積層グラフで、指定した要素の色を変更するには、各シリーズのSymbolRenderingイベントを使用し、e.Indexで要素番号を指定してEngine.SetFillメソッド、SetStrokeメソッドを実行します。

以下に、シリーズ１の要素番号０，シリーズ２の要素番号１，シリーズ３の要素番号１ の色を変更するためのサンプルコードを記載します。



◎サンプルコード（VB）

Imports C1.Chart
Imports C1.Win.Chart

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        FlexChart1.Series.Clear()

        ' 積層棒グラフのデータ系列の作成
        FlexChart1.BeginUpdate()

        Dim item1 As Series = New Series() With
        {
            .Name = "系列1",
            .Binding = "Y",
            .BindingX = "X",
            .DataSource = New PointF() {New PointF(1, 1), New PointF(2, 1), New PointF(3, 1)}
        }
        FlexChart1.Series.Add(item1)

        Dim item2 As Series = New Series() With
        {
            .Name = "系列2",
            .Binding = "Y",
            .BindingX = "X",
            .DataSource = New PointF() {New PointF(1, 1), New PointF(2, 1), New PointF(3, 1)}
        }
        FlexChart1.Series.Add(item2)

        Dim item3 As Series = New Series() With
        {
            .Name = "系列3",
            .Binding = "Y",
            .BindingX = "X",
            .DataSource = New PointF() {New PointF(1, 2), New PointF(2, 2), New PointF(3, 2)}
        }
        FlexChart1.Series.Add(item3)

        ' チャートの設定
        FlexChart1.ChartType = ChartType.Column
        FlexChart1.Stacking = Stacking.Stacked
        FlexChart1.Legend.Position = Position.Bottom

        ' SymbolRenderingイベントの追加
        AddHandler item1.SymbolRendering, AddressOf series1_SymbolRendering
        AddHandler item2.SymbolRendering, AddressOf series2_SymbolRendering
        AddHandler item3.SymbolRendering, AddressOf series3_SymbolRendering

        FlexChart1.EndUpdate()
    End Sub

    ' 特定の要素の色を変更
    Private Sub series1_SymbolRendering(ByVal sender As Object, ByVal e As RenderSymbolEventArgs)
        If e.Index = 0 Then
            e.Engine.SetFill(Brushes.Red)
            e.Engine.SetStroke(Brushes.Red)
        End If
    End Sub

    Private Sub series2_SymbolRendering(ByVal sender As Object, ByVal e As RenderSymbolEventArgs)
        If e.Index = 1 Then
            e.Engine.SetFill(Brushes.Red)
            e.Engine.SetStroke(Brushes.Red)
        End If
    End Sub

    Private Sub series3_SymbolRendering(ByVal sender As Object, ByVal e As RenderSymbolEventArgs)
        If e.Index = 2 Then
            e.Engine.SetFill(Brushes.Red)
            e.Engine.SetStroke(Brushes.Red)
        End If
    End Sub
End Class

◎サンプルコード（C#）

using C1.Chart;
using C1.Win.Chart;

namespace prj_FlexChart_Stacked
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            flexChart1.Series.Clear();

            // 積層棒グラフのデータ系列の作成
            flexChart1.BeginUpdate();

            Series item1 = new Series()
            {
                Name = "系列1",
                Binding = "Y",
                BindingX = "X",
                DataSource = new PointF[] { new PointF(1, 1), new PointF(2, 1), new PointF(3, 1) }
            };
            flexChart1.Series.Add(item1);

            Series item2 = new Series()
            {
                Name = "系列1",
                Binding = "Y",
                BindingX = "X",
                DataSource = new PointF[] { new PointF(1, 1), new PointF(2, 1), new PointF(3, 1) }
            };
            flexChart1.Series.Add(item2);

            Series item3 = new Series()
            {
                Name = "系列1",
                Binding = "Y",
                BindingX = "X",
                DataSource = new PointF[] { new PointF(1, 2), new PointF(2, 2), new PointF(3, 2) }
            };
            flexChart1.Series.Add(item3);

            // チャートの設定
            flexChart1.ChartType = ChartType.Column;
            flexChart1.Stacking = Stacking.Stacked;
            flexChart1.Legend.Position = Position.Bottom;

            // SymbolRenderingイベントの追加
            item1.SymbolRendering += series1_SymbolRendering;
            item2.SymbolRendering += series2_SymbolRendering;
            item3.SymbolRendering += series3_SymbolRendering;
            flexChart1.EndUpdate();

        }

        // 特定の要素の色を変更
        private void series1_SymbolRendering(object sender, RenderSymbolEventArgs e)
        {
            if ((e.Index == 0))
            {
                e.Engine.SetFill(Brushes.Red);
                e.Engine.SetStroke(Brushes.Red);
            }
        }

        private void series2_SymbolRendering(object sender, RenderSymbolEventArgs e)
        {
            if ((e.Index == 1))
            {
                e.Engine.SetFill(Brushes.Red);
                e.Engine.SetStroke(Brushes.Red);
            }
        }

        private void series3_SymbolRendering(object sender, RenderSymbolEventArgs e)
        {
            if ((e.Index == 2))
            {
                e.Engine.SetFill(Brushes.Red);
                e.Engine.SetStroke(Brushes.Red);
            }
        }
    }
}