Add FlDotCrossPainter

CHANGELOG.md

@@ -3,6 +3,7 @@
 * [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).
 * [IMPROVEMENT] Enabled `sectionsSpace` in PieChart for the web.
 * [IMPROVEMENT] Added [Makefile](https://makefiletutorial.com) commands which makes it comfortable for verifying your code before push (It is related to contributors, red more about it in [CONTRIBUTING.md](https://github.com/imaNNeoFighT/fl_chart/blob/master/CONTRIBUTING.md)).
+* [IMPROVEMENT] Added `FlDotCrossPainter` which extends `FlDotPainter` to paint X marks on line chart spots.
 * [BUGFIX] Fixed some bugs on drawing PieChart (for example when we have only one section), #582, 
 * [BREAKING] Border of pieChart now is hide by default (you can show it using `borderData: FlBorderData(show: true)`.
 * [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.

lib/src/chart/line_chart/line_chart_data.dart

@@ -923,6 +923,62 @@ class FlDotSquarePainter extends FlDotPainter {
       ];
 }
 
+/// This class is an implementation of a [FlDotPainter] that draws
+/// a cross (X mark) shape
+class FlDotCrossPainter extends FlDotPainter {
+  /// The fill color to use for the X mark
+  Color color;
+
+  /// Determines size (width and height) of shape.
+  double size;
+
+  /// Determines thickness of X mark.
+  double width;
+
+  /// The [color] and [width] properties determines the color and thickness of the cross shape,
+  /// [size] determines the width and height of the shape.
+  FlDotCrossPainter({
+    Color? color,
+    double? size,
+    double? width,
+  })  : color = color ?? Colors.green,
+        size = size ?? 8.0,
+        width = width ?? 2.0;
+
+  /// Implementation of the parent class to draw the cross
+  @override
+  void draw(Canvas canvas, FlSpot spot, Offset offsetInCanvas) {
+    final path = Path()
+      ..moveTo(offsetInCanvas.dx, offsetInCanvas.dy)
+      ..relativeMoveTo(-size / 2, -size / 2)
+      ..relativeLineTo(size, size)
+      ..moveTo(offsetInCanvas.dx, offsetInCanvas.dy)
+      ..relativeMoveTo(size / 2, -size / 2)
+      ..relativeLineTo(-size, size);
+
+    final paint = Paint()
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = width
+      ..color = color;
+
+    canvas.drawPath(path, paint);
+  }
+
+  /// Implementation of the parent class to get the size of the circle
+  @override
+  Size getSize(FlSpot spot) {
+    return Size(size, size);
+  }
+
+  /// Used for equality check, see [EquatableMixin].
+  @override
+  List<Object?> get props => [
+        color,
+        size,
+        width,
+      ];
+}
+
 /// It determines showing or hiding [FlDotData] on the spots.
 ///
 /// It gives you the checking [FlSpot] and you should decide to