Develop Reference

How can I navigate in WPF MVVM page

I have viewlist in which contain elements. When I click on them, my ItemViewModel handler clicks. Then I can select information about that element. Afthe I must to open new page in which will be all information about it. For example like hypertext in browser.
<Border MaxHeight="300" MaxWidth="1140" CornerRadius="25" Margin="73,269,65,182">
<Grid x:Name="MainGrid" RenderTransformOrigin="0.5,0.5" Margin="0,0,10,-3">
<Grid.ColumnDefinitions>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<ListView Width="1031" ItemsSource="{Binding GetTopItem}"
ScrollViewer.VerticalScrollBarVisibility="Disabled" HorizontalAlignment="Left" ScrollViewer.HorizontalScrollBarVisibility="Hidden"
Background="{x:Null}" BorderBrush="{x:Null}" Foreground="#DD000000"
x:Name="ListBook">
<ListView.DataContext>
<vm:BookMainVM/>
</ListView.DataContext>
<ListView.ItemTemplate>
<DataTemplate>
<Border HorizontalAlignment="Left" CornerRadius="25,25,25,25" BorderThickness="1" BorderBrush="#FF474747" Height="288" Margin="0,0,0,0" MouseDown="Border_MouseDown" >
<Grid Grid.Column="0" Height="Auto" Width="216" Margin="-1" IsEnabled="False">
<Grid.InputBindings>
<MouseBinding Gesture="LeftClick"
Command="{Binding DataContext.DelegateCommands,
RelativeSource={RelativeSource AncestorType=ListView}}"
CommandParameter="{Binding}">
</MouseBinding>
</Grid.InputBindings>
<Grid.RowDefinitions>
<RowDefinition Height="49*"/>
<RowDefinition Height="5*"/>
<RowDefinition Height="18*"/>
</Grid.RowDefinitions>
<Border CornerRadius="25,25,0,0" RenderTransformOrigin="0.5,0.5">
<Border.Background>
<ImageBrush ImageSource="{Binding Img_src}" Stretch="Fill" />
</Border.Background>
</Border>
<Label Content="{Binding Rate}" Background="#FFBFBFBF" RenderTransformOrigin="0.5,0.5" Grid.Row="1" FontSize="11" FontFamily="Meiryo UI" HorizontalContentAlignment="Center"/>
<Border CornerRadius="0,0,25,25" Grid.Row="2" Background="#FF8F8F8F">
<TextBlock Margin="6,0,0,0" Text="{Binding Name}" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" Grid.Row="2" Height="61" Width="190"/>
</Border>
</Grid>
</Border>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Grid>
</Border>
class ItemMainVM:ViewModel
{
private LibraryModel libraryModel;
private ItemDb itemsDb;
private const string Dir = "D:\\repos\\Frame\\Frame\\src";
public ItemMainVM()
{
libraryModel = new LibraryModel();
itemsDb = new BooksDb();
DelegateCommands = new DelegateCommand(o => EventHandler(o));
}
public ObservableCollection<BookPreviewInfo> GetTopItem
{
get
{
return libraryModel.GetTopItems();
}
}
public ICommand DelegateCommands { get; }
public void EventHandler(dynamic item)
{
itemDb.SelectItemId(item.Id);
}
}
Code Behind is empty.
When I click an element and executing EventHandler in ItemMainVM. And next must be create new page with new ElementViewModel.
ElementViewModel should to get information about element in ItemMainVM.

How to add row style to ListBox ItemTemplate in silverlight

I have problem in add alternate row style for ListBox.ItemTemplate
This is the way I code
<ListBox x:Name="NListBox" ItemsSource="{Binding NList,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
SelectedItem="{Binding SelectedItem,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
Style="{StaticResource CommonListBoxStyle}" Loaded="NListBox_Loaded">
<ListBox.ItemTemplate >
<DataTemplate >
<Grid Margin="0" Width="1600"
<Grid.ColumnDefinitions>
<ColumnDefinition Width="6*"/>
<ColumnDefinition Width="2*" ></ColumnDefinition>
<ColumnDefinition Width="2*" ></ColumnDefinition>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<TextBlock FontSize="20" Loaded="TextBlock_Loaded" Grid.ColumnSpan="3" Text="{Binding H}" />
<TextBlock Grid.Row="0" Grid.Column="1" FontSize="12" HorizontalAlignment="Right">Publish Date</TextBlock>
<TextBlock Grid.Row="0" Grid.Column="3" FontSize="12" Text="{Binding PublishDate,StringFormat=\{0:dd.MM.yy\}}"
/>
<TextBlock Grid.Row="1" FontSize="15" TextWrapping="Wrap" Grid.ColumnSpan="3" Text="{Binding Description}"
Height="50" />
<TextBlock Grid.Row="2" Grid.Column="0" FontSize="12" Text="{Binding link}" />
<TextBlock Grid.Row="2" Grid.Column="1" FontSize="12" HorizontalAlignment="Right">Expiry Date</TextBlock>
<TextBlock Grid.Row="2" Grid.Column="3" FontSize="12" Text="{Binding ExpiryDate,StringFormat=\{0:dd.MM.yy\}}"
/>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>

This the why I did this
.xml
<converters:RowStyleConverter x:Key="RowStyleConverter"/>
<ListBox>
<ListBox.ItemTemplate >
<DataTemplate >
<Grid Background="{Binding Converter={StaticResource RowStyleConverter}}"></Grid>
</DataTemplate >
</ListBox.ItemTemplate >
</ListBox>
C#
public class RowStyleConverter : IValueConverter
{
int counter = 0;
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (counter % 2 == 1)
{
return new SolidColorBrush(Color.FromArgb(255, 233, 252, 251));
}
else
{
return new SolidColorBrush(Color.FromArgb(255, 220, 239, 238));
}
counter++;
}
}

Mahapps : ScrollViewer update list on event KeyDown in WPF ( C # )

I have a problem I can not solve.
As you can see in the picture , there is a label , a textobx and a ScrollViewer .
Now , I have to update the ScrollViewer when the user searches through the textbox .
Part of an event every time you make a keydown .
So if I write Statut ... should put first in the file list with the names "statuto rai"
the list can have N elements
Image list:
Xaml code:
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="25"></RowDefinition>
<RowDefinition Height="25"></RowDefinition>
<RowDefinition Height="*"></RowDefinition>
</Grid.RowDefinitions>
<Grid Grid.Row="0" Background="GhostWhite"/>
<Grid Grid.Row="1" Background="Gray"/>
<TextBlock HorizontalAlignment="Center" VerticalAlignment="Center">Documenti allegati</TextBlock>
<Border Grid.Row="1" Margin="3" BorderBrush="White" Height="22" Background="#fff">
<TextBox BorderBrush="#465E76" KeyDown="TextBox_KeyDown" BorderThickness="0" FontSize="10" Background="#fff" Foreground="#565656" controls:TextBoxHelper.Watermark="Ricerca Locale" FontFamily="{StaticResource Lato Thin}" HorizontalContentAlignment="Center" ></TextBox>
</Border>
<ScrollViewer Grid.Row="2" VerticalScrollBarVisibility="Hidden" PanningMode="Both" Name="scrollDocuments">
<ItemsControl ItemsSource="{Binding Path=attachmentsList}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel Grid.Column="0" Grid.Row="0">
<Button Grid.ColumnSpan="2">
<Button.Template>
<ControlTemplate TargetType="{x:Type Button}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="450"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="60"/>
</Grid.RowDefinitions>
<Grid Grid.Row="0" Background="#fff"></Grid>
<TextBlock Foreground="#565656" FontFamily="{StaticResource Lato Semibold}" Grid.Row="0" Grid.Column="0" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="10" Margin="10,3,0,0" Style="{DynamicResource Lato-Semibold}" Text="{Binding contList}"/>
<Image Source="/Resources/Images/icon-document-browser.png" HorizontalAlignment="Left" Margin="22,-12,0,0" Width="22"/>
<TextBlock Foreground="#565656" FontFamily="{StaticResource Lato Semibold}" Grid.Row="0" Grid.Column="0" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="10" Margin="21,32,0,0" Style="{DynamicResource Lato-Semibold}" Text="{Binding FileSizeConverted}"/>
<TextBlock Foreground="#565656" FontFamily="{StaticResource Lato Semibold}" Grid.Row="0" Grid.Column="0" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="12" Margin="55,-10,0,0" Style="{DynamicResource Lato-Semibold}" Text="{Binding Name}"/>
<TextBlock Foreground="#565656" FontFamily="{StaticResource Lato Semibold}" Grid.Row="0" Grid.Column="0" HorizontalAlignment="Right" VerticalAlignment="Center" FontSize="12" Margin="55,-10,10,0" Style="{DynamicResource Lato-Semibold}" Text="{Binding ModifiedDate}"/>
<TextBlock Foreground="#565656" FontFamily="{StaticResource Lato Semibold}" Grid.Row="0" Grid.Column="0" HorizontalAlignment="Right" VerticalAlignment="Center" FontSize="10" Margin="55,25,10,0" FontWeight="Bold" Style="{DynamicResource Lato-Semibold}" Text="Nessuna copia locale"/>
<Border Grid.Row="0" Grid.ColumnSpan="2" BorderBrush="#DDD" BorderThickness="0,0,0,1"></Border>
</Grid>
</ControlTemplate>
</Button.Template>
</Button>
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</ScrollViewer>
<Viewbox Grid.Row="2" Name="testoNessunAllegato" Visibility="Collapsed" Margin="20">
<TextBlock Text="Nessun allegato disponibile."></TextBlock>
</Viewbox>
</Grid>
CodeBehind event code:
private void TextBox_KeyDown(object sender, System.Windows.Input.KeyEventArgs e)
{
string find = ((TextBox)sender).Text;
attachmentsList = attachmentsList.Where(x => x.Name == find).ToList();
InitializeComponent();
}
in practice I do the intelligiente research, so every time I insert a letter filtrale list , and print it again , of course real time .
I hope I explained myself .
Thank you

I see you use bindings, in this case there is a much better stuff to reach your goal. It's CollectionView.
Here is a simple app for you which more or less fullfill your requirements:
View
<StackPanel Orientation="Horizontal">
<Label Content="Search" />
<TextBox MinWidth="30" Text="{Binding FilterText, UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>
<ListBox ItemsSource="{Binding Data}" />
UpdateSorceTrigger=PropertyChanges updates FilterText in ViewModel every time when you press any key.
Data is a ICollectionView
ViewModel
public ICollectionView Data { get; private set; }
...
// Create default view for the list
Data = CollectionViewSource.GetDefaultView(list);
// Set filter delegate for CollectionView
Data.Filter = FilterData;
....
private bool FilterData(object obj)
{
DataContainer cont = (DataContainer)obj;
return string.IsNullOrEmpty(FilterText) || cont.Name.StartsWith(FilterText, StringComparison.OrdinalIgnoreCase);
}
private string myfiltertext;
public string FilterText
{
get { return myfiltertext; }
set
{
myfiltertext = value;
// Refresh collection view after Filter text modification
Data.Refresh();
}
}

how to get listboxitem's value on listbox hold event?

xmal code:
<ListBox x:Name="listbox2" Margin="0,0" SelectionChanged="listbox2_SelectionChanged" Hold="listbox2_Hold" >
<ListBox.ItemContainerStyle >
<Style TargetType="ListBoxItem">
<Setter Property="HorizontalContentAlignment" Value="Stretch"></Setter>
</Style>
</ListBox.ItemContainerStyle>
<ListBox.ItemTemplate>
<DataTemplate>
<Border BorderThickness="0,0,0,1" BorderBrush="Gray">
<Grid Width="auto" HorizontalAlignment="Stretch" >
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="150"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<TextBlock VerticalAlignment="Center" FontSize="40" Grid.Column="1" Grid.Row="0" Foreground="White" Text="{Binding NAME}"></TextBlock>
<TextBlock VerticalAlignment="Center" FontSize="25" Grid.Column="1" Grid.Row="1" Foreground="Blue" Text="{Binding PHONE}"></TextBlock>
<Image Name="c1" HorizontalAlignment="Left" VerticalAlignment="Top" Width="100" Height="100" Stretch="Fill" Margin="0" Source="{Binding IMGS}" Grid.RowSpan="2" Grid.Column="0" />
</Grid>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
class list which is bind to list box is
List < contactsclass > contacts = new List < contactsclass >();
PHONE and NAME are getter setter of the contactclass's variables
how can i get this variable's value on hold event of listbox .. i am trying following code
private void listbox2_Hold(object sender, System.Windows.Input.GestureEventArgs e)
{
//contextmenucontact = (contactsclass)(sender as ListBox).DataContext;
contextmenucontact = (contactsclass)listbox2.SelectedItem;
MessageBox.Show(contextmenucontact.name);
}

if is just the selected item is just use the ToString Function, see this:
if (listBox1.SelectedItem != null)
{
string itemText = listBox1.SelectedItem.ToString();
contextmenucontact = new contactsclass();
contextmenucontact.name = itemText;
MessageBox.Show(contextmenucontact.name);
}

Out of memory exception while using <ScrollViewer> with multiple ListViews in it

I have a usercontrol with 2 ListViews in it. One for holding a list of predefined categories and one for the list with all the categories in it.
When i place the ListViews inside a <Grid> than everything works perfect.
The working xaml code (with Grid):
<Grid Style="{StaticResource ResourceKey=ContentStyle}">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<ListView x:Name="lstPredefinedCategories" Grid.Row="0" ItemsSource="{Binding PredefinedCategories}" SelectionMode="Multiple" Margin="20">
<ListView.Header>
<StackPanel>
<TextBlock Text="Voorgestelde categorieën" Style="{StaticResource TextBlockStyle}" FontWeight="SemiBold" Foreground="Black" />
<Rectangle Style="{StaticResource DividerStyle}" Fill="Black"/>
</StackPanel>
</ListView.Header>
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}" Style="{StaticResource TextBlockStyle}" HorizontalAlignment="Left" TextWrapping="Wrap" Width="300" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Grid Grid.Row="1">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<StackPanel Grid.Row="0" Margin="20,0">
<TextBlock Text="Alle categorieën" Style="{StaticResource TextBlockStyle}" FontWeight="SemiBold" Foreground="Black" />
<Rectangle Style="{StaticResource DividerStyle}" Fill="Black"/>
</StackPanel>
<TextBox x:Name="txtSearch" PlaceholderText="Zoek categorie" Grid.Row="1" Style="{StaticResource SearchboxStyle}" Margin="20,0" TextChanged="txtSearch_TextChanged" />
<Rectangle Grid.Row="2" Style="{StaticResource DividerStyle}" Margin="20, 0" />
<ListView x:Name="lstCategories" Grid.Row="3" Margin="20,10,20,0" ItemsSource="{Binding Categories}" SelectionMode="Multiple" SelectionChanged="lstCategories_SelectionChanged">
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Key}" Style="{StaticResource TextBlockStyle}" HorizontalAlignment="Left" TextWrapping="Wrap" Width="300" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Rectangle Grid.Row="4" Style="{StaticResource DividerStyle}" Margin="20, 0" />
<Grid Grid.Row="5">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Button x:Name="btnAnnuleren" Grid.Column="0" Content="Annuleren" Style="{StaticResource ButtonAnnulerenStyle}" Click="btnAnnuleren_Click"/>
<Rectangle Grid.Column="1" Fill="#A9A9A9" Width="0.5" Margin="10,0" />
<Button x:Name="btnSelecteren" Grid.Column="2" Content="Selecteren" Style="{StaticResource ButtonAnnulerenStyle}" Click="btnSelecteren_Click"/>
</Grid>
</Grid>
</Grid>
The only problem with this is that I dont get the UI behaviour that I want. If I use a grid then only the red border is scrollable (because of the ListView). But what I need is that the entire green border is scrollable.
So I want to put everything in a <ScrollViewer><StackPanel></StackPanel></ScrollViewer>.
But when I do so, I occasionally get an out-of-memory exception (sometimes the apps just freezes and close without an exception).
Here is my not working xaml with the <ScrollViewer>:
<ScrollViewer>
<StackPanel>
<ListView x:Name="lstPredefinedCategories" ItemsSource="{Binding PredefinedCategories}" SelectionMode="Multiple" Margin="20">
<ListView.Header>
<StackPanel>
<TextBlock Text="Voorgestelde categorieën" Style="{StaticResource TextBlockStyle}" FontWeight="SemiBold" Foreground="Black" />
<Rectangle Style="{StaticResource DividerStyle}" Fill="Black"/>
</StackPanel>
</ListView.Header>
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}" Style="{StaticResource TextBlockStyle}" HorizontalAlignment="Left" TextWrapping="Wrap" Width="300" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<StackPanel Grid.Row="0" Margin="20,0">
<TextBlock Text="Alle categorieën" Style="{StaticResource TextBlockStyle}" FontWeight="SemiBold" Foreground="Black" />
<Rectangle Style="{StaticResource DividerStyle}" Fill="Black"/>
</StackPanel>
<TextBox x:Name="txtSearch" PlaceholderText="Zoek categorie" Grid.Row="1" Style="{StaticResource SearchboxStyle}" Margin="20,0" TextChanged="txtSearch_TextChanged" />
<Rectangle Grid.Row="2" Style="{StaticResource DividerStyle}" Margin="20, 0" />
<ListView x:Name="lstCategories" Grid.Row="3" Margin="20,10,20,0" ItemsSource="{Binding Categories}" SelectionMode="Multiple" SelectionChanged="lstCategories_SelectionChanged">
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Key}" Style="{StaticResource TextBlockStyle}" HorizontalAlignment="Left" TextWrapping="Wrap" Width="300" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Rectangle Grid.Row="4" Style="{StaticResource DividerStyle}" Margin="20, 0" />
<Grid Grid.Row="5">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Button x:Name="btnAnnuleren" Grid.Column="0" Content="Annuleren" Style="{StaticResource ButtonAnnulerenStyle}" Click="btnAnnuleren_Click"/>
<Rectangle Grid.Column="1" Fill="#A9A9A9" Width="0.5" Margin="10,0" />
<Button x:Name="btnSelecteren" Grid.Column="2" Content="Selecteren" Style="{StaticResource ButtonAnnulerenStyle}" Click="btnSelecteren_Click"/>
</Grid>
</Grid>
</StackPanel>
</ScrollViewer>
Any thoughts on why my app is freezing or get an OOM-exception?
Update
It comes because in the 2nd ListView they are too much objects loaded. So I'm gonna try to fix it with ISupportIncrementalLoading.
Or is there an other way?

The solution was to use virtualization (ISupportIncrementalLoading) like suggested in the comments.
Here you can find my implementation class of ISupportIncrementalLoading:
public class StringKeyValueIncrementalCollection : ObservableCollection<StringKeyValue>, ISupportIncrementalLoading
{
private List<StringKeyValue> allCategories;
private int lastItem = 1;
public StringKeyValueIncrementalCollection(List<StringKeyValue> categories)
{
this.allCategories = categories;
}
public bool HasMoreItems
{
get
{
if (lastItem == allCategories.Count)
{
return false;
}
else
{
return true;
}
}
}
public IAsyncOperation<LoadMoreItemsResult> LoadMoreItemsAsync(uint count)
{
CoreDispatcher coreDispatcher = Window.Current.Dispatcher;
return Task.Run<LoadMoreItemsResult>(async () =>
{
List<StringKeyValue> items = new List<StringKeyValue>();
for (int i = 0; i < count; i++)
{
items.Add(allCategories[i]);
lastItem++;
Debug.WriteLine(lastItem);
if (lastItem == allCategories.Count)
{
break;
}
}
await coreDispatcher.RunAsync(CoreDispatcherPriority.Normal,
() =>
{
foreach (StringKeyValue item in items)
{
this.Add(item);
}
});
return new LoadMoreItemsResult() { Count = count };
}).AsAsyncOperation<LoadMoreItemsResult>();
}
}
And then my code in the ViewModel. As you can see, I use the StringKeyValueIncrementalCollection instead of a regular List<object>:
private StringKeyValueIncrementalCollection categories;
private StringKeyValueIncrementalCollection allCategories;
public StringKeyValueIncrementalCollection Categories
{
get { return categories; }
set
{
filteredCategories = value;
RaisePropertyChanged("Categories");
}
}
public async void LoadCategories()
{
List<StringKeyValue> temp = await this.openVlaanderenService.GetCategoriesData();
allCategories = new StringKeyValueIncrementalCollection(temp);
Categories = allCategories;
}
The only problem that you than have is that the ScollViewer will allow it's content to fill as much space as it wants, so the data just will keep loading. To fix that I did what was suggested in ISupportIncrementalLoading inside ScrollViewer not supported?
So I added a SizeChanged="ScrollViewer_SizeChanged" event to my ScrollViewer and in code behind set the size of the ListView based on the viewport size properties of the ScrollViewer:
private void ScrollViewer_SizeChanged(object sender, SizeChangedEventArgs e)
{
lstCategories.Height = scrollViewer.ViewportHeight;
}