fixes #1555

Updated ViewModel to modify ScatterSeries configurations, including changing GeometrySize from 50 to 100 and adding a new ScatterSeries with StackGroup. In CoreScatterSeries.cs, removed _weightBounds and added _stackGroup, _minGeometrySize, and _geometrySize fields. Updated MinGeometrySize and GeometrySize properties, added StackGroup property, and modified Invalidate and GetBounds methods to use StackGroup. In SeriesContext.cs, added _weightBounds dictionary and methods to manage weight bounds. Added StackGroup property to IScatterSeries.cs.

samples/ViewModelsSamples/Scatter/Bubbles/ViewModel.cs

@@ -42,14 +42,25 @@ public ViewModel()
             new ScatterSeries<WeightedPoint>
             {
                 Values = values1,
-                GeometrySize = 50,
-                MinGeometrySize = 5
+                GeometrySize = 100,
+                MinGeometrySize = 5,
             },
             new ScatterSeries<WeightedPoint, RoundedRectangleGeometry>
             {
                 Values = values2,
-                GeometrySize = 50,
-                MinGeometrySize = 5
+                GeometrySize = 100,
+                MinGeometrySize = 5,
+                StackGroup = 1
+            },
+            new ScatterSeries<WeightedPoint>
+            {
+                Values = [ new() { X = 10, Y = 10, Weight = 500 } ],
+                GeometrySize = 100,
+                MinGeometrySize = 5,
+                // use the stack group to shhare the Weight between series. // mark
+                // in this case, the previous series shares the same
+                // StackGroup, thus series share the Weigth bounds.
+                StackGroup = 1
             }
         ];
     }

src/LiveChartsCore/CoreScatterSeries.cs

@@ -21,7 +21,6 @@
 // SOFTWARE.
 
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using LiveChartsCore.Drawing;
 using LiveChartsCore.Kernel;
@@ -48,8 +47,10 @@ public class CoreScatterSeries<TModel, TVisual, TLabel, TDrawingContext, TErrorG
         where TDrawingContext : DrawingContext
         where TErrorGeometry : class, ILineGeometry<TDrawingContext>, new()
 {
-    private Bounds _weightBounds = new();
     private IPaint<TDrawingContext>? _errorPaint;
+    private int? _stackGroup;
+    private double _minGeometrySize = 6d;
+    private double _geometrySize = 24d;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="CoreScatterSeries{TModel, TVisual, TLabel, TDrawingContext, TErrorGeometry}"/> class.
@@ -80,15 +81,14 @@ public CoreScatterSeries(ICollection<TModel>? values)
     /// <value>
     /// The minimum size of the geometry.
     /// </value>
-    public double MinGeometrySize { get; set; } = 6d;
-
+    public double MinGeometrySize { get => _minGeometrySize; set => SetProperty(ref _minGeometrySize, value); }
     /// <summary>
     /// Gets or sets the size of the geometry.
     /// </summary>
     /// <value>
     /// The size of the geometry.
     /// </value>
-    public double GeometrySize { get; set; } = 24d;
+    public double GeometrySize { get => _geometrySize; set =>SetProperty(ref _geometrySize, value); }
 
     /// <summary>
     /// Gets a value indicating whether the points in this series use weight.
@@ -102,6 +102,9 @@ public IPaint<TDrawingContext>? ErrorPaint
         set => SetPaintProperty(ref _errorPaint, value, true);
     }
 
+    /// <inheritdoc cref="IScatterSeries{TDrawingContext}.StackGroup"/>
+    public int? StackGroup { get => _stackGroup; set => SetProperty(ref _stackGroup, value); }
+
     /// <inheritdoc cref="ChartElement{TDrawingContext}.Invalidate(Chart{TDrawingContext})"/>
     public override void Invalidate(Chart<TDrawingContext> chart)
     {
@@ -117,6 +120,9 @@ public override void Invalidate(Chart<TDrawingContext> chart)
         var actualZIndex = ZIndex == 0 ? ((ISeries)this).SeriesId : ZIndex;
         var clipping = GetClipRectangle(cartesianChart);
 
+        var weightStackIndex = StackGroup ?? ((ISeries)this).SeriesId;
+        var weightBounds = chart.SeriesContext.GetWeightBounds(weightStackIndex);
+
         if (Fill is not null)
         {
             Fill.ZIndex = actualZIndex + 0.1;
@@ -148,8 +154,8 @@ public override void Invalidate(Chart<TDrawingContext> chart)
         var gs = (float)GeometrySize;
         var hgs = gs / 2f;
         var sw = Stroke?.StrokeThickness ?? 0;
-        IsWeighted = _weightBounds.Max - _weightBounds.Min > 0;
-        var wm = -(GeometrySize - MinGeometrySize) / (_weightBounds.Max - _weightBounds.Min);
+        IsWeighted = weightBounds.Max - weightBounds.Min > 0;
+        var wm = -(GeometrySize - MinGeometrySize) / (weightBounds.Max - weightBounds.Min);
 
         var uwx = xScale.MeasureInPixels(secondaryAxis.UnitWidth);
         var uwy = yScale.MeasureInPixels(secondaryAxis.UnitWidth);
@@ -188,7 +194,7 @@ public override void Invalidate(Chart<TDrawingContext> chart)
 
             if (IsWeighted)
             {
-                gs = (float)(wm * (_weightBounds.Max - coordinate.TertiaryValue) + GeometrySize);
+                gs = (float)(wm * (weightBounds.Max - coordinate.TertiaryValue) + GeometrySize);
                 hgs = gs / 2f;
             }
 
@@ -310,7 +316,10 @@ public override void Invalidate(Chart<TDrawingContext> chart)
     public override SeriesBounds GetBounds(CartesianChart<TDrawingContext> chart, ICartesianAxis secondaryAxis, ICartesianAxis primaryAxis)
     {
         var seriesBounds = base.GetBounds(chart, secondaryAxis, primaryAxis);
-        _weightBounds = seriesBounds.Bounds.TertiaryBounds;
+
+        chart.SeriesContext.AppendWeightBounds(
+            StackGroup ?? ((ISeries)this).SeriesId, seriesBounds.Bounds.TertiaryBounds);
+
         return seriesBounds;
     }
 

src/LiveChartsCore/Kernel/SeriesContext.cs

@@ -55,6 +55,7 @@ public class SeriesContext<TDrawingContext>(IEnumerable<IChartSeries<TDrawingCon
     private readonly Dictionary<IChartSeries<TDrawingContext>, int> _boxPositions = [];
     private readonly Dictionary<int, int> _stackColumnPositions = [];
     private readonly Dictionary<int, int> _stackRowsPositions = [];
+    private readonly Dictionary<int, Bounds> _weightBounds = [];
 
     private readonly Dictionary<string, Stacker<TDrawingContext>> _stackers = [];
 
@@ -311,4 +312,36 @@ private void CalculatePieLabelsOuterSpace<TLabel>()
     }
 
     #endregion
+
+    #region scatter
+
+    /// <summary>
+    /// Gets the weight bounds.
+    /// </summary>
+    /// <param name="key"></param>
+    /// <returns></returns>
+    public Bounds GetWeightBounds(int key)
+    {
+        if (_weightBounds.TryGetValue(key, out var bounds)) return bounds;
+
+        bounds = new Bounds();
+        _weightBounds[key] = bounds;
+
+        return bounds;
+    }
+
+    /// <summary>
+    /// Appends the weight bounds.
+    /// </summary>
+    /// <param name="key"></param>
+    /// <param name="value"></param>
+    public void AppendWeightBounds(int key, Bounds value)
+    {
+        var bounds = GetWeightBounds(key);
+
+        if (value.Max > bounds.Max) bounds.Max = value.Max;
+        if (value.Min < bounds.Min) bounds.Min = value.Min;
+    }
+
+    #endregion
 }

src/LiveChartsCore/Kernel/Sketches/IScatterSeries.cs

@@ -48,4 +48,10 @@ public interface IScatterSeries<TDrawingContext> :
     /// The minimum size of the geometry.
     /// </value>
     double MinGeometrySize { get; set; }
+
+    /// <summary>
+    /// Gets or sets and index for the stack group, if multiple weighed series share
+    /// the same stack group, they will be stacked, defualt is null and means that it is not stacked.
+    /// </summary>
+    int? StackGroup { get; set; }
 }