Images loaded into an imagelist aren't displaying in ListView window.

**Mugsy323** · Aug 24th, 2024, 06:26 PM

Short version:
I'm reading png images into an ImageList which are then loaded into a ListView, but no images appear.

Long version:
I'm reading over 200 image files (eg: "File01.png"... "File10.png"... "File100.png", etc.) using a "For/Each loop"
Problem is, it reads "File100.png" before "File11.png", so my program was displaying them in the wrong order.

My "solution" was to extract the file number from the filename and plug the paths into an array using the file number for its position, then (once the For/Each loop has finished), I read the image at those paths into an ImageList and then assign the ImageList to a ListView. But when I try (using a For/Next loop after the array is filled), the ListView comes up empty and I have no idea why.

Code:

    Sub LoadImageList()
        ' Clear old items.
        lsvCollection.Clear()
        ImageList2.Images.Clear()
        lsvCollection.Refresh()
        Dim strTempSortBuffer(256) As String    ' NEW. File100 comes before File11,
        ' so we must sort icons using an array.

        ' Read Items.
        intCnt = 1
        strTempSortBuffer.Initialize()      ' NEW
        For Each ClosetFile As String In IO.Directory.GetFiles(strClosetPath, strCategory & "*.png")
                ' Fill array in "File number" order.
                strTempSortBuffer(Val(Mid(Path.GetFileNameWithoutExtension(ClosetFile.ToString), Len(strCategory) + 1))) = ClosetFile.ToString
                ' Old code: Dim img = Image.FromFile(strTempSortBuffer(intCnt)) ' pre-sorted array has gaps, so we must add images later AFTER array is filled.
                '   ImageList2.Images.Add((intCnt - 1).ToString, img)
                '   img.Dispose()
                intCnt += 1
        Next
        ' NEW code:
        intTotalNumberOfFiles = intCnt - 1
        For intCnt = 1 To intTotalNumberOfFiles
                Dim img As Image = Image.FromFile(strTempSortBuffer(intCnt))
                ImageList2.Images.Add(intCnt - 1, img)
                img.Dispose()   ' Tried WITH & WITHOUT this line.
        Next
        ' after adding items to the listview, set the columns to autosize.
        lsvCollection.Columns.Add("Column 1", 60, HorizontalAlignment.Left)
        lsvCollection.AutoResizeColumn(0, ColumnHeaderAutoResizeStyle.HeaderSize)
        lsvCollection.SmallImageList = ImageList2                                                                                   ' Reassign to list with icons.
        lsvCollection.View = View.Details
        ...

The old code "worked" (images appear) but in the wrong order after "File10". SAME code performed outside the ForEach loop results in NO images being displayed. Debugger says the image list has images in it. Paths are fine. I even tried using a hard coded path and it still didn't work.

Any ideas? I'm stumped. TIA

**jdelano** · Aug 25th, 2024, 05:52 AM

This worked for me (I used .net framework 4.8.1)

Code:

        Dim imgList As New ImageList
        Dim imgFileName As String = ""
        Dim img As Image
        Dim fileNumber As String
        Dim fileIndex As Int16 = 0
        Dim imgFileNames(400) As String
        Dim maxFileIndex As Integer

        ' assign the filename to the appropriate array index
        For Each imgFileName In IO.Directory.GetFiles("F:\Temp\ListViewImages\", "*.jpg")
            fileNumber = imgFileName.Substring(imgFileName.IndexOf("File") + 4, (imgFileName.IndexOf(".jpg") - 1) - (imgFileName.IndexOf("File") + 4) + 1)
            fileIndex = Convert.ToInt16(fileNumber)
            imgFileNames(fileIndex) = imgFileName

            If fileIndex > maxFileIndex Then maxFileIndex = fileIndex

        Next

        ReDim Preserve imgFileNames(maxFileIndex)

        For fileIndex = 0 To UBound(imgFileNames)

            If Not imgFileNames(fileIndex) Is Nothing Then
                ' add the file if there is a path in the array
                img = Image.FromFile(imgFileNames(fileIndex))
                imgList.Images.Add(img)
                img = Nothing

                lvImages.Items.Add(IO.Path.GetFileName(imgFileNames(fileIndex))) ' display the filename in the listview
                lvImages.Items(lvImages.Items.Count - 1).ImageIndex = lvImages.Items.Count - 1
            End If

        Next

        lvImages.Columns.Add("FileName", 60, HorizontalAlignment.Left)
        lvImages.AutoResizeColumn(0, ColumnHeaderAutoResizeStyle.HeaderSize)
        lvImages.SmallImageList = imgList                                                                                   ' Reassign to list with icons.
        lvImages.View = View.Details