Calculating side titles and horizontal lines from minY value

lib/src/chart/base/axis_chart/axis_chart_data.dart

@@ -185,6 +185,7 @@ class SideTitles with EquatableMixin {
     this.getTitlesWidget = defaultGetTitle,
     this.reservedSize = 22,
     this.interval,
+    this.startMin = false,
     this.minIncluded = true,
     this.maxIncluded = true,
   }) : assert(interval != 0, "SideTitles.interval couldn't be zero");
@@ -209,6 +210,9 @@ class SideTitles with EquatableMixin {
   /// we try to find a suitable value to set as [interval] under the hood.
   final double? interval;
 
+  /// If [startMin] is true, then the interval will start from the min value.
+  final bool startMin;
+
   /// If true (default), a title for the minimum data value is included
   /// independent of the sampling interval
   final bool minIncluded;
@@ -587,6 +591,7 @@ class FlGridData with EquatableMixin {
     this.verticalInterval,
     this.getDrawingVerticalLine = defaultGridLine,
     this.checkToShowVerticalLine = showAllGrids,
+    this.startMin = false,
   })  : assert(
           horizontalInterval != 0,
           "FlGridData.horizontalInterval couldn't be zero",
@@ -623,6 +628,9 @@ class FlGridData with EquatableMixin {
   /// Gives you a x value, and gets a boolean that determines showing or hiding specified line.
   final CheckToShowGrid checkToShowVerticalLine;
 
+  /// If true then the horizontal interval will start from the min value.
+  final bool startMin;
+
   /// Lerps a [FlGridData] based on [t] value, check [Tween.lerp].
   static FlGridData lerp(FlGridData a, FlGridData b, double t) => FlGridData(
         show: b.show,

lib/src/chart/base/axis_chart/axis_chart_helper.dart

@@ -27,9 +27,16 @@ class AxisChartHelper {
     bool maxIncluded = true,
     required double baseLine,
     required double interval,
+    bool startMin = false,
   }) sync* {
-    final initialValue = Utils()
-        .getBestInitialIntervalValue(min, max, interval, baseline: baseLine);
+    final initialValue = startMin
+        ? min
+        : Utils().getBestInitialIntervalValue(
+            min,
+            max,
+            interval,
+            baseline: baseLine,
+          );
     var axisSeek = initialValue;
     final firstPositionOverlapsWithMin = axisSeek == min;
     if (!minIncluded && firstPositionOverlapsWithMin) {

lib/src/chart/base/axis_chart/axis_chart_painter.dart

@@ -72,6 +72,7 @@ abstract class AxisChartPainter<D extends AxisChartData>
         maxIncluded: false,
         baseLine: data.baselineX,
         interval: verticalInterval,
+        startMin: data.gridData.startMin,
       );
       for (final axisValue in axisValues) {
         if (!data.gridData.checkToShowVerticalLine(axisValue)) {
@@ -117,6 +118,7 @@ abstract class AxisChartPainter<D extends AxisChartData>
         maxIncluded: false,
         baseLine: data.baselineY,
         interval: horizontalInterval,
+        startMin: data.gridData.startMin,
       );
       for (final axisValue in axisValues) {
         if (!data.gridData.checkToShowHorizontalLine(axisValue)) {
@@ -125,6 +127,7 @@ abstract class AxisChartPainter<D extends AxisChartData>
         final flLine = data.gridData.getDrawingHorizontalLine(axisValue);
 
         final bothY = getPixelY(axisValue, viewSize, holder);
+
         const x1 = 0.0;
         final y1 = bothY;
         final x2 = viewSize.width;

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

@@ -165,6 +165,7 @@ class _SideTitlesWidgetState extends State<SideTitlesWidget> {
         maxIncluded: sideTitles.maxIncluded,
         baseLine: axisBaseLine,
         interval: interval,
+        startMin: sideTitles.startMin,
       );
       axisPositions = axisValues.map((axisValue) {
         final axisDiff = axisMax - axisMin;