vb.net - 多 CustomUnboundColumnData 图像 gridview 想要成为缩略图图像

Question

多 CustomUnboundColumnData 图像 gridview devexpress 的性能非常慢，因为每个图像文件的大小约为 600 kb，总图像文件约为 15000。是否有多个 CustomUnboundColumnData 图像 gridview 想要成为缩略图的解决方案？让它变得更快。还是有其他最好的推荐？

谢谢 roykana

Imports Microsoft.VisualBasic
Imports DevExpress.XtraEditors
Imports System
Imports System.Data
Imports System.Linq
Imports DevExpress.XtraEditors.Repository
Imports DevExpress.XtraGrid.Views.Grid
Imports System.Drawing
Imports System.Collections
Namespace Example
    Partial Public Class XtraForm1
        Inherits XtraForm
        Public Sub New()
            InitializeComponent()

        End Sub
 Private Images As Hashtable = New Hashtable()
        Private Sub PopulateDataGridView()
            gridControl1.DataSource = GetPersonDataTable()
End Sub
        Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
            PopulateDataGridView()
            Dim repItemGraphicsEdit As New RepositoryItemPictureEdit() 'RepositoryItemGraphicsEdit()
            repItemGraphicsEdit.SizeMode = DevExpress.XtraEditors.Controls.PictureSizeMode.Squeeze
            gridControl1.RepositoryItems.Add(repItemGraphicsEdit)
            gridView1.Columns("IMAGE1").ColumnEdit = repItemGraphicsEdit
            gridView1.Columns("IMAGE2").ColumnEdit = repItemGraphicsEdit
            gridView1.Columns("IMAGE3").ColumnEdit = repItemGraphicsEdit
            gridView1.Columns("IMAGE4").ColumnEdit = repItemGraphicsEdit
            gridView1.Columns("IMAGE5").ColumnEdit = repItemGraphicsEdit
            gridView1.Columns("IMAGE6").ColumnEdit = repItemGraphicsEdit
        End Sub
        Private Sub gridView1_CustomUnboundColumnData(ByVal sender As Object, ByVal e As DevExpress.XtraGrid.Views.Base.CustomColumnDataEventArgs) Handles gridView1.CustomUnboundColumnData
            Dim view As GridView = TryCast(sender, GridView)
            Dim filename1 As String
            If Not DBNull.Value.Equals(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME1")) Then
                filename1 = CStr(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME1"))
            Else
                filename1 = String.Empty 'or Nothing depending what comes next.
            End If
            Dim filename2 As String
            If Not DBNull.Value.Equals(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME2")) Then
                filename2 = CStr(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME2"))
            Else
                filename2 = String.Empty 'or Nothing depending what comes next.
            End If
            Dim filename3 As String
            If Not DBNull.Value.Equals(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME3")) Then
                filename3 = CStr(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME3"))
            Else
                filename3 = String.Empty 'or Nothing depending what comes next.
            End If
            Dim filename4 As String
            If Not DBNull.Value.Equals(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME4")) Then
                filename4 = CStr(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME4"))
            Else
                filename4 = String.Empty 'or Nothing depending what comes next.
            End If
            Dim filename5 As String
            If Not DBNull.Value.Equals(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME5")) Then
                filename5 = CStr(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME5"))
            Else
                filename5 = String.Empty 'or Nothing depending what comes next.
            End If
            Dim filename6 As String
            If Not DBNull.Value.Equals(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME6")) Then
                filename6 = CStr(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "FILENAME6"))
            Else
                filename6 = String.Empty 'or Nothing depending what comes next.
            End If
            Dim SUBFOLDERP As String
            If Not DBNull.Value.Equals(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "SUBFOLDERP")) Then
                SUBFOLDERP = CStr(view.GetListSourceRowCellValue(e.ListSourceRowIndex, "SUBFOLDERP"))
            Else
                SUBFOLDERP = String.Empty 'or Nothing depending what comes next.
            End If
            Dim img As Image = Nothing
            Try
                If e.Column.Caption = "IMAGE1" Then
                    e.Value = GetImage(filename1)
                ElseIf e.Column.Caption = "IMAGE2" Then
                    e.Value = GetImage(filename2)
                ElseIf e.Column.Caption = "IMAGE3" Then
                    e.Value = GetImage(filename3)
                ElseIf e.Column.Caption = "IMAGE4" Then
                    e.Value = GetImage(filename4)
                ElseIf e.Column.Caption = "IMAGE5" Then
                    e.Value = GetImage(filename5)
                ElseIf e.Column.Caption = "IMAGE6" Then
                    e.Value = GetImage(filename6)
                End If
            Catch
            End Try
        End Sub
        Function GetImage(str As String) As Image
            If (Images.ContainsKey(str)) Then
                Return CType(Images(str), Image)
            Else
                Dim img = Image.FromFile(str)
                Images.Add(str, img)
                Return img
            End If
        End Function
        Private Function GetPersonDataTable() As DataTable
            Dim table As New DataTable()
            table.TableName = "Persons"
            table.Columns.Add(New DataColumn("FILENAME1", GetType(String)))
            table.Columns.Add(New DataColumn("FILENAME2", GetType(String)))
            table.Columns.Add(New DataColumn("FILENAME3", GetType(String)))
            table.Columns.Add(New DataColumn("FILENAME4", GetType(String)))
            table.Columns.Add(New DataColumn("FILENAME5", GetType(String)))
            table.Columns.Add(New DataColumn("FILENAME6", GetType(String)))
            For i As Integer = 0 To 15000
                table.Rows.Add("1.png", "2.png", "3.png", "4.png", "5.png", "6.png")
            Next i
            Return table
        End Function
    End Class
End Namespace