i've a app that starts from a sub in a module, do a few things, and then load the form.
But it doesn't work :/
Here we execute dBase.AddTemporalFilepath
module.vb
Public dBase As New Core.clsDatabase
Public Sub Main()
FurBase.Directory = My.Application.Info.DirectoryPath
If appMutex.WaitOne(TimeSpan.Zero, True) Then
ShowUploader()
End If
Dim returnValue As String()
returnValue = Environment.GetCommandLineArgs()
If returnValue.Length > 1 Then
If My.Computer.FileSystem.FileExists(returnValue(1).ToString) Then
dBase.AddTemporalFilepath(returnValue(1).ToString)
End If
End If
End Sub
Private Sub ShowUploader()
Application.EnableVisualStyles()
Application.Run(frmUploader)
End Sub
We raise the event TempFilepathAdded
clsDatabase.vb
Public Class clsDatabase
Public Event TempFilepathAdded()
Public Function AddTemporalFilepath(ByVal filepath As String)
...
RaiseEvent TempFilepathAdded()
...
End Function
End Class
We catch the event
form.vb
Private Sub form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
AddHandler dBase.TempFilepathAdded, AddressOf TempFilepathAddedHandler
End Sub
Private Sub TempFilepathAddedHandler()
MsgBox("Event raised")
End Sub
Any Idea?
More info:
The event is raised when the form is closed.
The line "Application.Run(frmUploader)" pauses your program until the Window closes. Basically it hijacks the main thread to handle stuff like users clicking buttons.
Normally your Main function should look like this:
Setup
Application.Run
Clean-up
Sorry, but it looks like its time to reorganize your code.
Related
Have some main form on which I am calling file downloading from FTP. When this operation is raised i want to see new form as ShowDialog and progress bar on it to be shown meantime, then show the progress and close new form and back to main form. My code is working however, when it will process is started my main form freezes and after while new form is appearing and then closing. What I would like to correct is to show this new form to be showed straightaway after process is executed. Can you take a look and tell me whats wrong?
This is out of my main form the download process called:
Dim pro As New FrmProgressBarWinscp(WinScp, myremotePicturePath, ladujZdjeciaPath, True)
FrmProgressBarWinscp is as follows:
Public Class FrmProgressBarWinscp
Property _winScp As WinScpOperation
Property _remotePicture As String
Property _ladujZdjecia As String
Property _removesource As String
Public Sub New()
InitializeComponent()
End Sub
Sub New(winscp As WinScpOperation, remotePicture As String, ladujzdjecia As String, removesource As Boolean)
' This call is required by the designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
_winScp = winscp
_remotePicture = remotePicture
_ladujZdjecia = ladujzdjecia
_removesource = removesource
ShowDialog()
End Sub
Sub Run()
Try
Cursor = Cursors.WaitCursor
_winScp.GetFile(_remotePicture, _ladujZdjecia, _removesource)
ProgressBar1.Minimum = 0
ProgressBar1.Maximum = 1
ProgressBar1.Value = 0
Do
ProgressBar1.Value = WinScpOperation._lastProgress
ProgressBar1.Refresh()
Loop Until ProgressBar1.Value = 1
Cursor = Cursors.Default
'Close()
Catch ex As Exception
Finally
If _winScp IsNot Nothing Then
_winScp.SessionDispose()
End If
System.Threading.Thread.Sleep(10000)
Close()
End Try
End Sub
Private Sub FrmProgressBarWinscp_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Run()
End Sub
End Class
Winscp my own class and used methods:
...
Function GetFile(source As String, destination As String, Optional removeSource As Boolean = False)
Dim result As Boolean = True
Try
session.GetFiles(source, destination, removeSource).Check()
Catch ex As Exception
result = False
End Try
Return result
End Function
Private Shared Sub SessionFileTransferProgress(sender As Object, e As FileTransferProgressEventArgs)
'Print transfer progress
_lastProgress = e.FileProgress
End Sub
Public Shared _lastProgress As Integer
...
Further discussion nr 3:
Main form:
Dim tsk As Task(Of Boolean) = Task.Factory.StartNew(Of Boolean)(Function()
Return WinScp.GetFile(myremotePicturePath, ladujZdjeciaPath, True)
End Function)
Dim forma As New FrmProgressBar
forma.ShowDialog()
Progress bar form:
Public Class FrmProgressBar
Public Sub New()
InitializeComponent()
End Sub
Sub Run()
Try
Do
ProgressBar1.Value = WinScpOperation._lastProgress
ProgressBar1.Refresh()
Loop Until ProgressBar1.Value = 1
Cursor = Cursors.Default
Catch ex As Exception
Finally
MsgBox("before sleep")
System.Threading.Thread.Sleep(10000)
MsgBox("after sleep sleep")
Close()
End Try
End Sub
Private Sub FrmProgressBarWinscp_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Run()
End Sub
End Class
Point nr. 4:
Dim tsk As Task(Of Boolean) = Task.Factory.StartNew(Of Boolean)(Function()
Return WinScp.GetFile(myremotePicturePath, ladujZdjeciaPath, True)
End Function)
Dim pic As New Waiting
pic.ShowDialog()
Task.WaitAll(tsk)
pic.Close()
Point 5:
Dim pic As New Waiting
pic.ShowDialog()
Dim tsk As Task = Task.Factory.StartNew(Sub() WinScp.GetFile(myremotePicturePath, ladujZdjeciaPath, pic, True))
Task.WaitAll(tsk)
'pic.Close()
In some other class (maybe didn't mentioned before this method is placed in diffrent class - my custom one)
Public Function GetFile(source As String, destination As String, formclose As InvokeCloseForm, Optional removeSource As Boolean = False) As Boolean
Dim result As Boolean = True
Try
session.GetFiles(source, destination, removeSource).Check()
Catch ex As Exception
result = False
End Try
formclose.RUn()
Return result
End Function
Interface:
Public Interface InvokeCloseForm
Sub RUn()
End Interface
Waiting form :
Public Class Waiting
Implements InvokeCloseForm
Public Sub RUn() Implements InvokeCloseForm.RUn
Me.Close()
End Sub
End Class
The Session.GetFiles method in blocking.
It means it returns only after the transfer finishes.
The solution is to:
Run the WinSCP transfer (the Session.GetFiles) in a separate thread, not to block the GUI thread.
For that see WinForm Application UI Hangs during Long-Running Operation
Handle the Session.FileTransferProgress event.
Though note that the event handler will be called on the background thread, so you cannot update the progress bar directly from the handler. You have to use the Control.Invoke to make sure the progress bar is updated on the GUI thread.
For that see How do I update the GUI from another thread?
A trivial implementation is below.
For a more version of the code, see WinSCP article Displaying FTP/SFTP transfer progress on WinForms ProgressBar.
Public Class ProgressDialog1
Private Sub ProgressDialog1_Load(
sender As Object, e As EventArgs) Handles MyBase.Load
' Run download on a separate thread
ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf Download))
End Sub
Private Sub Download(stateInfo As Object)
' Setup session options
Dim mySessionOptions As New SessionOptions
With mySessionOptions
...
End With
Using mySession As Session = New Session
AddHandler mySession.FileTransferProgress,
AddressOf SessionFileTransferProgress
' Connect
mySession.Open(mySessionOptions)
mySession.GetFiles(<Source>, <Destination>).Check()
End Using
' Close form (invoked on GUI thread)
Invoke(New Action(Sub() Close()))
End Sub
Private Sub SessionFileTransferProgress(
sender As Object, e As FileTransferProgressEventArgs)
' Update progress bar (on GUI thread)
ProgressBar1.Invoke(
New Action(Of Double)(AddressOf UpdateProgress), e.OverallProgress)
End Sub
Private Sub UpdateProgress(progress As Double)
ProgressBar1.Value = progress * 100
End Sub
End Class
You may want to disable the progress form (or its parts) during the operation, if you want to prevent the user from doing some operations.
Use the .Enabled property of the form or control(s).
Easier, but hacky and generally not recommendable solution, is to call the Application.DoEvents method from your existing SessionFileTransferProgress handler.
And of course, you have to update the progress bar from the the SessionFileTransferProgress as well.
Private Shared Sub SessionFileTransferProgress(
sender As Object, e As FileTransferProgressEventArgs)
'Print transfer progress
ProgressBar1.Value = e.FileProgress
Application.DoEvents
End Sub
And the progress bar's .Minimum and .Maximum must be set before the Session.GetFiles.
But do not do that! That's a wrong approach.
And still, you need to disable the forms/controls the same way as in the correct solution above.
This is my situation, there are 2 Classes and my main form Form1:
Class1: has a method doSomethingAndCall(callback) which creates a new thread
Class2: has dynamic created controls with a button that fires Class1.doSomethingAndCall(newCallback)
in code it looks like this (it starts at Class2.Button_Click):
Class Class1
public shared sub doSomethingAndCallAsync(state as object)
Console.WriteLine(Form1.InvokeRequired) 'output: false
Console.WriteLine(Form1.IsHandleCreated) 'output: false
Form1.Invoke(state.callback) 'throws System.InvalidOperationException
end sub
public shared sub doSomethingAndCall(callback as object)
System.Threading.ThreadPool.QueueUserWorkItem(AddressOf doSomethingAndCallAsync, New With {.callback = callback})
end sub
End Class
Class Class2
Public Delegate Sub doSomethingDelegate()
Public Sub doSomething()
Console.WriteLine("success!")
End Sub
Public Sub Button_Click(ByVal sender As Object, ByVal e As System.EventArgs)
Class1.doSomethingAndCall(New doSomethingDelegate(AddressOf doSomething))
End Sub
End Class
The exact exception I get is:
Invoke or BeginInvoke cannot be called on a control until the window handle has been created
and as I can see the console.WriteLine in line 4 shows me that the form is realy not created. So I added this handlers, and now it get's really confusing:
Private Sub Form1_HandleCreated(sender As Object, e As System.EventArgs) Handles Me.HandleCreated
Console.WriteLine("Handle created") 'Output: Handle created, when running program
End Sub
Private Sub Form1_HandleDestroyed(sender As Object, e As System.EventArgs) Handles Me.HandleDestroyed
Console.WriteLine("Handle destroyed") 'Will never Output!
End Sub
So it's created and never destroyed but if i click the button it's nevertheless not avaible? -Can anyone explain me what is going on and how to call a callback correct, thanks!
The instance of My.Forms.Form1 aka. Form1 will be different in each thread. You need a handle to the correct instance. Drop a button onto your Form1 and add the following code:
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Threading.Tasks.Task.Factory.StartNew(Sub() Class1.Wrong())
Threading.Tasks.Task.Factory.StartNew(Sub() Class1.Correct(Me))
End Sub
End Class
Public Class Class1
Public Shared Sub Wrong()
Debug.WriteLine(String.Format("(Other thread, wrong) InvokeRequired={0}, IsHandleCreated={1}", Form1.InvokeRequired, Form1.IsHandleCreated))
End Sub
Public Shared Sub Correct(instance As Form1)
Debug.WriteLine(String.Format("(Other thread, correct) InvokeRequired={0}, IsHandleCreated={1}", instance.InvokeRequired, instance.IsHandleCreated))
End Sub
End Class
Output
(Other thread, correct) InvokeRequired=True, IsHandleCreated=True
(Other thread, wrong) InvokeRequired=False, IsHandleCreated=False
Maybe this is a simple question and I just don't know the correct search terms to find the answer, but my Google-fu has failed me on this one.
My vb.net application has a background thread that controls all the socket communication. Occasionally, I need this communication thread to open up a modal form to display a message and block UI interaction until the communication thread completes a series of tasks at which point, the communication thread will remove the modal form, allowing the user to continue interaction.
Currently, my communications class containing the background thread has two events, StartBlockingTask and EndBlockingTask. My main form has event listeners for these events that call like-named subs. They call code looking like this:
Private Delegate Sub BlockingDelegate(ByVal reason As String)
Private Sub StartBlockingTask(ByVal reason As String)
If Me.InvokeRequired Then
Dim del As New BlockingDelegate(AddressOf StartBlockingTask)
Me.Invoke(del, New Object() {reason})
Else
Try
_frmBlock.lblBlock.Text = reason
_frmBlock.ShowDialog()
Catch ex As Exception
'stuff
End Try
End If
End Sub
Private Sub EndBlockingTask()
If Me.InvokeRequired Then
Dim del As New BlockingDelegate(AddressOf EndBlockingTask)
Me.Invoke(del, New Object() {""})
Else
Try
If (Not _frmBlock Is Nothing) Then
_frmBlock.DialogResult = Windows.Forms.DialogResult.OK
End If
Catch ex As Exception
'stuff
End Try
End If
End Sub
This successfully blocks the UI from interaction, but it also blocks the communications thread so the EndBlockingTask event never actually gets raised. How can I open this modal dialog from the communications thread and allow the communications thread to still continue running?
Thanks in advance!
I disagree.
All that needs to be done is to change Invoke() to BeginInvoke() and you're golden.
This is because Invoke() is actually synchronous which causes it block until ShowDialog() resolves.
Using BeginInvoke() makes it asynchronous and allows the UI to be blocked while the thread continues:
Public Class Form1
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
If Not BackgroundWorker1.IsBusy Then
BackgroundWorker1.RunWorkerAsync()
End If
End Sub
Private Delegate Sub BlockingDelegate(ByVal reason As String)
Private Sub StartBlockingTask(ByVal reason As String)
If Me.InvokeRequired Then
Dim del As New BlockingDelegate(AddressOf StartBlockingTask)
Me.BeginInvoke(del, New Object() {reason})
Else
Try
_frmBlock.lblBlock.Text = reason
_frmBlock.ShowDialog()
Catch ex As Exception
'stuff
End Try
End If
End Sub
Private Sub EndBlockingTask()
If Me.InvokeRequired Then
Dim del As New BlockingDelegate(AddressOf EndBlockingTask)
Me.BeginInvoke(del, New Object() {""})
Else
Try
If (Not _frmBlock Is Nothing) Then
_frmBlock.DialogResult = Windows.Forms.DialogResult.OK
End If
Catch ex As Exception
'stuff
End Try
End If
End Sub
Private Sub BackgroundWorker1_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
For i As Integer = 1 To 10
BackgroundWorker1.ReportProgress(i)
System.Threading.Thread.Sleep(1000)
If i = 4 Then
Dim del As New BlockingDelegate(AddressOf StartBlockingTask)
del("bada...")
ElseIf i = 7 Then
Dim del As New BlockingDelegate(AddressOf EndBlockingTask)
del("bing!")
End If
Next
End Sub
Private Sub BackgroundWorker1_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
Label1.Text = e.ProgressPercentage
End Sub
End Class
You are calling the address from within the sub it is created in. The Address needs to be called from outside this sub.
Private Sub StartBlockingTask(ByVal reason As String)
If Me.InvokeRequired Then
Dim del As New BlockingDelegate(AddressOf StartBlockingTask)
Private Sub EndBlockingTask()
If Me.InvokeRequired Then
Dim del As New BlockingDelegate(AddressOf EndBlockingTask)
You need to create two delegates. One for StartBlockingTask and one for EndBlockingTask
This is an example from MSDN,
Delegate Sub MySubDelegate(ByVal x As Integer)
Protected Sub Test()
Dim c2 As New class2()
' Test the delegate.
c2.DelegateTest()
End Sub
Class class1
Sub Sub1(ByVal x As Integer)
MessageBox.Show("The value of x is: " & CStr(x))
End Sub
End Class
Class class2
Sub DelegateTest()
Dim c1 As Class1
Dim msd As MySubDelegate
c1 = New Class1()
' Create an instance of the delegate.
msd = AddressOf c1.Sub1
msd.Invoke(10) ' Call the method.
End Sub
End Class
http://msdn.microsoft.com/en-us/library/5t38cb9x(v=vs.71).aspx
Let me know if this helps.
I have come up with a solution that did solve my problem however, I am curious as to why my initial approach failed. My scenario was as described below:
I have a form that raises the event:
Public Class frmDgvLb
Public Delegate Sub ProfileChanged()
Public Event UpdateProfile As ProfileChanged
Private Sub lbDgvEdit_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles lbDgvEdit.SelectedIndexChanged
If UpdateHotlist(cmdStr) = True Then
If DgvName = "dgvHotlist" Then
Hotlist.LoadDGV()
ElseIf DgvName = "dgvJobProfile" Then
RaiseEvent UpdateProfile()
End If
Me.Close()
End If
End Sub
End Class
I have another form where the event is defined and handled:
Public Class frmGraph
Public Sub New()
InitializeComponent()
AddHandler frmDgvLb.UpdateProfile, AddressOf RefreshProfiles
End Sub
Public Sub RefreshProfiles()
GetProfiles(lbMach.SelectedItem, dtpJobDate.Value)
CreateGraph(dtpJobDate.Value, _machList)
zgc.Refresh()
End Sub
End Class
My problem was that the RaiseEvent UpdateProfile() would only execute once. All subsequent index changes of the listbox would not raise the event? When stepping through with the debugger, when the conditional evaluated to true, the debugger would step to the RaiseEvent line and then step to the line closing the conditional statement and the RefreshProfile Sub never executes. Again, the first time the index of the listbox changes, everything functions fine. Why is this?
You have to add the handler to the instance, not the class:
Public Sub New()
InitializeComponent()
AddHandler frmDgvLbInstance.UpdateProfile, AddressOf RefreshProfiles
End Sub
I have a small form that notifies the user on the completion of events (such as SMO restore).
I want this form to appear from various sources (such as the below SMO Restore complete event) so I guess I need to create a new thread before creating the form? As it could be called from outside the UI thread. (I also need to pass a string to this form)
The child form fades in out using a timer + Opacity.
What am I doing wrong here?
Private Sub CompleteEventHandler(ByVal sender As Object, ByVal e As Microsoft.SqlServer.Management.Common.ServerMessageEventArgs)
MyThread = New System.Threading.Thread(AddressOf DoStuff)
MyThread.Start("meh")
End Sub
Private Delegate Sub DoStuffDelegate(ByVal MsgString As String)
Private Sub DoStuff(ByVal MsgString As String)
If Me.InvokeRequired Then
Me.Invoke(New DoStuffDelegate(AddressOf DoStuff))
Else
Dim TempMessage As New frmNotification
TempMessage.lblMessage.Text = MsgString
TempMessage.Show()
End If
End Sub
Don't start a new thread, there's no point since you're already running on another thread and InvokeRequired will always be True. The mistake is that you call Me.Invoke() but forget to pass the "MsgString" argument. You'll also want to use Me.BeginInvoke(), no need to wait. Thus:
Private Sub CompleteEventHandler(ByVal sender As Object, ByVal e As EventArgs)
Me.BeginInvoke(New DoStuffDelegate(AddressOf DoStuff), "meh")
End Sub
Private Sub DoStuff(ByVal MsgString As String)
Dim TempMessage As New frmNotification
TempMessage.lblMessage.Text = MsgString
TempMessage.Show()
End Sub