Handled click in scatter_chart.

example/lib/scatter_chart/samples/scatter_chart_sample2.dart

@@ -13,8 +13,6 @@ class _ScatterChartSample2State extends State {
 
   List<int> selectedSpots = [];
 
-  int lastPanStartOnIndex = -1;
-
   @override
   Widget build(BuildContext context) {
     return AspectRatio(
@@ -99,16 +97,14 @@ class _ScatterChartSample2State extends State {
                 tooltipBgColor: Colors.black,
               ),
               touchCallback: (ScatterTouchResponse touchResponse) {
-                if (touchResponse.touchInput is PointerDownEvent) {
-                  lastPanStartOnIndex = touchResponse.touchedSpotIndex;
-                } else if (touchResponse.touchInput is PointerUpEvent) {
-                  final PointerUpEvent PointerUpEven = touchResponse.touchInput;
+                if (touchResponse.clickHappened && touchResponse.touchedSpot != null) {
+                  final sectionIndex = touchResponse.touchedSpot.spotIndex;
                   // Tap happened
                   setState(() {
-                    if (selectedSpots.contains(lastPanStartOnIndex)) {
-                      selectedSpots.remove(lastPanStartOnIndex);
+                    if (selectedSpots.contains(sectionIndex)) {
+                      selectedSpots.remove(sectionIndex);
                     } else {
-                      selectedSpots.add(lastPanStartOnIndex);
+                      selectedSpots.add(sectionIndex);
                     }
                   });
                 }

lib/src/chart/scatter_chart/scatter_chart.dart

@@ -64,11 +64,12 @@ class _ScatterChartState extends AnimatedWidgetBaseState<ScatterChart> {
   void _handleBuiltInTouch(ScatterTouchResponse touchResponse) {
     widget.data.scatterTouchData.touchCallback?.call(touchResponse);
 
-    if (touchResponse.touchInput is PointerDownEvent ||
+    final desiredTouch = touchResponse.touchInput is PointerDownEvent ||
         touchResponse.touchInput is PointerMoveEvent ||
-        touchResponse.touchInput is PointerHoverEvent) {
+        touchResponse.touchInput is PointerHoverEvent;
+    if (desiredTouch && touchResponse.touchedSpot != null) {
       setState(() {
-        touchedSpots = [touchResponse.touchedSpotIndex];
+        touchedSpots = [touchResponse.touchedSpot!.spotIndex];
       });
     } else {
       setState(() {

lib/src/chart/scatter_chart/scatter_chart_data.dart

@@ -290,23 +290,58 @@ typedef ScatterTouchCallback = void Function(ScatterTouchResponse);
 /// You can override [ScatterTouchData.touchCallback] to handle touch events,
 /// it gives you a [ScatterTouchResponse] and you can do whatever you want.
 class ScatterTouchResponse extends BaseTouchResponse {
-  final ScatterSpot? touchedSpot;
-  final int touchedSpotIndex;
+  final ScatterTouchedSpot? touchedSpot;
 
   /// If touch happens, [ScatterChart] processes it internally and
   /// passes out a [ScatterTouchResponse], it gives you information about the touched spot.
   ///
-  /// [touchedSpot], and [touchedSpotIndex] tells you
+  /// [touchedSpot] tells you
   /// in which spot (of [ScatterChartData.scatterSpots]) touch happened.
   ///
   /// [touchInput] is the type of happened touch.
+  ///
+  /// [clickHappened] will be true, if we detect a click event.
   ScatterTouchResponse(
     PointerEvent touchInput,
-    ScatterSpot? touchedSpot,
-    int touchedSpotIndex,
+    ScatterTouchedSpot? touchedSpot,
+    bool clickHappened,
   )   : touchedSpot = touchedSpot,
-        touchedSpotIndex = touchedSpotIndex,
-        super(touchInput);
+        super(touchInput, clickHappened);
+
+  /// Copies current [ScatterTouchResponse] to a new [ScatterTouchResponse],
+  /// and replaces provided values.
+  ScatterTouchResponse copyWith({
+    PointerEvent? touchInput,
+    ScatterTouchedSpot? touchedSpot,
+    bool? clickHappened,
+  }) {
+    return ScatterTouchResponse(
+      touchInput ?? this.touchInput,
+      touchedSpot ?? this.touchedSpot,
+      clickHappened ?? this.clickHappened,
+    );
+  }
+}
+
+/// Holds the touched spot data
+class ScatterTouchedSpot with EquatableMixin {
+
+  /// Touch happened on this spot
+  final ScatterSpot spot;
+
+  /// Touch happened on this spot index
+  final int spotIndex;
+
+  /// [spot], and [spotIndex] tells you
+  /// in which spot (of [ScatterChartData.scatterSpots]) touch happened.
+  ScatterTouchedSpot(this.spot, this.spotIndex);
+
+  /// Used for equality check, see [EquatableMixin].
+  @override
+  List<Object?> get props => [
+    spot,
+    spotIndex,
+  ];
 }
 
 /// Holds representation data for showing tooltip popup on top of spots.

lib/src/chart/scatter_chart/scatter_chart_painter.dart

@@ -417,12 +417,14 @@ class ScatterChartPainter extends AxisChartPainter<ScatterChartData> {
     return sum;
   }
 
-  /// Makes a [ScatterTouchResponse] based on the provided [FlTouchInput]
+  /// Makes a [ScatterTouchedSpot] based on the provided [touchInput]
   ///
-  /// Processes [FlTouchInput.getOffset] and checks
+  /// Processes [touchInput.localPosition] and checks
   /// the elements of the chart that are near the offset,
-  /// then makes a [ScatterTouchResponse] from the elements that has been touched.
-  ScatterTouchResponse handleTouch(
+  /// then makes a [ScatterTouchedSpot] from the elements that has been touched.
+  /// 
+  /// Returns null if finds nothing!
+  ScatterTouchedSpot? handleTouch(
     PointerEvent touchInput,
     Size size,
     PaintHolder<ScatterChartData> holder,
@@ -440,10 +442,9 @@ class ScatterChartPainter extends AxisChartPainter<ScatterChartData> {
               (spot.radius / 2) + data.scatterTouchData.touchSpotThreshold &&
           (touchInput.localPosition.dy - spotPixelY).abs() <=
               (spot.radius / 2) + data.scatterTouchData.touchSpotThreshold) {
-        return ScatterTouchResponse(touchInput, spot, i);
+        return ScatterTouchedSpot(spot, i);
       }
     }
-
-    return ScatterTouchResponse(touchInput, null, -1);
+    return null;
   }
 }

lib/src/chart/scatter_chart/scatter_chart_renderer.dart

@@ -75,6 +75,8 @@ class RenderScatterChart extends RenderBox {
     return PaintHolder(data, targetData, textScale);
   }
 
+  ScatterTouchedSpot? _lastTouchedSpot;
+
   @override
   void performLayout() {
     size = computeDryLayout(constraints);
@@ -99,6 +101,27 @@ class RenderScatterChart extends RenderBox {
 
   @override
   void handleEvent(PointerEvent event, covariant BoxHitTestEntry entry) {
-    _touchCallback?.call(_painter.handleTouch(event, size, paintHolder));
+    if (_touchCallback == null) {
+      return;
+    }
+    var response = ScatterTouchResponse(event, null, false);
+
+    var touchedSpot = _painter.handleTouch(event, size, paintHolder);
+    if (touchedSpot == null) {
+      _touchCallback!.call(response);
+      return;
+    }
+    response = response.copyWith(touchedSpot: touchedSpot);
+
+    if (event is PointerDownEvent) {
+      _lastTouchedSpot = touchedSpot;
+    } else if (event is PointerUpEvent) {
+      if (_lastTouchedSpot != null && _lastTouchedSpot == touchedSpot) {
+        response = response.copyWith(clickHappened: true);
+      }
+      _lastTouchedSpot = null;
+    }
+
+    _touchCallback!.call(response);
   }
 }