如何检测列表视图何时加载了项目？ [英] How do I detect when a listview has items loaded in it?

问题描述

我的程序中有2个表单，其中包含带有复选框的列表视图。当用户单击打开时，系统会提示他们加载哪些自定义数据库文件（随机访问）。我可以正常加载文件，但它们可能包含多达6500个单词，需要几秒钟。我不希望用户点击按钮来操作列表视图中的数据，直到完成绘图（显示所有项目）。



什么我试过了：



这是加载listview的代码。我无法找到一个解决方案来检测控件何时显示和完全加载。

I have 2 forms in my program that have listviews in them with checkboxes. When the user clicks "OPEN", they are prompted which of my custom database files to load (Random access). I am able to load the files fine, but they may contain up to 6500 words which takes a few seconds. I don't want the user to click on a button to manipulate the data in the listview until it is completed drawing (all items shown).

What I have tried:

This is the code that loads the listview. I haven't been able to come up with a solution for detecting when the control is shown and fully loaded.

<pre>Private Sub OPENToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles OPENToolStripMenuItem.Click
        ' ***** This is the FILE/OPEN menu item *****

        ' Step 1: Establish the variables I will use in this subroutine.
        Dim tmpInt1 As Integer = 0
        Dim tmpInt2 As Integer = 0
        Dim tmpString1 As String = Nothing
        Dim tmpString2 As String = Nothing

        ' Step 2: Set the variable ListLoaded to false to prevent unwanted code from running.
        ListLoaded = False

        ' Step 3: Set up the OpenFile dialog box.
        OpenFileDialog1.Reset()
        OpenFileDialog1.DefaultExt = "dat"
        OpenFileDialog1.CheckFileExists = True
        OpenFileDialog1.CheckPathExists = True
        OpenFileDialog1.Multiselect = False
        OpenFileDialog1.ValidateNames = True
        OpenFileDialog1.Title = "Select the word dictionary that you wish to export from:"
        OpenFileDialog1.Filter = "ERea Chances Are Word Dictionary Files (*.dat)|*.dat"
        OpenFileDialog1.InitialDirectory = DictPath

        ' Step 4: Open the dialog box.  If the user clicks cancel, exit the sub.
        If OpenFileDialog1.ShowDialog = DialogResult.Cancel Then Exit Sub

        ' Step 5: Set the back color for label6 to white, and put the selected file path in the label.
        Label6.BackColor = System.Drawing.Color.White
        Label6.Text = OpenFileDialog1.FileName

        ' Step 6: Refresh the entire form.
        Me.Refresh()

        ' Step 7: Hide Label1 & enable GroupBox2
        Label1.Hide()
        GroupBox2.Enabled = True

        ' Step 8: Get a free file number and open the selected dictionary file.
        FileNum = FreeFile()
        FileOpen(FileNum, Trim(Label6.Text), OpenMode.Random, OpenAccess.Read, OpenShare.LockRead)

        ' Step 9: Get the first entry in this file and set the progressbar maximum to it.
        FileGet(FileNum, tmpInt1, 1)

        If tmpInt1 > 6500 Then
            MsgBox("There are more than 6500 words in the selected dictionary file." & Chr(10) & "Only the first 6500 words will be loaded.")
            tmpInt1 = 6500
        End If

        ' Step 11: Set the back color for Label7 to WHITE and populate the field with the word count.
        Label7.BackColor = System.Drawing.Color.White
        Label7.Text = tmpInt1

        ' Step 12: Loop thru the dictionary file and place the words and their lengths into the listview control.
        For x As Integer = 3 To (tmpInt1 + 2)
            FileGet(FileNum, tmpString1, x)
            If tmpString1 <> String.Empty Then
                Dim wrditem As New ListViewItem
                tmpString2 = Trim(Mid(tmpString1, 1, 15))
                tmpInt2 = Len(Trim(tmpString2))
                wrditem.Text = tmpString2
                wrditem.SubItems.Add(Str(tmpInt2))
                ListView1.Items.Add(wrditem)
            End If
        Next

        ' Step 13: Close the dictionary file.
        FileClose(FileNum)

        ' Step 14: Reset the variable ListLoaded to its default value.
        ListLoaded = True

        ' Step 15: Set the sort order for the listview control and sort the list ascending (alphabetically).
        ListView1.Sorting = SortOrder.Ascending
        ListView1.Sort()

        ' Step 16: Make the back color of Label8 white & place the checked items count in the label.
        Label8.BackColor = System.Drawing.Color.White
        Label8.Text = ListView1.CheckedItems.Count.ToString

        ' Step 17:Enable GroupBoxes 3 & 4.
        If ListView1.Items.Count > 0 Then
            GroupBox3.Enabled = True
            Button1.Enabled = True
            Button2.Enabled = False
            GroupBox4.Enabled = False
        End If

        ' Step 18: Return the menu items to their proper status.
        EXPORTToolStripMenuItem.Enabled = False
        SAVEASToolStripMenuItem.Enabled = True
        STARTToolStripMenuItem.Enabled = False
        CLOSEToolStripMenuItem.Enabled = True
        OPENToolStripMenuItem.Enabled = False
        EXITToolStripMenuItem.Enabled = False

    End Sub

推荐答案

笨拙，但你可以添加一个计时器，并在listview1.items.count = tmpInt1的计时器事件检查中，当这是真的时打开所有内容。

Clumsy, but you could add a timer and in the timer event check for listview1.items.count = tmpInt1, turn everything on when this is true.

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