I am using VB.NET with Visual Studio 2017.
I am testing a form which has a datagridview. That grid is being populated with initial trading symbols. After loading symbols, I need to press Start button, which starts a timer1 to look for latest price of that symbol from exchange and start timer2. Timer2 will look for certain conditions of price, if met, will place an order to exchange and again look for another loop. While this is happening, timer1 is also running at 2 seconds interval to get latest trading price.
I am using two different BackgroundWorker for each timer to do these two tasks with grid.
This works almost fine, but sometimes, both or one of timers gets disabled.
I am looking for another good and best approach to this as far as code, design and architechure is concerned. If anyone can help.
Private Sub BackgroundWorker1_DoWork(sender As Object, e As DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Me.Timer1.Stop()
Try
With Me.DataGridView4
For RowIndex = 0 To .RowCount - 1
With .Rows(RowIndex)
'CODE FOR CHECKING LTP OF SYMBOL
End With
Next
End With
Catch ex As Exception
End Try
End Sub
Private Sub BackgroundWorker2_DoWork(sender As Object, e As DoWorkEventArgs) Handles BackgroundWorker2.DoWork
Me.Timer2.Stop()
Try
For Each row As DataGridViewRow In Me.DataGridView4.Rows
Dim TRDSYM As String = row.Cells(1).Value
Dim orderid As String = row.Cells(6).Value
Dim Ltp As Decimal = row.Cells(2).Value
Dim EntryPrice As Decimal = Ltp
'PLACING AN ORDER TO EXCHANGE BASED ON CONDITION
Next
Catch ex As Exception
End Try
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
'SetLog("Market Watch For Ltp Background Worker going on...", LogType.Others)
BackgroundWorker1.RunWorkerAsync()
End Sub
Private Sub Timer2_Tick(sender As Object, e As EventArgs) Handles Timer2.Tick
'SetLog("Order Placement Algorithm Background Worker going on...", LogType.Others)
BackgroundWorker2.RunWorkerAsync()
End Sub
Private Sub BackgroundWorker1_RunWorkerCompleted(sender As Object, e As RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
If Me.Timer2.Enabled = False Then
Timer2.Enabled = True
Me.Timer2.Start()
Me.btnOrderplacementstatus.Text = "Order Placement Running..."
Me.btnOrderplacementstatus.BackColor = Color.Green
End If
'SetLog("BackgroundWorker 2 Order Placement Thread started...", LogType.Others)
Me.Timer1.Enabled = True
Me.Timer1.Start()
Me.btnMarketwatchstatus.Text = "Market Watch Running..."
Me.btnMarketwatchstatus.BackColor = Color.Green
End If
End Sub
Private Sub BackgroundWorker2_RunWorkerCompleted(sender As Object, e As RunWorkerCompletedEventArgs) Handles BackgroundWorker2.RunWorkerCompleted
If Me.Timer2.Enabled = False Then
Me.Timer2.Enabled = True
Me.Timer2.Start()
Me.btnOrderplacementstatus.Text = "Order Placement Running..."
Me.btnOrderplacementstatus.BackColor = Color.Green
End If
End Sub
Related
I am building a standalone application with MS Access as the database. When I update the data from the application, I want the data in the DataGridView to also be updated on all of the other computers that are running the application. For that I have LoadData() but when a new ROW is added I am not getting the notification popup.
I really appreciate any help. Thanks in advance. I am not a pro in coding.
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
LoadData()
End Sub
Private Sub dgvNotify_RowsAdded(sender As Object, e As DataGridViewRowsAddedEventArgs) Handles dgvNotify.RowsAdded
Dim targetRow = Me.dgvNotify.Rows.Cast(Of DataGridViewRow)().OrderByDescending(Function(r) r.Cells("ID").Value).FirstOrDefault
If targetRow IsNot Nothing Then
targetRow.Selected = True
New_Notification()
End If
End Sub
Private Sub Form1_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing
Me.WindowState = FormWindowState.Minimized
Me.Visible = False
e.Cancel = True
End Sub
Private Sub New_Notification()
NotifyIcon1.BalloonTipTitle = "New Important Notification"
NotifyIcon1.BalloonTipText = "Open the notification application to check the notifications" & vbCrLf & "If you have any question reachout to ops leads:)"
NotifyIcon1.ShowBalloonTip(3000)
End Sub
I have a Stopwatch in my form with Interval = 1000 displayed in the hh:mm:ss format.
When it reaches the 5th second it should start to blink the label background as green but so far I can only make the background color turn to green without any flash.
This is how I turn the background color to green:
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
Label1.Text = SW.Elapsed.ToString("hh\:mm\:ss")
If Label1.Text = "00:00:05" Then
Label1.BackColor = Color.Green
End If
End Sub
How do I make the label blink?
You could use a simple Async method to do this.
The following code will give Label1 the effect of flashing. Since we have used While True this will continue indefinitely once you hit "00:00:05".
Private Async Sub Flash()
While True
Await Task.Delay(100)
Label1.Visible = Not Label1.Visible
End While
End Sub
You would call this inside your Timer1_Tick method:
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
Label1.Text = SW.Elapsed.ToString("hh\:mm\:ss")
If Label1.Text = "00:00:05" Then
Label1.BackColor = Color.Green
Flash()
End If
End Sub
If you only want to flash a couple of times we can make a simple change to Flash():
Private Async Sub Flash()
For i = 0 To 10
Await Task.Delay(100)
Label1.Visible = Not Label1.Visible
Next
'set .Visible to True just to be sure
Label1.Visible = True
End Sub
By changing the number 10 to a number of your choice you can shorten or lengthen the time taken to flash. I have added in Label1.Visible = True after the For loop just to be sure that we see the Label once the flashing has finished.
You will have to import System.Threading.Tasks to make use of Task.Delay.
You need a label, two textboxes, and a button.
The screen allows you to 'set' a couple of colours - this could be taken further, by adding an Error colour, a Warning colour (where you haven't filled a field in...?) and more.
This colour selection would, in a real application, be done by an admin person, from a separate screen, and stored in the DB.
The timer frequency would also be set in the Admin screen/function.
This particular screen needs the textboxes to be double-clicked, and a colour selected for each one.
The back colour for each box changes. Then press the Start button.
If you press the Start button again, it toggles the timer (on/off)
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
' not quite correct for what I want, but close...
' https://bytes.com/topic/visual-basic-net/answers/368433-blinking-text
Me.Label1.Text = "A blinking text box"
Me.Label1.BackColor = TextBox2.BackColor
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
If Me.Label1.BackColor = TextBox2.BackColor Then
Me.Label1.BackColor = TextBox1.BackColor
Else
Me.Label1.BackColor = TextBox2.BackColor
End If
End Sub
Private Sub TextBox1_MouseDoubleClick(sender As Object, e As MouseEventArgs) Handles TextBox1.MouseDoubleClick
Dim dlg As New ColorDialog()
If dlg.ShowDialog() = DialogResult.OK Then
TextBox1.BackColor = dlg.Color
End If
End Sub
Private Sub TextBox2_MouseDoubleClick(sender As Object, e As MouseEventArgs) Handles TextBox2.MouseDoubleClick
Dim dlg As New ColorDialog()
If dlg.ShowDialog() = DialogResult.OK Then
TextBox2.BackColor = dlg.Color
End If
End Sub
Private Sub btnStart_Click(sender As Object, e As EventArgs) Handles btnStart.Click
Timer1.Enabled = Not Timer1.Enabled
End Sub
End Class
Try to put something like this in Timer1_Tick event handler -
Label1.Visible = Not Label1.Visible
Set the timer to enabled and it will do the job.
If you specify the color when the Text is 00:00:05 then you should also specify what the Backcolor should be when the text is something else i.e 00:00:06
Try this and see if it works:
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
Label1.Text = SW.Elapsed.ToString("hh\:mm\:ss")
If Label1.Text = "00:00:05" Then
Label1.BackColor = Color.Green
else
Label1.Backcolor = Color.Yellow '(Change color as needed)
End If
End Sub
I'm having an issue where BackgroundWorker.CancelAsync() isn't working. I have WorkerSupportsCancellation set to TRUE. I am also polling BackgroundWorker1.CancellationPending in DoWork. Here is sample code of what I am trying to achieve. I have background worker looping through a time stamp and assigning a value to Measurement variable. I have a subroutine that queries the last reported Measurement variable and writes to listbox. After 5 loops I send BackgroundWorker.CancelAsync(). I can see the cancellation is pending, but it doesn't actually cancel the background worker. Is this a race condition?
Public Class Form1
Dim Measurement As String
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
BackgroundWorker1.RunWorkerAsync()
Delay(0.5)
For x = 1 To 5
ListBox1.Items.Add(Measurement)
ListBox1.TopIndex = ListBox1.Items.Count - 1
TextBox1.Text = BackgroundWorker1.CancellationPending
Delay(1)
Next
BackgroundWorker1.CancelAsync()
TextBox1.Text = BackgroundWorker1.CancellationPending
ListBox1.Items.Add("Cancel Pend: " & BackgroundWorker1.CancellationPending)
Delay(5)
ListBox1.Items.Add("Busy: " & BackgroundWorker1.IsBusy)
End Sub
Private Sub BackgroundWorker1_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
If BackgroundWorker1.CancellationPending = True Then
e.Cancel = True
BackgroundWorker1.Dispose()
Exit Sub
Else
Do
Measurement = Now()
Loop
End If
End Sub
End Class
You just need to move the check for the cancellation inside the Do...Loop otherwise it will be tested only at the start of the DoWork event handler and never after that
Private Sub BackgroundWorker1_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
If BackgroundWorker1.CancellationPending = True Then
e.Cancel = True
BackgroundWorker1.Dispose()
Else
Do
If BackgroundWorker1.CancellationPending = True Then
e.Cancel = True
BackgroundWorker1.Dispose()
Exit Do
Else
Measurement = Now()
End If
Loop
End if
End Sub
I have a listview loop that is adding 150,000 items to my listview. For testing purposes I moved this code to a background worker with delegates, but it still freezes up the UI. I am trying to find a solution so that it can add these items in the background while I do other stuff in the app. What solutions do you guys recommend?
this is what I am using
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
ListView1.Clear()
ListView1.BeginUpdate()
bw.WorkerReportsProgress = True
bw.RunWorkerAsync()
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
If bw.IsBusy Then bw.CancelAsync()
End Sub
Private Sub bw_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bw.DoWork
For x = 1 To 125000
Dim lvi As New ListViewItem("Item " & x)
If bw.CancellationPending Then
e.Cancel = True
Exit For
Else
bw.ReportProgress(0, lvi)
End If
Next
End Sub
Private Sub bw_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles bw.ProgressChanged
Try
Dim lvi As ListViewItem = DirectCast(e.UserState, ListViewItem)
Me.ListView1.Items.Add(lvi)
Catch ex As Exception
Throw New Exception(ex.Message)
End Try
End Sub
Private Sub bw_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bw.RunWorkerCompleted
ListView1.EndUpdate()
If Not e.Cancelled Then
Debug.Print("Done")
Else
Debug.Print("Cancelled")
End If
End Sub
End Class
Give this a try, it's a great example for what you would need... I also had a progress bar that shows the progress and such, see example image that is attached. Also I wasn't seeing any delegate that you need to perform such operation, mine has one that will be required. The reason is you are adding items to a control on the UI thread, in order to add items we need to know if an Invoke is required, if so we invoke otherwise we add the item to the control... Also I made the thread sleep, so it can take a break; this also prevents the UI from wanting to lock up here and there, now it's responsive with NO FREEZING.
Option Strict On
Option Explicit On
Public Class Form1
Delegate Sub SetListItem(ByVal lstItem As ListViewItem) 'Your delegate..
'Start the process...
Private Sub btnStartProcess_Click(sender As Object, e As EventArgs) Handles btnStartProcess.Click
lvItems.Clear()
bwList.RunWorkerAsync()
End Sub
Private Sub AddListItem(ByVal lstItem As ListViewItem)
If Me.lvItems.InvokeRequired Then 'Invoke if required...
Dim d As New SetListItem(AddressOf AddListItem) 'Your delegate...
Me.Invoke(d, New Object() {lstItem})
Else 'Otherwise, no invoke required...
Me.lvItems.Items.Add(lstItem)
End If
End Sub
Private Sub bwList_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles bwList.DoWork
Dim intCount As Integer = CInt(txtCount.Text)
Dim dblPercent As Integer = 100
Dim intComplete As Integer = 0
Dim li As ListViewItem = Nothing
For i As Integer = 1 To CInt(txtCount.Text)
If Not (bwList.CancellationPending) Then
li = New ListViewItem
li.Text = "Item " & i.ToString
AddListItem(li)
Threading.Thread.Sleep(1) 'Give the thread a very..very short break...
ElseIf (bwList.CancellationPending) Then
e.Cancel = True
Exit For
End If
intComplete = CInt(CSng(i) / CSng(intCount) * 100)
If intComplete < dblPercent Then
bwList.ReportProgress(intComplete)
End If
If li IsNot Nothing Then
li = Nothing
End If
Next
End Sub
Private Sub bwList_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles bwList.ProgressChanged
pbList.Value = e.ProgressPercentage
End Sub
Private Sub bwList_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bwList.RunWorkerCompleted
If pbList.Value < 100 Then pbList.Value = 100
MessageBox.Show(lvItems.Items.Count.ToString & " items were added!")
End Sub
Private Sub btnStopWork_Click(sender As Object, e As EventArgs) Handles btnStopWork.Click
bwList.CancelAsync()
End Sub
Private Sub btnRestart_Click(sender As Object, e As EventArgs) Handles btnRestart.Click
pbList.Value = 0
lvItems.Items.Clear()
txtCount.Text = String.Empty
End Sub
End Class
Screenshot in action...
The progress bar is repeated two or three times before completing the operation on my backgroundworker
this code:
Private Sub BackgroundWorker1_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
'Load Data
For i As Integer = 0 To ListData.Count
BackgroundWorker1.ReportProgress((i / ListData.Count) * 100)
Next
If BackgroundWorker1.CancellationPending Then
e.Cancel = True
End If
End Sub
Private Sub BackgroundWorker1_ProgressChanged(sender As System.Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
Me.ProgressBar1.Value = e.ProgressPercentage
End Sub
Private Sub BackgroundWorker1_RunWorkerCompleted(sender As System.Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
'set datasource of DatagridView
ProgressBar1.Style = ProgressBarStyle.Blocks
End Sub
In my load form
BackgroundWorker1.WorkerReportsProgress = True
BackgroundWorker1.WorkerSupportsCancellation = True
BackgroundWorker1.RunWorkerAsync()
ProgressBar1.Style = ProgressBarStyle.Marquee
please help me
You have several mistakes. First, if you intend to display an increasing progress bar, you should use:
ProgressBar1.Style = ProgressBarStyle.Continuous
in your load form. Next, you are checking BackgroundWorker1.CancellationPending only after going through all your ListData. That is too late, you have to check it every iteration of the loop. I also really doubt you want your loop to go from 0 to ListData.Count; you probably either want to start at 1 or go to ListData.Count - 1. I can't tell from your question. Your loop should look more like this:
For i as Integer = 0 To ListData.Count - 1
If BackgroundWorker1.CancellationPending Then
e.Cancel = True
Exit For
Else
' You should be doing some work here, not just calling ReportProgress
BackgroundWorker1.ReportProgress(100 * (i+1) / ListData.Count)
End If
Next
Another mistake is calculating (i / ListData.Count) * 100; i and ListData.Count are integers, so their division will always be zero until the end, when it will be 1. Instead, multiply the numerator by 100 to get percentages.