ListView strange behavoiur with blend trigger

ListView strange behavoiur with blend trigger - c#

I have simple ListView with trigger also I am using mvvm light RelayCommand.
The main question is why when function ChangeShowingMode(ObservableCollection<Employee> items) fires in console it displays only Firing: 0. Why it do not show also Firing: 1,Firing: 5,Firing: 11,Firing: 99. How to make it?
xmlns:i="http://schemas.microsoft.com/expression/2010/interactions"
xmlns:ei="http://schemas.microsoft.com/expression/2010/interactivity"
<Grid>
<ListView ItemsSource="{Binding Items}">
<ListView.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<CheckBox IsChecked="{Binding IsChecked}" VerticalAlignment="Center">
<ei:Interaction.Triggers>
<ei:EventTrigger EventName="Checked">
<ei:InvokeCommandAction Command="{Binding DataContext.IsCheckedTrueCommand,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Views:MainWindow}}}" CommandParameter="{Binding .}"/>
</ei:EventTrigger>
</ei:Interaction.Triggers>
</CheckBox>
<Label Grid.Column="1" Content="{Binding Name}" VerticalAlignment="Center"/>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Grid>
Code Looks like:
namespace WpfApplication
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
DataContext = new ListViewModel();
}
}
public class Employee : ViewModelBase
{
private bool isChecked;
public bool IsChecked
{
get
{
return this.isChecked;
}
set
{
this.isChecked = value;
this.RaisePropertyChanged("IsChecked");
}
}
public string Name { get; set; }
}
public class ListViewModel : ViewModelBase
{
private ObservableCollection<Employee> items;
public ObservableCollection<Employee> Items
{
get
{
return this.items;
}
set
{
this.items = value;
this.RaisePropertyChanged("Items");
}
}
public ListViewModel()
{
Items = new ObservableCollection<Employee>();
LoadAsync();
}
public void LoadAsync()
{
Task t = null;
t = Task.Factory.StartNew(new Action(() =>
{
System.Threading.Thread.Sleep(5000);
ObservableCollection<Employee> temporaryItems = new ObservableCollection<Employee>();
for (int i = 0; i < 100; i++)
{
temporaryItems.Add(new Employee { IsChecked = false, Name = i.ToString() });
}
Items = temporaryItems;
}));
t.ContinueWith((key) => { ChangeShowingMode(Items); });
}
public void ChangeShowingMode(ObservableCollection<Employee> items)
{
Items[0].IsChecked = true;
Items[1].IsChecked = true;
Items[5].IsChecked = true;
Items[11].IsChecked = true;
Items[99].IsChecked = true;
}
public RelayCommand<Employee> IsCheckedTrueCommand
{
get
{
return new RelayCommand<Employee>((emp) => Command(emp));
}
}
public void Command(Employee emp)
{
Console.WriteLine("Firing: {0}", emp.Name);
}
}
}

The Checked Event will raise only for visible Checkboxes. So the command is only called for the visible ones.
By test your provided example, the Properties are set by the task and also reflected as expected by the UI. But the Command is only called, when I manually check a checkbox, not through initialisation.
Changing
t.ContinueWith((key) => { ChangeShowingMode(Items); });
to
t.ContinueWith((key) => { Syste.Threading.Thread.Sleep(5000); ChangeShowingMode(Items); });
has the result, that the Command is called for the visible Checkboxes.
If you scoll down when the checkboxes are displayed, the command is called for Checkbox 99.
But this behavior isn't strange at all. I think, it is a timming-Issue when your viewmodel is connected to the Datacontext or not.
The answer to your question "How to make it?" depends on what is your problem with the current solution.
To watch the property changes, you could
How to Listen to Property Changes of Items of an ObservableCollection
and call a command on changes.
But I think you don't need this at all. The checked-State is reflected by your IsChecked-Property through the Two-Way binding.
<CheckBox IsChecked="{Binding IsChecked, Mode=TwoWay}" VerticalAlignment="Center">
So you can easily get them by
var checkedItemsList = Items.Where(ele => ele.IsChecked).ToList();
And if you make Changes by Code, you can call the Command manually in your viewmodel.
Items[0].IsChecked = true;
if (IsCheckedTrueCommand.CanExecute(Items[0]))
IsCheckedTrueCommand.Execute(Items[0]);
But I'm not sure if I get you here. The question remains what the command should do in an enhanced scenario.
Btw, which Version of Framework you are using? See check box binding not working on .NET 3.5 SP1
And to call a Comand on User-Interaction you can use:
<CheckBox CommandParameter="{Binding}"
Command="{Binding DataContext.CheckBoxCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}"
IsChecked="{Binding IsChecked, Mode=TwoWay}" VerticalAlignment="Center">

Related

WPF - How to trigger an event for each element(button) in a ListBox?

I'd like to trigger event for the elemens which is button in a listbox, the view is as below. It is a listbox with 32 buttons.The purpose is to toggle the button between 0-1 and trigger event for each element.
There are two solutions I am thinking about. The solution one is to set command for each button, it works but the problem is I can't catch a selectedItem or a selectedIndex successfully so that even thougn I know the button is toggled, but I don't know the item index.
<ListBox x:Name="lbDirection"
Grid.Row="1"
Grid.Column="1"
SelectionMode="Extended"
ScrollViewer.HorizontalScrollBarVisibility="Disabled"
ScrollViewer.VerticalScrollBarVisibility="Disabled"
Margin="30,26,44,83"
Style="{StaticResource ListBoxHorz}"
ItemContainerStyle="{StaticResource ItemNoBorder}"
SelectedItem="{Binding SelectedLineItem}"
ItemsSource="{Binding ButtonList}"
IsSynchronizedWithCurrentItem="True">
<ListBox.ItemTemplate>
<DataTemplate>
<Button Style="{StaticResource ChangeButton}"
Command="{Binding DataContext.ToggleDirectionCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType= ListBox}}">
<Button.Content>
<TextBlock Text="{Binding BtnText}"
TextDecorations="Underline" />
</Button.Content>
</Button>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
ViewModel:
public class DigitalIOViewModel : BindableBase
{
public ICommand ToggleDirectionCommand { get; set; }
public ICommand ToggleStateCommand { get; set; }
private ObservableCollection<LineButtons> btnlist;
private LineButtons _selectedLineItem;
public LineButtons SelectedLineItem
{
get { return _selectedLineItem; }
set {
_selectedLineItem=value;
OnPropertyChanged("SelectedLineItem");
}
}
public DigitalIOViewModel()
{
btnlist = new ObservableCollection<LineButtons>();
CreateButtonList();
ToggleDirectionCommand = new RelayCommand(ToggleDirectionAction);
}
private void ToggleDirectionAction()
{
LineButtons selectedLineItem = SelectedLineItem;
int lineIndex=(SelectedLineItem!= null && ButtonList!=null)? ButtonList.IndexOf(SelectedLineItem) : -1;
if (selectedLineItem.BtnText == "1" && lineIndex == 0)
{
ButtonList[lineIndex] = new LineButtons() { BtnText = "0" };
}
else
ButtonList[lineIndex] = new LineButtons() { BtnText = "1" };
}
public ObservableCollection<LineButtons> ButtonList
{
get { return btnlist; }
set { btnlist = value; OnPropertyChanged("ButtonList"); }
}
public void CreateButtonList()
{
for (int i = 0; i < 32; i++)
{
ButtonList.Add(new LineButtons() { BtnText = "1"});
}
}
}
public class LineButtons : BindableBase
{
private string btnText;
public string BtnText
{
get { return btnText; }
set { btnText = value; OnPropertyChanged("BtnText"); }
}
}
I cannot get a correct selectedIndex from this code.
The second solution is to use the IsSelected/SelectedItem property instead of button command binding, I was wondering if there is conflict with the button command binding for item and IsSelected property fot listbox,so we can't use them at the same time, can someone help me out which is the best solution? Thanks in advance.

In addition to the Command property you can set the CommandParameter to the current LineButtons item (class names should be singular, names of collections use plural):
<ListBox.ItemTemplate>
<DataTemplate>
<Button Style="{StaticResource ChangeButton}"
Command="{Binding DataContext.ToggleDirectionCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType= ListBox}}"
CommandParameter="{Binding}">
<Button.Content>
<TextBlock Text="{Binding BtnText, UpdateSourceTrigger=PropertyChanged}"
TextDecorations="Underline" />
</Button.Content>
</Button>
</DataTemplate>
</ListBox.ItemTemplate>
Then get the current item, the item that triggered the command, by accessing the command parameter:
private void Execute(object commandParameter)
{
var currentLineButton = commandParameter as LineButtons;
...
}

Returning bound checkbox values using MVVM in a WPF form

I have an object that consists of a string and an array. The string populates a ComboBox and the array populates a ListView depending on the selected string value. Each line of the ListViewconsists of a TextBlock and a CheckBox.
On submit I want to be able to verify which items have been selected for further processing but there's a disconnect when using the MVVM approach. I currently have the DataContext of the submit Button binding to the ListView but only the first value is being returned upon submit (somewhere I need to save the selected values to a list I assume but I'm not sure where). I added an IsSelected property to the model which I think is the first step, but after that I've been grasping at straws.
Model
namespace DataBinding_WPF.Model
{
public class ExampleModel { }
public class Example : INotifyPropertyChanged
{
private string _name;
private string[] _ids;
private bool _isSelected;
public bool IsSelected
{
get => _isSelected;
set
{
if (_isSelected != value)
{
_isSelected = value;
RaisePropertyChanged("IsSelected");
}
}
}
public string Name
{
get => _name;
set
{
if (_name != value)
{
_name = value;
RaisePropertyChanged("Name");
}
}
}
public string[] IDs
{
get => _ids;
set
{
if (_ids != value)
{
_ids = value;
RaisePropertyChanged("IDs");
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged(string property)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new
PropertyChangedEventArgs(property));
}
}
}
}
ViewModel
namespace DataBinding_WPF.ViewModel
{
public class ExampleViewModel : INotifyPropertyChanged
{
public ObservableCollection<Example> Examples
{
get;
set;
}
// SelectedItem in the ComboBox
// SelectedItem.Ids will be ItemsSource for the ListBox
private Example _selectedItem;
public Example SelectedItem
{
get => _selectedItem;
set
{
_selectedItem = value;
RaisePropertyChanged(nameof(SelectedItem));
}
}
// SelectedId in ListView
private string _selectedId;
public string SelectedId
{
get => _selectedId;
set
{
_selectedId = value;
RaisePropertyChanged(nameof(SelectedId));
}
}
private string _selectedCheckBox;
public string IsSelected
{
get => _selectedCheckBox;
set
{
_selectedCheckBox = value;
RaisePropertyChanged(nameof(IsSelected));
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged(string property)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new
PropertyChangedEventArgs(property));
}
}
public void LoadExample()
{
ObservableCollection<Example> examples = new ObservableCollection<Example>();
examples.Add(new Example { Name = "Mark", IDs = new string[] { "123", "456" }, IsSelected = false });
examples.Add(new Example { Name = "Sally", IDs = new string[] { "789", "101112" }, IsSelected = false });
Examples = examples;
}
/* BELOW IS A SNIPPET I ADDED FROM AN EXAMPLE I FOUND ONLINE BUT NOT SURE IF IT'S NEEDED */
private ObservableCollection<Example> _bindCheckBox;
public ObservableCollection<Example> BindingCheckBox
{
get => _bindCheckBox;
set
{
_bindCheckBox = value;
RaisePropertyChanged("BindingCheckBox");
}
}
}
}
View
<UserControl x:Class = "DataBinding_WPF.Views.StudentView"
xmlns = "http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x = "http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc = "http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d = "http://schemas.microsoft.com/expression/blend/2008"
xmlns:local = "clr-namespace:DataBinding_WPF"
mc:Ignorable = "d"
d:DesignHeight = "300" d:DesignWidth = "300">
<Grid>
<StackPanel HorizontalAlignment = "Left" >
<ComboBox HorizontalAlignment="Left"
VerticalAlignment="Top"
Width="120"
ItemsSource="{Binding Path=Examples}"
SelectedItem="{Binding SelectedItem}"
DisplayMemberPath="Name"/>
<ListView x:Name="myListView"
ItemsSource="{Binding SelectedItem.IDs}"
DataContext="{Binding DataContext, ElementName=submit_btn}"
SelectedItem="{Binding SelectedId}"
Height="200" Margin="10,50,0,0"
Width="Auto"
VerticalAlignment="Top"
Background="AliceBlue">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" >
<CheckBox
Name="myCheckBox"
IsChecked="{Binding IsSelected,
RelativeSource={RelativeSource AncestorType=ListViewItem}}"
Margin="5, 0"/>
<TextBlock Text="{Binding}" FontWeight="Bold" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Button HorizontalAlignment="Left" Height="20" Width="100"
Click="Submit" x:Name="submit_btn">Submit</Button>
</StackPanel>
</Grid>
</UserControl>
View.cs
namespace DataBinding_WPF.Views
{
/// <summary>
/// Interaction logic for StudentView.xaml
/// </summary>
public partial class StudentView : UserControl
{
public StudentView()
{
InitializeComponent();
}
private void Submit(object sender, EventArgs e)
{
var selectedItems = ((Button)sender).DataContext;
// process each selected item
// foreach (var selected in ....) { }
}
}
}

The ListView control already exposes a selected items collection as property SelectedItems.
private void Submit(object sender, RoutedEventArgs e)
{
var selectedIds = myListView.SelectedItems.Cast<string>().ToList();
// ...do something with the items.
}
However, I doubt that you want to do this in the code-behind, but rather in the view model. For this purpose, WPF offers the concept of commands.
MVVM - Commands, RelayCommands and EventToCommand
What you need is a relay command or delegate command (the name varies across frameworks). It encapsulates a method that should be executed for e.g. a button click and a method to determine whether the command can be executed as an object that can be bound in the view. Unfortunately, WPF does not provide an implementation out-of-the-box, so you either have to copy an implementation like here or use an MVVM framework that already provides one, e.g. Microsoft MVVM Tookit.
You would expose a property Submit of type ICommand in your ExampleViewModel and initialize it in the constructor with an instance of RelayCommand<T> that delegates to a method to execute.
public class ExampleViewModel : INotifyPropertyChanged
{
public ExampleViewModel()
{
Submit = new RelayCommand<IList>(ExecuteSubmit);
}
public RelayCommand<IList> Submit { get; }
// ...other code.
private void ExecuteSubmit(IList selectedItems)
{
// ...do something with the items.
var selectedIds = selectedItems.Cast<string>().ToList();
return;
}
}
In your view, you would remove the Click event handler and bind the Submit property to the Command property of the Button. You can also bind the SelectedItems property of the ListView to the CommandParameter property, so the selected items are passed to the command on execution.
<Button HorizontalAlignment="Left"
Height="20"
Width="100"
x:Name="submit_btn"
Command="{Binding Submit}"
CommandParameter="{Binding SelectedItems, ElementName=myListView}">Submit</Button>
Additionally, a few remarks about your XAML.
Names of controls in XAML should be Pascal-Case, starting with a capital letter.
You should remove the DataContext binding from ListView completely, as it automatically receives the same data context as the Button anyway.
DataContext="{Binding DataContext, ElementName=submit_btn}"
You can save yourself from exposing and binding the SelectedItem property in your ExampleViewModel, by using Master/Detail pattern for hierarchical data.
<Grid>
<StackPanel HorizontalAlignment = "Left" >
<ComboBox HorizontalAlignment="Left"
VerticalAlignment="Top"
Width="120"
ItemsSource="{Binding Path=Examples}"
IsSynchronizedWithCurrentItem="True"
DisplayMemberPath="Name"/>
<ListView ItemsSource="{Binding Examples/IDs}"
SelectedItem="{Binding SelectedId}"
Height="200" Margin="10,50,0,0"
Width="Auto"
VerticalAlignment="Top"
Background="AliceBlue">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" >
<CheckBox Name="myCheckBox"
IsChecked="{Binding IsSelected, RelativeSource={RelativeSource AncestorType=ListViewItem}}"
Margin="5, 0"/>
<TextBlock Text="{Binding}"
FontWeight="Bold" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Button HorizontalAlignment="Left"
Height="20"
Width="100"
Command="{Binding Submit}"
CommandParameter="{Binding SelectedItems, ElementName=myListView}">Submit</Button>
</StackPanel>
</Grid>

If the view's data context is bound to the view then remove the DataContext from the ListView.
You could remove the item template and instead use a GridView like:
<ListView.View>
<GridView >
<GridViewColumn Header="Selected" >
<GridViewColumn.CellTemplate>
<DataTemplate>
<CheckBox IsChecked="{Binding IsSelected}" Content="{Binding Name}" />
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
</GridView>
</ListView.View>
Since the ItemSource is an Observable collection, there are several options to monitor changes in the checkboxes:
Add an event handler to the item changed event of the collection and then you can add the Name or the collection index to a local collection. e.g Examples[e.CollectionIndex].Name
Alternatively iterate over the observable collection and select those Examples where Selected = "true"

WPF Tabcontrol (TabItem Content is not appearing)

I implemented a TabControl with Closable TabItems in my App. For this, I am using a Collection which I fill with the SubMenuItems of MenuItem "Öffne", which are bound to ICommands in the MainViewModel.
So if I click on MenuItem "Open Tab1", then the header of Tab 1 is created, but I can not see any content. The content of the TabItem is shown AFTER I click on the Header of the TabItem. But I want it to be shown directly when the TabItem is "created" without any need of clicking on the header. Closing the TabItems from the "X" button works fine.
I looked at a couple of examples and tried a ContentTemplate, but it didn't work (Maybe I made something wrong?).
I Hope you can tell me what i have done wrong or show me a good example.
Thanks in advance!
Here are my code snippets:
MainWindow.XAML:
<Window.Resources>
<vm:MainViewModel x:Key="viewModel"/>
</Window.Resources>
<TabControl Background="#FFE5E5E5" ItemsSource="{Binding TabControlViews}" SelectedItem="{Binding CurrentTabItem}" Margin="0,21,0,0">
<TabControl.ItemTemplate>
<DataTemplate>
<DockPanel Width="120">
<TextBlock Text="{Binding Header}"/>
<Button
Command="{Binding ParameterizedCommand, Source={StaticResource viewModel}}"
CommandParameter="{Binding Header, RelativeSource={RelativeSource AncestorType={x:Type TabItem}}}"
Content="X"
Cursor="Hand"
DockPanel.Dock="Right"
Focusable="False"
FontFamily="Courier"
FontSize="9"
FontWeight="Bold"
Margin="0,1,0,0"
Padding="0"
VerticalContentAlignment="Bottom"
Width="16" Height="16" />
<ContentPresenter
Content="{Binding Path=DisplayName}"
VerticalAlignment="Center" />
</DockPanel>
</DataTemplate>
</TabControl.ItemTemplate>
<!--<TabControl.ContentTemplate>
<DataTemplate>
</DataTemplate>
</TabControl.ContentTemplate>-->
<TabControl.Resources>
<DataTemplate x:Name="test" DataType="{x:Type vm:MenueVM}">
<cu:MenueSearch/>
</DataTemplate>
<DataTemplate DataType="{x:Type vm:FieldPointsVM}">
<cu:FieldPointsSearch/>
</DataTemplate>
<DataTemplate DataType="{x:Type vm:DataTransferVM}">
<cu:DataTransfer/>
</DataTemplate>
</TabControl.Resources>
</TabControl>
MainWindow.cs:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
var vm = (MainViewModel)Resources["viewModel"];
this.DataContext = vm;
}
}
MainViewModel.cs:
public MainViewModel()
{
TabControlViews = new ObservableCollection<BaseViewModel>();
_menueVM = new MenueVM("Menüpunkte", "Menue");
_fieldVM = new FieldPointsVM("Feldpunkte", "FieldPoint");
_dataVM = new DataTransferVM("DatenTransfer", "DataTransfer");
ParameterizedCommand = new RelayCommand(DoParameterizedCommand);
}
private void DoParameterizedCommand(object parameter)
{
if (parameter.ToString() == "App.ViewModel.MenueVM")
{
TabControlViews.Remove(_menueVM);
}
else if (parameter.ToString() == "App.ViewModel.FieldPointsVM")
{
TabControlViews.Remove(_fieldVM);
}
else if (parameter.ToString() == "App.ViewModel.DataTransfer")
{
TabControlViews.Remove(_dataVM);
}
}
private ICommand _parameterizedCommand;
public ICommand ParameterizedCommand
{
get
{
return _parameterizedCommand;
}
set
{
_parameterizedCommand = value;
}
}
private TabItem _propCurrentTabItem;
public TabItem CurrentTabItem
{
get
{
return _propCurrentTabItem;
}
set
{
_propCurrentTabItem = value;
}
}
private ObservableCollection<BaseViewModel> _TabControlViews = new ObservableCollection<BaseViewModel>();
public ObservableCollection<BaseViewModel> TabControlViews
{
get
{
return _TabControlViews;
}
set
{
_TabControlViews = value;
OnPropertyChanged();
}
}
public ICommand OpenMenupunkteCommand
{
get
{
return new BaseCommand(OpenMenuPunkte);
}
}
public ICommand OpenFeldpunkteCommand
{
get
{
return new BaseCommand(OpenFeldpunkte);
}
}
public ICommand OpenDataTransferCommand
{
get
{
return new BaseCommand(OpenDataTransfer);
}
}
private void OpenMenuPunkte()
{
if (!TabControlViews.Contains(_menueVM))
{
TabControlViews.Add(_menueVM);
}
}
private void OpenFeldpunkte()
{
if (!TabControlViews.Contains(_fieldVM))
{
TabControlViews.Add(_fieldVM);
}
}
private void OpenDataTransfer()
{
if (!TabControlViews.Contains(_dataVM))
{
TabControlViews.Add(_dataVM);
}
}
MenueVM.cs
public class MenueVM : BaseViewModel
{
public MenueVM()
{
//Here are some actions done for Data, but I think they are unimportant for this question
}
public MenueVM(string header, string content)
{
Header = header;
Content = content;
}
private string _header;
public string Header
{
get
{
return _header;
}
set
{
_header = value;
}
}

Still time to post an answer?
Try this :
XAML:
<TabControl ItemsSource="{Binding....}" IsSynchronizedWithCurrentItem="True">
<!-- style, template, ... -->
</TabControl>
CS:
//Adding your viewModel to your ObservableCollection<> TabControlViews
TabControlViews.Add(_viewModelToAdd);
ICollectionView collectionView = CollectionViewSource.GetDefaultView(TabControlViews);
if (collectionView != null)
{
collectionView.MoveCurrentTo(_viewModelToAdd);
//And this is because you don't want your tabItem to be selected :
collectionView.MoveCurrentToPrevious();
}
Found in the downloadable DemoMVVMApp here : https://msdn.microsoft.com/en-us/magazine/dd419663.aspx#id0090030
I've also spent a huge amount of time to solve this problem... ;-)

The problem is that your tab is been created, but it´s not been selected. So, in addition to calling
TabControlViews.Add(_dataVM)
, you should also update your CurrentTabItem
CurrentTabItem = _dataVM;
and bind your TabControl SelectedItem property to your CurrentTabItem, like this:
<TabControl ItemsSource="{Binding TabControlViews}" SelectedItem="{Binding CurrentTabItem}">
Also, if you remove a TabItem and want to get back to the last one, you have to call
CurrentTabItem = TabControlViews.LastOrDefault();

setting the DataContex correctly

im building a UserControl MyUserControl that has his own ViewModel MyUserControlViewModel. MyUserControl contains 6 VehicleSelectionBlock (V1, ... V6). VehicleSelectionBlock is a UserControl i've made. it has 3 RadioButton: car, train, bus; all are of enum type Vehicle and of the same GroupName VehicleGroup.
my goal is to represent each of MyUserControl's VehicleSelectionBlocks in MyUserControlViewModel.
to make my self clear: in MyUserControlViewModel i want to be able to know&change what RadioButton is checked in every one of the 6 VehicleSelectionBlock. i think my main problem is not the converter but rather the DataContex - i'm not sure how to set it correctly for each of the controllers.
iv'e tried Binding (which is the obvious solution). i tried reading here, here , and here. unfortunately neither one helped my acheive my goal.
my code is below - im kinda new to wpf and data binding in generally. i've read almost every chapter in this tutorial but still lost sometimes.
please help me get through this and understand better the DataContex concept.
ty
MyUserContlor.xaml.cs:
namespace Project01
{
/// <summary>
/// Interaction logic for MyUserContlor.xaml
/// </summary>
public partial class MyUserContlor : UserControl
{
public MyUserContlorViewModel ViewModel { get; set; }
public MyUserContlor()
{
ViewModel = new MyUserContlorViewModel();
InitializeComponent();
this.DataContext = ViewModel;
}
private void BtnImReady_OnClick(object sender, RoutedEventArgs e)
{
//this code is irrelevant to the question
throw NotImplementedException();
}
}
}
MyUserContlor.xaml:
<UserControl x:Class="Project01.MyUserContlor"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:loc="clr-namespace:Project01"
mc:Ignorable="d"
HorizontalContentAlignment="Center" VerticalContentAlignment="Center">
<Viewbox Stretch="Uniform">
<StackPanel>
<loc:VehicleSelectionBlock Name="V1"/>
<loc:VehicleSelectionBlock Name="V2"/>
<loc:VehicleSelectionBlock Name="V3"/>
<loc:VehicleSelectionBlock Name="V4"/>
<loc:VehicleSelectionBlock Name="V5"/>
<loc:VehicleSelectionBlock Name="V6"/>
<Button x:Name="BtnImReady" Click="BtnImReady_OnClick">Im Ready!</Button>
</StackPanel>
</Viewbox>
</UserControl>
MyUserContlorViewModel.cs:
namespace Project01
{
public class MyUserContlorViewModel : INotifyPropertyChanged
{
public MyUserContlorViewModel()
{
VehicleArr = new MyViewModel_Vehicle[6];
PropertyChanged+=MyUserControlViewModel_PropertyChanged;
}
public MyViewModel_Vehicle[] VehicleArr;
public event PropertyChangedEventHandler PropertyChanged;
public PropertyChangedEventHandler GetPropertyChangedEventHandler() { return PropertyChanged; }
private void MyUserControlViewModel_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
//might be useful
throw NotImplementedException();
}
}
//this class should represent a VehicleSelectionBlock
public class MyViewModel_Vehicle
{
public Vehicle VehicleSelected {get; set;}
MyViewModel_Vehicle(){}
MyViewModel_Vehicle(Vehicle v){ VehicleSelected = v;}
}
}
VehicleSelectionBlock.xaml:
<UserControl x:Class="Project01.VehicleSelectionBlock"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:Project01"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid DataContext="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}">
<Border VerticalAlignment="Center" HorizontalAlignment="Center" Background="GhostWhite"
BorderBrush="Gainsboro" BorderThickness="1">
<StackPanel >
<Label Content="{Binding Name}"
FontWeight="Bold" HorizontalContentAlignment="Center"></Label>
<RadioButton GroupName="VehicleGroup" >car</RadioButton>
<RadioButton GroupName="VehicleGroup">train</RadioButton>
<RadioButton GroupName="VehicleGroup" IsChecked="True">bus</RadioButton>
</StackPanel>
</Border>
</Grid>
</UserControl>
VehicleSelectionBlock.xaml.cs:
namespace Project01
{
/// <summary>
/// Interaction logic for VehicleSelectionBlock.xaml
/// </summary>
public partial class VehicleSelectionBlock : UserControl
{
public VehicleSelectionBlock()
{
InitializeComponent();
}
public VehicleSelectionBlock(String name)
{
name = Name;
InitializeComponent();
}
public static readonly DependencyProperty NameProperty = DependencyProperty.Register(
"Name", typeof (String), typeof (VehicleSelectionBlock), new PropertyMetadata(default(String)));
public String Name
{
get { return (String) GetValue(NameProperty); }
set { SetValue(NameProperty, value); }
}
}
public enum Vehicle { Car, Train, Bus}
}

here is a quick solution. keep in mind that the code needs to change if you want to add more values to your Vehicle enum.
the MyUserControlViewModel.cs file
public class MyUserControlViewModel
{
public MyUserControlViewModel()
{
VehicleArr = new VehicleViewModel[6];
for (int i = 0; i < 6;i++ )
VehicleArr[i] = new VehicleViewModel();
}
public VehicleViewModel[] VehicleArr { get; set; }
}
this will expose your 6 items. They could be more. As a result they will be displayed in an ItemsControl, as you will see later.
public class VehicleViewModel:ViewModelBase
{
private bool isCar, isTrain, isBus;
public bool IsCar
{
get { return isCar; }
set
{
if (isCar == value) return;
isCar = value;
OnChanged("IsCar");
}
}
public bool IsTrain
{
get { return isTrain; }
set
{
if (isTrain == value) return;
isTrain = value;
OnChanged("IsTrain");
}
}
public bool IsBus
{
get { return isBus; }
set
{
if (isBus == value) return;
isBus = value;
OnChanged("IsBus");
}
}
}
instances of VehicleViewModel will contain your radio selection using 3 bool properties. this is the solution disadvantage. If you want more values you'll have to add more properties. you can see this inherits ViewModelBase. ViewModelBase just implements INPC so i'm not going to put it here. ViewModelBase also exposes the OnChange method that triggers the INPC event.
displaying the list can be done in your MyUserControl by using an ItemsControl like below.
<ItemsControl ItemsSource="{Binding VehicleArr}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<loc:VehicleControl />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
each item is also a UserControl. The VehicleControl user control is just a StackPanel that displays the RadioButons. This can be seen below.
<StackPanel Orientation="Horizontal">
<RadioButton Content="Car" Margin="5" VerticalAlignment="Center" IsChecked="{Binding Path=IsCar, Mode=TwoWay}"/>
<RadioButton Content="Train" Margin="5" VerticalAlignment="Center" IsChecked="{Binding Path=IsTrain, Mode=TwoWay}"/>
<RadioButton Content="Bus" Margin="5" VerticalAlignment="Center" IsChecked="{Binding Path=IsBus, Mode=TwoWay}"/>
</StackPanel>
please notice that each RadioButton is bound to one of the 3 properties in the VehicleViewModel instance.
Once you press your button you should have all the selections recorded. if you want you could have a function that returns an enum value by analysing the 3 bool properties if that is what you need.
the best solution will be to get rid of the radio buttons and replace them with combo boxes. in this way you can change the enum members and everything will continue to work without changing anything else. this might look as below.
public class VehicleViewModel:ViewModelBase
{
private Vehicle selOption;
private readonly Vehicle[] options;
public VehicleViewModel()
{
this.options = (Vehicle[])Enum.GetValues(typeof(Vehicle));
}
public Vehicle[] Options { get { return options; } }
public Vehicle SelectedOption
{
get { return selOption; }
set
{
if (selOption == value) return;
selOption = value;
OnChanged("SelectedOption");
}
}
}
and for the view:
<ItemsControl ItemsSource="{Binding VehicleArr}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<ComboBox ItemsSource="{Binding Options}"
SelectedItem="{Binding SelectedOption, Mode=TwoWay}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>

You can do directly in the code-behind of your control (in the default constructor)
public VehicleSelectionBlock()
{
InitializeComponent();
this.DataContext = new MyUserContlorViewModel ();
}
You can also do that in XAML (http://msdn.microsoft.com/en-us/library/ms746695(v=vs.110).aspx) declaration, as you wish.

How could I add combox and other items in a listbox?

I need to create an UI which allows me to select entries from one list box and add it to another listbox at the run time. Now, the listbox1 may contain combo box and checkbox as the items.
For example, if I add a combo box labelled Quarter with values "Q1, Q2, Q3, Q4" as an item in listbox1 and select the entry Q1 in it, and click on the "Add" button, it should be added to listbox2. Vice versa should also be possible. This should be possible at the run time. How could I add combo box and checkbox as an item to the listbox? Also, please suggest if for the add-remove buttons, the code I've is correct.
private void MoveListBoxItems(ListBox source, ListBox destination)
{
ListBox.SelectedObjectCollection sourceItems = source.SelectedItems;
foreach (var item in sourceItems)
{
destination.Items.Add(item);
}
while (source.SelectedItems.Count > 0)
{
source.Items.Remove(source.SelectedItems[0]);
}
}
private void button1_Click(object sender, EventArgs e)
{
MoveListBoxItems(listBox1, listBox2);
}
private void button2_Click(object sender, EventArgs e)
{
MoveListBoxItems(listBox2, listBox1);
}

This is a WPF solution to your need. I am posting it because you told me it could be useful for you. It largely surpasses anything you can ever hope to achieve in winforms, which is a very limited and outdated technology.
This is how it looks in my screen:
I am using some simple ViewModels to represent the data:
ListItemViewModel (the "base" one):
public class ListItemViewModel: ViewModelBase
{
private string _displayName;
public string DisplayName
{
get { return _displayName; }
set
{
_displayName = value;
NotifyPropertyChange(() => DisplayName);
}
}
}
BoolListItemViewModel (for CheckBoxes):
public class BoolListItemViewModel: ListItemViewModel
{
private bool _value;
public bool Value
{
get { return _value; }
set
{
_value = value;
NotifyPropertyChanged(() => Value);
}
}
}
SelectableListItemViewModel (for ComboBoxes):
public class SelectableListItemViewModel: ListItemViewModel
{
private ObservableCollection<ListItemViewModel> _itemsSource;
public ObservableCollection<ListItemViewModel> ItemsSource
{
get { return _itemsSource ?? (_itemsSource = new ObservableCollection<ListItemViewModel>()); }
}
private ListItemViewModel _selectedItem;
public ListItemViewModel SelectedItem
{
get { return _selectedItem; }
set
{
_selectedItem = value;
NotifyPropertyChange(() => SelectedItem);
}
}
}
This is the "Main" ViewModel, which holds the 2 lists and the Commands (the Button actions)
public class ListBoxSampleViewModel: ViewModelBase
{
private ObservableCollection<ListItemViewModel> _leftItems;
public ObservableCollection<ListItemViewModel> LeftItems
{
get { return _leftItems ?? (_leftItems = new ObservableCollection<ListItemViewModel>()); }
}
private ObservableCollection<ListItemViewModel> _rightItems;
public ObservableCollection<ListItemViewModel> RightItems
{
get { return _rightItems ?? (_rightItems = new ObservableCollection<ListItemViewModel>()); }
}
private DelegateCommand<ListItemViewModel> _moveToRightCommand;
public DelegateCommand<ListItemViewModel> MoveToRightCommand
{
get { return _moveToRightCommand ?? (_moveToRightCommand = new DelegateCommand<ListItemViewModel>(MoveToRight)); }
}
private void MoveToRight(ListItemViewModel item)
{
if (item != null)
{
LeftItems.Remove(item);
RightItems.Add(item);
}
}
private DelegateCommand<ListItemViewModel> _moveToLeftCommand;
public DelegateCommand<ListItemViewModel> MoveToLeftCommand
{
get { return _moveToLeftCommand ?? (_moveToLeftCommand = new DelegateCommand<ListItemViewModel>(MoveToLeft)); }
}
private void MoveToLeft(ListItemViewModel item)
{
if (item != null)
{
RightItems.Remove(item);
LeftItems.Add(item);
}
}
}
This is the entire XAML for the Window:
<Window x:Class="WpfApplication4.Window14"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication4"
Title="Window14" Height="300" Width="300">
<Window.Resources>
<DataTemplate DataType="{x:Type local:ListItemViewModel}">
<TextBlock Text="{Binding DisplayName}"/>
</DataTemplate>
<DataTemplate DataType="{x:Type local:BoolListItemViewModel}">
<CheckBox Content="{Binding DisplayName}" IsChecked="{Binding Value}" HorizontalAlignment="Left"/>
</DataTemplate>
<DataTemplate DataType="{x:Type local:SelectableListItemViewModel}">
<ComboBox ItemsSource="{Binding ItemsSource}" SelectedItem="{Binding SelectedItem}"
HorizontalAlignment="Stretch" MinWidth="100"/>
</DataTemplate>
</Window.Resources>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition Width="100"/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<ListBox ItemsSource="{Binding LeftItems}"
x:Name="LeftList"/>
<StackPanel Grid.Column="1" VerticalAlignment="Center">
<Button Content="Move to Right"
Command="{Binding MoveToRightCommand}"
CommandParameter="{Binding SelectedItem,ElementName=LeftList}"/>
<Button Content="Move to Left"
Command="{Binding MoveToLeftCommand}"
CommandParameter="{Binding SelectedItem,ElementName=RightList}"/>
</StackPanel>
<ListBox ItemsSource="{Binding RightItems}"
Grid.Column="2" x:Name="RightList"/>
</Grid>
</Window>
and finally, this is the Window Code-behind, which only initializes the ViewModel with some items:
public partial class Window14 : Window
{
public Window14()
{
InitializeComponent();
DataContext = new ListBoxSampleViewModel()
{
LeftItems =
{
new ListItemViewModel(){DisplayName = "Item1"},
new BoolListItemViewModel() {DisplayName = "Check Item 2", Value = true},
new SelectableListItemViewModel()
{
ItemsSource =
{
new ListItemViewModel() {DisplayName = "Combo Item 1"},
new BoolListItemViewModel() {DisplayName = "Check inside Combo"},
new SelectableListItemViewModel()
{
ItemsSource =
{
new ListItemViewModel() {DisplayName = "Wow, this is awesome"},
new BoolListItemViewModel() {DisplayName = "Another CheckBox"}
}
}
}
}
}
};
}
}
At first glance, this might seem like a LOT of code... but if you take 2 seconds to analyze it... Its just "simple, simple properties and INotifyPropertyChanged. That's how you program in WPF.
I'm talking about a completely different paradigm from what you might be used to in winforms, but it's really worth the effort of learning it. Notice that nowhere in my code I am interacting with UI elements. I just create the ViewModel structure and let the WPF Binding System to take care of generating the UI for me, using the provided DataTemplates.
I'm using the ViewModelBase from MVVM Light and the DelegateCommand from WPFTutorial.net. You can copy and paste my code in a File -> New Project -> WPF Application and see the results for yourself (you will also need these 2 classes from the links above)
If you need to integrate this in an existing winforms application, you will need the ElementHost

Develop Reference

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

ListView strange behavoiur with blend trigger - c#

Related

WPF - How to trigger an event for each element(button) in a ListBox?

Returning bound checkbox values using MVVM in a WPF form

WPF Tabcontrol (TabItem Content is not appearing)

setting the DataContex correctly

How could I add combox and other items in a listbox?

Categories

Resources