Save and Load the whole content of a ListView Control

Option Strict On

Public Class frmMain
	Dim _invisibleColumnExists As Boolean = False
	ReadOnly _formSize As Size = New Size(380, 353)
	
	''' <summary>
	''' Adjusts all Headers in the given ListView
	''' </summary>
	''' <param name="lsv_">The ListView the Headers will be adjusted</param>
	''' <param name="alignment">The alignment to adjust</param>
	Private Sub AdjustHeaderAlignments(ByVal lsv_ As ListView, ByVal alignment As HorizontalAlignment)
		For i As Integer = 0 To lsv.Columns.Count - 1
			lsv.Columns(i).TextAlign = alignment
		Next
	End Sub

#Region "Save and load the content"

	Private Sub cmdSave_Click(sender As Object, e As EventArgs) Handles cmdSave.Click
		Dim dlg As New SaveFileDialog
		Dim errMsg As String = ""

		With dlg
			.DefaultExt = ".xml"
			.Filter = "All files|*.*"
			.RestoreDirectory = True
			.Title = "Save..."
		End With
	
		If dlg.ShowDialog = DialogResult.OK Then
			errMsg = ListViewContent.Save(lsv, dlg.FileName)

			If errMsg <> String.Empty Then MessageBox.Show("An error occured during operation")

		End If

	End Sub

	Private Sub cmdLoad_Click(sender As Object, e As EventArgs) Handles cmdLoad.Click
		Dim dlg As New OpenFileDialog
		Dim index As Integer = If(lsv.Groups.Count > 0, 1, 0)
		Dim errMsg As String = ""

		With dlg
			.DefaultExt = ".xml"
			.Filter = "All files|*.*"
			.RestoreDirectory = True
			.Title = "Save..."
		End With

		If dlg.ShowDialog = DialogResult.OK Then
			errMsg = ListViewContent.Load(lsv, dlg.FileName, False, True, True)

			If errMsg <> String.Empty Then
				MessageBox.Show(errMsg, "Error during operation")

				Exit Sub
			End If

			For i As Integer = 0 To lsv.Groups.Count - 1
				If lsv.Groups(i).Items.Count > 0 Then cmbGroups.Items.Insert(index, lsv.Groups(i).Header)
			Next

			If chkCenterColumnHeaderText.Checked Then
				AdjustHeaderAlignments(lsv, HorizontalAlignment.Center)

			Else
				AdjustHeaderAlignments(lsv, HorizontalAlignment.Left)

			End If

			If lsv.Columns(0).Width = 0 Then _invisibleColumnExists = True
		End If
	End Sub

#End Region

#Region "Manage the ListView control"

	Private Sub cmdAddToGroups_Click(sender As Object, e As EventArgs) Handles cmdAddToGroups.Click
		' If the trimmed text isn't an empty String, the new group is added to the ListView's Group-Collection
		If txtNewGroupName.Text.Replace("  ", "").Trim <> "" Then
			Dim index As Integer = If(lsv.Groups.Count > 0, 1, 0)

			lsv.Groups.Insert(index, New ListViewGroup(txtNewGroupName.Text, txtNewGroupName.Text))
			cmbGroups.Items.Insert(index, txtNewGroupName.Text)
			cmbGroups.SelectedIndex = index
		End If
	End Sub

	Private Sub cmdAddToLsv_Click(sender As Object, e As EventArgs) Handles cmdAddToLsv.Click
		' If the trimmed text isn't an empty String then the new item is added to the ListView
		If txtColumn1.Text.Replace("  ", "").Trim <> "" AndAlso txtColumn2.Text.Replace("  ", "").Trim <> "" Then

			' If the user doesn't want to show groups, they are disabled 
			If cmbGroups.SelectedItem Is "-None-" Or cmbGroups.SelectedIndex = -1 Then
				lsv.Items.Add(txtColumn1.Text).SubItems.Add(txtColumn2.Text)
				lsv.ShowGroups = False

			Else

				' If there is an "invisible" column, the new item has an empty column
				If _invisibleColumnExists Then
					Dim listItem As New ListViewItem("", 0, lsv.Groups(cmbGroups.SelectedItem.ToString))
					listItem.SubItems.Add(txtColumn1.Text)
					listItem.SubItems.Add(txtColumn2.Text)

					lsv.Items.Add(listItem)
					lsv.ShowGroups = True

				Else ' Otherwise there's now empty column for the new item
					Dim listItem As New ListViewItem(txtColumn1.Text, 0, lsv.Groups(cmbGroups.SelectedItem.ToString))
					listItem.SubItems.Add(txtColumn2.Text)

					lsv.Items.Add(listItem)
					lsv.ShowGroups = True
				End If

			End If
		End If
	End Sub

#End Region

#Region "Other"

	Private Sub frmMain_DoubleClick(sender As Object, e As EventArgs) Handles MyBase.DoubleClick
		Me.Size = _formSize	' Reset the size of the form to default Values
	End Sub

	Private Sub lsv_ColumnWidthChanging(sender As Object, e As ColumnWidthChangingEventArgs) Handles lsv.ColumnWidthChanging
		' If an "Invisible" Column exists, its size is set to 0 px, so that the user doesn't see it
		If e.ColumnIndex = 0 AndAlso _invisibleColumnExists Then
			e.Cancel = True
			e.NewWidth = 0
		End If
	End Sub

	Private Sub chkCenterColumnHeaderText_CheckedChanged(sender As Object, e As EventArgs) Handles chkCenterColumnHeaderText.CheckedChanged
		' If the user checks the CheckBox for centering the HeaderAlignments, they will be centered. Else it is left-aligned
		If chkCenterColumnHeaderText.Checked Then
			AdjustHeaderAlignments(lsv, HorizontalAlignment.Center)

		Else
			AdjustHeaderAlignments(lsv, HorizontalAlignment.Left)

		End If
	End Sub
	
#End Region

End Class