XtraReports > 示例 > 如何： 为字段列表项提供自定义图像

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在 DevExpress Code Central 数据库中可以找到完整的示例项目，网址是 http://www.devexpress.com/example=E2706。 取决于目标平台类型 (ASP.NET、WinForms 等)，可以在线运行本示例，或者下载自动可执行的示例。

下面的示例演示了如何为 Field List(字段列表) 元素提供自定义图像。

要完成此任务，需要创建一个继承自 FieldListService 基本类的自定义 Field List(字段列表) 服务，并重写 FieldListService.GetColumnImageIndex 方法。 然后，为了激活此自定义服务，需要把它的实例指派到 FieldListService.Instance 静态属性。

C#CopyCode image复制代码
 (Form1.cs)
using System;
using System.Windows.Forms;
using DevExpress.XtraReports.UserDesigner;

namespace FieldListCustomIcons {
    public partial class Form1 : Form {

        public Form1() {
            InitializeComponent();
            FieldListService.Instance = new CustomFieldListService();
        }

        private void button1_Click(object sender, EventArgs e) {
            new XtraReport1().ShowDesignerDialog();
        }
    }
}
C#CopyCode image复制代码
 (CustomFieldListService.cs)
using System.Drawing;
using System.ComponentModel;
using DevExpress.Utils;
using DevExpress.XtraReports.UserDesigner;

namespace FieldListCustomIcons {

    class CustomFieldListService : FieldListService {
        int categoryNameIndex;

        public override int GetColumnImageIndex(PropertyDescriptor property,
            string dataMember, bool isList) {

            if (dataMember.Contains("CategoryName")) {
                return categoryNameIndex;
            }

            return base.GetColumnImageIndex(property, dataMember, isList);
        }

        public override DevExpress.Utils.ImageCollection CreateImageCollection() {
            ImageCollection result = base.CreateImageCollection();
            Image image =
                ResourceImageHelper.CreateBitmapFromResources("FieldListCustomIcons.DataPickerImage.png",
                typeof(CustomFieldListService).Assembly);

            result.AddImage(image);
            categoryNameIndex = result.Images.Count - 1;

            return result;
        }
    }
}
Visual BasicCopyCode image复制代码
 (CustomFieldListService.vb)
Imports Microsoft.VisualBasic
Imports System.Drawing
Imports System.ComponentModel
Imports DevExpress.Utils
Imports DevExpress.XtraReports.UserDesigner

Namespace FieldListCustomIcons

    Friend Class CustomFieldListService
        Inherits FieldListService
        Private categoryNameIndex As Integer

        Public Overrides Function GetColumnImageIndex(ByVal [property] As PropertyDescriptor, ByVal dataMember As String, ByVal isList As Boolean) As Integer

            If dataMember.Contains("CategoryName") Then
                Return categoryNameIndex
            End If

            Return MyBase.GetColumnImageIndex([property], dataMember, isList)
        End Function

        Public Overrides Function CreateImageCollection() As DevExpress.Utils.ImageCollection
            Dim result As ImageCollection = MyBase.CreateImageCollection()
            Dim image As Image = ResourceImageHelper.CreateBitmapFromResources("FieldListCustomIcons.DataPickerImage.png", GetType(CustomFieldListService).Assembly)

            result.AddImage(image)
            categoryNameIndex = result.Images.Count - 1

            Return result
        End Function
    End Class
End Namespace
Visual BasicCopyCode image复制代码
 (Form1.vb)
Imports Microsoft.VisualBasic
Imports System
Imports System.Windows.Forms
Imports DevExpress.XtraReports.UserDesigner

Namespace FieldListCustomIcons
    Partial Public Class Form1
        Inherits Form

        Public Sub New()
            InitializeComponent()
            FieldListService.Instance = New CustomFieldListService()
        End Sub

        Private Sub button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles button1.Click
            CType(New XtraReport1(), XtraReport1).ShowDesignerDialog()
        End Sub
    End Class
End Namespace

在下面的插图中显示了结果。

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