Progress bar for my project, multi-threading needed?

[kimiraikkonen]

Hello experts,
I've been already working on a project and also asked and i've managed
to create a basic Gmail mail sender, but i want to add a progressbar
that shows "sending is in progress" but when i add the
progressbar1.show() when sending then progressbar.hide() after sending
finishes, as known well progressbar is shown after sending is finished
because the main form is in use.

So, must i add multi-threading function to show my progress bar at the
same while my mail is sending simultaneously? Where can i add the code
of that code?

Thanks:

Imports System.Net.mail
Public Class Form1
Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As
System.EventArgs) Handles btnSubmit.Click
Try

Dim message As New MailMessage(txtfrom.Text, txtto.Text,
txtsubject.Text, txtbody.Text)
Dim emailClient As New SmtpClient("smtp.gmail.com")
message.Priority = MailPriority.High


Dim SMTPUserInfo As New System.Net.NetworkCredential(txtSMTPUser.Text
+ "@gmail.com",
txtSMTPPass.Text)
emailClient.UseDefaultCredentials = False
emailClient.Credentials = SMTPUserInfo
emailClient.Port = 587
emailClient.EnableSsl = True
emailClient.Send(message)

MsgBox("Mail was sent successfully",
MsgBoxStyle.Information, "Success!")
Catch ex As Exception
MsgBox("Mail couldn't be send" + vbNewLine + "Make sure
you entered correct username/password then try again later",
MsgBoxStyle.Exclamation, "Fail")
End Try

End Sub

End Class

 

[Guest]

it seems like using a progress bar for sending one email is a bit overkill.
usually progress bars are used to show the progress of a long running task.
by the time the progressbar could be re-drawn to show how far it is, the
email would be sent. as for the use of multi-threading, it would be bad
practice (plus it would throw an error in VS2005) to access a control from
another thread. you should only access controls from the main thread. now if
you still want to show a progress bar, youl need to use the forms invoke
method, but as i said, IMHO its a little overkill for sending one email.

hope this helps

 

[eBob.com]

Because I am trying to multi-thread an application, I was interested in this
and some other recent posts in this general area and would like to seek some
additional information and clarification.

it seems like using a progress bar for sending one email is a bit
overkill.
usually progress bars are used to show the progress of a long running
task.
by the time the progressbar could be re-drawn to show how far it is, the
email would be sent. as for the use of multi-threading, it would be bad
practice (plus it would throw an error in VS2005) to access a control from
another thread. you should only access controls from the main thread. now
if
you still want to show a progress bar, youl need to use the forms invoke
method, but as i said, IMHO its a little overkill for sending one email.

hope this helps

Does "it would be bad practice (...) to access a control from another
thread." mean it would be bad practice (etc) to access a control from a
thread other than the one which created it?

Is it also the case that controls on a form should be, or must be, created
by the same thread which created the form?

Thanks, Bob

 

[Armin Zingler]

Does "it would be bad practice (...) to access a control from
another thread." mean it would be bad practice (etc) to access a
control from a thread other than the one which created it?

Is it also the case that controls on a form should be, or must be,
created by the same thread which created the form?

Yes and yes (must be).


Armin

 

[rowe_newsgroups]

Hello experts,
I've been already working on a project and also asked and i've managed
to create a basic Gmail mail sender, but i want to add a progressbar
that shows "sending is in progress" but when i add the
progressbar1.show() when sending then progressbar.hide() after sending
finishes, as known well progressbar is shown after sending is finished
because the main form is in use.

So, must i add multi-threading function to show my progress bar at the
same while my mail is sending simultaneously? Where can i add the code
of that code?

Thanks:

Imports System.Net.mail
Public Class Form1
Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As
System.EventArgs) Handles btnSubmit.Click
Try

Dim message As New MailMessage(txtfrom.Text, txtto.Text,
txtsubject.Text, txtbody.Text)
Dim emailClient As New SmtpClient("smtp.gmail.com")
message.Priority = MailPriority.High

Dim SMTPUserInfo As New System.Net.NetworkCredential(txtSMTPUser.Text
+ "@gmail.com",
txtSMTPPass.Text)
emailClient.UseDefaultCredentials = False
emailClient.Credentials = SMTPUserInfo
emailClient.Port = 587
emailClient.EnableSsl = True
emailClient.Send(message)

MsgBox("Mail was sent successfully",
MsgBoxStyle.Information, "Success!")
Catch ex As Exception
MsgBox("Mail couldn't be send" + vbNewLine + "Make sure
you entered correct username/password then try again later",
MsgBoxStyle.Exclamation, "Fail")
End Try

End Sub

End Class

Nothing personal, but haven't we been over this topic multiple times?
It seems you are constantly asking the same type of question over and
over, and Armin, I, and others keep giving you the same answers? I
really hate being rude, and I apologize for the tone of the message,
but it gets rather frustrating answering the same questions from the
same person over and over...

Thanks,

Seth Rowe

 

[Guest]

Does "it would be bad practice (...) to access a control from another

thread." mean it would be bad practice (etc) to access a control from a
thread other than the one which created it?

Is it also the case that controls on a form should be, or must be, created
by the same thread which created the form?

yes, controls should only be accessed, created, etc from the main thread,
which is the thread that the main form is on. you can have your form update
controls based on info from other threads, which is how progressbars are
usually used. in this case, you need to look at the forms "invoke" method.

hope this helps

 

[rowe_newsgroups]

Does "it would be bad practice (...) to access a control from another

thread." mean it would be bad practice (etc) to access a control from a
thread other than the one which created it?

Is it also the case that controls on a form should be, or must be, created
by the same thread which created the form?

Yes, accessing a control from a thread different than the one it was
created on will throw a cross-thread exception error.

Also, what multithreading topics where/are you seeking information on?
For a broad overview and theory, you're best bet is to go find a book
on it, but for simpler questions I (and many others I'm sure) will do
what we can to help you out.

Thanks,

Seth Rowe

 

[kimiraikkonen]

Yes and yes (must be).

Armin

OK, but i haven't undestood well something solid, still trying to
learn like multi-threading or working with progress bar simultaneously
with the main form, could you show some example code that shows a
continuous progress bar while sending/connecting is in progress?
Because after i click to send button, the software tries to reach SMTP
server and authenticates, then sends. That procedure usually takes
much time due to slow connections, in that time the form is locked (is
busy, cannot be inteacted) as well.(so that progressbar cannot be
shown without special multi-threading code)

The sample code would be welcomed for running long-length processes in
interaction with progress bar.

 

[kimiraikkonen]

Nothing personal, but haven't we been over this topic multiple times?
It seems you are constantly asking the same type of question over and
over, and Armin, I, and others keep giving you the same answers? I
really hate being rude, and I apologize for the tone of the message,
but it gets rather frustrating answering the same questions from the
same person over and over...

Thanks,

Seth Rowe

OK, but i haven't undestood well something solid, still trying to
learn like multi-threading or working with progress bar simultaneously
with the main form, could you show some example code that shows a
continuous progress bar while sending/connecting is in progress?
Because after i click to send button, the software tries to reach SMTP
server and authenticates, then sends. That procedure usually takes
much time due to slow connections, in that time the form is locked (is
busy, cannot be inteacted) as well.(so that progressbar cannot be
shown without special multi-threading code)

The sample code would be welcomed for running long-length processes in
interaction with progress bar.

That's why i have asked similiar questions more than one time and if
it will be hard to help/reply for you, it's OK not to get help. But
thanks for the help so far in that group.

 

[Armin Zingler]

The sample code would be welcomed for running long-length processes
in interaction with progress bar.

There are many samples in the documentation and in this and other groups,
also in the web. In FW 2.0, you can use the BackgroundWorker class.


Armin

 

[eBob.com]

<snip>
Also, what multithreading topics where/are you seeking information on?
For a broad overview and theory, you're best bet is to go find a book
on it, but for simpler questions I (and many others I'm sure) will do
what we can to help you out.

Thanks,

Seth Rowe


Also, what multithreading topics where/are you seeking information on?
For a broad overview and theory, you're best bet is to go find a book
on it, but for simpler questions I (and many others I'm sure) will do
what we can to help you out.

Hi Seth,

You and others here (Tom Shelton, iwdu15 and Armin come immediately to mind)
are expremely helpful and that is much appreciated.

I've been reading the Threading chapter in Balena which in my opinion is an
excellent book. But I have not noticed in his Threading chapter any
discussion of how a thread might go about updating a control on another
thread's form. (On the other hand I have not read every word of the chapter
yet.) I know from iwdu15's reply to this thread and others (that's thread
in the ng sense!) that I need to look at Invoke and I'll be doing that ASAP.
I also use the Petzold book but have to admit that I have not yet looked at
what he has to say about threading.

Thanks again to all who have responded to this query.

Bob