无法获取项目和列以显示listview [英] Can not get items and columns to appear listview
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问题描述
截至目前，我正在查看列表视图，但是列表视图中没有显示任何内容。这很奇怪，因为我可以看到listview预运行中显示的项目和列。程序运行后，列表视图为空白。
这是我正在使用的代码：
这是创建的listview控件：< br $>
As of now I am getting the listview to appear, however, nothing is appearing in the listview. This is strange because I can see the items and columns show in listview pre-run. Once the program runs the listview is blank.
Here is the code I am using:
Here is the listview control that is created:
Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.Drawing
Imports System.Windows.Forms
Imports System.Runtime.InteropServices
Namespace ListViewEmbeddedControls
Public Class ListViewEx
Inherits ListView
<DllImport("user32.dll")>
Private Shared Function SendMessage(hWnd As IntPtr, msg As Integer, wPar As IntPtr, lPar As IntPtr) As IntPtr
End Function
Private Const LVM_FIRST As Integer = &H1000
Private Const LVM_GETCOLUMNORDERARRAY As Integer = (LVM_FIRST + 59)
Private Const WM_PAINT As Integer = &HF
Private Structure EmbeddedControl
Public Control As Control
Public Column As Integer
Public Row As Integer
Public Dock As DockStyle
Public Item As ListViewItem
End Structure
Private _embeddedControls As New ArrayList()
Protected Function GetColumnOrder() As Integer()
Dim lPar As IntPtr = Marshal.AllocHGlobal(Marshal.SizeOf(GetType(Integer)) * Columns.Count)
Dim res As IntPtr = SendMessage(Handle, LVM_GETCOLUMNORDERARRAY, New IntPtr(Columns.Count), lPar)
If res.ToInt32() = 0 Then
Marshal.FreeHGlobal(lPar)
Return Nothing
End If
Dim order As Integer() = New Integer(Columns.Count) {}
Marshal.Copy(lPar, order, 0, Columns.Count)
Marshal.FreeHGlobal(lPar)
Return order
End Function
Protected Function GetSubItemBounds(Item As ListViewItem, SubItem As Integer) As Rectangle
Dim subItemRect As Rectangle = Rectangle.Empty
If Item Is Nothing Then
Throw New ArgumentNullException("Item")
End If
Dim order As Integer() = GetColumnOrder()
If order Is Nothing Then
Return subItemRect
End If
If SubItem >= order.Length Then
Throw New IndexOutOfRangeException("SubItem " + SubItem + " out of range")
End If
Dim lviBounds As Rectangle = Item.GetBounds(ItemBoundsPortion.Entire)
Dim subItemX As Integer = lviBounds.Left
Dim col As ColumnHeader
Dim i As Integer
i = 0
While i < order.Length
col = Me.Columns(order(i))
If col.Index = SubItem Then
Exit While
End If
subItemX += col.Width
System.Math.Max(System.Threading.Interlocked.Increment(i), i - 1)
End While
subItemRect = New Rectangle(subItemX, lviBounds.Top, Me.Columns(order(i)).Width, lviBounds.Height)
Return subItemRect
End Function
Public Sub AddEmbeddedControl(c As Control, col As Integer, row As Integer)
AddEmbeddedControl(c, col, row, DockStyle.Fill)
End Sub
Public Sub AddEmbeddedControl(c As Control, col As Integer, row As Integer, dock As DockStyle)
If c Is Nothing Then
Throw New ArgumentNullException()
End If
If col >= Columns.Count OrElse row >= Items.Count Then
Throw New ArgumentOutOfRangeException()
End If
Dim ec As EmbeddedControl
ec.Control = c
ec.Column = col
ec.Row = row
ec.Dock = dock
ec.Item = Items(row)
_embeddedControls.Add(ec)
Me.Controls.Add(c)
End Sub
Public Function GetEmbeddedControl(col As Integer, row As Integer) As Control
For Each ec As EmbeddedControl In _embeddedControls
If ec.Row = row AndAlso ec.Column = col Then
Return ec.Control
End If
Next
Return Nothing
End Function
Protected Overloads Overrides Sub WndProc(ByRef m As Message)
Select Case m.Msg
Case WM_PAINT
If View <> View.Details Then
Exit Select
End If
For Each ec As EmbeddedControl In _embeddedControls
Dim rc As Rectangle = Me.GetSubItemBounds(ec.Item, ec.Column)
If (Me.HeaderStyle <> ColumnHeaderStyle.None) AndAlso (rc.Top < Me.Font.Height) Then
ec.Control.Visible = False
Continue For
Else
ec.Control.Visible = True
End If
Select Case ec.Dock
Case DockStyle.Fill
Exit Select
Case DockStyle.Top
rc.Height = ec.Control.Height
Exit Select
Case DockStyle.Left
rc.Width = ec.Control.Width
Exit Select
Case DockStyle.Bottom
rc.Offset(0, rc.Height - ec.Control.Height)
rc.Height = ec.Control.Height
Exit Select
Case DockStyle.Right
rc.Offset(rc.Width - ec.Control.Width, 0)
rc.Width = ec.Control.Width
Exit Select
Case DockStyle.None
rc.Size = ec.Control.Size
Exit Select
End Select
ec.Control.Bounds = rc
Next
Exit Select
End Select
MyBase.WndProc(m)
End Sub
End Class
End Namespace
当控件被拖到表格时，表格中会出现以下内容：
Here is what appears in the form when the control is dragged over to the form:
Imports System
Imports System.Drawing
Imports System.Collections
Imports System.ComponentModel
Imports System.Windows.Forms
Imports System.Data
Namespace ListViewEmbeddedControls
Public Class Form1
Inherits System.Windows.Forms.Form
Private components As System.ComponentModel.IContainer
Public Sub New()
InitializeComponent()
End Sub
Protected Overloads Overrides Sub Dispose(disposing As Boolean)
If disposing Then
If components Is Nothing Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
Private Sub InitializeComponent()
Dim ListViewGroup1 As System.Windows.Forms.ListViewGroup = New System.Windows.Forms.ListViewGroup("personal", System.Windows.Forms.HorizontalAlignment.Left)
Dim ListViewItem1 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item1")
Dim ListViewItem2 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item2")
Dim ListViewItem3 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item3")
Dim ListViewItem4 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item4")
Dim ListViewItem5 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item5")
Dim ListViewItem6 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item6")
Dim ListViewItem7 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item7")
Dim ListViewItem8 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item8")
Dim ListViewItem9 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item1")
Dim ListViewItem10 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item2")
Dim ListViewItem11 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item3")
Dim ListViewItem12 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item4")
Dim ListViewItem13 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item5")
Dim ListViewItem14 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item6")
Dim ListViewItem15 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item7")
Dim ListViewItem16 As System.Windows.Forms.ListViewItem = New System.Windows.Forms.ListViewItem("Item8")
Me.listview1 = New listviewcreatedcontrols.ListViewEmbeddedControls.ListViewEx()
Me.columnHeader1 = CType(New System.Windows.Forms.ColumnHeader(), System.Windows.Forms.ColumnHeader)
Me.columnHeader2 = CType(New System.Windows.Forms.ColumnHeader(), System.Windows.Forms.ColumnHeader)
Me.SuspendLayout()
'
'listview1
'
Me.listview1.AllowColumnReorder = True
Me.listview1.Anchor = CType((((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom) _
Or System.Windows.Forms.AnchorStyles.Left) _
Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles)
Me.listview1.Columns.AddRange(New System.Windows.Forms.ColumnHeader() {Me.columnHeader1, Me.columnHeader2})
Me.listview1.FullRowSelect = True
Me.listview1.GridLines = True
ListViewGroup1.Header = "personal"
ListViewGroup1.Name = "Personal"
Me.listview1.Groups.AddRange(New System.Windows.Forms.ListViewGroup() {ListViewGroup1})
Me.listview1.HeaderStyle = System.Windows.Forms.ColumnHeaderStyle.None
Me.listview1.HideSelection = False
Me.listview1.HoverSelection = False
Me.listview1.Items.AddRange(New System.Windows.Forms.ListViewItem() {ListViewItem1, ListViewItem2, ListViewItem3, ListViewItem4, ListViewItem5, ListViewItem6, ListViewItem7, ListViewItem8, ListViewItem9, ListViewItem10, ListViewItem11, ListViewItem12, ListViewItem13, ListViewItem14, ListViewItem15, ListViewItem16})
Me.listview1.LabelWrap = False
Me.listview1.Location = New System.Drawing.Point(16, 32)
Me.listview1.MultiSelect = False
Me.listview1.Name = "listview1"
Me.listview1.OwnerDraw = True
Me.listview1.Size = New System.Drawing.Size(368, 240)
Me.listview1.TabIndex = 0
Me.listview1.UseCompatibleStateImageBehavior = False
Me.listview1.View = System.Windows.Forms.View.Details
'
'columnHeader1
'
Me.columnHeader1.Text = "ColumnHeader1"
Me.columnHeader1.Width = 119
'
'columnHeader2
'
Me.columnHeader2.Text = "ColumnHeader2"
Me.columnHeader2.Width = 124
'
'Form1
'
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.ClientSize = New System.Drawing.Size(400, 302)
Me.Controls.Add(Me.listview1)
Me.Name = "Form1"
Me.Text = "Sample for Controls embedded in a ListView"
Me.ResumeLayout(False)
End Sub
<STAThread>
Shared Sub Main()
Application.EnableVisualStyles()
Application.Run(New Form1())
End Sub
Private WithEvents columnHeader1 As ColumnHeader
Private WithEvents columnHeader2 As ColumnHeader
Friend WithEvents ListViewEx As ListViewEx
Private listview1 As ListViewEx
Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles MyBase.Load
Dim cb As New ComboBox()
cb.Text = "tryme"
listview1.AddEmbeddedControl(cb, 0, 4)
For I = 0 To listview1.Items.Count - 1
listview1.Items.Item(I).SubItems.Add("")
Next
End Sub
End Class
End Namespace
如上所述，我认为有可能在课堂上干扰了正在制作的物品。这就是为什么我刚刚发布课程的原因。
我尝试了什么：
我试图用项目实现加载阶段。但是，如果有办法将项加载到可能有用的实际类中。
As stated above I thought is was possible that something in the class was interfering with the items being produced. That is why originally I just posted the class.
What I have tried:
I have tried to implement the load phase with the items. However, if there is a way to load the items into the actual class that may help.
推荐答案
不确定为什么在表单中有一个main方法。转到应用程序设置并检查启动表单中的设置是什么。
还放置几个断点查看您的初始化代码是否实际被命中。
Not sure why you have a main method inside the form. Go to the application settings and check, what is the setting inStartup form.
Also place a few breakpoints to see if your initialization code is actually hit.
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