I'm writing an app to play streaming music, In app I have many list (Ranking list, Search Result List, Highlight song list .....), Each list have a same datatemplate which I bind to a LongListSelector for each Page. So I use this datatemplate as resources and put it in app.xaml
<DataTemplate x:Key="BasicVideoTemplate">
<Grid Tap="ChangeSong_Tap" RowsAuto="50,50" ColumnsAuto="150,*" Background="White" Margin="5,0,5,10">
<Grid.ColumnDefinition>
<ColumnDefinition Width = "150"/>
<ColumnDefinition Width = "*"/>
</Grid.ColumnDefinition>
<Grid.RowDefinition>
<RowDefinition Height = "50"/>
<RowDefinition Height = "50"/>
</Grid.RowDefinition>
<Border BorderThickness="1" BorderBrush="Black" Grid.RowSpan="2" Grid.Column="0" VerticalAlignment="Center" Margin="5,0,5,0">
<Image Source="{Binding Cover}"/>
</Border>
<TextBlock Text="{Binding Name}" Grid.Row="0" Grid.Column="1" Style="{StaticResource BlackTextBlock}" Margin="5,0,0,0"/>
<TextBlock Text="{Binding Artist}" Grid.Row="1" Grid.Column="1" Foreground="Black" Margin="5,0,0,0"/>
<!-- .............. -->
</Grid>
</DataTemplate>
And this code (which i put in app.xaml.cs) to select a song from list, create a AudioTrack from this item and navigate to playSongPage:
private void ChangeSong_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
var item = (SongItemModel)(sender as FrameworkElement).DataContext;
App.Model.ChangeSong(item.Id); /// this code will create a audio track for this item
(Application.Current.RootVisual as PhoneApplicationFrame).Navigate(new Uri("/Pages/DetailSongPage.xaml", UriKind.Relative));
}
Problem here is, I have to create a List< AudioTrack> for my playlist , So how can I get the parent list of clicked item and add it to the List< AudioTrack> , while all this code was put in app.xaml.cs ???
I would handle it in the SelectionChanged event of each longlistselector instead. The whole Tap thing on the grid doesn't sit well with me.
<phone:LongListSelector x:Name="myLSS" SelectionChanged="myLSS_SelectionChanged"/>
// event handler changes to
private void myLSS_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
LongListSelector lls = sender as LongListSelector; // get lls
var item = (SongItemModel) lls.SelectedItem;
App.Model.ChangeSong(item.Id); /// this code will create a audio track for this item
// now your ObservableCollection is just the ItemsSource, save a reference to it
// in the State manager so you can reference it on another page if you wish
ObservableCollection<SongItemModel> obs = (ObservableCollection<SongItemModel>) lls.ItemsSource;
PhoneApplicationService.Current.State["current_obs"] = obs;
// navigate..............
(Application.Current.RootVisual as PhoneApplicationFrame).Navigate(new Uri("/Pages/DetailSongPage.xaml", UriKind.Relative));
}
Related
<GridView x:Name="MainGridStations" ItemsSource="{x:Bind Stations}" IsItemClickEnabled="True" ItemClick="GridView_ItemClick">
<GridView.ItemTemplate>
<DataTemplate x:DataType="local:Station">
<Grid x:Name="WantToSelectByCode">
<Grid Background="White" HorizontalAlignment="Center" Width="300" Height="200" VerticalAlignment="Center">
<Grid Background="#e4f0fc" Height="65" VerticalAlignment="Bottom" Opacity="0.8">
<TextBlock x:Name="StationName" Text="{Binding Name}" FontWeight="Bold" Foreground="#2c9a8b" HorizontalAlignment="Center" />
</Grid>
</Grid>
</Grid>
</DataTemplate>
</GridView.ItemTemplate>
</GridView>
I'm trying to select a child by index of a dynamically filled gridview but what i've tried always returns null.
Like so for the first child for example:
var container = MainGridStations.ContainerFromIndex(0);
var presenter = VisualTreeHelper.GetChild(container, 0) as GridViewItem;
What am I doing wrong here?
You can get the corresponding GridViewItem from the method ItemsControl.ContainerFromIndex(Int32) directly and don't need to use the VisualTreeHelper to get it again.
var container = MainGridStations.ContainerFromIndex(0);
GridViewItem gridViewItem= container as GridViewItem;
gridViewItem.Background = new SolidColorBrush(Colors.Red);
The container have been the corresponding GridViewItem got from the index.
Note that: since your inner Grid have a Background="White" property configuration, you can delete the code to see the effect more obviously using my above code to change the gridViewItem.Background.
---Update---
You must get the GridViewItem after the items loaded. You can try the code in your GridView_ItemClick event handler or the page's loaded event hander. Also pay attention to my above note that to get more obvious effect, please delete the Background="White" in your above xaml code.
private void MainPage_Loaded(object sender, RoutedEventArgs e)
{
var container = MainGridStations.ContainerFromIndex(0);
GridViewItem gridViewItem = container as GridViewItem;
gridViewItem.Background = new SolidColorBrush(Colors.Green);
}
//get the item here
private void GridView_ItemClick(object sender, ItemClickEventArgs e)
{
var container = MainGridStations.ContainerFromIndex(0);
GridViewItem gridViewItem= container as GridViewItem;
gridViewItem.Background = new SolidColorBrush(Colors.Red);
//var presenter = VisualTreeHelper.GetChild(container, 0) as GridViewItem;
}
I have an array that keeps changing its values, because of this I want to have the apps UI refreshing every time the array's values do. I have this bound with an itemsControl. I can show the first array's values but then I can't update them I have tried .items.Clear() but its not working. Here are snippets of the .xaml and the xaml.cs. I actually took the code of the .xaml from a question from this site.
.xaml
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
<TextBox Text="Testing" IsReadOnly="True"></TextBox>
<ItemsControl x:Name="itemsControl"
ItemsSource="{Binding itemsControl}"
FontSize="24">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid Width="Auto"
Margin="0 12"
HorizontalAlignment="Center">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<StackPanel Grid.Column="0"
Grid.Row="0"
Orientation="Horizontal">
<TextBlock Name="txtblk0" Text="{Binding}" />
</StackPanel>
</Grid>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
.xaml.cs
String c = (new String(cArray));
string[] arr = null;
string[] data = null;
if (c != null)
{
arr = c.Split('\n');
if (arr.Length > 0)
{
data = arr[0].Split(',');
}
}
for(int index = 0; index < 4; index++)
{
itemsControl.Items.Add(float.Parse(data[index]));
}
itemsControl.Clear();
If anyone has an idea of how I can do this I will be very grateful, thanks in advance and I will try to answer any questions as soon as possible!
What you're missing is an understanding of how bindings are triggered to update.
The INotifyPropertyChanged interface contains a method (PropertyChanged) and when called and passed the name of a property will tell the binding system that the property has changed and the binding should be updated.
INotifyCollectionChanged is the equivalent for collections, and communicates when a collection has changed. i.e. something added, removed, or the list cleared.
ObservableCollection<T> contains an implementation of INotifyCollectionChanged that makes it easy to work with lists, collections, etc. that change.
If you used an ObservableCollection<float> instead of an array you'd be able to modify the list and have the UI updated to reflect this easily.
As a starter, see the following which demonstrates how easy it is to use an ObservableCollection.
XAML:
<StackPanel>
<Button Click="Button_Click">add an item</Button>
<ItemsControl ItemsSource="{Binding Items}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</StackPanel>
code behind;
public MainPage()
{
this.InitializeComponent();
// Initialize the property
this.Items = new ObservableCollection<string>();
// Use self as datacontext (but would normally use a separate viewmodel)
this.DataContext = this;
}
private void Button_Click(object sender, RoutedEventArgs e)
{
// add a new item to the UI
this.Items.Add(DateTime.Now.ToString());
}
// The "collection" that is shown in the UI
public ObservableCollection<string> Items { get; set; }
Is there a way I can get the index of a tapped item in the AdaptiveGridView toolkit.
Heres my code:
Page Resources:
<Page.Resources>
<DataTemplate x:Key="Photos">
<Grid>
<Image Source="{Binding ImageURL}"
Stretch="UniformToFill"
HorizontalAlignment="Center"
VerticalAlignment="Center">
</Image>
<TextBlock Text="{Binding ImageText}"
FontSize="20">
</TextBlock>
</Grid>
</DataTemplate>
</Page.Resources>
XAML:
<UWPToolkit:AdaptiveGridView x:Name="AdaptiveGV" ItemHeight="200" ItemClick="AdaptiveGV_ItemClick" DesiredWidth="200" ItemTemplate="{StaticResource Photos}"/>
Code behind:
List<Images> ImageCollection = new List<Images>();
ImageCollection.Add(new Images()
{
ImageURL = Response[i].ProjectImageURL,
ImageText = Response[i].ProjectName
});
}
AdaptiveGV.ItemsSource = ImageCollection;
I want the get an index of the item i clicked. Is there a way to do that?
I want the get an index of the item i clicked. Is there a way to do that?
Yes you can, in the ItemClickEventArgs, you can get the clicked item and its index like this:
private void AdaptiveGV_ItemClick(object sender, ItemClickEventArgs e)
{
var item = e.ClickedItem as Images;
var index = ImageCollection.IndexOf(item);
}
For my Windows Phone 8 App I have a Listbox element like below;
when I press multiselect icon on AppBar, I want to show checkboxes inside DataTemplate.
So users can make multiselect on items.
I have 50 elements bound on this Listbox and always at the index 11 ItemContainerGenerator.ContainerFromIndex returns null, plus some other items at rest of the list. So around 10 items out of 50 as returning as null.
There are some answers for WPF like applying Dispatcher.BeginInvoke or UpdateLayout, ScrollIntoView but none of them is working.
On the other hand if I scroll through list and then press AppBar icon it just works fine. But users can directly press on icon right after data bound and they will not see some of the checkboxes.
Is there any workaround for this issue for Windows Phone 8?
<ListBox Name="ResultListBox" ItemsSource="{Binding}"
SelectionChanged="ResultListBox_OnSelectionChanged">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Margin="0,0,0,10" Orientation="Horizontal">
<StackPanel Orientation="Horizontal">
<CheckBox Name="CheckBox" Visibility="Collapsed">
</CheckBox>
<Image Source="{Binding url}"
Width="125"
Height="125"
VerticalAlignment="Top"
Margin="0,0,5,0"></Image>
</StackPanel>
<StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding title}"
VerticalAlignment="Top"
FontFamily="Portable User Interface"></TextBlock>
</StackPanel>
<StackPanel>
<TextBlock Text="{Binding description}"
FontFamily="Portable User Interface"></TextBlock>
</StackPanel>
</StackPanel>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
void appBarButtonSelect_Click(object sender, EventArgs e)
{
//Dispatcher.BeginInvoke(delegate
//{
//});
for (int i = 0; i < ResultListBox.Items.Count; i++)
{
//ResultListBox.UpdateLayout();
//ResultListBox.ScrollIntoView(i);
DependencyObject item = ResultListBox.ItemContainerGenerator.ContainerFromIndex(i);
if (item != null)
{
CheckBox checkBox = FindFirstElementInVisualTree<CheckBox>(item);
if (checkBox != null)
{
checkBox.Visibility = Visibility.Visible;
}
}
else
{
Debugger.Break();
}
}
}
I think you're using ScrollIntoView + UpdateLayout incorrectly,
You're passing it an index, when it needs an object that is directly related to the ItemsSource
So if your ItemsSource is an ObservableCollection do this:
object o = ((ObservableCollection<sample_model>)this.myListBox.ItemsSource)[INDEX];
this.myListBox.ScrollIntoView(o); // call this first
this.myListBox.UpdateLayout(); // call this second
Then your ItemContainerGenerator.ContainerFromIndex(INDEX) will not be NULL.
i have a listbox which has a data template binded to task from xml file,i want to delete selected template on button click,but its throws me an exception "Operation is not valid while ItemsSource is in use. Access and modify elements with ItemsControl.ItemsSource instead."
here is the code for xaml
<TabItem>
<Canvas Height="700" Width="850">
<Canvas.Resources>
<XmlDataProvider x:Key="Tasks" XPath="tasks"
Source="http://store.tymesheet.com/templates/Graphic-Designer.xml"/>
<DataTemplate x:Key="tasktemplate1">
<Canvas Height="50" Width="850" >
<Label Content="{Binding XPath=name}" Height="30"
Width="170" Canvas.Top="10" Canvas.Left="150"
Background="LightGray"/>
<TextBox Height="30" Width="120" Canvas.Top="10"
Canvas.Left="370" Background="AliceBlue"/>
<Label Canvas.Left="500" Canvas.Top="10">$</Label>
<Button Tag="{Binding}" Click="deletebuttonclick"
Canvas.Top="12" Height="10" Width="30"
Canvas.Left="600"/>
</Canvas>
</DataTemplate>
</Canvas.Resources>
<ListBox ItemTemplate="{StaticResource tasktemplate1}"
ItemsSource="{Binding Path=ChildNodes, Source={StaticResource Tasks}}"
x:Name="tasklistbox" Height="700" Width="850"/>
<Label Canvas.Top="-18" Canvas.Left="185">Select Task</Label>
<Label Canvas.Top="-18" Canvas.Left="377" RenderTransformOrigin="0.58,0.462">Enter Bill Rates</Label>
<Button Canvas.Left="39" Canvas.Top="575" Width="139">Click to add the task</Button>
</Canvas>
</TabItem>
here is the code behind for delete button
private void deletebuttonclick(object sender,RoutedEventArgs e)
{
tasklistbox.Items.Remove(tasklistbox.SelectedItem);
}
where am i wrong?,help.thanx.
The error that you displayed is fairly self explanatory:
Operation is not valid while ItemsSource is in use. Access and modify elements with ItemsControl.ItemsSource instead.
Clearly, as you should know, you used the ItemsSource property on the ListBox:
<ListBox ItemTemplate="{StaticResource tasktemplate1}"
ItemsSource="{Binding Path=ChildNodes, Source={StaticResource Tasks}}"
x:Name="tasklistbox" Height="700" Width="850" />
The error is telling you to Access and modify elements with ItemsControl.ItemsSource instead. So instead of not doing what it says:
private void deletebuttonclick(object sender,RoutedEventArgs e)
{
tasklistbox.Items.Remove(tasklistbox.SelectedItem);
}
Try actually doing what it says:
private void deletebuttonclick(object sender,RoutedEventArgs e)
{
tasklistbox.ItemsSource = null;
}
Or even better:
private void deletebuttonclick(object sender,RoutedEventArgs e)
{
ChildNodes = null;
}
UPDATE >>>
So it seems that we have another new user that asks one thing and when given that thing asks for another thing without so much as a 'thank you'... shame... a real shame.
First you need to data bind to the ListBox.SelectedItem property so that you know which item is selected:
<ListBox ItemTemplate="{StaticResource tasktemplate1}" SelectedItem="{Binding Item}"
ItemsSource="{Binding Path=ChildNodes, Source={StaticResource Tasks}}"
x:Name="tasklistbox" Height="700" Width="850" />
This Item property should be of the same type as the items in the ChildNodes collection... if it's not clear enough - you need to add that property next to your collection property. Then to remove that item in your handler, you just need to do this:
private void deletebuttonclick(object sender,RoutedEventArgs e)
{
ChildNodes.Remove(Item);
}
If you want to remove the item, then I would suggest to create ObservableCollection of XmlNode and bind ItemsSource with that. I suggested to use ObservableCollection because it implements INotifyCollectionChanged so whenever list is updated target which in your case is ListBox will automatically be updated.
In code behind
(Add System.Collections.ObjectModel namespace to use ObservableCollection<T>)
public MainWindow()
{
InitializeComponent();
XmlDocument doc = new XmlDocument();
doc.Load("http://store.tymesheet.com/templates/Software-Developer.xml");
var taskList = doc.ChildNodes.OfType<XmlNode>()
.Where(node => node.Name == "tasks")
.SelectMany(node => node.ChildNodes.OfType<XmlNode>());
Tasks = new ObservableCollection<XmlNode>(taskList);
this.DataContext = this;
}
public ObservableCollection<XmlNode> Tasks { get; set; }
private void deletebuttonclick(object sender, RoutedEventArgs e)
{
XmlNode selectedNode = ((Button)sender).DataContext as XmlNode;
Tasks.Remove(selectedNode);
}
Of course you need to update XAML as well:
<ListBox ItemsSource="{Binding Tasks}"
ItemTemplate="{StaticResource tasktemplate1}"
x:Name="listBox" Height="700" Width="850"/>