FlexChartの横棒グラフ（ChartType.Bar）を使用し、1行に複数のタスクを表示したガントチャートを作成する方法を紹介します。

最初に、タスクを表す「Taskクラス」を作成し、タスクのIDEx／StartEx／EndExプロパティ（それぞれ、タスクのID値／開始時間／終了時間に該当）を定義します。
次いで、同じID値を持つ複数のデータを設定し、Series_SymbolRenderingイベントで、独自に横棒（バー）を描画することで、1行に複数のタスクを表示したガントチャートを生成します。



◎サンプルコード（VB）

Imports C1.Chart
Imports C1.Win.Chart

Public Class Form1
    Dim testTask1 As List(Of Task)
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ' データの作成
        testTask1 = New List(Of Task)()
        Dim tempRect = New Rectangle()
        testTask1.Add(New Task(0, 2, 0, tempRect, Color.FromArgb(171, 208, 237)))
        testTask1.Add(New Task(0, 5, 3, tempRect, Color.FromArgb(171, 208, 237)))
        testTask1.Add(New Task(1, 6, 4, tempRect, Color.FromArgb(177, 220, 182)))
        testTask1.Add(New Task(1, 9, 7, tempRect, Color.FromArgb(177, 220, 182)))
        testTask1.Add(New Task(2, 8, 6, tempRect, Color.FromArgb(252, 201, 137)))
        testTask1.Add(New Task(2, 11, 9, tempRect, Color.FromArgb(252, 201, 137)))
        testTask1.Add(New Task(3, 10, 9, tempRect, Color.FromArgb(248, 195, 217)))
        testTask1.Add(New Task(3, 12, 11, tempRect, Color.FromArgb(248, 195, 217)))
        testTask1.Add(New Task(3, 14, 13, tempRect, Color.FromArgb(248, 195, 217)))
        testTask1.Add(New Task(4, 12, 10, tempRect, Color.FromArgb(185, 185, 247)))
        testTask1.Add(New Task(4, 15, 13, tempRect, Color.FromArgb(185, 185, 247)))
        testTask1.Add(New Task(4, 18, 16, tempRect, Color.FromArgb(185, 185, 247)))

        ' 描画の停止
        FlexChart1.BeginUpdate()

        ' ガントチャートの作成
        FlexChart1.ChartType = ChartType.Bar
        Dim series1 As Series = New Series()
        series1.Name = "Series1"
        series1.DataSource = testTask1
        series1.BindingX = "IDEx"
        series1.Binding = "EndEx"
        AddHandler series1.SymbolRendering, AddressOf Series_SymbolRendering
        FlexChart1.Series.Clear()
        FlexChart1.Series.Add(series1)
        FlexChart1.Legend.Position = Position.None
        FlexChart1.Stacking = Stacking.Stacked
        FlexChart1.ToolTip.Content = "ID={ID} Start={Start} End={End}"
        FlexChart1.ToolTip.Active = False

        ' 軸ラベルの設定
        Dim axisLabels = New KeyValuePair(Of Int32, String)(4) {}
        axisLabels(0) = New KeyValuePair(Of Int32, String)(0, "A")
        axisLabels(1) = New KeyValuePair(Of Int32, String)(1, "B")
        axisLabels(2) = New KeyValuePair(Of Int32, String)(2, "C")
        axisLabels(3) = New KeyValuePair(Of Int32, String)(3, "D")
        axisLabels(4) = New KeyValuePair(Of Int32, String)(4, "E")
        FlexChart1.AxisY.DataSource = axisLabels
        FlexChart1.AxisY.Binding = "Key,Value"

        ' 軸の最小値／最大値の設定
        Dim vMin As Integer = Integer.MaxValue
        Dim vMax As Integer = Integer.MinValue
        For i As Integer = 0 To testTask1.Count - 1
            If testTask1(i).StartEx < vMin Then
                vMin = testTask1(i).StartEx
            End If
            If testTask1(i).EndEx > vMax Then
                vMax = testTask1(i).EndEx
            End If
        Next
        FlexChart1.AxisX.Min = vMin
        FlexChart1.AxisX.Max = vMax

        ' 描画の再開
        FlexChart1.EndUpdate()
    End Sub

    Private Sub Series_SymbolRendering(ByVal sender As Object, ByVal e As RenderSymbolEventArgs)
        ' 既定の描画のキャンセル
        e.Cancel = True

        ' 独自にバーを描画
        Dim task As Task = CType(e.Item, Task)
        Dim height As Double = FlexChart1.PlotRect.Height / testTask1.Count / 2
        Dim left As Double = FlexChart1.AxisX.Convert(task.StartEx)
        Dim right As Double = FlexChart1.AxisX.Convert(task.EndEx)
        e.Engine.SetFill(New SolidBrush(testTask1(e.Index).ColorEx))
        e.Engine.SetStroke(New SolidBrush(Color.FromArgb(200, testTask1(e.Index).ColorEx)))
        e.Engine.DrawRect(left, e.Point.Y - (height / 2), right - left, height)

        ' 描画したバーの矩形（MouseMoveイベントで利用）を保存
        testTask1(e.Index).RectangleEx = New RectangleF(CType(left, Single), CType((e.Point.Y _
                        - (height / 2)), Single), CType((right - left), Single), CType(height, Single))
    End Sub

    Private Sub FlexChart1_MouseMove(sender As Object, e As MouseEventArgs) Handles FlexChart1.MouseMove
        ' バー以外ではツールチップを非表示に設定
        Dim isContained = False
        For Each task As Task In testTask1
            If task.RectangleEx.Contains(e.Location) Then
                isContained = True
                Exit For
            End If
        Next
        FlexChart1.ToolTip.Active = isContained
    End Sub

    Public Class Task
        Public Property IDEx As Integer
        Public Property EndEx As Integer
        Public Property StartEx As Integer
        Public Property RectangleEx As RectangleF
        Public Property ColorEx As Color

        Public Sub New(ByVal idex As Integer, ByVal endex As Integer, ByVal startex As Integer, ByVal rectangleex As RectangleF, ByVal colorex As Color)
            Me.IDEx = idex
            Me.EndEx = endex
            Me.StartEx = startex
            Me.RectangleEx = rectangleex
            Me.ColorEx = colorex
        End Sub
    End Class
End Class

◎サンプルコード（C#）

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

namespace prj_FlexChart
{
    public partial class Form1 : Form
    {
        private List testTask1;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // データの作成
            testTask1 = new List();
            testTask1.Add(new Task() { IDEx = 0, EndEx = 2, StartEx = 0, ColorEx = Color.FromArgb(171, 208, 237) });
            testTask1.Add(new Task() { IDEx = 0, EndEx = 5, StartEx = 3, ColorEx = Color.FromArgb(171, 208, 237) });
            testTask1.Add(new Task() { IDEx = 1, EndEx = 6, StartEx = 4, ColorEx = Color.FromArgb(177, 220, 182) });
            testTask1.Add(new Task() { IDEx = 1, EndEx = 9, StartEx = 7, ColorEx = Color.FromArgb(177, 220, 182) });
            testTask1.Add(new Task() { IDEx = 2, EndEx = 8, StartEx = 6, ColorEx = Color.FromArgb(252, 201, 137) });
            testTask1.Add(new Task() { IDEx = 2, EndEx = 11, StartEx = 9, ColorEx = Color.FromArgb(252, 201, 137) });
            testTask1.Add(new Task() { IDEx = 3, EndEx = 10, StartEx = 9, ColorEx = Color.FromArgb(248, 195, 217) });
            testTask1.Add(new Task() { IDEx = 3, EndEx = 12, StartEx = 11, ColorEx = Color.FromArgb(248, 195, 217) });
            testTask1.Add(new Task() { IDEx = 3, EndEx = 14, StartEx = 13, ColorEx = Color.FromArgb(248, 195, 217) });
            testTask1.Add(new Task() { IDEx = 4, EndEx = 12, StartEx = 10, ColorEx = Color.FromArgb(185, 185, 247) });
            testTask1.Add(new Task() { IDEx = 4, EndEx = 15, StartEx = 13, ColorEx = Color.FromArgb(185, 185, 247) });
            testTask1.Add(new Task() { IDEx = 4, EndEx = 18, StartEx = 16, ColorEx = Color.FromArgb(185, 185, 247) });

            // 描画の停止
            flexChart1.BeginUpdate();

            // ガントチャートの作成
            flexChart1.ChartType = ChartType.Bar;
            var series1 = new Series();
            series1.Name = "Series1";
            series1.DataSource = testTask1;
            series1.BindingX = "IDEx";
            series1.Binding = "EndEx";
            series1.SymbolRendering += Series_SymbolRendering;
            flexChart1.Series.Clear();
            flexChart1.Series.Add(series1);
            flexChart1.Legend.Position = Position.None;
            flexChart1.Stacking = Stacking.Stacked;
            flexChart1.ToolTip.Content = "ID={IDEx} Start={StartEx} End={EndEx}";
            flexChart1.ToolTip.Active = false;

            // 軸ラベルの設定
            var axisLabels = new KeyValuePair<Int32, String>[5];
            axisLabels[0] = new KeyValuePair<Int32, String>(0, "A");
            axisLabels[1] = new KeyValuePair<Int32, String>(1, "B");
            axisLabels[2] = new KeyValuePair<Int32, String>(2, "C");
            axisLabels[3] = new KeyValuePair<Int32, String>(3, "D");
            axisLabels[4] = new KeyValuePair<Int32, String>(4, "E");
            flexChart1.AxisY.DataSource = axisLabels;
            flexChart1.AxisY.Binding = "Key,Value";

            // 軸の最小値／最大値の設定
            int vMin = int.MaxValue;
            int vMax = int.MinValue;
            for (int i = 0; i < testTask1.Count; i++)
            {
                if (testTask1[i].StartEx < vMin)
                {
                    vMin = testTask1[i].StartEx;
                }
                if (testTask1[i].EndEx > vMax)
                {
                    vMax = testTask1[i].EndEx;
                }
            }
            flexChart1.AxisX.Min = vMin;
            flexChart1.AxisX.Max = vMax;

            // 描画の再開
            flexChart1.EndUpdate();
        }

        private void Series_SymbolRendering(object sender, RenderSymbolEventArgs e)
        {
            // 既定の描画のキャンセル
            e.Cancel = true;

            // 独自にバーを描画
            var task = (Task)e.Item;
            double height = flexChart1.PlotRect.Height / testTask1.Count / 2;
            double left = flexChart1.AxisX.Convert(task.StartEx);
            double right = flexChart1.AxisX.Convert(task.EndEx);
            e.Engine.SetFill(new SolidBrush(testTask1[e.Index].ColorEx));
            e.Engine.SetStroke(new SolidBrush(Color.FromArgb(200, testTask1[e.Index].ColorEx)));
            e.Engine.DrawRect(left, e.Point.Y - height / 2, right - left, height);

            // 描画したバーの矩形（MouseMoveイベントで利用）を保存
            testTask1[e.Index].RectangleEx = new RectangleF((float)left, (float)(e.Point.Y - height / 2), (float)(right - left), (float)height);
        }

        private void flexChart1_MouseMove(object sender, MouseEventArgs e)
        {
            // バー以外ではツールチップを非表示に設定
            var isContained = false;
            foreach (Task task in testTask1)
            {
                if (task.RectangleEx.Contains(e.Location))
                {
                    isContained = true;
                    break;
                }
            }
            flexChart1.ToolTip.Active = isContained;
        }

        public class Task
        {
            public int IDEx { get; set; }
            public int EndEx { get; set; }
            public int StartEx { get; set; }
            public RectangleF RectangleEx { get; set; }
            public Color ColorEx { get; set; }
        }
    }
}