Here is another virtual mode example for the .NET 2.0 framework while
working with the list view. Since you can not access the items collection of
the list view you need to do sorting another way... here is my code on how I
did it to help anyone starting out get an idea of how to use virtual mode in
..NET 2.0
Imports CrystalDecisions.CrystalReports.Engine
Imports CrystalDecisions.Shared
Public Class Form1
''' <summary>
''' Retrieve thousands of rows of data from database server to fill dataset
to populate list view
''' </summary>
''' <remarks></remarks>
Dim aItems(0) As ListViewItem
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
' fill data then process it into an array
da.Fill(ds, "entries")
LoadData()
End Sub
''' <summary>
''' Moves data from data set into an array of list view items (speeds things
up when you preprocess the
''' data set into list view items so you dont have to make them on the fly
when retrieveing virtual items
''' </summary>
''' <remarks></remarks>
Private Sub LoadData()
Me.ListView1.VirtualListSize = 0
If Not aItems Is Nothing Then
Array.Clear(aItems, 0, aItems.Length)
End If
Array.Resize(aItems, ds.Tables("entries").Rows.Count)
Dim i As Integer = 0
for each dr as datarow in ds.tables("entries").rows
dim lvitem as listviewitem
' pre process list view items now the add them to the array here
aItems(i) = lvItem
i += 1
Application.DoEvents()
Next
Me.ListView1.VirtualMode = True
Me.ListView1.VirtualListSize = aItems.Length
End Sub
''' <summary>
''' This is the column clicked event of the list view
''' you need to sort the array that contains the list view items
''' when ever this happens based on the column that was clicked on
''' after this, the array will be sorted, but the list view will not
''' reflect this change. Because of this, you must invalidate the
''' list view to force it to reflect the change of the array that was
''' sorted on screen
''' </summary>
''' <param name="sender"></param>
''' <param name="e"></param>
''' <remarks>Must invalidate list view after sorting to force on screen
changes</remarks>
Private Sub ListView1_ColumnClick(ByVal sender As Object, ByVal e As
System.Windows.Forms.ColumnClickEventArgs) Handles ListView1.ColumnClick
Debug.WriteLine("Column header clicked")
If Me.ListView1.Sorting = SortOrder.Ascending Then
Me.ListView1.Sorting = SortOrder.Descending
Else
Me.ListView1.Sorting = SortOrder.Ascending
End If
Dim sorter As New ListViewSortOrder(e.Column, Me.ListView1.Sorting)
Array.Sort(aItems, sorter)
Me.ListView1.Invalidate()
End Sub
Private Sub ListView1_DrawColumnHeader(ByVal sender As Object, ByVal e As
System.Windows.Forms.DrawListViewColumnHeaderEvent Args) Handles
ListView1.DrawColumnHeader
e.DrawDefault = True
End Sub
''' <summary>
''' Sort comparision class which implements IComparable
''' This will be used to sort the array of list view items
''' that the virtual mode list view uses to display
''' </summary>
''' <remarks></remarks>
Private Class ListViewSortOrder
Implements IComparer
Dim column As Integer
Dim order As SortOrder = SortOrder.Ascending
Public Sub New(ByVal aColumn As Integer, ByVal aorder As SortOrder)
column = aColumn
order = aorder
End Sub
Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer
Implements System.Collections.IComparer.Compare
Dim xItem, yItem As System.Windows.Forms.ListViewItem
xItem = CType(x, ListViewItem)
yItem = CType(y, ListViewItem)
If order = SortOrder.Ascending Then
Return (xItem.SubItems(column).Text).CompareTo(yItem.SubI tems(column).Text)
Else
Return (yItem.SubItems(column).Text).CompareTo(xItem.SubI tems(column).Text)
End If
End Function
End Class
''' <summary>
''' Pulls the virtual item out of the list as it is needed to display on the
screen from the
''' array of preprocessed list view items from the initially loaded data set
''' </summary>
''' <param name="sender"></param>
''' <param name="e"></param>
''' <remarks></remarks>
Private Sub ListView1_RetrieveVirtualItem(ByVal sender As Object, ByVal e As
System.Windows.Forms.RetrieveVirtualItemEventArgs) Handles
ListView1.RetrieveVirtualItem
e.Item = aItems(e.ItemIndex)
End Sub
''' <summary>
''' This happens when a selection is reset to no items selected, like when a
user clicks off a selection
''' </summary>
''' <param name="sender"></param>
''' <param name="e"></param>
''' <remarks></remarks>
Private Sub ListView1_VirtualItemsSelectionRangeChanged(ByVal sender As
Object, ByVal e As
System.Windows.Forms.ListViewVirtualItemsSelection RangeChangedEventArgs)
Handles ListView1.VirtualItemsSelectionRangeChanged
Me.ListBox1.BeginUpdate()
Debug.WriteLine(String.Format("{3}: Start {0}, End {1}, IsSelected {2}",
e.StartIndex, e.EndIndex, e.IsSelected, Now.ToLongTimeString))
Me.ListBox1.Items.Clear()
Me.ListBox1.EndUpdate()
End Sub
''' <summary>
''' This happens when a user selects items or multiple selects items or
deselects one of the multi selected items
''' This does not fire though if you have an item selected then click off it
or have multiple items selected then
''' click off them... the virutal selection range change happens at that
point and need to reset your selected
''' items list at that point
''' </summary>
''' <param name="sender"></param>
''' <param name="e"></param>
''' <remarks></remarks>
Private Sub ListView1_ItemSelectionChanged(ByVal sender As Object, ByVal e
As System.Windows.Forms.ListViewItemSelectionChangedE ventArgs) Handles
ListView1.ItemSelectionChanged
Me.ListBox1.BeginUpdate()
Debug.WriteLine(String.Format("Item Changed: {0}, Is selected: {1}",
e.ItemIndex, e.IsSelected))
If e.IsSelected = True Then
Me.ListBox1.Items.Add(CStr(e.ItemIndex))
Else
Me.ListBox1.Items.Remove(CStr(e.ItemIndex))
End If
Me.ListBox1.EndUpdate()
End Sub
End Class
'======================================
Form designer partial class for control setup on form
' =========================================
<Global.Microsoft.VisualBasic.CompilerServices.Des ignerGenerated()> _
Partial Class Form1
Inherits System.Windows.Forms.Form
'Form overrides dispose to clean up the component list.
<System.Diagnostics.DebuggerNonUserCode()> _
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing AndAlso components IsNot Nothing Then
components.Dispose()
End If
MyBase.Dispose(disposing)
End Sub
'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer
'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
<System.Diagnostics.DebuggerStepThrough()> _
Private Sub InitializeComponent()
Me.components = New System.ComponentModel.Container
Dim resources As System.ComponentModel.ComponentResourceManager = New
System.ComponentModel.ComponentResourceManager(Get Type(Form1))
Me.ImageList1 = New System.Windows.Forms.ImageList(Me.components)
Me.ListBox1 = New System.Windows.Forms.ListBox
Me.ListView1 = New WindowsApplication9.DoubleBufferedListView
Me.clmTypeIcon = New System.Windows.Forms.ColumnHeader
Me.clmStatusIcon = New System.Windows.Forms.ColumnHeader
Me.clmAttachmentIcon = New System.Windows.Forms.ColumnHeader
Me.clmJournalType = New System.Windows.Forms.ColumnHeader
Me.clmEntryType = New System.Windows.Forms.ColumnHeader
Me.clmCreatedBy = New System.Windows.Forms.ColumnHeader
Me.clmDateCreated = New System.Windows.Forms.ColumnHeader
Me.clmAccount = New System.Windows.Forms.ColumnHeader
Me.clmEntryMessage = New System.Windows.Forms.ColumnHeader
Me.clmStatus = New System.Windows.Forms.ColumnHeader
Me.clmDueDate = New System.Windows.Forms.ColumnHeader
Me.clmEnrollee = New System.Windows.Forms.ColumnHeader
Me.SuspendLayout()
'
'ImageList1
'
Me.ImageList1.ImageStream =
CType(resources.GetObject("ImageList1.ImageStream" ),
System.Windows.Forms.ImageListStreamer)
Me.ImageList1.TransparentColor = System.Drawing.Color.Transparent
Me.ImageList1.Images.SetKeyName(0, "EMAILhighimportance.png")
Me.ImageList1.Images.SetKeyName(1, "EMAILlowimportance.png")
Me.ImageList1.Images.SetKeyName(2, "bookclosedpurple.png")
Me.ImageList1.Images.SetKeyName(3, "bookopengreen.png")
Me.ImageList1.Images.SetKeyName(4, "bookopenred.png")
Me.ImageList1.Images.SetKeyName(5, "bookopenyellow.png")
'
'ListBox1
'
Me.ListBox1.FormattingEnabled = True
Me.ListBox1.Location = New System.Drawing.Point(0, 307)
Me.ListBox1.Name = "ListBox1"
Me.ListBox1.Size = New System.Drawing.Size(265, 225)
Me.ListBox1.TabIndex = 1
'
'ListView1
'
Me.ListView1.Columns.AddRange(New System.Windows.Forms.ColumnHeader()
{Me.clmTypeIcon, Me.clmStatusIcon, Me.clmAttachmentIcon, Me.clmJournalType,
Me.clmEntryType, Me.clmCreatedBy, Me.clmDateCreated, Me.clmAccount,
Me.clmEntryMessage, Me.clmStatus, Me.clmDueDate, Me.clmEnrollee})
Me.ListView1.Dock = System.Windows.Forms.DockStyle.Top
Me.ListView1.FullRowSelect = True
Me.ListView1.HideSelection = False
Me.ListView1.Location = New System.Drawing.Point(0, 0)
Me.ListView1.Name = "ListView1"
Me.ListView1.Size = New System.Drawing.Size(929, 301)
Me.ListView1.SmallImageList = Me.ImageList1
Me.ListView1.Sorting = System.Windows.Forms.SortOrder.Ascending
Me.ListView1.TabIndex = 0
Me.ListView1.UseCompatibleStateImageBehavior = False
Me.ListView1.View = System.Windows.Forms.View.Details
'
'clmTypeIcon
'
Me.clmTypeIcon.Name = "clmTypeIcon"
Me.clmTypeIcon.Width = 21
'
'clmStatusIcon
'
Me.clmStatusIcon.Name = "clmStatusIcon"
Me.clmStatusIcon.Width = 21
'
'clmAttachmentIcon
'
Me.clmAttachmentIcon.Name = "clmAttachmentIcon"
Me.clmAttachmentIcon.Width = 21
'
'clmJournalType
'
Me.clmJournalType.Name = "clmJournalType"
'
'clmEntryType
'
Me.clmEntryType.Name = "clmEntryType"
'
'clmCreatedBy
'
Me.clmCreatedBy.Name = "clmCreatedBy"
'
'clmDateCreated
'
Me.clmDateCreated.Name = "clmDateCreated"
'
'clmAccount
'
Me.clmAccount.Name = "clmAccount"
'
'clmEntryMessage
'
Me.clmEntryMessage.Name = "clmEntryMessage"
Me.clmEntryMessage.Width = 300
'
'clmStatus
'
Me.clmStatus.Name = "clmStatus"
'
'clmDueDate
'
Me.clmDueDate.Name = "clmDueDate"
'
'clmEnrollee
'
Me.clmEnrollee.Name = "clmEnrollee"
'
'Form1
'
Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
Me.ClientSize = New System.Drawing.Size(929, 533)
Me.Controls.Add(Me.ListBox1)
Me.Controls.Add(Me.ListView1)
Me.Name = "Form1"
Me.Text = "Form1"
Me.ResumeLayout(False)
End Sub
Friend WithEvents ListView1 As DoubleBufferedListView
Friend WithEvents clmIconA As System.Windows.Forms.ColumnHeader
Friend WithEvents clmIconB As System.Windows.Forms.ColumnHeader
Friend WithEvents clmAttachments As System.Windows.Forms.ColumnHeader
Friend WithEvents clmJournalType As System.Windows.Forms.ColumnHeader
Friend WithEvents clmType As System.Windows.Forms.ColumnHeader
Friend WithEvents clmUser As System.Windows.Forms.ColumnHeader
Friend WithEvents clmDate As System.Windows.Forms.ColumnHeader
Friend WithEvents clmAccount As System.Windows.Forms.ColumnHeader
Friend WithEvents clmMessage As System.Windows.Forms.ColumnHeader
Friend WithEvents clmStatus As System.Windows.Forms.ColumnHeader
Friend WithEvents clmDueDate As System.Windows.Forms.ColumnHeader
Friend WithEvents clmEnrollee As System.Windows.Forms.ColumnHeader
Friend WithEvents clmTypeIcon As System.Windows.Forms.ColumnHeader
Friend WithEvents clmStatusIcon As System.Windows.Forms.ColumnHeader
Friend WithEvents clmAttachmentIcon As System.Windows.Forms.ColumnHeader
Friend WithEvents clmEntryType As System.Windows.Forms.ColumnHeader
Friend WithEvents clmCreatedBy As System.Windows.Forms.ColumnHeader
Friend WithEvents clmDateCreated As System.Windows.Forms.ColumnHeader
Friend WithEvents clmEntryMessage As System.Windows.Forms.ColumnHeader
Friend WithEvents ImageList1 As System.Windows.Forms.ImageList
Friend WithEvents ListBox1 As System.Windows.Forms.ListBox
End Class
