UWP - can't access values in ItemsPanel - c#

I have the following XAML but I can't seem to access the contents of the ItemsWrapGrid in the corresponding .CS file - can anyone tell me what I should be doing (here's the code behind and xaml) :
private void wifiTapped(object sender, TappedRoutedEventArgs e)
{
Debug.WriteLine("in here " + e.GetType().ToString());
ItemsWrapGrid wg = (ItemsWrapGrid) sender;
Debug.WriteLine(e.OriginalSource.ToString());
foreach (Control c in wg.Children)
{
Debug.WriteLine("Control " + c.Name);
}
Debug.WriteLine("leaving ");
}
<GridView VerticalAlignment="Top" ItemsSource="{Binding nets}" x:Name="GDView" ItemClick="gdViewClick" >
<GridView.ItemTemplate>
<DataTemplate x:Name="configDataTemplate" x:DataType="data:wifiNets" >
<StackPanel Height="300" Width="350" Margin="10" Name="dtStackPanel" >
<Image Source="Assets\wifiIcon.png" Width="200" Height="201" />
<StackPanel Orientation="Horizontal">
<TextBlock Text="Name" Margin="0,0,10,0"/>
<TextBlock Name="configSSID" Width="auto" Text="{x:Bind NetSSID}" FontSize="24" />
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock Text="Strength" Margin="0,0,10,0"/>
<!--<TextBlock Name="configStrength" Width="auto" Text="{x:Bind NetSSIDStrength}" FontSize="20" />-->
<ProgressBar Name="configProgBar" Maximum="5" Value="{x:Bind NetSSIDStrength}" Foreground="Green" />
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock Text="Connected" Margin="0,0,10,0"/>
<TextBlock Name="configConnectedTo" Text="{x:Bind NetSSIDConnected}" FontSize="20"/>
</StackPanel>
</StackPanel>
</DataTemplate>
</GridView.ItemTemplate>
<GridView.ItemsPanel>
<ItemsPanelTemplate>
<ItemsWrapGrid MaximumRowsOrColumns="10" Orientation="Vertical" Tapped="wifiTapped" />
</ItemsPanelTemplate>
</GridView.ItemsPanel>
</GridView>
Just to be clear, when I run this I have three items of data (so it's working) - but what I'd like to be able to do is click on any one of the three data items and be able to identify the individual controls and their values within the data panel.
Thanks in advance, this is driving me nuts.
Paul.

Set IsItemClickEnabled to true on your GridView, and hook into the ItemClick event on the GridView itself. From the event args, you can get the sender (most likely the GridViewItem UI element itself, of which your DataTemplate content is a child), and the ClickedItem, which is the bound datacontext of the datatemplate - in your case the instance of the data:wifiNets - which if your bindings work mean you won't actually have to look in the VisualTree at all.
If for some reason you want to recurse through the VisualChildren for the items of any ItemsControl, use the ContainerFromIndex or ContainerFromItem methods on the ItemsControl to get the ItemContainer hosting each instance of the datatemplate - although I wouldn't recommend doing this unless you really need too. Ideally you shouldn't often have a need for manually trawling the visual tree.

Related

Can a user control perform binding when part of a ListView in WinUI?

I'm trying to use a UserControl-derived control (UpdateBlockControl) inside the DataTemplate of a ListView, like this:
<ListView x:Name="AppsListView">
<ListView.ItemTemplate>
<DataTemplate x:DataType="model:AppBase">
<StackPanel Orientation="Horizontal">
<local:UpdateBlockControl ImageSource="{x:Bind ImageSource}" AppName="{x:Bind Name}"/>
<TextBlock Text="{x:Bind Name}" Foreground="Orange" Margin="8,0,0,0" />
<TextBlock Text="{x:Bind ImageSource}" Margin="8,0,0,0" Foreground="LimeGreen"/>
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
UpdateBlockControl is derived from UserControl and I'm trying to bind its properties (ImageSource and AppName) to the model's (AppBase) properties.
You can see me trying to set up these bindings in the first item in the StackPanel. Just to see if the binding works at all, I also bind a couple of TextBlocks to these properties.
The XAML for UserBlockControl is essentially this:
<StackPanel Orientation="Vertical">
<TextBlock Text=":-)"/>
<TextBlock Text="{x:Bind AppName}"/>
<TextBlock Text="{x:Bind ImageSource}"/>
</StackPanel>
When I run the application I see the following:
So the UserControl properties aren't working correctly it would seem: I get the :-) for the first TextBlock but the second and third TextBlocks are empty. Their equivalents in the ListView do work however (see image, above).
Should I be able to use a user control insisde a DataTemplate like this? If so, why aren't the bindings working?
x:Bind is Mode=OneTime by default. So, once a DependencyProperty is initialized inside the UserControl, it won't be updated anymore.
You need to add Mode=OneWay to x:Bind in UpdateBlockControl.
<StackPanel Orientation="Vertical">
<TextBlock Text=":-)" />
<TextBlock Text="{x:Bind AppName, Mode=OneWay}" />
<TextBlock Text="{x:Bind ImageSource, Mode=OneWay}" />
</StackPanel>

How to nest ItemsControl with multiple ItemsSource?

I have a ConfigList object with a name and a Dictionary and I need to nest ItemsControls with different ItemsSource.
I tried to do it this way :
<ItemsControl x:Name="TestStep" Grid.Row="0" Grid.Column="0" ItemsSource="{Binding Path=ConfigList }" HorizontalAlignment="Center" VerticalAlignment="Center">
<ItemsControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Ictrl.Nom}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl
ItemsSource="{Binding Path=Param}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Path=Key}" />
<TextBlock Text=" : " />
<TextBlock Text="{Binding Path=Value}" />
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</ItemsControl>
When I start my application, I've got this error :
System.Windows.Markup.XamlParseException : '' Adding a value to the
collection of type 'System.Windows.Controls.ItemCollection' threw an
exception. ' line number '25' and line position '14'. '
Internal Exception
InvalidOperationException: Invalid operation when ItemsSource is in
use. Access and edit items with ItemsControl.ItemsSource.
Any idea what ​​the problem is?
You set an ItemsSource on the ItemsControl. The data template is used to create the controls that display the data. The created items are then put into the Items collection of the ItemsControl. If you add an element to the ItemsControl directly in XAML this will put them into the Items collection, too. Doing both is not allowed. You either specify an ItemsSource or add to Items directly. From the documentation:
Note that you use either the Items or the ItemsSource property to specify the collection that should be used to generate the content of your ItemsControl. When the ItemsSource property is set, the Items collection is made read-only and fixed-size.
However, in your case this is not the real issue, because your markup is wrong for what you want to achieve. If you you really intended to nest ItemsControls, you would simply change the data template for the outer ItemsControl to contain another ItemsControl that binds to a collection property within the outer data item. Since there is already a TextBox, you have to use a panel (e.g. StackPanel) to host multiple controls in the template.
<ItemsControl x:Name="TestStep" Grid.Row="0" Grid.Column="0" ItemsSource="{Binding Path=ConfigList }" HorizontalAlignment="Center" VerticalAlignment="Center">
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Text="{Binding Path=Ictrl.Nom}" />
<ItemsControl ItemsSource="{Binding Path=Param}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Path=Key}" />
<TextBlock Text=" : " />
<TextBlock Text="{Binding Path=Value}" />
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
If you want to have a hierarchical view of your data, using a TreeView might be a better fit.

How to bind properties of one ObservableCollection of ListView to properties of SelectedItem of another ListView?

So I have a few ListViews. The first is binded to ObservaleCollection<ComPort>. All properties of ComPort may take some predefined values. Other ListViews are responsible for that properties: they show all that possible (predefined) values and SelectedItem should be the current value of that property of ComPort from the first ObservaleCollection.
I can't attach images so here is an external picture, it would make the situation clean: http://i.stack.imgur.com/ZBRRx.png
<Window.Resources>
<ResourceDictionary x:Name="rd">
<l:ComPorts x:Key="vComPorts"/>
<l:SystemPorts x:Key="vSystemPorts"/>
<l:BaudRates x:Key="vBaudRate"/>
<l:Parities x:Key="vParities"/>
<l:DataBits x:Key="vDataBits"/>
<l:StopBits x:Key="vStopBits"/>
<l:Timeouts x:Key="vTimeouts"/>
<l:ComPort x:Key="vSelectedPort"/>
</ResourceDictionary>
</Window.Resources>
...
<ListView
Name="PortsList"
Grid.Row="1"
Grid.Column="0"
Margin="5"
VerticalAlignment="Stretch"
ItemsSource="{StaticResource vComPorts}"
DataContext="{StaticResource vComPorts}"
SelectedValuePath="PortName"
SelectedValue="{Binding ElementName=SystemPortsList, Path=SelectedItem.Value}"
SelectionChanged="PortsList_SelectionChanged"
MouseDoubleClick="PortsList_MouseDoubleClick">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<CheckBox />
<TextBlock Margin="5,0,0,0" Text="{Binding Path=Name}" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<ListView
x:Name="SystemPortsList"
Margin="5"
VerticalAlignment="Stretch"
DataContext="{Binding Source={StaticResource vSelectedPort}}"
ItemsSource="{Binding Source={StaticResource vSystemPortsView}}"
SelectedItem="{Binding Source={StaticResource vSelectedPort}, Path=PortName}"
MouseEnter="SystemPortsList_Refresh"
MouseLeave="SystemPortsList_Refresh"
Grid.Row="1"
Grid.Column="1" SelectionChanged="SystemPortsList_SelectionChanged">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Name="tb" Margin="5,0,0,0" Text="{Binding Path=Name}" />
</StackPanel>
</ListView.ItemTemplate>
</ListView>
I've tried to make an instance of class ComPort for saving current value of selected item from the first ListView, but anyway I can't cope with it without help. How this task should be solved?
1) Instead of handling SelectionChanged on the PortsList ListView, bind your checkbox to the ListViewItemsPanel like so:
<CheckBox IsChecked={Binding IsSelected, RelativeSource=Parent/>
2) Add an x:Name to your first ListBox, say x:Name="ComPortLB";
3) Remove DataContext on SystemPortsList;
4) Fix SelectedItem on SystemPortsList like so:
SelectedValue="{Binding ElementName=ComPortLB, Path=SelectedValue.PortName}"
I haven't tested any of this code and I haven't done this kind of stuff for a while, so I apologize for errors, but it should get you closer. I've also had to make some assumptions about your classes since you don't provide enough information.

Adding a List of Songs to a ListBox

i am trying to make my own mediaplayer for Windows Phone 7 and for the first step, i want to display a List of all songs in my media library to select them.
As i understood the ListBox, i just have to name the texblocks like the attributes of my class, which would be "Song"
<ListBox FontSize="30" Name="songListGUI" Height="330" Margin="0,120,0,0">
<Button Width="430" Height="60" BorderThickness="0" Margin="0" >
<Button.Content>
<StackPanel Orientation="Horizontal" Width="420" Height="auto">
<TextBlock Name="Name" Text="{Binding Name}" FontSize="22"></TextBlock>
<TextBlock Text=" - " FontSize="22"></TextBlock>
<TextBlock Name="Artist" Text="{Binding Artist}" FontSize="22"></TextBlock>
</StackPanel>
</Button.Content>
</Button>
</ListBox>
And now i think, i should handle my list of songs to the GUI and i try to do that with:
songListGUI.ItemsSource = songs;
But then i get a "InvalidOperationException" - Items collection must be empty before using ItemsSource.
I found several problems like this, and they all created a new class, to display this content. But i would like to stick with the song class, as it comes in quite handy :/
Do you know what i am doing wrong here?
edit:
i just found the solution. Don´t know exactly why, but this change in the .xaml made my da :):
<ListBox FontSize="30" Name="songListGUI" Height="330" Margin="0,120,0,0">
<ListBox.ItemTemplate>
<DataTemplate>
<Button Width="430" Height="60" BorderThickness="0" Margin="0" >
<Button.Content>
<StackPanel Orientation="Horizontal" Width="420" Height="auto">
<TextBlock Name="Name" Text="{Binding Name}" FontSize="22"></TextBlock>
<TextBlock Text=" - " FontSize="22"></TextBlock>
<TextBlock Name="Artist" Text="{Binding Artist}" FontSize="22"></TextBlock>
</StackPanel>
</Button.Content>
</Button>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Anybody could explan this to me?
ListBox is an ItemsControl. The content of an ItemsControl maps to the Items property. So by doing this:
<ListBox>
<SomeContent/>
</ListBox>
you're setting the Items property to <SomeContent/>. Since you aren't allowed to set the Items property and the ItemsSource property you get an exception.
When you do this:
<ListBox>
<ListBox.ItemTemplate>...</ListBox.ItemTemplate>
</ListBox>
You're not setting the content you're setting an attribute of the ListBox so there's no conflict.

Different Object-Types in Grid- or ListView

I'm currently trying to figure out how to show different types of objects in a GridView, look at this Pic for example:
the last element on the right side is different than the other elements, so if i bind an observablecollection to the GridView, how can i say that the last element is shown up in anohter layout.
currently I'm using this XAML-Code
<GridView x:Name="startView" ItemsSource="{Binding}" Grid.Column="1" Grid.Row="2" SelectionMode="None" Width="Auto">
<GridView.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock x:Name="DetailTitle" Height="74" Text="{Binding Title}" />
<Image x:Name="Image" Height="Auto" Width="Auto" Margin="0" Stretch="None" Source="{Binding LocalCoverUrl}" Visibility="Collapsed" />
</StackPanel>
</DataTemplate>
</GridView.ItemTemplate>
<GridView.ItemsPanel>
<ItemsPanelTemplate>
<WrapGrid Orientation="Horizontal" MaximumRowsOrColumns="2" />
</ItemsPanelTemplate>
</GridView.ItemsPanel>
</GridView>
and this Code in the Back:
ObservableCollection<Movie> recentlyStarted = await Api.RecentlyStarted(3);
startView.DataContext = recentlyStarted;
but I have currently no clue how to let the last element show up in a different style
The easy way would be to have the two types of object as different classes (e.g. MoviePicStyle + MoviePlainStyle. Then move your DataTemplate out of the GridView, so that each object is picked up by type,
e.g.
<Window.Resources>
<DataTemplate DataType="{x:Type ViewModel:MoviePicStyle}">
<StackPanel>
<TextBlock x:Name="DetailTitle" Height="74" Text="{Binding Title}" />
<Image x:Name="Image" Height="Auto" Width="Auto" Margin="0" Stretch="None" Source="{Binding LocalCoverUrl}" Visibility="Collapsed" />
</StackPanel>
<DataTemplate DataType="{x:Type ViewModel:MoviePlainStyle}">
...Different View...
</DataTemplate>
</Window.Resources>
<GridView...
Use template selector property of gridview and depending upon the type of object select the template. I did the same in my project. you need to write your own DataTemplateSelector.
I referred below link
http://babaandthepigman.wordpress.com/2012/02/08/datatemplateselector-winrt/

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