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Each button calls the same event (Command) and passes in the commandparameter which should be bound to the object in the collection. So the method receives and object that can then be cast as the item in the collection.
Never underestimate the power of human stupidity
RAH
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Button btn = new Button();
btn.Click += new RoutedEventHandler( button_Click );
...
void button_Click( object sender, RoutedEventArgs e ) {
Button btn = sender as Button;
...
}
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I'm struggling to get my MVVM WPF app to work with a set of Tasks updating the UI.
I've got a Command that starts X number of tasks off, for each task I'd like the UI to update when started and when finished. I've also got a second Command to cancel the task, which I'd obviously like working (the code does but as the UI locks the button doesn't)
I've used a ListBox bound to an ObvservableCollection<string> for the results, as this seemed better than binding to a string.
At the moment I get the UI lockup until all tasks are finished. This is with or without a Task.WaitAll. The results are correct, the tasks don't always start/finish in the same order so they're obviously being generated and updating the collection asynchronously.
I've tried an AysncObservableCollection (as per this SO answer)
I've tried using the Dispatcher in my method that adds a item to the collection.
I've tried variations on the Binding parameters.
Can someone give me some hints  Surely people have created a status log with async stuff in MVVM before??
Do I need to move the task creation to the Model?
I've seen mention of making sure the Collection is initiated on/by the View, not sure I understand that!
The View has a DataContext that's set to my ViewModel. Do they mean I've got to create the Collection in the code behind of the View? that doesn't seem right.
Oh this is .NET4.0 on XP, and I'm not using any MVVM frameworks (didn't think that was a good idea as I'm still learning)
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How are you binding the ListBox and ObservableCollection<string>?
Are you creating the ObservableCollection in the ViewModel?
Is it bound to the ItemsSource on the ListBox?
If you can show some of the code/xaml we can provide more assistance.
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Ok,
In my view XAML I think the only relevant bits are:
<UserControl.DataContext>
<local:ViewModelLoadTest />
</UserControl.DataContext>
<Button Height="32"
Width="128"
Margin="5"
Content="Run Test"
Command="{Binding RunTestCommand}"/>
<ListBox ScrollViewer.VerticalScrollBarVisibility="Visible"
FontFamily="Consolas"
FontSize="12"
ItemsSource="{Binding Path=Results}">
</ListBox>
I've tried some of the Binding options like Async.
There's nothing in the .xaml.cs file apart from the initialize call. Oh and its in a UserControl because my app has two modes so I'm using a tab control displaying two UserControls.
For my ViewModel, I've got an abstract base ViewModel then a design time and run time classes.
All the child classes do is set some properties, there's no other methods or additional properties.
In the base ViewModel class the collection is defined:
private ObservableCollection<string> _results = new ObservableCollection<string>();
public ObservableCollection<string> Results
{
get { return _results; }
set
{
_results = value;
RaisePropertyChanged("Results");
}
}
I've tried the creation of the collection in the constructor of the BaseViewModel and in the constructors of the child classes.
And in case its my Task stuff that's wrong:
private void DoRunTestCommand()
{
_cancellationTokenSource = new CancellationTokenSource();
Log(String.Format("Submitting {0} requests, every {1}ms, {2} at time."
, Model.NumberOfRequests
, Model.MSBetweenRequests
, Model.NumberOfConcurrentRequests));
CancellationToken cancellationToken = _cancellationTokenSource.Token;
Task[] tasks = new Task[Model.NumberOfRequests];
for (int i = 0; i < Model.NumberOfRequests; i++)
{
int idx = i;
Task r = Task.Factory.StartNew((state) =>
{
SubmitRequest((int) state);
cancellationToken.ThrowIfCancellationRequested();
}
, i
, cancellationToken
, TaskCreationOptions.LongRunning
, TaskScheduler.FromCurrentSynchronizationContext());
tasks[i] = r;
Thread.Sleep(Model.MSBetweenRequests);
}
Log("Done");
}
private void SubmitRequest(int reqNum)
{
Log(String.Format("{0} Started", reqNum));
Thread.Sleep(1000);
Log(String.Format("{0} Finished", reqNum));
}
private void Log(string text)
{
Results.Add(String.Format("{0}: {1}", DateTime.Now, text));
}
Obviously SubmitRequest will do something else, I was just trying to get the UI working before I put the exact details in.
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Solved it I think.
I mentioned that I was trying the AsyncObservableCollection, apparently if I use that then I don't want to pass TaskScheduler.FromCurrentSynchronizationContext() to the task. I don't understand why (I guess a conflict somewhere)...but not sure if I need to understand either 
So my ObservableCollection is now defined as:
private ObservableCollection<string> _results = new AsyncObservableCollection<string>();
public ObservableCollection<string> Results
{
get { return _results; }
set
{
_results = value;
RaisePropertyChanged("Results");
}
}
And my tasks updated the ListBox as and when they start/finish.
So I've just got to check if cancellation works, and see if I can still use WaitAll. Ideally I'd like a message when the tasks have all been started and finished (more a WhenAll (if that even exists)), at the moment I get that in the middle. But if I use WaitAll then I don't get the async updating.
Note for any others if your using .NET 4.5 then I don't think any of this is an issue as they changed the ObversableCollection.
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Using TaskScheduler.Default or TaskScheduler.Current work when using the AsyncObservableCollection, its just FromCurrentSynchronizationContext that doesn't.
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Use the INotifyPropertyChanged event on the observable collection.
This will be a neater and simpler solution.
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How do you mean? The ViewModel already had that, and that on its own didn't work. No items were added until the end.
private ObservableCollection<string> _results = new ObservableCollection<string>();
public ObservableCollection<string> Results
{
get { return _results; }
set
{
_results = value;
RaisePropertyChanged("Results");
}
}
Or do you mean create a class that derives from ObservableCollection and implement it there?
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Please Help me
How can i get the listview item one by one from the
selected row in WPF?
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You could check the lstSomething.SelectedItems it should give you all the selected items. Then use a for each or iterate through the collection.
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i have created a control template for flashing button
<ControlTemplate x:Key="buttonTemplate" TargetType="{x:Type Button}">
<Border x:Name="AnimatedColorButton" Width="100" Height="30" BorderThickness="2" BorderBrush="{TemplateBinding BorderBrush}" Background="{TemplateBinding Background}">
<Border.Triggers>
<EventTrigger RoutedEvent="Border.Loaded"> <BeginStoryboard><pre lang="text">
<Storyboard >
<DoubleAnimation Storyboard.TargetName="AnimatedColorButton" Storyboard.TargetProperty="Background.Opacity"
RepeatBehavior="Forever"
AutoReverse="True"
To="0.0"
Duration="0:0:0.5" ></DoubleAnimation>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Border.Triggers>
</Border>
</ControlTemplate>
Its displays the button with Flashing while loading.
But when i Change the border color from code behind
button1.BorderBrush = Brushes.Blue;
Then the a flashing stops .
How to active it again ?how to trigger the border.loaded event from code behind ?
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Hi All, i am attaching my class design and the xaml code which i am using to create a treeview item with circular reference. I am able to update the collecitons from the codebehind but unfortuntely it is not reflecting in the code behind. Please help me in esolving this
public class EntityDesignElement : NotifyPropertyChangedBase
{
private string _id;
private ObservableCollection<EntityDesignElement> _children = new ObservableCollection<EntityDesignElement>();
private ObservableCollection<WrapperMetadataExtension> _extensions = new ObservableCollection<WrapperMetadataExtension>();
public ObservableCollection<WrapperMetadataExtension> Extensions
{
get { return _extensions; }
set
{
_extensions = value;
}
}
protected EntityDesignElement(EntityDesignElement parent)
{
Parent = parent;
_children.CollectionChanged += delegate(object sender, NotifyCollectionChangedEventArgs args) { OnPropertyChanged("HasChildren"); };
_children.CollectionChanged += delegate(object sender, NotifyCollectionChangedEventArgs args) { OnPropertyChanged("IsExtensionAddedToChildren"); };
_extensions.CollectionChanged += delegate(object sender, NotifyCollectionChangedEventArgs args) { OnPropertyChanged("IsExtensionAddedToChildren"); };
}
public EntityDesignElement(EntityDesignElement parent, EntityInfo info)
: this(parent)
{
Name = info.Name;
Type = info.Id;
ElementType = "Entity";
IsChildrenAllowed = true;
foreach (var property in info.Properties)
{
Children.Add(new EntityDesignElement(this, property));
}
}
public EntityDesignElement(EntityDesignElement parent, EntityPropertyInfo propertyInfo)
: this(parent)
{
Name = propertyInfo.Name;
ElementType = "Property";
Type = propertyInfo.DataType;
IsChildrenAllowed = (((propertyInfo.PropertyType == EntityPropertyType.Reference)
|| (propertyInfo.PropertyType == EntityPropertyType.ReferenceCollection))
&& (!IsCircularReference(Type)));
if (IsChildrenAllowed)
{
var entity = ClientConnector.Current.Metadata.GetEntity(propertyInfo.DataType);
if (entity != null)
foreach (var property in entity.Properties)
{
EntityDesignElement child = new EntityDesignElement(this, property);
Children.Add(child);
}
}
}
public void AddExtension(EntityDesignElement parent, WrapperMetadataExtension extension)
{
Parent.Extensions.Add(extension);
}
public EntityDesignElement Parent { get; private set; }
public string Name
{
get { return _id; }
set { SetAndNotifyPropertyChanged<string>("Id", ref _id, value); }
}
public string ElementType { get; private set; }
public string Type { get; private set; }
public bool IsChildrenAllowed { get; private set; }
public bool HasChildren { get { return (_children.Count > 0); } }
public bool IsExtensionAddedToChildren {
get { return (Parent.Extensions.Count>0); }
}
public ObservableCollection<EntityDesignElement> Children { get { return _children; } }
private bool IsCircularReference(string type)
{
if (Parent == null)
return false;
if (Parent.Type.Equals(type))
return true;
return Parent.IsCircularReference(type);
}
public ObservableCollection<MetadataExtension> GetMetadataExtensions()
{
ObservableCollection<MetadataExtension> colls = new ObservableCollection<MetadataExtension>();
return colls;
}
}
<UserControl x:Class="CeniumDesignTool.Controls.Designer.MetadataEntityControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:Utitlity="clr-namespace:CeniumDesignTool.Utilities"
xmlns:metadata="clr-namespace:Cenium.Framework.Client.Application.ResourceModel.Metadata;assembly=Cenium.Framework.Client.Resources"
mc:Ignorable="d" x:Name="MetadataEntityControlRoot"
d:DesignHeight="300" d:DesignWidth="300">
<Grid x:Name="LayoutRoot" DataContext="{Binding ElementName=MetadataEntityControlRoot}">
<Grid.Resources>
<Utitlity:ExtensionConverter x:Key="extConverter"/>
<Style TargetType="TextBlock" x:Key="txtEntityInfoStyle">
<Setter Property="FontWeight" Value="Bold" />
<Setter Property="HorizontalAlignment" Value="Center"/>
<Setter Property="VerticalAlignment" Value="Center"/>
</Style>
<Utitlity:MetadataTemplateSeletor x:Key="TempSelector"/>
<BitmapImage x:Key="imgLock" UriSource="pack://application:,,,/Resources/Images/lock.png" />
<BitmapImage x:Key="imgExtension" UriSource="pack://application:,,,/Resources/Images/extension.png" />
<HierarchicalDataTemplate x:Key="MetadataEntityParentTemplate" ItemTemplateSelector="{StaticResource ResourceKey=TempSelector}">
<HierarchicalDataTemplate.ItemsSource>
<MultiBinding Converter="{StaticResource extConverter}">
<Binding Path="Children" UpdateSourceTrigger="PropertyChanged"/>
<Binding Path="Extensions" UpdateSourceTrigger="PropertyChanged"/>
</MultiBinding>
</HierarchicalDataTemplate.ItemsSource>
<Border BorderBrush="Black" Margin="2,2,2,2" BorderThickness="1" CornerRadius="17" Background="Gray" Padding="0,0,5,0">
<Grid Width="Auto" MinWidth="200">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition />
</Grid.RowDefinitions>
<TextBlock Grid.Column="1" Text="{Binding Type}"
Margin="0" HorizontalAlignment="Center" VerticalAlignment="Center" Style="{StaticResource txtEntityInfoStyle}" />
<Rectangle Grid.Column="2" Height="20" Width="20" Margin="5" Stroke="Black" HorizontalAlignment="Right" VerticalAlignment="Center">
<Rectangle.Fill>
<ImageBrush ImageSource="{StaticResource imgLock}"/>
</Rectangle.Fill>
</Rectangle>
</Grid>
</Border>
</HierarchicalDataTemplate>
<HierarchicalDataTemplate x:Key="MeatadataEntityExtensions" ItemsSource="{Binding Path=Parameters}">
<Grid Width="250">
<Border BorderBrush="Black" BorderThickness="1" CornerRadius="17" Margin="2,2,2,2" Padding="0,0,5,0" Background="LightGreen">
<StackPanel Width="auto" MinWidth="200" Orientation="Horizontal">
<TextBlock Margin="5" Text="{Binding ExtensionType, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Center" Style="{StaticResource txtEntityInfoStyle}" ></TextBlock>
<TextBlock Margin="5" Text="{Binding Property}" VerticalAlignment="Center" Grid.Column="1" Style="{StaticResource txtEntityInfoStyle}" ></TextBlock>
<Rectangle Height="20" Width="20" Margin="5" Stroke="Black" HorizontalAlignment="Right">
<Rectangle.Fill>
<ImageBrush ImageSource="{StaticResource imgExtension}"/>
</Rectangle.Fill>
</Rectangle>
</StackPanel>
</Border>
</Grid>
</HierarchicalDataTemplate>
<DataTemplate x:Key="MeatadataEntityProperties">
<Border BorderBrush="Black" BorderThickness="1" CornerRadius="17" Padding="0,0,0,0" Background="Gray" Margin="2,2,2,2">
<Grid Width="auto" MinWidth="200" HorizontalAlignment="Center" VerticalAlignment="Center">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition />
</Grid.RowDefinitions>
<TextBlock Grid.Column="0" Margin="20,0,0,0" Text="{Binding Name}" Style="{StaticResource txtEntityInfoStyle}"></TextBlock>
<TextBlock Grid.Column="1" Margin="0" Text=" : " Style="{StaticResource txtEntityInfoStyle}"/>
<TextBlock Grid.Column="2" Margin="0" Text="{Binding PropertyType}" Style="{StaticResource txtEntityInfoStyle}"/>
<TextBlock Grid.Column="3" Margin="0" Text=" ( " Style="{StaticResource txtEntityInfoStyle}"/>
<TextBlock Grid.Column="4" Margin="0" Text="{Binding Reference}" Style="{StaticResource txtEntityInfoStyle}"/>
<TextBlock Grid.Column="5" Margin="0" Text=" ) " Style="{StaticResource txtEntityInfoStyle}"/>
<Rectangle Grid.Column="6" Height="20" Width="20" Margin="5" Stroke="Black" HorizontalAlignment="Right">
<Rectangle.Fill>
<ImageBrush ImageSource="{StaticResource imgLock}"/>
</Rectangle.Fill>
</Rectangle>
</Grid>
</Border>
</DataTemplate>
<HierarchicalDataTemplate x:Key="ClassReferenceMetadataEntity" ItemsSource="{Binding Path=Children}">
<Border BorderBrush="Black" Margin="2,2,2,2" BorderThickness="1" CornerRadius="17" Background="Gray" Padding="0,0,0,0">
<Grid Width="Auto" MinWidth="200">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition />
</Grid.RowDefinitions>
<Grid Grid.Column="1">
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<TextBlock Text="{Binding Name}" Grid.Column="0"
Margin="0" HorizontalAlignment="Center" VerticalAlignment="Center" Style="{StaticResource txtEntityInfoStyle}" />
<TextBlock Text=":" Grid.Column="1"
Margin="0" HorizontalAlignment="Center" VerticalAlignment="Center" Style="{StaticResource txtEntityInfoStyle}" />
<TextBlock Text="{Binding Type}" Grid.Column="2"
Margin="0" HorizontalAlignment="Center" VerticalAlignment="Center" Style="{StaticResource txtEntityInfoStyle}" />
</Grid>
<Rectangle Grid.Column="2" Height="20" Width="20" Margin="5" Stroke="Black" HorizontalAlignment="Right" VerticalAlignment="Center">
<Rectangle.Fill>
<ImageBrush ImageSource="{StaticResource imgLock}"/>
</Rectangle.Fill>
</Rectangle>
</Grid>
</Border>
</HierarchicalDataTemplate>
</Grid.Resources>
<TreeView x:Name="ListViewExtensionTypesDesign" AllowDrop="True" Width="auto" Height="auto" ItemsSource="{Binding}" ItemTemplate="{StaticResource MetadataEntityParentTemplate}" TreeViewItem.Selected="ListViewExtensionTypesDesign_Selected">
</TreeView>
</Grid>
</UserControl>
Geetha
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Hello,
I want to add dynamically many controls to a window.
I wanted to use a stack panel container but a stack panel has either horizontal or vertical orientation.
I want to add the control horizontally and when there are three user controls in one row i want to go to next row and start adding the controls there and so on.
The user can also delete a control so the other controls have to be reorganized automatically.
Any one has an idea how to do it?
Thanks.
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Use a "UniformGrid" with 3 columns for organizing the controls, and the .Children.Add method to add controls.
Use the .Children.Remove method to "delete" a control.
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I used a wrap panel from the tool kit for this, bind it to a collection and add/delete the items in the collection.
<ItemsControl Grid.Row="1" ItemsSource="{Binding FleetList}" HorizontalAlignment="Center" VerticalAlignment="Center">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<toolkit:WrapPanel/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<HyperlinkButton Click="HyperlinkButton_Click" Tag="{Binding Path=FleetID}" HorizontalContentAlignment="Center" >
<Grid HorizontalAlignment="Center" >
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<Image Grid.Row="0" Stretch="None" Source="{Binding Path=FleetLogoUri}" HorizontalAlignment="Center" ImageFailed="GetDefaultImage" Loaded="ImageLoaded" />
<TextBlock Grid.Row="1" Foreground="Blue" Text="{Binding Path=Fleet}" HorizontalAlignment="Center" />
</Grid>
</HyperlinkButton>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
Never underestimate the power of human stupidity
RAH
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How to add multiple button into same datacell in DataGrid column. i know how to add one button into datacell but i want to add two button into same cell please let me know that? please help me 
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Use a DataGridTemplateColumn and host the buttons inside there. Have a look at this[^].
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Yes that i have done so cool 
<sdk:DataGridTemplateColumn>
<sdk:DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Width="170" HorizontalAlignment="Right" VerticalAlignment="Bottom">
<Button Name="btn_Close" Style="{StaticResource FormContentButtonStyle_LA}" Content="Close" Click="btn_Close_Click" />
<Button Name="btn_Delete" Style="{StaticResource FormContentButtonStyle_LA}" Visibility="{Binding IsDeleted, Mode=TwoWay}" Content="Delete" Click="btn_Delete_Click" />
</StackPanel>
</DataTemplate>
</sdk:DataGridTemplateColumn.CellTemplate>
</sdk:DataGridTemplateColumn>
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The common convention is to up vote a good answer (little arrows that appear on the right of the answer)
Never underestimate the power of human stupidity
RAH
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Hi,
I'm working on loading xaml code at runtime.
Until now, I can do it with XAML files which are set as "Resource"...but I would like to load it from a user's folder (let's say the "Desktop Folder" for example)
How should I please proceed?
The XAML example file, loaded as resource file in my project (but I would like to use it "independently")
<Grid xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Border Width="385" Height="385" Margin="0,0,0,0" HorizontalAlignment="Left" VerticalAlignment="Top" CornerRadius="8" Background="#FF0085C8">
</Grid>
The Application XAML code
<Window x:Class="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">
</Window>
The Application VB.Net code
Class MainWindow
Private Sub MainWindow_Loaded(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded
Dim GridUri As New Uri("Resources\theme.xaml", UriKind.Relative)
Dim sri As Windows.Resources.StreamResourceInfo = Application.GetResourceStream(GridUri)
Dim xrdr As New System.Windows.Markup.XamlReader()
Dim grd As Grid = CType(xrdr.LoadAsync(sri.Stream), Grid)
Me.Content = grd
End Sub
End Class
Thank you!
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if your application is WPF application you can load a physical file
Imports System.Windows.Markup
Class MainWindow
Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs)
Dim objXaml = XamlReader.Load(IO.File.Open(Environment.CurrentDirectory & "Resource\theme.xaml", IO.FileMode.Open))
End Sub
End Class
if it was a silverlight application you cant do that 
... Marimuthu
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Hi! I have some WPF windows built in a class library. Also I have unmanaged app that calls these windows through ComVisible interface.
The problem: I have a big delay on calling WPF windows first time.
I suppose it happens because WPF engine loading.
Please, suggest some ideas or workarounds on performance improvements.
Thanks!
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If you want performance improvements then you should not be using managed code from an unmanaged application.
Use the best guess
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Iam new to WPF .can anybody give some sample application with feature like add,delete and update data from grid control using MVVM approach.
Bit confused with this approach.
Thanks in advance.
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