Fixed PieChart draw problem, imaNNeo#582.

CHANGELOG.md

@@ -1,6 +1,8 @@
 ## newVersion
 * [IMPROVEMENT] Added `children` property in the [LineTooltipItem](https://github.com/imaNNeoFighT/fl_chart/blob/master/repo_files/documentations/line_chart.md#linetooltipitem), [BarTooltipItem](https://github.com/imaNNeoFighT/fl_chart/blob/master/repo_files/documentations/bar_chart.md#bartooltipitem) and [ScatterTooltipItem](https://github.com/imaNNeoFighT/fl_chart/blob/master/repo_files/documentations/scatter_chart.md#scattertooltipitem) which accepts a list of [TextSpan](https://api.flutter.dev/flutter/painting/TextSpan-class.html). It allows you to have more customized texts inside the tooltip. See [BarChartSample1](https://github.com/imaNNeoFighT/fl_chart/blob/master/repo_files/documentations/bar_chart.md#sample-1-source-code) and [ScatterSample2](https://github.com/imaNNeoFighT/fl_chart/blob/master/repo_files/documentations/scatter_chart.md#sample-2-source-code).
 * [IMPROVEMENT] Added `getTouchLineStart` and `getTouchLineEnd` in [LineTouchData](https://github.com/imaNNeoFighT/fl_chart/blob/master/repo_files/documentations/line_chart.md#linetouchdata-read-about-touch-handling) to give more customizability over showing the touch lines. see [SampleLineChart9](https://github.com/imaNNeoFighT/fl_chart/blob/master/repo_files/documentations/line_chart.md#sample-8-source-code).
+* [BUGFIX] Fixed some bugs on drawing PieChart (for example when we have only one section), #582, 
+* [BREAKING] You cannot set `0` value on [PieChartSectionData](https://github.com/imaNNeoFighT/fl_chart/blob/master/repo_files/documentations/pie_chart.md#piechartsectiondata).value anymore, instead remove it from list.
 * [BREAKING] Removed `fullHeightTouchLine` property from [LineTouchData](https://github.com/imaNNeoFighT/fl_chart/blob/master/repo_files/documentations/line_chart.md#linetouchdata-read-about-touch-handling). Now you can have a full line with following snippet:
 ```dart
 LineTouchData(

lib/src/chart/pie_chart/pie_chart_data.dart

@@ -54,7 +54,10 @@ class PieChartData extends BaseChartData with EquatableMixin {
     double? startDegreeOffset,
     PieTouchData? pieTouchData,
     FlBorderData? borderData,
-  })  : assert(!_sectionsContainsZero(sections), "section's value can't be zero", ),
+  })  : assert(
+          !_sectionsContainsZero(sections),
+          "section's value can't be zero",
+        ),
         sections = sections ?? const [],
         centerSpaceRadius = centerSpaceRadius ?? double.infinity,
         centerSpaceColor = centerSpaceColor ?? Colors.transparent,

lib/src/chart/pie_chart/pie_chart_painter.dart

@@ -73,7 +73,7 @@ class PieChartPainter extends BaseChartPainter<PieChartData> {
     PaintHolder<PieChartData> holder,
   ) {
     final data = holder.data;
-    final shouldDrawSeparators = data.sectionsSpace != 0 && data.sections.length != 1;
+    final shouldDrawSeparators = data.sectionsSpace != 0 && data.sections.length > 1;
 
     final viewSize = canvasWrapper.size;
 
@@ -99,8 +99,13 @@ class PieChartPainter extends BaseChartPainter<PieChartData> {
         radius: centerRadius,
       );
 
-      _sectionPaint.color = section.color;
-      _sectionPaint.strokeWidth = section.radius;
+      if (sectionDegree == 360) {
+        _sectionPaint.color = section.color;
+        _sectionPaint.strokeWidth = section.radius;
+        _sectionPaint.style = PaintingStyle.stroke;
+        canvasWrapper.drawCircle(center, centerRadius + section.radius / 2, _sectionPaint);
+        return;
+      }
 
       final startRadians = radians(tempAngle);
       final sweepRadians = radians(sectionDegree);
@@ -112,13 +117,14 @@ class PieChartPainter extends BaseChartPainter<PieChartData> {
       final startLine = Line(startLineFrom, startLineTo);
 
       final endLineDirection = Offset(math.cos(endRadians), math.sin(endRadians));
-      final endLineFrom = center + endLineDirection * data.centerSpaceRadius;
+      final endLineFrom = center + endLineDirection * centerRadius;
       final endLineTo = endLineFrom + endLineDirection * section.radius;
       final endLine = Line(endLineFrom, endLineTo);
 
       final sectionPath = _generateSectionPath(
           startLine, endLine, startRadians, endRadians, sectionRadiusRect, centerRadiusRect);
 
+      _sectionPaint.color = section.color;
       _sectionPaint.style = PaintingStyle.fill;
       canvasWrapper.drawPath(sectionPath, _sectionPaint);
       tempAngle += sectionDegree;

lib/src/chart/pie_chart/pie_chart_renderer.dart

@@ -110,11 +110,15 @@ class RenderPieChart extends RenderBox
     var counter = 0;
     var badgeOffsets = _painter.getBadgeOffsets(size, paintHolder);
     while (child != null) {
+      if (counter >= badgeOffsets.length) {
+        break;
+      }
       child.layout(childConstraints, parentUsesSize: true);
       final childParentData = child.parentData! as MultiChildLayoutParentData;
       final sizeOffset = Offset(child.size.width / 2, child.size.height / 2);
-      childParentData.offset = badgeOffsets[counter++]! - sizeOffset;
+      childParentData.offset = badgeOffsets[counter]! - sizeOffset;
       child = childParentData.nextSibling;
+      counter++;
     }
   }