Re: WPF Slider project - WPF Discussion Boards

Mark Salsbery25-Jun-09 7:23

25-Jun-09 7:23

In addition to my other reply...

The magic DataContext:

Any time you have a binding that doesn't explicitly set a source (be it a direct
source, RelativeSource, etc), then an attempt is made to bind to the object set
on the DataContext property of the target element.

If there's a DataContext set and the Path of the binding is not found on that object,
then the binding silently fails (almost silently - you'll get a handy warning in the
debugger output window).

If no DataContext is set on the element, then the system walks up the tree and tries the next
(parent) element's DataContext. This is repeated to the root element. If a source
still wasn't found after all that, the binding will fail and you'll get the message in the
debugger output window.

This allows you to set the DataContext at an appropriate place in the tree so it is
accessible by more than a single element if necessary - very flexible.

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Data binding from a List to a Grid

fjparisIII25-Jun-09 7:40

fjparisIII

25-Jun-09 7:40

I'm not sure this post is relevant to what I'm doing since I'm using neither Linq nor SQL. Is this thinking on my part correct?

Re: Data binding from a List to a Grid

Mark Salsbery25-Jun-09 7:46

Mark Salsbery

25-Jun-09 7:46

You looked at the wrong DataContext. The DataContext we're referring to
is a property of every UIElement.

I think it's very relevant - you'll probably want to set the DataContext to
your list object instances somewhere in your visual tree so you don't have to
use a "global" Application object as your binding source (which is just silly
except for data that needs to be at application scope Smile | :)

From what I gathered, you want data at the scope of each Window (different set of data
for each window, so set the DataContext to that data on the Window or any appropriate
child element of the window).

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Data binding from a List to a Grid

fjparisIII25-Jun-09 8:33

fjparisIII

25-Jun-09 8:33

Mark Salsbery wrote:
You looked at the wrong DataContext.

I do stuff like that all the time. I bring up a class in MSDN and start reading and think, what is this nonsense? Then I look where the article stems from and its Visual Basic or something!

Re: Data binding from a List to a Grid (Everything works now) [modified]

fjparisIII25-Jun-09 12:19

fjparisIII

25-Jun-09 12:19

I've got it all working now, exactly the way I want it. But things got solved in unexpected ways. I couldn't support updating the ListView in XAML if I wanted to replace the values in it multiple times in the same instance of the containing window. I had to initially set ItemsSource to null and Clear() the ListView, and only after setting all the values in the ItemsSource could I bind the data to the control through a simple assignment statement in code-behind.

This solved all my problems! so Mark Salsbery was on the right track when he advised me not to use XAML for the data binding. Maybe there's a way of assigning it in XAML but in this case, I don't know what it is. And where XAML is supposed to be so much more concise than code behind, in this case it is horrendously more complicated! I don't have to worry about "RelativeSource", "AncestorType", "Path", or any of that other BS in XAML. I just prepare my data source and do a one line assignment when it's done, like this:

metadataGrid.ItemsSource = PhotoMetadataList;

Voila! Mission accomplished! What could be simpler? PhotoMetaDataList is local to the window instance and I don't have to worry about binding to something in Application.Current, which was about as ugly as you can get. Each window instance has its own data source and everything works perfectly!

My apologies for not following up on all the posters who gave me fine suggestions, but as the saying goes, if it ain't broken, don't fix it! Thre's valuable suggestions in this thread that will come in handy in the future. And BTW, my problems had absolutely nothing to do with the 3rd party control I'm using, which is just about the spiffiest control in the universe. All my problems were with understanding the basics of pure WPF data binding. No wonder the 3rd party tech support was impatient with me.

Look up Matthew MacDonald's suggestion on page 608 for a replacement to the Windows Forms' DataGridView to find out what control I'm actually using. Unfortunately the book is out of date in suggesting that you can get the standard edition for free. However, it was correct information when I bought the book and I jumped at the chance to get it free! It will currently set you back $300, and thousands if you want the Professional edition. They must have had an army putting this thing together.

modified on Thursday, June 25, 2009 6:28 PM

WPF Slider project

fgimenez24-Jun-09 8:14

fgimenez

24-Jun-09 8:14

Howdy Fellow's:

I've been searching information about WPF's transitions on the web.
I'm trying to develop a "slide" transition to make my appllication look smother, but I keep encoutering issue with all the examples I've found on the net.
in the transition, the image flicks in the borders. I don't want this to happen, but all the examples seem to have to same problem.
I also tried to run my applicattion on a faster and newer machine, but the result was the same. Could it be that windows XP handles the bitmap effects and transitions with software instead of using the hardware?

Thanks for the help.

Cheers

Re: WPF Slider project

Christian Graus24-Jun-09 15:26

Christian Graus

24-Jun-09 15:26

fgimenez wrote:
Could it be that windows XP handles the bitmap effects and transitions with software instead of using the hardware?

No. Windows XP handles all our transitions just fine. Do you have a good video card ? Are your drivers up to date ? What are you doing exactly ?

Christian Graus

Driven to the arms of OSX by Vista.

"! i don't exactly like or do programming and it only gives me a headache." - spotted in VB forums.

I can do things with my brain that I can't even google. I can flex the front part of my brain instantly anytime I want. It can be exhausting and it even causes me vision problems for some reason. - CaptainSeeSharp

Re: WPF Slider project

fgimenez29-Jun-09 2:49

fgimenez

29-Jun-09 2:49

Yes, I've tested in several machines( with different and better video cards) and the result was always the same, the animation flicks.
I'm new to all the wpf developing so I'm building a very simple animation. There is a rectangule with a gradient on the screen and I move it from left to right. That's all.
The size of the rectangule remains the same, only it's position changes.
I'm using the Expression Blend to create the animation and the see the XAML code. The animation looks generated is this one:

<Storyboard x:Key="TextAnimation">
    <ColorAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="{x:Null}" Storyboard.TargetProperty="(Panel.Background).(SolidColorBrush.Color)">
        <SplineColorKeyFrame KeyTime="00:00:02" Value="#FFFF0000"/>
    </ColorAnimationUsingKeyFrames>
</Storyboard>
<Storyboard x:Key="testAnimation">
    <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="rectangle" Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.X)">
        <SplineDoubleKeyFrame KeyTime="00:00:00" Value="0" KeySpline="0,0,1,1"/>
        <SplineDoubleKeyFrame KeyTime="00:00:01" Value="340" KeySpline="0,0,1,1"/>
    </DoubleAnimationUsingKeyFrames>
    <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="rectangle" Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.Y)">
        <SplineDoubleKeyFrame KeyTime="00:00:00" Value="0" KeySpline="0,0,1,1"/>
        <SplineDoubleKeyFrame KeyTime="00:00:01" Value="225" KeySpline="0,0,1,1"/>
    </DoubleAnimationUsingKeyFrames>
</Storyboard>

As you can see, the propertys being changed are the X and Y positions.
The problem is that as the rectangule moves throught the screen, the borders flick( you can see how they are been drawn very quickly) and this gives a very shaby effect.
Is there any other way to do this? All the examples and libreries I've found have the same problem.

Again, thanks!

Cheers

Silverlight2Chat

deep7624-Jun-09 4:59

deep76

24-Jun-09 4:59

I am beginner, trying to understand Silverlight2Chat application. I followed instructions on Build a Silverlight 2 Web Chat Application[^]to create Silverlight2Chat project in visual studio. My solution explorer show the project exactly as in the picture on the above link.

In the web.config file I changed the connection string as follows:
<add name="LinqChatConnectionString" connectionString="Data Source=[STUDYMG];Initial Catalog=LinqChat;Integrated Security=True;" providerName="System.Data.SqlClient"/>

I created two records in dboUsers, and one record in dbo.Room tables.

Now to see how it works, I right click on Silverlight2Chat in the solution explorer in Visual Studio, then choose 'View in Browser', It shows me the login page, I enter credentials and then click on login button, but nothing happens.
I also did 'View in Browser' for Silverlight2ChatTestPage.html, which also shows me the login page, but nothing happens when I enter credentials, and click on login button.

What am I missing? Confused | :confused: