Cant use DoEvents in WPF application

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Don - 18 Mar 2008 16:23 GMT

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?

Reply to this Message

Tom Shelton - 18 Mar 2008 17:16 GMT

> 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
[quoted text clipped - 23 lines]
> response to a button push?
> How do I replace the DoEvents functionality in a WPF application?

Are you referencing System.Windows.Forms.dll?

Signature

Tom Shelton

Reply to this Message

Don - 18 Mar 2008 18:53 GMT

On Mar 18, 12:16 pm, Tom Shelton
<tom_shel...@YOUKNOWTHEDRILLcomcast.net> wrote:

> > 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
[quoted text clipped - 30 lines]
>
> - Show quoted text -

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.

Reply to this Message

Patrice - 18 Mar 2008 19:20 GMT

> > 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?

You could try :
http://shevaspace.spaces.live.com/blog/cns!FD9A0F1F8DD06954!411.entry

Not familiar yet with WPF but you could perhaps do that by using a WPF
animation ?

--
Patrice

Reply to this Message

Tom Shelton - 18 Mar 2008 19:21 GMT

> On Mar 18, 12:16 pm, Tom Shelton
><tom_shel...@YOUKNOWTHEDRILLcomcast.net> wrote:
[quoted text clipped - 36 lines]
> 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?

Signature

Tom Shelton

Reply to this Message

Don - 19 Mar 2008 16:54 GMT

On Mar 18, 2:21 pm, Tom Shelton
<tom_shel...@YOUKNOWTHEDRILLcomcast.net> wrote:

> > On Mar 18, 12:16 pm, Tom Shelton
> ><tom_shel...@YOUKNOWTHEDRILLcomcast.net> wrote:
[quoted text clipped - 61 lines]
> --
> Tom Shelton

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.

Reply to this Message

Cor Ligthert[MVP] - 19 Mar 2008 06:20 GMT

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

>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
[quoted text clipped - 23 lines]
> response to a button push?
> How do I replace the DoEvents functionality in a WPF application?

Reply to this Message

Herfried K. Wagner [MVP] - 19 Mar 2008 22:43 GMT

"Cor Ligthert[MVP]" <notmyfirstname@planet.nl> schrieb:

> 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).

Signature

M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>

Reply to this Message

Cor Ligthert[MVP] - 20 Mar 2008 07:03 GMT

">> 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).

Yes and?

Cor

Reply to this Message

Steve Gerrard - 20 Mar 2008 07:31 GMT

> ">> Why are you using a Ready To Marked version while the version is
> allready
[quoted text clipped - 5 lines]
>
> Yes and?

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

Reply to this Message

Cor Ligthert [MVP] - 20 Mar 2008 12:40 GMT

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

But there is no need to express that here

:-)

Cor

Reply to this Message

Steve Gerrard - 20 Mar 2008 15:41 GMT

>> and it is therefore okay and good to use a RTM version...
>>
[quoted text clipped - 3 lines]
>
> Cor

You asked the question: "Why are you using a Ready To Marked version while the
version is allready for quiet a while on the marked."

Therefore you got an answer.

By the way, RTM = Released to Manufacturing.

Reply to this Message

Cant use DoEvents in WPF application

Free Magazines