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• Entity Framework 4.0 Databinding with sorting not working

  - by Mike Gates

  I want to do something that I thought would be very simple. I want to bind a generated Entity Framework EntityCollection to a WPF DataGrid. I also want this grid to be sortable. I have tried all kinds of things to make this happen, including using a CollectionViewSource. However, nothing seems to work. Using a normal CollectionViewSource around the EntityCollection gives me: 'System.Windows.Data.BindingListCollectionView' view does not support sorting. Ok...strange. I would have thought this would work. Next on the CollectionViewSource, I try setting: CollectionViewType="ListCollectionView" Great, sorting now works. But wait, I can't add or remove entities using the grid now, presumably because ListCollectionView doesn't support this with an entity framework context. So, I guess I need to capture events coming out of the datagrid in order to add or remove entities manually from my context. Now I can't find an event to capture to detect an add...! Why is this so hard? This should be the standard "demo" case that Microsoft should have designed around. Any ideas?

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• Binding to an ObservableCollection attached property.

  - by bwreichle

  I want to create an attached property of type ObservableCollection<Notification> and bind it to a property of the same type on the DataContext. Currently I have: internal static class Squiggle { public static readonly DependencyProperty NotificationsProperty = DependencyProperty.RegisterAttached( "Notifications", typeof(ObservableCollection<Notification>), typeof(TextBox), new FrameworkPropertyMetadata(null, NotificationsPropertyChanged, CoerceNotificationsPropertyValue)); public static void SetNotifications(TextBox textBox, ObservableCollection<Notification> value) { textBox.SetValue(NotificationsProperty, value); } public static ObservableCollection<Notification> GetNotifications(TextBox textBox) { return (ObservableCollection<Notification>)textBox.GetValue(NotificationsProperty); } ... } With the following XAML: <TextBox x:Name="configTextBox" Text="{Binding Path=ConfigText, UpdateSourceTrigger=PropertyChanged}" AcceptsReturn="True" AcceptsTab="True" local:Squiggle.Notifications="{Binding Path=Notifications}" /> Unfortunatly, when I actually run this I get an exception stating: A 'Binding' cannot be used within a 'TextBox' collection. A 'Binding' can only be set on a DependencyProperty of a DependencyObject. This only seems to be a problem when the attached property is of type ObservableCollection so it seems like WPF is trying to do something magical when binding properties of this type and getting confused in the process. Anyone know what I need to do to make it work?

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• Databinding between UserControls?

  - by Dave

  I've got a situation where one of my UserControls would like to display a list of strings in a droplist, and the ItemsSource is set to another UserControl's ObservableCollection. The consumer of this data has its droplist defined in XAML like this: <ComboBox Grid.Column="1" SelectedItem="{Binding MyItem, Mode=TwoWay}" ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.MyItems}" Margin="3"></ComboBox> MyItems is defined as an ObservableCollection<string> in the producer UserControl. Now everything works fine when the controls are loaded. As long as MyItems is populated first, and then the consumer UserControl is displayed, all of the items are there. I obviously don't get any errors in the Output Window or anything like that. The issue I have is that when the ObservableCollection is modified, those changes are not reflected in the consumer UserControl! I've never had this problem before, but all of my previous uses of ObservableCollection with updating the collection are within a single control, and databinding is not inter-UserControl. Is there something I did wrong? Is there a good way to actually debug this? Reed Copsey indicates here that inter-UserControl databinding is possible. Unfortunately, my favorite Bea Stollnitz article on WPF databinding debugging doesn't suggest anything that I could use for this particular problem.

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• Windows Forms Host + System.Windows.Forms.DataVisualization.Chart

  - by dark-elf2

  Good day all I have the following question: I would like to use Chart from Windows Forms due to the fact that it allows to build much more types of graphical visualisation that one from WPF Toolkit does. So, I am adding Chart control for Windows Forms as a child element into the WindowsFormsHost. But, when I run the application I and all my clients see only white area. Though, any other Windows Forms Control works great in Windows Forms Host. What is wrong with the Chart control? Here is the XAML code <Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:wfi="clr-namespace:System.Windows.Forms.Integration;assembly=WindowsFormsIntegration" xmlns:wf="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms" xmlns:CHR="clr-namespace:System.Windows.Forms.DataVisualization.Charting;assembly=System.Windows.Forms.DataVisualization" Title="Window1" Height="300" Width="300"> <Grid> <wfi:WindowsFormsHost x:Name="mainFGrid" > <CHR:Chart x:Name="mainChart" /> </wfi:WindowsFormsHost> </Grid> </Window> Kind regards, Anatoliy Sova

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• System Tray Popup Windows 7 Style

  - by Mason Blier

  Hey All, I want something like this: http://cybernetnews.com/wp-content/uploads/2008/10/windows-7-wireless.jpg This window is not resizable, and aligns itself above the system tray icon which it is related to. I have this: http://i.imgur.com/79FZi.png Which is resizeable, and it goes wherever it feels like. If you click the volume control in Win 7, it always pops up directly above the icon. This is ideal. I've found this reference which I think is trying to solve the same problem (can't tell though as the images are dead), http://stackoverflow.com/questions/2169006/create-a-system-tray-styled-box-in-winforms-c but I'm using WPF and I'm not sure how to get these Form objects they refer to from my Window object. This is the XAML declaration of my window atm, <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" x:Class="WirelessControl.Window1" x:Name="Window" Title="Window1" Width="260" Height="370" mc:Ignorable="d" WindowStyle="None"></Window> I feel like based on how common this is in Windows that there must be a fairly easy way to do this. ResizeMode="NoResize" causes my window border to disappear, so that's no help. Thanks guys, I hope I was comprehensive enough.

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• ICollectionView.SortDescriptions sort does not work if underlying DataTable has zero rows

  - by BigBlondeViking

  We have a WPF app that has a DataGrid inside a ListView. private DataTable table_; We do a bunch or dynamic column generation ( depending on the report we are showing ) We then do the a query and fill the DataTable row by row, this query may or may not have data.( not the problem, an empty grid is expected ) We set the ListView's ItemsSource to the DefaultView of the DataTable. lv.ItemsSource = table_.DefaultView; We then (looking at the user's pass usage of the app, set the sort on the column) Sort Method below: private void Sort(string sortBy, ListSortDirection direction) { ICollectionView dataView = CollectionViewSource.GetDefaultView(lv.ItemsSource); dataView.SortDescriptions.Clear(); var sd = new SortDescription(sortBy, direction); dataView.SortDescriptions.Add(sd); dataView.Refresh(); } In the Zero DataTable rows scenario, the sort does not "hold"? and if we dynamically add rows they will not be in sorted order. If the DataTable has at-least 1 row when the sort is applied, and we dynamically add rows to the DataTable, the rows com in sorted correctly. I have built a standalone app that replicate this... It is an annoyance and I can add a check to see if the DataTable was empty, and re-apply the sort... Anyone know whats going on here, and am I doing something wrong? FYI: What we based this off if comes from the MSDN as well: http://msdn.microsoft.com/en-us/library/ms745786.aspx

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• New to MVVM - Best practices for seperating Data processing thread and UI Thread?

  - by OffApps Cory

  Good day. I have started messing around with the MVVP pattern, and I am having some problems with UI responsiveness versus data processing. I have a program that tracks packages. Shipment and package entities are persisted in SQL database, and are displayed in a WPF view. Upon initial retrieval of the records, there is a noticeable pause before displaying the new shipments view, and I have not even implemented the code that counts shipments that are overdue/active yet (which will necessitate a tracking check via web service, and a lot of time). I have built this with the Ocean framework, and all appears to be doing well, except when I first started my foray into multi-threading. It broke, and it appeared to break something in Ocean... Here is what I did: Private QueryThread As New System.Threading.Thread(AddressOf GetShipments) Public Sub New() ' Insert code required on object creation below this point. Me.New(ViewManagerService.CreateInstance, ViewModelUIService.CreateInstance) 'Perform initial query of shipments 'QueryThread.Start() GetShipments() Console.WriteLine(Me.Shipments.Count) End Sub Public Sub New(ByVal objIViewManagerService As IViewManagerService, ByVal objIViewModelUIService As IViewModelUIService) MyBase.New(objIViewModelUIService) End Sub Public Sub GetShipments() Dim InitialResults = From shipment In db.Shipment.Include("Packages") _ Select shipment Me.Shipments = New ShipmentsCollection(InitialResults, db) End Sub So I declared a new Thread, assigned it the GetShipments method and instanced it in the default constructor. Ocean freaks out at this, so there must be a better way of doing it. I have not had the chance to figure out the usage of the SQL ORM thing in Ocean so I am using Entity Framework (perhaps one of these days i will look at NHibernate or something too). Any information would be greatly appreciated. I have looked at a number of articles and they all have examples of simple uses. Some have mentioned the Dispatcher, but none really go very far into how it is used. Anyone know any good tutorials? Cory

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• How to remove space between chart area and plot area?

  - by Gopalakrishnan Subramani

  I am using chartingToolKit:Chart control. I want to remove the white space appear in between the chart and plot area. Attached the WPF sample and image of area to be removed. <Window x:Class="WpfApplication2.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525" xmlns:chartingToolkit="clr-namespace:System.Windows.Controls.DataVisualization.Charting;assembly=System.Windows.Controls.DataVisualization.Toolkit"> <Grid> <chartingToolkit:Chart x:Name="chart" Width="500" Height="300" Margin="0, 0, 0, 0" LegendStyle="{StaticResource LegendStyle}" > <chartingToolkit:AreaSeries ItemsSource="{Binding}" DependentValuePath="Value" IndependentValuePath="Key" Background="Red" > </chartingToolkit:AreaSeries> <chartingToolkit:Chart.Axes> <chartingToolkit:LinearAxis Orientation="X" ShowGridLines="False" Visibility="Hidden"> </chartingToolkit:LinearAxis> <chartingToolkit:LinearAxis Orientation="Y" ShowGridLines="False" Visibility="Hidden"/> </chartingToolkit:Chart.Axes> </chartingToolkit:Chart> </Grid> The area marked in red arrow must be removed

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• How do I stop inheritance in xaml?

  - by cfouche

  Hi Let's say I have some Control that has been disabled. It contains a bunch of elements, but I want one of those child elements to remain enabled. Something like this: <ContentControl IsEnabled="False"> <Border> <Button Content="Button" IsEnabled="True"/> </Border> </ContentControl> So in this example, the Button's IsEnabled="True" setting gets overridden by its parent. Is there a way of stopping this from happening? This seems like a strange thing to be doing, but I have a situation where, when a Control is disabled and a user mouses down on it, I still want an event to be triggered. I read in WPF Unleashed that wrapping something in a Frame control, "..isolates the content from the rest of the UI [and] properties that would normally be inherited down the element tree stop when they reach the Frame", but wrapping the Button in the example above in a Frame doesn't work. Am I on the wrong track here?

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• Performance penalty of typecasting and boxing/unboxing types in C# when storing generic values

  - by kitsune

  I have a set-up similar to WPF's DependencyProperty and DependencyObject system. My properties however are generic. A BucketProperty has a static GlobalIndex (defined in BucketPropertyBase) which tracks all BucketProperties. A Bucket can have many BucketProperties of any type. A Bucket saves and gets the actual values of these BucketProperties... now my question is, how to deal with the storage of these values, and what is the penalty of using a typecasting when retrieving them? I currently use an array of BucketEntries that save the property values as simple objects. Is there any better way of saving and returning these values? Beneath is a simpliefied version: public class BucketProperty<T> : BucketPropertyBase { } public class Bucket { private BucketEntry[] _bucketEntries; public void SaveValue<T>(BucketProperty<T> property, T value) { SaveBucketEntry(property.GlobalIndex, value) } public T GetValue<T>(BucketProperty<T> property) { return (T)FindBucketEntry(property.GlobalIndex).Value; } } public class BucketEntry { private object _value; private uint _index; public BucketEntry(uint globalIndex, object value) { ... } }

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• Please suggest me the ( Interaction model of view model) MVVM design in the simple scenario discusse

  - by Jack

  Data Layer I have an Order class as an entity. This Order entity is my model object. Order can be different types, let it be A B C D Also Order class may have common properties like Name, Time of creation, etc. Also based on the order type there are different fields that are not common. View Layer The view contains the following Main Menu ListView The Main Menu contains the drop down menu button which is used to create the order based on the type selected from the drop down. The drop down contains the Order types ( A ,B , C and D). There are different user control based on the order type. Like for example if user chooses to create an order of type A then different view with different inputs field is popped up. Hence, there are four user control for each order type. If user selects A option from the drop down then Order of type A is created and vica versa. Now below is the List View that contains the List of orders so far created by the user. To Edit any particular order user may double click the list view row. Based on the order type clicked by the user in the listview, the view of that order type opens in edit mode. For example if user selects an order type A from the list view then view for order type A open in edit mode. Please suggest me interaction model for view model's in the scenario discussed above. Please excume me if the query is very basic, since I am new new to MVVM and WPF ,

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• Refactoring Bloated ViewModel

  - by Holy Christ

  Hi, I am writing a PRISM/MVVM/WPF application. It's a LOB application, so there are a lot of complicated rules. I've noticed the View Model is starting to get bloated. There are two main issues. One is that to maintain MVVM, I'm doing a lot of things that feel hacky like adding a bunch of properties to my VM. The view binds to those properties to keep track of what feels like view specific information. For example, a boolean keeping track of the status of a long running process in the VM, so the view can disable some of its controls while the long running process is working. I've read that this issue could be solved with Attached Behaviors. I'll look more into that. In the example MVVM apps you see online, this isn't a big deal because they are over-simplified. The other issue is the number of commands in my VM. Right now there are four commands. I'm defining the commands in the VM using Josh Smith's RelayCommand (basically the DelegateCommand in PRISM) so all the business logic lives in the VM. I considered moving each command into separate unit of works. I'm not sure the best way to do this. Which patterns are you guys using to keep your VMs clean? I can already feel someone responding with "your view and VM is too complicated, you should break them into many view/VMs". It is certainly not too complicated from a Ux perspective - there are 2 buttons, a combobox, and a listbox. Also, from a logical perspective, it is one cohesive domain. Having said that, I'm very interested in hearing how others are dealing with this type of issue. Thanks for your input.

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• Draw a column graph with no space between columns

  - by Andrew Shepherd

  I am using the WPF toolkit, and am trying to render a graph that looks like a histogram. In particular, I want each column to be right up against each other column. There should be no gaps between columns. There are a number of components that you apply when creating a column graph. (See example XAML below). Does anybody know if there is a property you can set on one of the elements which refers to the width of the white space between columns? <charting:Chart Height="600" Width="Auto" HorizontalAlignment="Stretch" Name="MyChart" Title="Column Graph" LegendTitle="Legend"> <charting:ColumnSeries Name="theColumnSeries" Title="Series A" IndependentValueBinding="{Binding Path=Name}" DependentValueBinding="{Binding Path=Population}" Margin="0" > </charting:ColumnSeries> <charting:Chart.Axes> <charting:LinearAxis Orientation="Y" Minimum="200000" Maximum="2500000" ShowGridLines="True" /> <charting:CategoryAxis Name="chartCategoryAxis" /> </charting:Chart.Axes> </charting:Chart>

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• Context menu event handling error - CS1061

  - by MrTemp

  I am still new to c# and wpf This program is a clock with different view and I would like to use the context menu to change between view, but the error says that there is no definition or extension method for the events. Right now I have the event I'm working on popping up a MessageBox just so I know it has run, but I cannot get it to compile. public partial class MainWindow : NavigationWindow { public MainWindow() { //InitializeComponent(); } public void AnalogMenu_Click(object sender, RoutedEventArgs e) { /*AnalogClock analog = new AnalogClock(); this.NavigationService.Navigate(analog);*/ } public void DigitalMenu_Click(object sender, RoutedEventArgs e) { MessageBox.Show("Digital Clicked"); /*DigitalClock digital = new DigitalClock(); this.NavigationService.Navigate(digital);*/ } public void BinaryMenu_Click(object sender, RoutedEventArgs e) { /*BinaryClock binary = new BinaryClock(); this.NavigationService.Navigate(binary);*/ } } and the xaml call if you want it <NavigationWindow.ContextMenu> <ContextMenu Name="ClockMenu" > <MenuItem Name="ToAnalog" Header="To Analog" ToolTip="Changes to an analog clock"/> <MenuItem Name="ToDigital" Header="To Digital" ToolTip="Changes to a digital clock" Click="DigitalMenu_Click" /> <MenuItem Name="ToBinary" Header="To Binary" ToolTip="Changes to a binary clock"/> </ContextMenu> </NavigationWindow.ContextMenu>

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• Bind a subclass to property

  - by Neir0

  Hi i have a simple question. Ofcourse it has many answers but i cannt choose right keywords to google. How i can bind a subclass to my wpf control? for example: It's my class. public class SiteFieldInfo<T> { public string Name { get; set; } public T Value { get; set; } public List<string> PositiveXPathExpressions { get; set; } public List<string> NegativeXPathExpressions { get; set; } } public class SiteInfo { public SiteFieldInfo<string> Author { get; set; } public SiteFieldInfo<DateTime> Date { get; set; } public SiteFieldInfo<string> Source { get; set; } } And i want to bind property Value from SiteFieldInfo to Text property of TextBox control. c# code: stackPanel1.DataContext = SiteInfoInstance; xaml code: <StackPanel Name="stackPanel1"> <TextBlock Text="Author" Grid.Row="0" Grid.Column="0" /> <TextBox Grid.Row="0" Grid.Column="1" Text="{Binding Path=Author.Value}" /> </StackPanel> It's not working. What is right syntax or any alternatives?

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• How have you successfully implemented MessageBox.Show() functionality in MVVM?

  - by Edward Tanguay

  I've got a WPF application which calls MessageBox.Show() way back in the ViewModel (to check if the user really wants to delete). This actually works, but goes against the grain of MVVM since the ViewModel should not explicitly determine what happens on the View. So now I am thinking how can I best implement the MessageBox.Show() functionality in my MVVM application, options: I could have a message with the text "Are you sure...?" along with two buttons Yes and No all in a Border in my XAML, and create a trigger on the template so that it is collapsed/visible based on a ViewModelProperty called AreYourSureDialogueBoxIsVisible, and then when I need this dialogue box, assign AreYourSureDialogueBoxIsVisible to "true", and also handle the two buttons via DelegateCommand back in my ViewModel. I could also somehow try to handle this with triggers in XAML so that the Delete button actually just makes some Border element appear with the message and buttons in it, and the Yes button did the actually deleting. Both solutions seem to be too complex for what used to be a couple lines of code with MessageBox.Show(). In what ways have you successfully implemented Dialogue Boxes in your MVVM applications?

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• validation properties by attribute

  - by netmajor

  I create class with two property - name,link(below). I use simple property validation by Required and StringLength attribute. I bind this class object to WPF ListBox(with textBoxs). But when I have textbox empty or write words longer than 8 sign nothing happens :/ What should I do to fires ErrorMessage? Or how to implement validation in other way ? I also try use : if (value is int) { throw new ArgumentException("Wpisales stringa!!"); } But it only fires in debug mode :/ My class with implementation of attribute validation: public class RssInfo : INotifyPropertyChanged { public RssInfo() { } public RssInfo(string _nazwa, string _link) { nazwa = _nazwa; link = _link; } private string nazwa; [Required(ErrorMessage = "To pole jest obowiazkowe nAZWA")] public string Nazwa { get { return nazwa; } set { if (value != nazwa) { nazwa = value; onPropertyChanged("Nazwa"); } if (value is int) { throw new ArgumentException("Wpisales stringa!!"); } } } private string link; [Required(ErrorMessage="To pole jest obowiazkowe link")] [StringLength(8, ErrorMessage = "Link cannot be longer than 8 characters")] public string Link { get { return link; } set { if (value != link) { link = value; onPropertyChanged("Link"); } } } #region INotifyPropertyChanged Members public event PropertyChangedEventHandler PropertyChanged; #endregion private void onPropertyChanged(string propertyName) { if (this.PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } }

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• MVVM, ContextMenus and binding to ViewModel defined Command

  - by Simon Fox

  Hi I am having problems with the binding of a ContextMenu command to an ICommand property in my ViewModel. The binding seems to be attaching fine...i.e when I inspect the value of the ICommand property it is bound to an instance of RelayCommand. The CanExecute delegate does get invoked, however when I open the context menu and select an item the Execute delegate does not get invoked. Heres my View (which is defined as the DataTemplate to use for instances of the following ViewModel in a resource dictionary): <UserControl x:Class="SmartSystems.DragDropProto.ProductLinkView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:Proto"> <UserControl.Resources> <local:CenteringConverter x:Key="centeringConvertor"> </local:CenteringConverter> </UserControl.Resources> <UserControl.ContextMenu> <ContextMenu> <MenuItem Command="{Binding ChangeColor}">Change Color</MenuItem> </ContextMenu> </UserControl.ContextMenu> <Canvas> <Ellipse Width="5" Height="5" > <Ellipse.Fill> <SolidColorBrush Color="{Binding LinkColor}"></SolidColorBrush> </Ellipse.Fill> <Ellipse.RenderTransform> <TranslateTransform X="{Binding EndpointOneXPos, Converter={StaticResource centeringConvertor}}" Y="{Binding EndpointOneYPos, Converter={StaticResource centeringConvertor}}"/> </Ellipse.RenderTransform> </Ellipse> <Line X1="{Binding Path=EndpointOneXPos}" Y1="{Binding Path=EndpointOneYPos}" X2="{Binding Path=EndpointTwoXPos}" Y2="{Binding Path=EndpointTwoYPos}"> <Line.Stroke> <SolidColorBrush Color="{Binding LinkColor}"></SolidColorBrush> </Line.Stroke> </Line> <Ellipse Width="5" Height="5" > <Ellipse.Fill> <SolidColorBrush Color="{Binding LinkColor}"></SolidColorBrush> </Ellipse.Fill> <Ellipse.RenderTransform> <TranslateTransform X="{Binding EndpointTwoXPos, Converter={StaticResource centeringConvertor}}" Y="{Binding EndpointTwoYPos, Converter={StaticResource centeringConvertor}}"/> </Ellipse.RenderTransform> </Ellipse> </Canvas> </UserControl> and ViewModel (with uneccessary implementation details removed): class ProductLinkViewModel : BaseViewModel { public ICommand ChangeColor { get; private set; } public Color LinkColor { get; private set; } public ProductLinkViewModel(....) { ... ChangeColor = new RelayCommand(ChangeColorAction); LinkColor = Colors.Blue; } private void ChangeColorAction(object param) { LinkColor = LinkColor == Colors.Blue ? Colors.Red : Colors.Blue; OnPropertyChanged("LinkColor"); } }

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• GridViewColumn not subscribing to PropertyChanged event in a ListView

  - by Chris Wenham

  I have a ListView with a GridView that's bound to the properties of a class that implements INotifyPropertyChanged, like this: <ListView Name="SubscriptionView" Grid.Column="0" Grid.ColumnSpan="2" Grid.Row="2" ItemsSource="{Binding Path=Subscriptions}"> <ListView.View> <GridView> <GridViewColumn Width="24" CellTemplate="{StaticResource IncludeSubscriptionTemplate}"/> <GridViewColumn Width="150" DisplayMemberBinding="{Binding Path=Name}" Header="Subscription"/> <GridViewColumn Width="75" DisplayMemberBinding="{Binding Path=RecordsWritten}" Header="Records"/> <GridViewColumn Width="Auto" CellTemplate="{StaticResource FilenameTemplate}"/> </GridView> </ListView.View> </ListView> The class looks like this: public class Subscription : INotifyPropertyChanged { public int RecordsWritten { get { return _records; } set { _records = value; if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("RecordsWritten")); } } private int _records; ... } So I fire up a BackgroundWorker and start writing records, updating the RecordsWritten property and expecting the value to change in the UI, but it doesn't. In fact, the value of PropertyChanged on the Subscription objects is null. This is a puzzler, because I thought WPF is supposed to subscribe to the PropertyChanged event of data objects that implement INotifyPropertyChanged. Am I doing something wrong here?

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• Why does ObservableCollection throws an exception when being modified?

  - by Oliver Hanappi

  Hi! My application uses a WPF DataGrid. One of the columns is a template column that containts a combobox bound to an ObservableCollection of the entity which feeds the row. When I add a value to the ObservableCollection, a NullReferenceException is thrown. Has anybody an idea why this happens? Here is the stacktrace of the exception: at MS.Internal.Data.PropertyPathWorker.DetermineWhetherDBNullIsValid() at MS.Internal.Data.PropertyPathWorker.get_IsDBNullValidForUpdate() at MS.Internal.Data.ClrBindingWorker.get_IsDBNullValidForUpdate() at System.Windows.Data.BindingExpression.ConvertProposedValue(Object value) at System.Windows.Data.BindingExpressionBase.UpdateValue() at System.Windows.Data.BindingExpression.Update(Boolean synchronous) at System.Windows.Data.BindingExpressionBase.Dirty() at System.Windows.Data.BindingExpression.SetValue(DependencyObject d, DependencyProperty dp, Object value) at System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, OperationType operationType, Boolean isInternal) at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value) at System.Windows.Controls.Primitives.Selector.UpdatePublicSelectionProperties() at System.Windows.Controls.Primitives.Selector.SelectionChanger.End() at System.Windows.Controls.Primitives.Selector.OnItemsChanged(NotifyCollectionChangedEventArgs e) at System.Windows.Controls.ItemsControl.OnItemCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e) at System.Collections.Specialized.NotifyCollectionChangedEventHandler.Invoke(Object sender, NotifyCollectionChangedEventArgs e) at System.Windows.Data.CollectionView.OnCollectionChanged(NotifyCollectionChangedEventArgs args) at System.Windows.Controls.ItemCollection.System.Windows.IWeakEventListener.ReceiveWeakEvent(Type managerType, Object sender, EventArgs e) at System.Windows.WeakEventManager.DeliverEventToList(Object sender, EventArgs args, ListenerList list) at System.Windows.WeakEventManager.DeliverEvent(Object sender, EventArgs args) at System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args) at System.Windows.Data.CollectionView.OnCollectionChanged(NotifyCollectionChangedEventArgs args) at System.Windows.Data.ListCollectionView.ProcessCollectionChangedWithAdjustedIndex(NotifyCollectionChangedEventArgs args, Int32 adjustedOldIndex, Int32 adjustedNewIndex) at System.Windows.Data.ListCollectionView.ProcessCollectionChanged(NotifyCollectionChangedEventArgs args) at System.Windows.Data.CollectionView.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args) at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e) at System.Collections.ObjectModel.ObservableCollection`1.InsertItem(Int32 index, T item) at System.Collections.ObjectModel.Collection`1.Add(T item) at ORF.PersonBook.IdentityModule.Model.SubsidiaryModel.AddRoom(RoomModel room) in C:\Project\Phoenix\Development\src\ORF.PersonBook.IdentityModule\Model\SubsidiaryModel.cs:line 127

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• BitmapFrame in another thread

  - by Lasse Lindström

  Hi I am using a WPF BackgroundWorker to create thumbnails. My worker function looks like: private void work(object sender, DoWorkEventArgs e) { try { var paths = e.Argument as string[]; var boxList = new List(); foreach (string path in paths) { if (!string.IsNullOrEmpty(path)) { FileInfo info = new FileInfo(path); if (info.Exists && info.Length 0) { BitmapImage bi = new BitmapImage(); bi.BeginInit(); bi.DecodePixelWidth = 200; bi.CacheOption = BitmapCacheOption.OnLoad; bi.UriSource = new Uri(info.FullName); bi.EndInit(); var item = new BoxItem(); item.FilePath = path; MemoryStream ms = new MemoryStream(); PngBitmapEncoder encoder = new PngBitmapEncoder(); encoder.Frames.Add(BitmapFrame.Create(bi)); encoder.Save(ms); item.ThumbNail = ms.ToArray(); ms.Close(); boxList.Add(item); } } } e.Result = boxList; } catch (Exception ex) { //nerver comes here } } When this fuction is finnished and before the BackgroundWorker "Completed" function is started, I can see on the output window on Vs2008, that a exception is generated. It looks like: A first chance exception of type 'System.NotSupportedException' occurred in PresentationCore.dll The number of exceptions generates equals the number of thumbnails to be generated. Using "trial and error" I have isolated the problem to: BitmapFrame.Create(bi) Removing that line (makes my function useless) also removes the exception. I have not found any explanation to this,,, or a better method to create thumbnails i a background thread. Can anyone help me? //lasse

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• How to dispatch a new property value in an object to the same property of two other objects

  - by WPFadvocate

  In WPF, I've three objects exposing the same DependencyProperty (let's say it's an integer). I want all three property values to remain synchronized, i.e. that whenever the int value changes in an object, this value is propagated to the two other objects. I think of multibinding to do the job, but I don't know how to detect which object changed, thus which value should be used and propagated to the other objects. Edited: here is my tentative code for multibinding, with the false hope that it would work without additional code: // create the multibinding MultiBinding mb = new MultiBinding() { Mode = BindingMode.TwoWay, UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged }; // create individual bindings to associate object_2 and object_3 to object_1 Binding b2 = new Binding() { Source = object_2, Path = new PropertyPath("X") }; Binding b3 = new Binding() { Source = object_3, Path = new PropertyPath("X") }; // add individual bindings to multibinding mb.Bindings.Add(b2); mb.Bindings.Add(b3); // bind object_2 and _3 to object_1 BindingOperations.SetBinding(object_1, TypeObject_1.XProperty, mb); But actually, there is a runtime error, saying the binding set by the last instruction is lacking a converter. But again I don't know how to write this converter (there is nothing to convert (as this is the case in the related MS sample of code linking 3 rgb properties to a color property), only to forward the value of the property changed to the two other properties). I understand I could solve the problem by creating an X_Changed event in the 3 types and then have each object registering to the two other objects event. I don't like this "manual" way and would prefer to bind the 3 properties together.

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• Conflict When Two Storyboards Sets the Opacity Property?

  - by kennethkryger

  Hi, Background: I have a WPF UserControl (MainControl - not shown in code below) that contains another one (called MyControl in the code below). MainControl has it's DataContext set to an object, that has a Project-property. When MainControl loads, the Project-property is always null. The problem: When MainControl loads, I want to fade in the MyControl using a special storyboard (only used this one time (this "specialFadeInStoryboard" changes Opacity-property of MyControl from 0 to 1). When the Project-property is set to a value other than null, I want the MyControl to fade out using the "fadeOutStoryboard" (changes Opacity-property of MyControl to 0) and if it's set to null afterwards I want to fade it in again this time using the "fadeInStoryboard" (changes Opacity-property of MyControl to 1). However, after adding the code for the "specialFadeInStoryboard", the MyControl is never faded out... What am I doing wrong? <local:MyControl Visibility="{Binding RelativeSource={RelativeSource Self}, Path=Opacity, Converter={StaticResource opacityToVisibilityConverter}, Mode=OneWay}"> <local:MyControl.Style> <Style> <Style.Triggers> <EventTrigger RoutedEvent="FrameworkElement.Loaded"> <BeginStoryboard Storyboard="{StaticResource specialFadeInStoryboard}"/> </EventTrigger> <DataTrigger Binding="{Binding Project, Converter={StaticResource nullToBooleanConverter}, Mode=OneWay}" Value="True"> <DataTrigger.EnterActions> <BeginStoryboard Storyboard="{StaticResource fadeOutStoryboard}"/> </DataTrigger.EnterActions> <DataTrigger.ExitActions> <BeginStoryboard Storyboard="{StaticResource fadeInStoryboard}"/> </DataTrigger.ExitActions> </DataTrigger> </Style.Triggers> </Style> </local:MyControl.Style> </local:MyControl>

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• Help with editing data in entity framework.

  - by Levelbit

  Title of this question is simple because there is no an easy explanation for what I'm trying to ask you. I hope you'll understand in the end :). I have to tables in my database: Company and Location (relationship:one to many) and corresponding entity sets. In my wpf application I have some datagrid which I want to fill with locations and to be able to edit every row in separate window as some form of details view (so I don't want to edit my data in datagrid). I did this by accessing Location entity from selected row and creating a new Location entity and then I copy properties from original entity to newly created. Something like cloning the object. After editing if I press OK changed data is copied to original object back, and if I press Cancel nothing happens. Of course, you probably thinking I could use NoTracking option and AttachAsModified method as was mentioned as solution in some earlier questions(see:http://stackoverflow.com/questions/803022/changing-entities-in-the-entityframework) by Alex James, but lets say I had some problems about that and I have my own reasons for doing this. Finally, because navigation property(Company) of my location entity is assigned to newly created location object(during cloning) from some reason in object context additional object as copy of object I want to edit from datagrid is created without my will(similar problem :http://blogs.msdn.com/alexj/archive/2009/12/02/tip-47-how-fix-up-can-make-it-hard-to-change-relationships.aspx). So, when I do ObjectContext.SaveChanges it inserts additional row of data into my database table Location, the same as the one i wanted to edit. I read about sth like this, but I don't quite understand why is that and how to block or override this. I hope I was clear as I could. Please, solutions or some other ideas.

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• HOW CAn I Differciate the button click Event

  - by SHASHANK

  hello All i have a problem. i m making Some wpf button Dynamic through C#.i m using it A loop for this now i m trying to find all button Click Event. i find it But It Work Same on All The button Click how Can i Differciate all the button . thanks in Advance shashank `for (int i = 0; i < 2; i++) { Button b1 = new Button(); //this.RegisterName("myAnimatedBrush", b1); b1.Name = "button" + i; b1.Height = 200; b1.Width = 200; b1.Margin = new Thickness(0, -100, 0, 0); b1.HorizontalAlignment = HorizontalAlignment.Left; b1.Content = "English"; b1.Background = System.Windows.Media.Brushes.Pink; b1.Click+=new RoutedEventHandler(b1_Click); canvasbtn.Children.Add(b1); Canvas.SetLeft(b1,b1.Width * i); }`

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