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Are you using INotifyPropertyChanged in your collection?
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I have an annoying problem with the WPF TreeView. I'll try to explain it.
The TreeView is populated with a root item which contains of 47 sub nodes. The scrollbar is automatically displayed since all sub nodes cannot fit into area where the TreeView is located in.
When I right click, to display a context menu, on a sub node while the scrollbar is at the top position; the correct sub node is selected and I can add sub nodes for that sub node.
But when I right click on a sub node which is only displayed when the scrollbar is moved down, either a bit or to the bottom, the problem occurs.
This cause the scrollbar to automatic jump back up to the top. The sub node which I right clicked on is not selected. The lowest displayed sub node, when the scrollbar is at the top, is instead selected.
I'll try to illustrate this with ASCII art
RootItem
SubNode1
SubNode2
SubNode3
SubNode4
SubNode5 <- This node is selected
--- Border which enables scrollbar
SubNode6
SubNode7
SubNode8
SubNode9 <- Right click here Ascii art FTW! 
Notice the "border"-line which indicates that only Subnode1 to SubNode5 is displayed when the scrollbar is at the top. SubNode6 to SubNode9 are only displayed when the scrollbar is at the bottom.
When right clicking on "SubNode9" the SubNode5" is selected.
I wish could display the source code but my boss forbids me to include the entire code section of the TreeView. Also the code is complicated to understand by just pasting clips of it into this post.
Any suggestions what could case this? I can include code if you ask for a section of it.
/Steffe - Today I have Age++ 
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In these cases, sometimes it's enough just to increase the height of the control a bit.
Any item in a "list / items" type of control that is not completely visible when it is clicked will generally cause scrolling.
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Hi all
I want to set webcam brightness and contrast in silverlight.after hours googleing i found ShaderEffectLibrary.but it adjust the preview brightness and contrast and when i capture image from webcam,it's image is in default brightness and contrast.here is part of my code :
capture.Start();
previewWindow.Background = capture.Brush;
ContrastAdjustEffect effect = new ContrastAdjustEffect();
effect.Brightness = 1.2;
effect.Contrast = 1.2;
previewWindow.Effect = effect;
can any one help me!sorry for my poor english
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Hi
I have a class called ErrorStatus. I am trying to use this class as a property in my interface. When a method is called and an error is thrown I want to populate this object.
I then call the methods of this interface from my viewmodel. I want to bind to properties of ErrorStatus from my xaml, through my viewmodel to the ErrorStatus property of the interface, but it doesn't seem to be working.
The error text isn't being displayed and the HasError isn't being retrieved. I suspect this is something to do with INotifyPropertyChanged and the scope.
I have cut the code down to the essentials.
I have the following class, ErrorStatus:
public class ErrorStatus : INotifyPropertyChanged
{
#region Properties
bool _hasError = false;
public bool HasError
{
get { return _hasError; }
set
{
_hasError = value;
this.RaisePropertyChanged("HasError");
}
}
string _text = String.Empty;
public string Text
{
get { return _text; }
set
{
_text = value;
if (value != String.Empty)
HasError = true;
this.RaisePropertyChanged("Text");
}
}
#endregion
public void Add(String error)
{
Text = error;
}
#region INotifyPropertyChanged Interface
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void RaisePropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion
}
I also have the interface, IService:
public interface IService : INotifyPropertyChanged
{
#region Properties
ErrorStatus ServiceStatus{get;}
#endregion
void TestMethod();
}
and the implementation, Service:
public class MyService : IService
{
private ErrorStatus _serviceStatus = new ErrorStatus();
public ErrorStatus ServiceStatus
{
get { return _serviceStatus; }
private set
{
if (_serviceStatus!= value)
{
_serviceStatus= value;
RaisePropertyChanged("ServiceStatus");
}
}
}
public void TestMethod()
{
ServiceStatus.Add("TEST MESSAGE");
}
#region INotifyPropertyChanged Interface
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void RaisePropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion
}
Any help would be much appreciated, thanks.
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What does your XAML look like? Assuming you are binding to MyService, I'd expect to see references to ServiceStatus.HasErrors, etc, in there.
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Hi Pete
In my ViewModelBase I have an instance of the interface, called MyService.
So then in my actual ViewModel I have the property, ErrorStatus which is what I am binding to in XAML:
private ErrorStatus _errorStatus;
public ErrorStatus ErrorStatus
{
get { return _errorStatus; }
set
{
if (_errorStatus != value)
{
_errorStatus = value;
RaisePropertyChanged("ErrorStatus");
}
}
}
I am also creating an event handler in my viewmodel for property changes in the interface.
MyService.PropertyChanged += MyService_PropertyChanged;
private void MyService_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
switch (e.PropertyName)
{
case "ServiceStatus":
ErrorStatus = MyService.ServiceStatus;
break;
}
}
Would this be the correct approach or should I just create a public property for the viewmodelbase interface instance and bind to the properties through that?
modified 29-May-12 8:52am.
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Does your XAML look like this?
<TextBlock Text="{Binding ErrorStatus.Text}" />
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I've just tried your sample and it works perfectly for me (OK, I cheated in doing a little bit of code behind to add the DataContext, but the principal is still valid). My code-behind looks like this:
private MyService status = new MyService();
public MainWindow()
{
InitializeComponent();
this.DataContext = status;
}
private void Button_Click(object sender, RoutedEventArgs e)
{
status.TestMethod();
}The XAML looks like this:
<Window
x:Class="ErrorStatusTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:vm="clr-namespace:ErrorStatusTest"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Width="525"
Height="350"
Title="MainWindow">
<Grid>
<TextBlock
HorizontalAlignment="Left"
Margin="116,93,0,0"
VerticalAlignment="Top"
Text="{Binding ServiceStatus.Text}"/>
<Button
Width="75"
HorizontalAlignment="Left"
VerticalAlignment="Top"
Click="Button_Click"
Content="Button"/>
</Grid>
</Window>
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Ah right ok, so you are binding to the service properties directly. If you saw in my previous post I have a property in my viewmodel and have a property changed event handler for when a property in the service changes. I was then setting the viewmodel property here.
Is it completely acceptable to declare a public property in my viewmodel for the interface instance in my viewmodelbase and bind to this directly?
So my ViewModelBase has this:
protected IService MyService
{
get { return GetService<IService>(); }
}
And in my ViewModel I would do this and bind to it directly from the XAML?:
public IService Service{get{return MyService;}}
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Right. Got it.
OK, you've got quite a complicated little setup going on here, but the problem lies in the fact that you ultimately aren't propagating the change notification back up the chain here. Basically, your property changed bit in your previous sample only sets the ErrorStatus if the objects are different (which they aren't going to be), so the change notification doesn't reach the XAML (effectively, you've swallowed the change notification).
If I were you, I would look at using a property observer instead - Josh Smith details how to do this here[^].
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Thanks Pete, yes I thought it was probably something like that.
How about the alternative of a public property for the interface instance?
I'll also take a look at the link you posted.
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UCLAdam wrote: How about the alternative of a public property for the interface instance?
You could do that (this, in effect, is what the flattened version I used did). I prefer the property observer though.
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Yes pretty much.
I've had a look at the post, looks interesting. Would you be able to give me pointers to how this would work in my sample?
Obviously I have the PropertyObserver class now. In my viewmodel would I do something like:
PropertyObserver<IService> _observer = new PropertyObserver<IService>(MyService).RegisterHandler(w => w.ErrorStatus, w=> ErrorChanged(w.ErrorStatus));
private object ErrorChanged(ErrorStatus errorStatus)
{
throw new NotImplementedException();
}
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That looks about right to me.
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I seem to get this error:
Error 2 The call is ambiguous between the following methods or properties: PropertyObserver<IService>.RegisterHandler(System.Linq.Expressions.Expression<System.Func<IService,object>>, System.Action<IService>)' and PropertyObserver<IService>.RegisterHandler(System.Func<IService,object>, System.Action<IService>)
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If you can put your project on DropBox, I'll download it tonight and have a look at it.
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Ok figured it out. In my frantic attempts to get it working I must have generated a method stub in the PropertyObserver class. This is why I was getting the error.
Thanks for your help Pete.
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No problem. I'm glad you've got it working.
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after put the control in wpf with winform, winform control in wpf control to cover
What is the reason, should I do?
picture
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I'm sorry, but I'm not clear what you're asking. I've looked at the picture and I can see that you have airspace issues there - is this what you are asking about? An airspace issue is where you try to overlay Winforms and WPF rendering or a web page and WPF rendering.
This is a known issue with WPF (and will be fixed in the next release of WPF) because you are trying to combine rendering stacks - the fix is not to use a Windows Forms control. Find a WPF one that does what you want and use that, or write one yourself - it's generally not that hard.
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There is a workaround which can be used to avoid this issue
You need to wrap the WinformHost with UserControl of WPF.
Follow these steps
1. Create a user control in the WPF (lookless control)
2. Create a style for this control
3. In the template of the style add WinformHost with x:name
4. Now override the OnApplyTemplate() of this control
5. Provide the .Child property of the Winformhost, added in the control
template to the actual winform control that you want to display.
Wrapping the winform control in the WPF control will avoid overlapping the WPF controls.
This overlapping is due to difference in the mechanism for rendering control in WPF and Winforms.
Winforms: uses GDI+ for rendering
WPF: uses DirectX for rendering
Hope this will help you to solve your problem
Happy Coding
modified 30-May-12 0:49am.
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HI All
I want to use DirectShow in silverlight to capture video from webcam . Can any one suggest me the solution .Share some url for reference
cheers
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The original DirectShow framework cannot be used with Silverlight.
This version[^] might help you.
Warning: I have never used this nor have a clue how it works, so I'm not sure how / what the results would be.
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