stats: improved histogram axis

lib/utils/time_utils.dart

@@ -14,6 +14,12 @@ extension ExtraDateTime on DateTime {
   bool get isThisMonth => isAtSameMonthAs(DateTime.now());
 
   bool get isThisYear => isAtSameYearAs(DateTime.now());
+
+  DateTime get date => DateTime(year, month, day);
+
+  DateTime addMonths(int months) => DateTime(year, month + months, day, hour, minute, second, millisecond, microsecond);
+
+  DateTime addDays(int days) => DateTime(year, month, day + days, hour, minute, second, millisecond, microsecond);
 }
 
 final epoch = DateTime.fromMillisecondsSinceEpoch(0, isUtc: true);

lib/widgets/stats/date/axis.dart

@@ -0,0 +1,97 @@
+import 'dart:math';
+
+import 'package:aves/model/filters/date.dart';
+import 'package:aves/utils/time_utils.dart';
+import 'package:charts_flutter/flutter.dart' as charts;
+import 'package:intl/intl.dart';
+
+// cf charts.DateTimeTickFormatter factory internals for default formats
+class TimeAxisSpec {
+  final List<charts.TickSpec<DateTime>> tickSpecs;
+
+  TimeAxisSpec(this.tickSpecs);
+
+  factory TimeAxisSpec.forLevel({
+    required String locale,
+    required DateLevel level,
+    required DateTime first,
+    required DateTime last,
+  }) {
+    switch (level) {
+      case DateLevel.ymd:
+        return TimeAxisSpec.days(locale, first, last);
+      case DateLevel.ym:
+        return TimeAxisSpec.months(locale, first, last);
+      case DateLevel.y:
+      default:
+        return TimeAxisSpec.years(locale, first, last);
+    }
+  }
+
+  factory TimeAxisSpec.days(String locale, DateTime first, DateTime last) {
+    final daysTickLongFormat = DateFormat.MMMd(locale);
+    final daysTickShortFormat = DateFormat.d(locale);
+
+    first = first.date;
+    last = last.date;
+    final rangeDays = last.difference(first).inDays;
+    final delta = max(1, (rangeDays / 5).ceil());
+
+    List<charts.TickSpec<DateTime>> ticks = [];
+    int lastContext = -1;
+    DateFormat dateFormat;
+    for (int i = 0; i < rangeDays; i += delta) {
+      final tickDate = first.addDays(i);
+      if (lastContext != tickDate.month) {
+        lastContext = tickDate.month;
+        dateFormat = daysTickLongFormat;
+      } else {
+        dateFormat = daysTickShortFormat;
+      }
+      ticks.add(charts.TickSpec<DateTime>(tickDate, label: dateFormat.format(tickDate)));
+    }
+    return TimeAxisSpec(ticks);
+  }
+
+  factory TimeAxisSpec.months(String locale, DateTime first, DateTime last) {
+    final monthsTickLongFormat = DateFormat.yMMM(locale);
+    final monthsTickShortFormat = DateFormat.MMM(locale);
+
+    first = DateTime(first.year, first.month);
+    last = DateTime(last.year, last.month);
+    final rangeMonths = last.month - first.month + (last.month < first.month ? 12 : 0);
+    if (rangeMonths < 12) {
+      first = first.addMonths(-((12 - rangeMonths) / 2).floor());
+    }
+
+    List<charts.TickSpec<DateTime>> ticks = [];
+    int lastContext = -1;
+    DateFormat dateFormat;
+    for (int i = 0; i < DateTime.monthsPerYear; i += 3) {
+      final tickDate = first.addMonths(2 + i);
+      if (lastContext != tickDate.year) {
+        lastContext = tickDate.year;
+        dateFormat = monthsTickLongFormat;
+      } else {
+        dateFormat = monthsTickShortFormat;
+      }
+      ticks.add(charts.TickSpec<DateTime>(tickDate, label: dateFormat.format(tickDate)));
+    }
+    return TimeAxisSpec(ticks);
+  }
+
+  factory TimeAxisSpec.years(String locale, DateTime first, DateTime last) {
+    final dateFormat = DateFormat.y(locale);
+
+    final firstYear = first.year;
+    final lastYear = last.year;
+    final delta = max(1, ((lastYear - firstYear) / 5).ceil());
+
+    List<charts.TickSpec<DateTime>> ticks = [];
+    for (int year = firstYear; year <= lastYear; year += delta) {
+      final tickDate = DateTime(year);
+      ticks.add(charts.TickSpec<DateTime>(tickDate, label: dateFormat.format(tickDate)));
+    }
+    return TimeAxisSpec(ticks);
+  }
+}

lib/widgets/stats/histogram.dart

@@ -1,11 +1,14 @@
 import 'package:aves/model/entry.dart';
 import 'package:aves/model/filters/date.dart';
 import 'package:aves/theme/durations.dart';
+import 'package:aves/widgets/common/extensions/build_context.dart';
 import 'package:aves/widgets/common/identity/aves_filter_chip.dart';
+import 'package:aves/widgets/stats/date/axis.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:collection/collection.dart';
 import 'package:equatable/equatable.dart';
 import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
 import 'package:provider/provider.dart';
 
 class Histogram extends StatefulWidget {
@@ -24,6 +27,7 @@ class Histogram extends StatefulWidget {
 
 class _HistogramState extends State<Histogram> {
   DateLevel _level = DateLevel.y;
+  DateTime? _firstDate, _lastDate;
   final Map<DateTime, int> _entryCountPerDate = {};
   final ValueNotifier<EntryByDate?> _selection = ValueNotifier(null);
 
@@ -33,20 +37,20 @@ class _HistogramState extends State<Histogram> {
   void initState() {
     super.initState();
 
-    final entries = widget.entries;
-    final firstDate = entries.firstWhereOrNull((entry) => entry.bestDate != null)?.bestDate;
-    final lastDate = entries.lastWhereOrNull((entry) => entry.bestDate != null)?.bestDate;
+    final entriesByDateDescending = List.of(widget.entries)..sort(AvesEntry.compareByDate);
+    _lastDate = entriesByDateDescending.firstWhereOrNull((entry) => entry.bestDate != null)?.bestDate;
+    _firstDate = entriesByDateDescending.lastWhereOrNull((entry) => entry.bestDate != null)?.bestDate;
 
-    if (lastDate != null && firstDate != null) {
-      final range = firstDate.difference(lastDate);
-      if (range > const Duration(days: 1)) {
-        if (range < const Duration(days: 30)) {
+    if (_lastDate != null && _firstDate != null) {
+      final rangeDays = _lastDate!.difference(_firstDate!).inDays;
+      if (rangeDays > 1) {
+        if (rangeDays <= 31) {
           _level = DateLevel.ymd;
-        } else if (range < const Duration(days: 365)) {
+        } else if (rangeDays <= 365) {
           _level = DateLevel.ym;
         }
 
-        final dates = entries.map((entry) => entry.bestDate).whereNotNull();
+        final dates = entriesByDateDescending.map((entry) => entry.bestDate).whereNotNull();
         late DateTime Function(DateTime) groupByKey;
         switch (_level) {
           case DateLevel.ymd:
@@ -84,8 +88,18 @@ class _HistogramState extends State<Histogram> {
       ),
     ];
 
+    final locale = context.l10n.localeName;
+    final timeAxisSpec = _firstDate != null && _lastDate != null
+        ? TimeAxisSpec.forLevel(
+            locale: locale,
+            level: _level,
+            first: _firstDate!,
+            last: _lastDate!,
+          )
+        : null;
     final axisColor = charts.ColorUtil.fromDartColor(theme.colorScheme.onPrimary.withOpacity(.9));
     final measureLineColor = charts.ColorUtil.fromDartColor(theme.colorScheme.onPrimary.withOpacity(.1));
+    final measureFormat = NumberFormat.decimalPattern(locale);
 
     return Column(
       mainAxisSize: MainAxisSize.min,
@@ -100,12 +114,17 @@ class _HistogramState extends State<Histogram> {
                 labelStyle: charts.TextStyleSpec(color: axisColor),
                 lineStyle: charts.LineStyleSpec(color: axisColor),
               ),
+              tickProviderSpec: timeAxisSpec != null && timeAxisSpec.tickSpecs.isNotEmpty ? charts.StaticDateTimeTickProviderSpec(timeAxisSpec.tickSpecs) : null,
             ),
             primaryMeasureAxis: charts.NumericAxisSpec(
               renderSpec: charts.GridlineRendererSpec(
                 labelStyle: charts.TextStyleSpec(color: axisColor),
                 lineStyle: charts.LineStyleSpec(color: measureLineColor),
               ),
+              tickFormatterSpec: charts.BasicNumericTickFormatterSpec((v) {
+                // localize and hide 0
+                return (v == null || v == 0) ? '' : measureFormat.format(v);
+              }),
             ),
             defaultRenderer: charts.BarRendererConfig<DateTime>(),
             defaultInteractions: false,
@@ -152,6 +171,8 @@ class _HistogramState extends State<Histogram> {
 
             return AnimatedSwitcher(
               duration: context.read<DurationsData>().formTransition,
+              switchInCurve: Curves.easeInOutCubic,
+              switchOutCurve: Curves.easeInOutCubic,
               transitionBuilder: (child, animation) => FadeTransition(
                 opacity: animation,
                 child: SizeTransition(