Concider fraction digits when formatting chart side titles, #1267

CHANGELOG.md

@@ -2,6 +2,7 @@
 * **BUGFIX** (by @Anas35) Fix Tooltip not displaying when value from BackgroundBarChartRodData is less than zero. #1345.
 * **BUGFIX** (by @imaNNeo) Fix Negative BarChartRodStackItem are not drawn correctly bug, #1347
 * **BUGFIX** (by @imaNNeo) Fix bar_chart_helper minY calculation bug, #1388
+* **IMPROVEMENT** (by @imaNNeo) Consider fraction digits when formatting chart side titles, #1267
 
 ## 0.63.0
 * **BUGFIX** (by @imaNNeo) Fix PieChart crash on web-renderer html by ignoring `sectionsSpace` when `Path.combine()` does not work (it's flutter engine [issue](https://github.com/flutter/flutter/issues/44572)), #955

lib/src/chart/base/axis_chart/side_titles/side_titles_widget.dart

@@ -160,7 +160,11 @@ class SideTitlesWidget extends StatelessWidget {
               max: axisMax,
               appliedInterval: interval,
               sideTitles: sideTitles,
-              formattedValue: Utils().formatNumber(metaData.axisValue),
+              formattedValue: Utils().formatNumber(
+                axisMin,
+                axisMax,
+                metaData.axisValue,
+              ),
               axisSide: side,
               parentAxisSize: axisViewSize,
               axisPosition: metaData.axisPixelLocation,

lib/src/utils/utils.dart

@@ -211,33 +211,62 @@ class Utils {
   /// kilo (thousands) number
   static const double kilo = 1000;
 
+  /// Returns count of fraction digits of a value
+  int getFractionDigits(double value) {
+    if (value >= 1) {
+      return 1;
+    } else if (value >= 0.1) {
+      return 2;
+    } else if (value >= 0.01) {
+      return 3;
+    } else if (value >= 0.001) {
+      return 4;
+    } else if (value >= 0.0001) {
+      return 5;
+    } else if (value >= 0.00001) {
+      return 6;
+    } else if (value >= 0.000001) {
+      return 7;
+    } else if (value >= 0.0000001) {
+      return 8;
+    } else if (value >= 0.00000001) {
+      return 9;
+    } else if (value >= 0.000000001) {
+      return 10;
+    }
+    return 1;
+  }
+
   /// Formats and add symbols (K, M, B) at the end of number.
   ///
   /// if number is larger than [billion], it returns a short number like 13.3B,
   /// if number is larger than [million], it returns a short number line 43M,
   /// if number is larger than [kilo], it returns a short number like 4K,
   /// otherwise it returns number itself.
   /// also it removes .0, at the end of number for simplicity.
-  String formatNumber(double number) {
-    final isNegative = number < 0;
+  String formatNumber(double axisMin, double axisMax, double axisValue) {
+    final isNegative = axisValue < 0;
 
     if (isNegative) {
-      number = number.abs();
+      axisValue = axisValue.abs();
     }
 
     String resultNumber;
     String symbol;
-    if (number >= billion) {
-      resultNumber = (number / billion).toStringAsFixed(1);
+    if (axisValue >= billion) {
+      resultNumber = (axisValue / billion).toStringAsFixed(1);
       symbol = 'B';
-    } else if (number >= million) {
-      resultNumber = (number / million).toStringAsFixed(1);
+    } else if (axisValue >= million) {
+      resultNumber = (axisValue / million).toStringAsFixed(1);
       symbol = 'M';
-    } else if (number >= kilo) {
-      resultNumber = (number / kilo).toStringAsFixed(1);
+    } else if (axisValue >= kilo) {
+      resultNumber = (axisValue / kilo).toStringAsFixed(1);
       symbol = 'K';
     } else {
-      resultNumber = number.toStringAsFixed(1);
+      final diff = (axisMin - axisMax).abs();
+      resultNumber = axisValue.toStringAsFixed(
+        getFractionDigits(diff),
+      );
       symbol = '';
     }
 

pubspec.yaml

@@ -19,12 +19,12 @@ dependencies:
     sdk: flutter
 
 dev_dependencies:
-  build_runner: ^2.4.2
+  build_runner: ^2.4.6
   flutter_test:
     sdk: flutter
-  mockito: ^5.4.0
+  mockito: ^5.4.2
   vector_math: ^2.1.4 #Added to use in some generated codes of mockito
-  very_good_analysis: ^5.0.0
+  very_good_analysis: ^5.1.0
 
 screenshots:
   - description: 'LineChartSample1 and LineChartSample2'

test/chart/bar_chart/bar_chart_painter_test.dart

@@ -795,7 +795,7 @@ void main() {
       when(mockUtils.normalizeBorderSide(any, any)).thenReturn(BorderSide.none);
       when(mockUtils.calculateRotationOffset(any, any)).thenReturn(Offset.zero);
       when(mockUtils.getBestInitialIntervalValue(any, any, any)).thenReturn(0);
-      when(mockUtils.formatNumber(captureAny)).thenAnswer((inv) {
+      when(mockUtils.formatNumber(any, any, captureAny)).thenAnswer((inv) {
         final value = inv.positionalArguments[0] as double;
         return '${value.toInt()}';
       });
@@ -987,7 +987,7 @@ void main() {
       when(mockUtils.normalizeBorderSide(any, any)).thenReturn(BorderSide.none);
       when(mockUtils.calculateRotationOffset(any, any)).thenReturn(Offset.zero);
       when(mockUtils.getBestInitialIntervalValue(any, any, any)).thenReturn(0);
-      when(mockUtils.formatNumber(captureAny)).thenAnswer((inv) {
+      when(mockUtils.formatNumber(any, any, captureAny)).thenAnswer((inv) {
         final value = inv.positionalArguments[0] as double;
         return '${value.toInt()}';
       });
@@ -1182,7 +1182,7 @@ void main() {
       when(mockUtils.normalizeBorderSide(any, any)).thenReturn(BorderSide.none);
       when(mockUtils.calculateRotationOffset(any, any)).thenReturn(Offset.zero);
       when(mockUtils.getBestInitialIntervalValue(any, any, any)).thenReturn(0);
-      when(mockUtils.formatNumber(captureAny)).thenAnswer((inv) {
+      when(mockUtils.formatNumber(any, any, captureAny)).thenAnswer((inv) {
         final value = inv.positionalArguments[0] as double;
         return '${value.toInt()}';
       });