Cant use DoEvents in WPF application

[Don]

I have a WPF application in VB in VSTS 2008 RTM. I am trying to
"blink" (momentarily clear) a field of data if the data is reloaded
from the database to give the user some visual indication of the LOAD
operation.

So on the LOAD button I clear the text fields, do
mainCanvas.UpdateLayout( ), and the reload the text field from the
database. But the text fields are not cleared long enough to see them
blink.

So I add a Thread.Sleep(200) before reloading the text fields. Still
no visual blink.

So I change the Sleep(200) to Sleep(2000), Still no visual blink.

So I attempt to add an Application.DoEvents so that the application
gets a chance to repaint the screen. But when I attempt to add the
"Imports System.Windows.Forms" for the DoEvents, the IDE says
"System.Windows.Forms doesn't contain any public member(s) or cannot
be found."

Apparently DoEvents can not be used in a WPF application because it is
not a Windows Forms.

OK, so how do I get WPF to visually "blink" some text fields in
response to a button push?
How do I replace the DoEvents functionality in a WPF application?

 

[Tom Shelton]

I have a WPF application in VB in VSTS 2008 RTM. I am trying to
"blink" (momentarily clear) a field of data if the data is reloaded
from the database to give the user some visual indication of the LOAD
operation.

So on the LOAD button I clear the text fields, do
mainCanvas.UpdateLayout( ), and the reload the text field from the
database. But the text fields are not cleared long enough to see them
blink.

So I add a Thread.Sleep(200) before reloading the text fields. Still
no visual blink.

So I change the Sleep(200) to Sleep(2000), Still no visual blink.

So I attempt to add an Application.DoEvents so that the application
gets a chance to repaint the screen. But when I attempt to add the
"Imports System.Windows.Forms" for the DoEvents, the IDE says
"System.Windows.Forms doesn't contain any public member(s) or cannot
be found."

Apparently DoEvents can not be used in a WPF application because it is
not a Windows Forms.

OK, so how do I get WPF to visually "blink" some text fields in
response to a button push?
How do I replace the DoEvents functionality in a WPF application?

Are you referencing System.Windows.Forms.dll?

 

[Don]

Are you referencing System.Windows.Forms.dll?

System.Windows.Forms is not listed in the available Namespaces under
References in Project Properties.
I do not think that System.Windows.Forms can be referenced in a WPF
application.

 

[Tom Shelton]

System.Windows.Forms is not listed in the available Namespaces under
References in Project Properties.

It wouldn't be unless you reference the dll - System.Windows.Forms.dll.

I do not think that System.Windows.Forms can be referenced in a WPF
application.

Huh? You just need to referece System.Windows.Forms.dll. You can use
Windows forms controls inside of a WPF app, so you most definately can
reference the dll. You just have to add the reference manually.

Of course, since this is a wpf app, using Application.DoEvents is
probably not the right solution anyway...

You might want to look here for a wpf implementation:

http://shevaspace.spaces.live.com/blog/cns!FD9A0F1F8DD06954!526.entry

The code is C#, but, it should be a fairly simple conversion (the code
is not very complex).

I wonder if you can get your blink effect without using a sleep... Have
you tried looking at the wpf animation support?

 

[Cor Ligthert[MVP]]

Don,

Why are you using a Ready To Marked version while the version is allready
for quiet a while on the marked.

Are you sure you use a non official released VS 2008 version, I have never
seen that a RTM version was not released.
VS 2008. Something is RTM as it is not *official* released.

By the way, for the progam languages is VSTS exactly the same as every VS
version, it has only tools extentions to be uses by teams.

Cor

 

[Don]

It wouldn't be unless you reference the dll - System.Windows.Forms.dll.


Huh? You just need to referece System.Windows.Forms.dll. You can use
Windows forms controls inside of a WPF app, so you most definately can
reference the dll. You just have to add the reference manually.

Of course, since this is a wpf app, using Application.DoEvents is
probably not the right solution anyway...

You might want to look here for a wpf implementation:

http://shevaspace.spaces.live.com/blog/cns!FD9A0F1F8DD06954!526.entry

The code is C#, but, it should be a fairly simple conversion (the code
is not very complex).

I wonder if you can get your blink effect without using a sleep... Have
you tried looking at the wpf animation support?

A modified version of the code that you referenced from shevaspace
worked just fine. I got the DoEvents and Blink functionality that I
was looking for. THANK YOU VERY MUCH !!

I wrote the two following routines in VB:

Imports System.Windows.Threading
Imports System.Threading
Public Sub DoEvents()

Application.Current.Dispatcher.Invoke(DispatcherPriority.Background,
New ThreadStart(AddressOf doNothing))
End Sub

Public Sub doNothing()

End Sub

And then in my application the pseudo code goes:
Public Sub OnLoadButton_Click( )
Clear TextFields
DoEvents( )
Fill TextFields from Database
End Sub

This gives me the "Blink" that I needed that visually shows Blank Text
fields briefly before the Text fields are reloaded so that the User
notices that something happened each time the LoadButton is clicked.

It is frequently helpful to be able to force(allow) a screen update
and a short time delay to occur before any remaining code is executed
for purposes like this.

This will be a helpful technique for many VB WPF developers.

THANKS again for your help.

 

[Herfried K. Wagner [MVP]]

Why are you using a Ready To Marked version while the version is allready
for quiet a while on the marked.

RTM <> "Ready To Market". The RTM version is the version which is finally
distributed (sent to the manufacturer who creates the CDs/DVDs).

 

[Cor Ligthert[MVP]]

">> Why are you using a Ready To Marked version while the version is
allready

RTM <> "Ready To Market". The RTM version is the version which is finally
distributed (sent to the manufacturer who creates the CDs/DVDs).

Yes and?

Cor

 

[Cor Ligthert [MVP]]

and it is therefore okay and good to use a RTM version...

But there is no need to express that here



Cor