Add shrink wrap for bar chart when overflow

lib/src/extensions/bar_chart_data_extension.dart

@@ -10,10 +10,19 @@ extension BarChartDataExtension on BarChartData {
     final spaceAvailable = viewWidth - sumWidth;
 
     void spaceEvenly() {
-      final eachSpace = spaceAvailable / (barGroups.length + 1);
+      if (barGroups.length == 1) {
+        groupsX[0] = viewWidth / 2;
+        return;
+      }
+
+      final eachSpace = spaceAvailable / (barGroups.length - 1);
+
       var tempX = 0.0;
       barGroups.asMap().forEach((i, group) {
-        tempX += eachSpace;
+        if (i != 0) {
+          tempX += eachSpace;
+        }
+
         tempX += group.width / 2;
         groupsX[i] = tempX;
         tempX += group.width / 2;

test/chart/bar_chart/bar_chart_painter_test.dart

@@ -615,7 +615,7 @@ void main() {
       expect(callWithAlignment(BarChartAlignment.end), [80.0, 122.5, 172.5]);
       expect(
         callWithAlignment(BarChartAlignment.spaceEvenly),
-        [40, 92.5, 152.5],
+        [20.0, 92.5, 172.5],
       );
       expect(
         callWithAlignment(BarChartAlignment.spaceAround),

test/extensions/bar_chart_data_extensions_test.dart

@@ -7,46 +7,48 @@ import '../chart/data_pool.dart';
 void main() {
   group('BarChartDataExtension.calculateGroupsX', () {
     test('calculates correct positions for basic alignments', () {
+      const width = 200.0;
+
       expect(
         MockData.barChartData1
             .copyWith(alignment: BarChartAlignment.start)
-            .calculateGroupsX(100),
+            .calculateGroupsX(width),
         [9.0, 43.0, 77.0],
       );
 
       expect(
         MockData.barChartData1
             .copyWith(alignment: BarChartAlignment.end)
-            .calculateGroupsX(100),
-        [23.0, 57.0, 91.0],
+            .calculateGroupsX(width),
+        [123.0, 157.0, 191.0],
       );
 
       expect(
         MockData.barChartData1
             .copyWith(alignment: BarChartAlignment.center)
-            .calculateGroupsX(100),
-        [16.0, 50.0, 84.0],
+            .calculateGroupsX(width),
+        [66.0, 100.0, 134.0],
       );
 
       expect(
         MockData.barChartData1
             .copyWith(alignment: BarChartAlignment.spaceBetween)
-            .calculateGroupsX(100),
-        [9.0, 50.0, 91.0],
+            .calculateGroupsX(width),
+        [9.0, 100.0, 191.0],
       );
 
       expect(
         MockData.barChartData1
             .copyWith(alignment: BarChartAlignment.spaceAround)
-            .calculateGroupsX(100),
-        [16.666666666666668, 50.0, 83.33333333333334],
+            .calculateGroupsX(width),
+        [33.33333333333333, 99.99999999999999, 166.66666666666666],
       );
 
       expect(
         MockData.barChartData1
             .copyWith(alignment: BarChartAlignment.spaceEvenly)
-            .calculateGroupsX(100),
-        [20.5, 50.0, 79.5],
+            .calculateGroupsX(width),
+        [9.0, 100.0, 191.0],
       );
     });
 
@@ -62,7 +64,7 @@ void main() {
             MockData.barChartData1
                 .copyWith(alignment: alignment)
                 .calculateGroupsX(60),
-            [10.5, 30.0, 49.5],
+            [9.0, 30.0, 51.0],
           );
         },
       );
@@ -75,5 +77,12 @@ void main() {
         throwsAssertionError,
       );
     });
+
+    test('Test shrinkWrapOnWidthOverflow calcualtes spacing correctly', () {
+      expect(
+        MockData.barChartData1.calculateGroupsX(100),
+        [9.0, 50.0, 91.0],
+      );
+    });
   });
 }