 1, 0, 12),
+          end: DateTime(2021, 12, 1, 17, 12),
+        ),
+      ];
+
+      processor.process(
+        data,
+        chartType: ChartType.amount,
+      );
+
+      expect(processor.topHour!, equals(20));
+    });
   });
 }