所以我一直在摆弄这个问题，我不知道我是不是在理解BackgroundWorker是如何工作的和/或我错误地使用它，或者我是不是＃39;我遗漏了什么。
基本上我尝试做的是从DragDrop函数调用BackgroundWorker，用户可以将一组图像放入表单中。然后BackgroundWorder将图像复制到临时位置，拉伸缩略图并将其转换为PictureBoxes，并将PictureBox添加到集合中。完成BackgroundWorker后，该函数将运行以将所有图片框添加到表单中。
除了进展之外，所有这些都正常工作。在此过程中，进度功能不会直到最后（在几乎所有图片都被复制之后）才会触发（此时我确定进度功能不是为什么不是我无法弄清楚UI锁定的原因。
我已逐步完成代码，并且ReportProgress方法被称为ever循环，但ProgressReported函数不会被调用，直到接近结束。
HELP！ LOL
这是我复制和创建缩略图的ControlClass
Imports System.ComponentModel
Imports System.IO
Namespace ThumbnailViewer
Public Class ThumbnailControl
Inherits FlowLayoutPanel
Private ImageExtensions As List(Of String) = New List(Of String) From {".JPG", ".JPE", ".BMP", ".GIF", ".PNG"}
Private tempStoragePath As String = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData) & "\tempPhotos"
Private WithEvents bkWPhotos As New BackgroundWorker
Public Property iThumbList As List(Of PictureBox)
Public Property sImageList As List(Of String(,))
Private PopupPrg As PopUpProgress.PopUpProgressControl
Public Sub New()
Me.AutoScroll = True
Me.AllowDrop = True
Me.DoubleBuffered = True
iThumbList = New List(Of PictureBox)()
sImageList = New List(Of String(,))()
AddHandler Me.DragDrop, AddressOf ThumbnailViewerControl_DragDrop
AddHandler Me.DragEnter, AddressOf ThumbnailViewerControl_DragEnter
If Not Directory.Exists(tempStoragePath) Then Directory.CreateDirectory(tempStoragePath)
bkWPhotos.WorkerReportsProgress = True
bkWPhotos.WorkerSupportsCancellation = True
End Sub
Public Sub BackGroundWorker_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs) Handles bkWPhotos.DoWork
AddImage(e.Argument)
End Sub
Public Sub BackGroundWorkder_Progress(ByVal sender As Object, ByVal e As ProgressChangedEventArgs) Handles bkWPhotos.ProgressChanged
PopupPrg.SetProgress(e.ProgressPercentage)
End Sub
Public Sub BackGroundWorker_Complete(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs) Handles bkWPhotos.RunWorkerCompleted
For Each i As PictureBox In iThumbList
Me.Controls.Add(i)
Next
PopupPrg.Destory()
Me.Cursor = Cursors.Default
End Sub
Public Sub AddImage(ByVal files As String())
Dim fImage As Image
Dim prg As Integer = 0
For Each f As String In files
If ImageExtensions.Contains(Path.GetExtension(f).ToUpperInvariant()) Then
bkWPhotos.ReportProgress(prg)
fImage = Image.FromFile(f)
File.Copy(f, tempStoragePath & "\" & Path.GetFileName(f), True)
sImageList.Add({{tempStoragePath & "\" & Path.GetFileName(f), fImage.Size.Width, fImage.Size.Height}})
Dim t As PictureBox = MakeThumbnail(fImage)
prg = prg + 1
GC.GetTotalMemory(True)
End If
Next
End Sub
Public Function MakeThumbnail(ByVal inImage As Image) As PictureBox
Dim thumb As PictureBox = New PictureBox()
thumb.Size = ScaleImage(inImage.Size, 200)
thumb.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle
thumb.SizeMode = PictureBoxSizeMode.Zoom
AddHandler thumb.MouseEnter, AddressOf thumb_MouseEnter
AddHandler thumb.MouseLeave, AddressOf thumb_MouseLeave
AddHandler thumb.DoubleClick, AddressOf thumb_DoubleClick
thumb.Image = inImage.GetThumbnailImage(thumb.Width - 2, thumb.Height - 2, Nothing, New IntPtr())
iThumbList.Add(thumb)
Return thumb
End Function
Private Sub thumb_DoubleClick(ByVal sender As Object, ByVal e As EventArgs)
Dim previewForm As Form = New Form()
Dim index As Integer = Me.Controls.GetChildIndex(CType(sender, PictureBox))
Dim img As Image = Image.FromFile(sImageList(index)(0, 0))
previewForm.FormBorderStyle = FormBorderStyle.SizableToolWindow
previewForm.MinimizeBox = False
previewForm.Size = ScaleImage(img.Size, Screen.GetWorkingArea(Me).Height / 4 * 3)
previewForm.StartPosition = FormStartPosition.CenterScreen
Dim view As PictureBox = New PictureBox()
view.Dock = DockStyle.Fill
view.Image = Image.FromFile(sImageList(index)(0, 0))
view.SizeMode = PictureBoxSizeMode.Zoom
previewForm.Controls.Add(view)
previewForm.ShowDialog()
End Sub
Private Sub thumb_MouseLeave(ByVal sender As Object, ByVal e As EventArgs)
CType(sender, PictureBox).Invalidate()
End Sub
Private Sub thumb_MouseEnter(ByVal sender As Object, ByVal e As EventArgs)
Dim rc = (CType(sender, PictureBox)).ClientRectangle
rc.Inflate(-2, -2)
ControlPaint.DrawBorder((CType(sender, PictureBox)).CreateGraphics(), (CType(sender, PictureBox)).ClientRectangle, Color.Red, ButtonBorderStyle.Solid)
ControlPaint.DrawBorder3D((CType(sender, PictureBox)).CreateGraphics(), rc, Border3DStyle.Bump)
End Sub
Private Sub ThumbnailViewerControl_DragEnter(ByVal sender As Object, ByVal e As DragEventArgs)
If e.Data.GetDataPresent(DataFormats.FileDrop) Then e.Effect = DragDropEffects.Copy Else e.Effect = DragDropEffects.None
End Sub
Private Sub ThumbnailViewerControl_DragDrop(ByVal sender As Object, ByVal e As DragEventArgs)
If e.Data.GetDataPresent(DataFormats.FileDrop) Then
Dim files As String() = CType(e.Data.GetData(DataFormats.FileDrop), String())
Me.Cursor = Cursors.WaitCursor
PopupPrg = New PopUpProgress.PopUpProgressControl(Me, files.Count)
bkWPhotos.RunWorkerAsync(files)
End If
End Sub
Public Function ScaleImage(ByVal oldImage As Size, ByVal TargetHeight As Integer) As Size
Dim NewHeight As Integer = TargetHeight
Dim NewWidth As Integer = NewHeight / oldImage.Height * oldImage.Width
NewHeight = NewWidth / oldImage.Width * oldImage.Height
Return New Size(NewWidth, NewHeight)
End Function
End Class
End Namespace
答案 0 :(得分：1)
.... FacePalm.. I figured it out. Apparently during my testing (before I decided to use this control and a background worker, I had added another drag drop function in another area of my code that was being called first. It was taking all the dragged images and turning them into Image data types. The rest of the function was commented out which is why I didn't notice it before because I was only stepping though the classes functions not the functions in the main UI. but it makes perfect sense now, the backgroundworker and the UI function were kicking off at the same time but while the UI thread was processing the Image data typing the report progress calls were stacking up.
After removing that secondary function it works exactly as it should, UI remains fully functional Images and PictureBoxes are processed in the background and the Progressbar updates properly and remains functional as well.