Develop Reference

ItemSource of Listbox is not updated on item change

In my WPF application I have ListBox which contains a collection of items. One item can be added when a button is clicked and it is selected in the opened dialogue. As soon as a item is selected the dialogue closes and the item's image and name should be displayed in my ListBox. Unfortunately the Listbox does not update and nothing changes.
Usercontrol with Listbox:
<ListBox ItemsSource="{Binding BlButtonCollection, UpdateSourceTrigger=PropertyChanged}" VerticalContentAlignment="Stretch" SelectedItem="{Binding SelectedSticker}"
HorizontalContentAlignment="Stretch" ItemContainerStyle="{StaticResource ListBoxItemStyle}">
<ListBox.Resources>
<viewmodels1:BindingProxy x:Key="ProxyElement" Data="{Binding}" />
</ListBox.Resources>
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<UniformGrid Columns="4" Rows="10"/>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<Border BorderBrush="Black" BorderThickness="1">
<Grid x:Name="f">
<Grid.RowDefinitions>
<RowDefinition Height="5*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Button x:Name="btnSelectArticle" Background="Transparent" Grid.RowSpan="2" BorderThickness="0"
Command="{Binding DataContext.ButtonClicked,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBox}}}"/>
<Image Height="1.5cm" HorizontalAlignment="Center" Source="{Binding ItemImage.ImageUrl, Converter={StaticResource ImageFormatConverter}}"/>
<TextBlock Text="{Binding ItemName}" Width="4cm" Height="0.8cm" TextWrapping="Wrap" Grid.Row="1" HorizontalAlignment="Center"/>
</Grid>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Controls with ListBoxes in main window:
<formats:OneXTwo x:Name="oneXTwo" BlButtonCollection="{Binding BlButtons_2}" IsBlVisible="Visible" Visibility="{Binding Are2StickersVisible}"
ButtonClicked="{Binding BlStickerButtonClickedCommand}"/>
<formats:ThreeXEight x:Name="threeXEight" BlButtonCollection="{Binding BlButtons_24}" IsBlVisible="Visible" Visibility="{Binding Are24StickersVisible}"
ButtonClicked="{Binding BlStickerButtonClickedCommand}"/>
<formats:FourXTen x:Name="fourXTen" BlButtonCollection="{Binding BlButtons_40, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" IsBlVisible="Visible" Visibility="{Binding Are40StickersVisible}"
ButtonClicked="{Binding BlStickerButtonClickedCommand}" SelectedSticker="{Binding SelectedBlSticker, Mode=TwoWay}" />
I should mention that I have three different formats and each format is a own user-control. Therfore, they are displayed in a shell-view and based on a ComboBox selection one format is displayed. If I am running the application, select a image nothing happens, but if I change the bound value of the textblock in the list view and switch it back to 'Itemname' the Image and Name are displayed.

Have you set the DataContext to a specific ViewModel?
ObservableCollection can only ensure the add/remove operation for items that can be updated to the UI. If you want to the item property to notify the UI, you should override the setter of the property and implement INotifyPropertyChanged.

How to access properties inside Listvew ItemsPanelTemplate and DataTemplate

I'm quite new to c# and WPF. I'm making a small Photo Viewer. I want to have a grid of photos in which I can change the number of columns and the size of the pictures depending on user preferences and the size of the screen. I can do everything I need at design time but I don't find how to change some properties during runtime.
In particular, I need to change the number of columns of the UniforGrid and the Width and Height of the Image.
<ListView x:Name="LVMiniaturasGrandes" Margin="23,10,464,270.5" Background="#FF272727" Foreground="White" Visibility="Hidden" BorderBrush="{x:Null}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<UniformGrid Columns="4" HorizontalAlignment="Stretch"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ListView.ItemTemplate>
<DataTemplate>
<ItemsControl Padding="10">
<StackPanel Orientation="Vertical" VerticalAlignment="Stretch" HorizontalAlignment="Stretch">
<Image Source="{Binding ImagenGrande2}" Width="200" Height="200" HorizontalAlignment="Stretch" VerticalAlignment="Top" Stretch="Uniform" />
<StackPanel Orientation="Horizontal" VerticalAlignment="Stretch" HorizontalAlignment="Stretch">
<TextBlock Text="{Binding NombreFichero}" HorizontalAlignment="Left" VerticalAlignment="Bottom" Foreground="White" />
<TextBlock Text="{Binding VerEstrellas}" Foreground="Red" TextAlignment="Right" HorizontalAlignment="Right" VerticalAlignment="Bottom"/>
</StackPanel>
</StackPanel>
</ItemsControl>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
I expect to be able both to change the number of columns and the height and width of the Image(s) depending on a slider control position and the actual pixel size of the screen.
Any help is welcome. Thanks in advance.
EDIT:
I've been able to modify the number of columns in the UniformGrid. It may not be very elegant but it works. But I'm still not able to access the Width and Height of the Images.
private void RejillaImagenesGrandes_Initialized(object sender, EventArgs e)
{
_UGImagenesGrandes = (UniformGrid)sender;
}
This way I can get access to the UniformGrid and modify the number of columns dynamically

WPF ListView->GridView->StackPanel

I have a ListView that uses GridView to display some data. One of the fields contains a list with image paths. Therefore I defin a GridViewColumn and create a DataTemplate. Dis DataTemplate contains another ListView with the Images list as new DataContext. When I don't write anything in the inner StackPanel, I can see that a list of string (in the format AppName.ClassName) is displayed in left to right order.
But whenever I try to display the strings as something else, eg
<Image Source="{Binding Name}" Height="32"/>
I get an System.Windows.Markup.XamlParseException . Even with data binding I get an exception. Eg
<Image Source="Images/Camera_32xLG.png" Height="32"/>
. Any hint, what I might do wrong?
<GridViewColumn Header="Images">
<GridViewColumn.CellTemplate>
<DataTemplate>
<ListView ItemsSource="{Binding Images}" BorderThickness="0">
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal">
--> here is where I don't know what to do next
</StackPanel>
</ItemsPanelTemplate>
</ListView.ItemsPanel>
</ListView>
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>

Since the StackPanel is a part of ItemsPanelTemplate, you should just define it's properties and not explicitly add any children. The way to specify appearance of each item is through the ListView.ItemTemplate property:
<ListView ItemsSource="{Binding Images}" BorderThickness="0">
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<ListView.ItemTemplate>
<DataTemplate>
<Image Source="{Binding Name}" Height="32" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>

Windows Store App - XAML UI element not visible in C# code

I have the following XAML code and the only element available in the C# code behind are the Grid and the FlipView. How can I make the ScrollViewer, Image or the Viewbox visibile in the code?
XAML:
<Grid x:Name="gridViewPages">
<FlipView x:Name="FlipView1" Loaded="FlipView1_Loaded" Style="{StaticResource FlipViewPreviewIndicator}" Tapped="FlipView1_Tapped">
<FlipView.ItemTemplate>
<DataTemplate>
<ScrollViewer x:Name="pagesScrollViewer" ZoomMode="Enabled"
HorizontalAlignment="Center"
VerticalAlignment="Center"
HorizontalScrollBarVisibility="Hidden"
VerticalScrollBarVisibility="Hidden"
MinZoomFactor="1.0"
MaxZoomFactor="3.0"
Margin="0"
Width="1500" DoubleTapped="PagesScrollViewer_DoubleTapped">
<Viewbox x:Name="pagesViewbox">
<Image Source="{Binding}"
Height="730"
x:Name="pageImage" Stretch="Uniform" Loaded="MainImage_Loaded"/>
</Viewbox>
</ScrollViewer>
</DataTemplate>
</FlipView.ItemTemplate>
</FlipView>
</Grid>
The flipview is customized and contains also a listview defined in which is not visible in the code too...:
<Page.Resources>
...
<ListView x:Name="pagesPreview" HorizontalAlignment="Center" Height="100" VerticalAlignment="Bottom" Width="Auto"
ItemsSource="{TemplateBinding ItemsSource}"
SelectedItem="{Binding SelectedItem, Mode=TwoWay, RelativeSource={RelativeSource Mode=TemplatedParent}}"
ScrollViewer.HorizontalScrollBarVisibility="Auto"
ScrollViewer.VerticalScrollBarVisibility="Disabled"
ScrollViewer.HorizontalScrollMode="Enabled"
ScrollViewer.VerticalScrollMode="Disabled"
Background="AliceBlue"
Opacity="1"
SelectionChanged="pagesPreview_SelectionChanged"
Visibility="Visible">
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<ListView.ItemTemplate>
<DataTemplate>
<Grid HorizontalAlignment="Center" VerticalAlignment="Center">
<Image Source="{Binding}" Stretch="UniformToFill"/>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
...
</Page.Resources>

See the basic concept of the flipview is to have multiple pages to have a flip effect. So whatever the Data template contains is repeated multiple times. So if you want the x:Name to come up then you wont have any success.
There are two ways As per my knowledge :
VisualTreeHelper -> for a better detail of it go through this link
Get elements from data template
you can manually iterate over the flipview elements and track down the children of the flipview. Try that in debug mode you'll get a fair idea of what comes after what. Just keep track of the element at which selected index position you want modified
Thanks.

Accessing group-headings sub elements in data-bound GridView

I'm developing a windows 8 metro application with a data-bound gridview xaml control.
I've added a ring progress bar named progressRingGroup to header of the groups as seen below.
<ProgressRing x:Name="progressRingGroup" IsActive="True" Visibility="Visible" Width="16" Height="16" Margin="0,-7,0,0"/>
I want to programmatically access the ring-progress-bar from my code (so I can start/stop it) but as my grid-view is databound I don't know how to do so.
I've multiple groups in the gridview and need to access all of them separately.
Here's my gridview's groupstyle xaml definition;
<GridView.GroupStyle>
<GroupStyle>
<GroupStyle.HeaderTemplate>
<DataTemplate>
<Grid Margin="1,0,0,6">
<Button
AutomationProperties.Name="Group Title"
Click="Header_Click"
Style="{StaticResource TextPrimaryButtonStyle}" >
<StackPanel Orientation="Horizontal">
<ProgressRing x:Name="progressRingGroup" IsActive="True" Visibility="Visible" Width="16" Height="16" Margin="0,-7,0,0"/>
<TextBlock Text="{Binding Title}" Margin="6,-7,10,10" Style="{StaticResource GroupHeaderTextStyle}" />
<TextBlock Text="{StaticResource ChevronGlyph}" FontFamily="Segoe UI Symbol" Margin="0,-7,0,10" Style="{StaticResource GroupHeaderTextStyle}"/>
</StackPanel>
</Button>
</Grid>
</DataTemplate>
</GroupStyle.HeaderTemplate>
<GroupStyle.Panel>
<ItemsPanelTemplate>
<VariableSizedWrapGrid ItemWidth="75" ItemHeight="150" Orientation="Vertical" Margin="0,0,80,0" MaximumRowsOrColumns="3"/>
</ItemsPanelTemplate>
</GroupStyle.Panel>
</GroupStyle>
</GridView.GroupStyle>
Help appreciated.

If you want to be able to control the IsActive property of each progress ring, add a bool property to your group data model, and bind IsActive to that property. That way you can control each ProgressRing without having to programatically access all of them.
For example:
<ProgressRing x:Name="progressRingGroup" IsActive="{Binding GroupLoading}" Visibility="Visible" Width="16" Height="16" Margin="0,-7,0,0"/>
If you still want to access each programmatically, you could assign a Loaded event to the ProgressRing in the DataTemplate, and when the event fires, grab a reference to the ring (sender).