Event timing

11-03-2009 6:22 AM |

Looking at the sample provided here (I couldn't add comment on the post at web site as it was timing out)

http://dotnetspeak.com/index.php/2009/10/silverlight-3-collectionviewsource-and-navigation/

I have 2 questions

1) In ProductList.xaml.cs I added a button and a handler

1    private void AddNewGroupButton_Click(object sender, RoutedEventArgs e)
2    {
3    	CollectionViewSource viewSource = Resources["ViewSource"] as CollectionViewSource;
4    	if (viewSource != null)
5    	{
6    		viewSource.GroupDescriptions.Add(new PropertyGroupDescription("Category"));
7    	}
8    }

When this executes I get a "Specified method is not supported." exception.Can anyone exaplain that?

2) Place breakpoints in ProductList.xaml.cs at

NavigationService.Navigate(((Button)sender).Tag as Uri);(in Button_Click)

and
Product product = e.Item as Product; (in MyFilter)

Now run the app and click on a Details button. I have observed the BP in  MyFilter is hit then I continue and the BP in Button_Click is not hit. I click the Details button again and the BP in MyFilter is not hit and the Button_Click BP is hit. This observation is not consistent. Can anyone explain why this is? A event timing thing?

Re: Event timing

11-03-2009 6:42 PM |

If you read the documentation on GroupDescriptions you will see:

This property is not implemented. Accessing it will cause a NotSupportedException.
 

What does your xaml look like? Sounds like maybe you have the events wired up backwards.

Re: Event timing

11-04-2009 4:09 AM |

Thanks, I spotted that documentation last night. I need to be more careful when reading WPF Vs Silverlight XAML

 With regard to the events it works fine and only behaves oddly when I introduce breakpoints. The XAML is shown below but you can get the full code from the url in the original question 

1    <UserControl.Resources>
2            <CollectionViewSource Source="{StaticResource ProductList}" 
3    							  x:Key="ViewSource" 
4    							  Filter="MyFilter"
5    							  />
6        </UserControl.Resources>
7        <Grid x:Name="LayoutRoot">
8            <Grid.RowDefinitions>
9                <RowDefinition Height="Auto"/>
10               <RowDefinition Height="*"/>
11           </Grid.RowDefinitions>
12           <Grid.ColumnDefinitions>
13               <ColumnDefinition Width="Auto"/>
14               <ColumnDefinition Width="*"/>
15           </Grid.ColumnDefinitions>
16           <TextBlock Text="Fitler:"/>
17           <TextBox Grid.Column="1" TextChanged="TextBox_TextChanged" x:Name="FilterBox" Text=""/>
18           <data:DataGrid 
19               ItemsSource="{Binding Source={StaticResource ViewSource}}" 
20               AutoGenerateColumns="False" 
21               Grid.Row="1" 
22               Grid.ColumnSpan="2">
23               <data:DataGrid.Columns>
24                   <data:DataGridTextColumn Binding="{Binding ProductId}" Header="Product ID"/>
25                   <data:DataGridTextColumn Binding="{Binding ProductName}" Header="Product Name"/>
26                   <data:DataGridTextColumn Binding="{Binding ProductDescription}" Header="Description"/>
27   				<data:DataGridTextColumn Binding="{Binding Category}" Header="Category"/>
28                   <data:DataGridTemplateColumn>
29                       <data:DataGridTemplateColumn.CellTemplate>
30                           <DataTemplate>
31                               <Button Content="Details"  Tag="{Binding Url}" Click="Button_Click"/>
32                           </DataTemplate>
33                       </data:DataGridTemplateColumn.CellTemplate>
34                   </data:DataGridTemplateColumn>
35               </data:DataGrid.Columns>
36           </data:DataGrid>
37   		<Button x:Name="AddNewGroupButton" 
38   				Content="Add Group"
39   				Click="AddNewGroupButton_Click"/>
40       </Grid>

Re: Event timing

11-05-2009 4:42 AM |

Thanks for the reply. Can you provide information on how I can track/learn more about the firing sequence? For instance I did not know that a button click was composed of two other events.

 What logic is used to process the events? Are they queued? Can they time out? Can one cancel another?

I think this is very important information to share with the community.

It is possible to write code inside an event handler "expecting" it to be fired in a particluar sequence with respect to other events. We need to know more about firing sequence especially when we have complicated compositions (more than just a button on a grid).

Re: Event timing

11-05-2009 8:53 PM |

Hi,

I noticed that when click button but event doesnt fire, the button stay in pressed appearance, then I guess that mouseleftbuttondown event may be ingored. For click event implementation, I use Reflector to check the code.