I made an application with Windows template studio, As MVVM,
The Problem exists in ShellPage which contains some Controls, 2 Image , TextBlock, the NavigationView, and of course the Frame that holds all other pages.
The code here is for the TextBlock, but the Problem same for the 2 Image controls also.
in ShellPage.xaml:
xmlns:myControls="using:Numbers_to_Text.MyControls"
d:DataContext="{d:DesignInstance Type=viewmodels:ShellViewModel}"
Height="650" Width="1000" MaxHeight="650" MaxWidth="1000" MinHeight="650" MinWidth="1000"
mc:Ignorable="d" Background="{x:Null}">
<Page.Resources>
<helpers:AppSettings x:Key="AppSettings" />
</Page.Resources>
<TextBlock x:FieldModifier="public" x:Name="PageTitle" Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="1"
Canvas.ZIndex="2" TextAlignment="DetectFromContent" HorizontalTextAlignment="DetectFromContent"
VerticalAlignment="Bottom" FontWeight="Bold" Text="{Binding ChangeTitle, Mode=TwoWay}"/>
in ShellPage.xaml.cs:
public ShellPage()
{
InitializeComponent();
DataContext = ViewModel;
ViewModel.Initialize(shellFrame, navigationView, KeyboardAccelerators);
}
and in ShellViewModel.cs
private void OnItemInvoked(WinUI.NavigationViewItemInvokedEventArgs args)
{
if (args.IsSettingsInvoked)
{
NavigationService.Navigate(typeof(SettingsPage), null, args.RecommendedNavigationTransitionInfo);
ChangeTitle = "Settings";
}
else
{
var selectedItem = args.InvokedItemContainer as WinUI.NavigationViewItem;
var pageType = selectedItem?.GetValue(NavHelper.NavigateToProperty) as Type;
if (pageType != null)
{
NavigationService.Navigate(pageType, null, args.RecommendedNavigationTransitionInfo);
ChangeTitle= pageType.Name;
}
}
}
private string _changeTitle;
public string ChangeTitle
{
get { return _changeTitle= GetTitle(); }
set
{
_changeTitle = value;
RaisePropertyChanged(nameof(ChangeTitle));
}
}
private static string GetTitle()
{
try
{
var resourceLoader = Windows.ApplicationModel.Resources.ResourceLoader.GetForCurrentView();
return NavigationService.Frame.Content != null
? resourceLoader.GetString(NavigationService.Frame.Content.GetType().Name)
: "Error Page Title";
}
catch
{
return "Welcome to Main Page";
}
}
public event PropertyChangedEventHandler propertyChanged;
public void NotifyPropertyChanged([CallerMemberName] string propName = "")
{
propertyChanged?.Invoke(this, new PropertyChangedEventArgs(propName));
}
public void RaisePropertyChanged([CallerMemberName] string propertyName = "")
{
this.propertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
Why ChangeTitle not changing when navigation occured?
I used breakPoints to trace the ChangeTitle, I implemented PropertyChangedEventHandler inside the shellViewModel instead to make sure that the property setter is call the NotifyPropertyChanged, with no luck.
Related
I am attempting to prevent my application from deleting a view and then creating a new one each time it's navigated around. I have a dashboard that will run a test program, if I select the settings view, then back to the dashboard, it has deleted the running test and initialized a new view. I need to keep the same view instance alive so that the test can continue to run while the user navigates to the settings view and back again but I cant exactly figure out how to successfully do that. I have attempted making the instance static but that doesn't seem to make a difference.
MainViewModel
class MainVM : ViewModelBase
{
private object _currentView;
public object CurrentView
{
get { return _currentView; }
set { _currentView = value; OnPropertyChanged(); }
}
public ICommand DashboardCommand { get; set; }
public ICommand SettingsCommand { get; set; }
public static DashboardVM DashboardInstance { get; } = new DashboardVM();
public static SettingsVM SettingsInstance { get; } = new SettingsVM();
private void Dashboard(object obj) => CurrentView = DashboardInstance;
private void Settings(object obj) => CurrentView = SettingsInstance;
public MainVM()
{
DashboardCommand = new RelayCommand(Dashboard);
SettingsCommand = new RelayCommand(Settings);
// Startup Page
CurrentView = DashboardInstance;
}
}
ViewModelBase
public partial class ViewModelBase : ObservableObject, INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged([CallerMemberName] string propName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propName));
}
public void NotifyPropertyChanged(string propName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propName));
}
}
}
MainView - Navigation
<!-- Navigation Panel -->
<Grid HorizontalAlignment="Left" Width="76">
<Border Background="#3D5A8A" CornerRadius="10,0,0,10" />
<StackPanel Height="1200" Width="76">
<!-- Dashboard Button -->
<nav:Button Style="{StaticResource NavButton_Style}"
Command="{Binding DashboardCommand}"
IsChecked="True">
<Grid>
<Image Source="Images/dash_black_50.png"
Style="{StaticResource NavImage_Style}" />
<TextBlock Text="Dashboard"
Style="{StaticResource NavText_Style}" />
</Grid>
</nav:Button>
<!-- Settings Button -->
<nav:Button Style="{StaticResource NavButton_Style}"
Command="{Binding SettingsCommand}">
<Grid>
<Image Source="Images/gear_black_50.png"
Style="{StaticResource NavImage_Style}" />
<TextBlock Text="Settings"
Style="{StaticResource NavText_Style}" />
</Grid>
</nav:Button>
</StackPanel>
</Grid>
DashboardVM
class DashboardVM : ViewModelBase
{
enum TestItemStatus
{
Reset,
Queued,
InProgress,
Pass,
Fail
}
private readonly PageModel _pageModel;
private string _StartButtonText,
_WaveRelayEthernetText;
private bool isTestRunning;
public DashboardVM()
{
_pageModel = new PageModel();
_StartButtonText = "Start Test";
_WaveRelayEthernetText = string.Empty;
StartButtonCommand = new RelayCommand(o => StartButtonClick("StartButton"));
}
#region Text Handlers
public string StartButtonText
{
get { return _StartButtonText; }
set { _StartButtonText = value; NotifyPropertyChanged("StartButtonText"); }
}
public string WaveRelayEthernetText
{
get { return _WaveRelayEthernetText; }
set { _WaveRelayEthernetText = value; NotifyPropertyChanged("WaveRelayEthernetText"); }
}
#endregion
private bool TestRunning
{
get { return isTestRunning; }
set { isTestRunning = value;
if (isTestRunning) { StartButtonText = "Stop Test"; }
else { StartButtonText = "Start Test";
ResetTestItems();
}
NotifyPropertyChanged("TestRunning");
}
}
public ICommand StartButtonCommand { get; set; }
private void StartButtonClick(object sender)
{
if(TestRunning)
{
TestRunning = false;
}
else
{
SetTestItemsToQueued();
MessageBox.Show("Please plug in Tube 1");
// Start program.
TestRunning = true;
WaveRelayEthernetText = TestItemStatusEnumToString(TestItemStatus.InProgress);
}
}
private string TestItemStatusEnumToString(TestItemStatus temp)
{
if (temp == TestItemStatus.Reset) { return string.Empty; }
else if (temp == TestItemStatus.Queued) { return "Queued"; }
else if (temp == TestItemStatus.InProgress) { return "In Progress"; }
else if (temp == TestItemStatus.Pass) { return "Pass"; }
else if (temp == TestItemStatus.Fail) { return "Fail"; }
else { return string.Empty; }
}
private void SetTestItemsToQueued()
{
WaveRelayEthernetText = TestItemStatusEnumToString(TestItemStatus.Queued);
}
private void ResetTestItems()
{
WaveRelayEthernetText = TestItemStatusEnumToString(TestItemStatus.Reset);
}
}
Image for reference:
My Issue was in the App.xaml, I link a DataTemplate file like this:
<ResourceDictionary Source="Utilities/DataTemplate.xaml" />
Inside the data template, I had this code that linked the views to the view models.
<ResourceDictionary [...]">
<DataTemplate DataType="{x:Type vm:DashboardVM}">
<view:Dashboard />
</DataTemplate>
<DataTemplate DataType="{x:Type vm:SettingsVM}">
<view:Settings />
</DataTemplate>
</ResourceDictionary>
I changed that code to link the two to this:
<ResourceDictionary [...]>
<view:Dashboard x:Key="DashboardViewKey"/>
<view:Settings x:Key="SettingsViewKey"/>
<DataTemplate DataType="{x:Type vm:DashboardVM}">
<ContentControl Content="{StaticResource DashboardViewKey}" />
</DataTemplate>
<DataTemplate DataType="{x:Type vm:SettingsVM}">
<ContentControl Content="{StaticResource SettingsViewKey}" />
</DataTemplate>
</ResourceDictionary>
I am now receiveing the expected behavior of being able to navigate without the Dashboard constructor being called, thus the view does not destory and recreate.
I hope someone else finds this useful.
I am currently developing a hamburger style menu in WPF. In this menu, there are some categories that each have an icon. When the menu is collapsed you can still see those icons. When you expand the menu, there should appear text next to it. My idea was to just set their visibility to Visible as soon as the menu opens but I've had a lot of trouble realizing this. Right now I'm trying to change their visibility by binding them to a property.
XAML:
<ListView x:Name="menuItemsListView" ScrollViewer.HorizontalScrollBarVisibility="Disabled">
<ListViewItem>
<StackPanel Orientation="Horizontal">
<Image x:Uid="Test" Name="InhoudImage" Source="Images/noimage.png" Height="30" Width="auto" VerticalAlignment="Center" Margin="3,0,0,0"></Image>
<TextBlock x:Uid="Test" Text="{Binding Path=TextboxVisibility}" Visibility="{Binding Path=TextboxVisibility}" VerticalAlignment="Center"></TextBlock>
</StackPanel>
</ListViewItem>
</ListView>
C# CS Class:
using System.Windows;
using System.Windows.Controls;
namespace APP
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
private bool menuOpen = false;
private int closedMenuWidth = 50;
private int openMenuWidth = 210;
private string textboxVisibility;
public string TextboxVisibility
{
get { return textboxVisibility; }
set { textboxVisibility = value; }
}
public MainWindow()
{
InitializeComponent();
this.DataContext = this;
this.TextboxVisibility = "Hidden";
}
private void MenuButton_Click(object sender, RoutedEventArgs e)
{
if (menuOpen)
{
menuGrid.Width = closedMenuWidth;
menuOpen = false;
this.TextboxVisibility = "Hidden";
}
else
{
menuGrid.Width = openMenuWidth;
menuOpen = true;
this.TextboxVisibility = "Visible";
//foreach (ListViewItem item in menuItemsListView.Items)
//{
// item.
// if (item.Uid == "Test")
// {
// item.Visibility = Visibility.Visible;
// }
//}
}
}
}
}
When I change the value within the MainWindow function, it does have an effect on it when it first starts. But the other times I try to change it, which is at runtime, nothing happens. I have tried all sorts of things with booleans and binding the actual Visibility type but nothing worked.
You should implemente INotifyPropertyChanged on your MainWindow class like this:
public partial class MainWindow: Window,INotifyPropertyChanged {
private string textboxVisibility;
public string TextboxVisibility {
get {
return textboxVisibility;
}
set {
textboxVisibility = value;
OnPropertyChanged();
}
}
//The rest of your code goes here
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null) {
PropertyChanged ? .Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
What OnPropertyChanged method does is, whenever the value is setted, it notifies the view and refreshes it.
This will solve the problem but isn't the right way to use MVVM.
The way you should do this is to change the visibility property of the TextBox instead of binding the visibility property to a value:
First you have to add a name to the TextBlock you want to hide:
<ListView x:Name="menuItemsListView" ScrollViewer.HorizontalScrollBarVisibility="Disabled">
<ListViewItem>
<StackPanel Orientation="Horizontal">
<Image x:Uid="Test" Name="InhoudImage" Source="Images/noimage.png" Height="30" Width="auto" VerticalAlignment="Center" Margin="3,0,0,0"></Image>
<TextBlock Name="textblock" x:Uid="Test" Text="{Binding Path=TextboxVisibility}" Visibility="{Binding Path=TextboxVisibility}" VerticalAlignment="Center"></TextBlock>
</StackPanel>
</ListViewItem>
</ListView>
And then you change the visibility in the code
private void MenuButton_Click(object sender, RoutedEventArgs e) {
if (menuOpen) {
menuGrid.Width = closedMenuWidth;
menuOpen = false;
textblock.Visibility = System.Windows.Visibility.Hidden;
}
else {
menuGrid.Width = openMenuWidth;
menuOpen = true;
textblock.Visibility = System.Windows.Visibility.Visible;
//foreach (ListViewItem item in menuItemsListView.Items)
//{
// item.
// if (item.Uid == "Test")
// {
// item.Visibility = Visibility.Visible;
// }
//}
}
}
If you want to implement MVVM the right way you have to create a ViewModel class and add it as Data Context to your view:
<Window.DataContext>
<local:MainWindowViewModel/>
</Window.DataContext>
And then on you MainWindowViewModel is where you change the property:
public class MainWindowViewModel: INotifyPropertyChanged {
private string textboxVisibility;
public string TextboxVisibility {
get {
return textboxVisibility;
}
set {
textboxVisibility = value;
OnPropertyChanged();
}
}
//The rest of your code goes here
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null) {
PropertyChanged ? .Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
XAML:
<ListBox x:Name="MyTitleBox" ItemsSource="{Binding}"/>
<ListBox x:Name="MyInfoBox" ItemsSource="{Binding}"/>
In C#:
MyTitleBox.ItemsSource = new List<string>(new string[] {"ID:", "Info:", "More Info:"});
MyInfoBox.ItemsSource = new ObservableCollection<string>(MyMainInfo.ToString().Split(',').ToList<string>());
I currently have 2 list boxes next to each other because I need to handle their ItemsSource programmatically.
I know there must be a better way to merge the two. Essentially the list box "on the left" is the titles like ID: and the list box "on the right" is the information.
I thought I could do something like MyTitleBox.Columns.Add like I've seen but it won't let me do .Columns. I'm using .NET 4.
Here is an example with a more MVVM approach:
Domain (The type of items you want to put in your list):
public class Movie : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private string _title;
public string Title
{
get { return _title; }
set
{
if (_title != value)
{
_title = value;
RaisePropertyChanged("Title");
}
}
}
private string _info;
public string Info
{
get { return _info; }
set
{
if (_info != value)
{
_info = value;
RaisePropertyChanged("Info");
}
}
}
protected void RaisePropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
ViewModel:
public class MyViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private ObservableCollection<Movie> _movies;
/// <summary>
/// Collection of movies.
/// </summary>
public ObservableCollection<Movie> Movies
{
get { return _movies; }
set
{
if (_movies != value)
{
_movies = value;
RaisePropertyChanged("Movies");
}
}
}
/// <summary>
/// Constructor
/// </summary>
public MyViewModel()
{
Movies = new ObservableCollection<Movie>();
Movies.Add(new Movie() { Title = "Gravity", Info = "Gravity is about..." });
Movies.Add(new Movie() { Title = "Avatar", Info = "Avatar is about..." });
}
protected void RaisePropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
XAML:
<Window x:Class="StackOverflow.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:StackOverflow"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<ListBox ItemsSource="{Binding Movies}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock>
<Run Text="{Binding Title}" /><Run Text=" - " /><Run Text="{Binding Info}" />
</TextBlock>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<Button Grid.Row="1" Content="Click To Change Info" Margin="5" Click="Button_Click" />
</Grid>
</Window>
Code Behind:
public partial class MainWindow : Window
{
public MyViewModel ViewModel { get; private set; }
public MainWindow()
{
InitializeComponent();
ViewModel = new MyViewModel();
DataContext = ViewModel;
}
private void Button_Click(object sender, RoutedEventArgs e)
{
Movie movie = ViewModel.Movies.FirstOrDefault();
if (movie != null)
{
movie.Info = "This is the new information";
}
}
}
Implementing INotifyPropertyChanged allows the code to notify the UI when something changes.
If you test this code out you will see that clicking the button updates the info for the first movie, and this changed is immediately reflected in the UI. (Normally you would use a convention like Commands for handling the button click, but for simplicity I did it this way)
Let me know if you have any questions.
I'm trying to create a simple WPF Application using data binding.
The code seems fine, but my view is not updating when I'm updating my property.
Here's my XAML:
<Window x:Class="Calculator.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:calculator="clr-namespace:Calculator"
Title="MainWindow" Height="350" Width="525"
Name="MainWindowName">
<Grid>
<Label Name="MyLabel" Background="LightGray" FontSize="17pt" HorizontalContentAlignment="Right" Margin="10,10,10,0" VerticalAlignment="Top" Height="40"
Content="{Binding Path=CalculatorOutput, UpdateSourceTrigger=PropertyChanged}"/>
</Grid>
</Window>
Here's my code-behind:
namespace Calculator
{
public partial class MainWindow
{
public MainWindow()
{
DataContext = new CalculatorViewModel();
InitializeComponent();
}
}
}
Here's my view-model
namespace Calculator
{
public class CalculatorViewModel : INotifyPropertyChanged
{
private String _calculatorOutput;
private String CalculatorOutput
{
set
{
_calculatorOutput = value;
NotifyPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
var handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
I'm can't see what I am missing here?? o.O
CalculatorOutput has no getter. How should the View get the value? The Property has to be public as well.
public String CalculatorOutput
{
get { return _calculatorOutput; }
set
{
_calculatorOutput = value;
NotifyPropertyChanged();
}
}
I'm just start working on metro app and i'm facing a problem that is dispatcher not updating the UI. My code is below please let me know what was the issue ?
public class Test : DependencyObject
{
public static readonly DependencyProperty CurrentItemProperty =
DependencyProperty.Register("NameOfPerson", typeof(string), typeof(Test), null);
public String NameOfPerson
{
get
{
return (string)GetValue(CurrentItemProperty);
}
set
{
runmethod(value);
}
}
public async void runmethod(String text)
{
await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
{
SetValue(CurrentItemProperty, text);
}
);
}
}
In main page i have an event button click which when fire update textbox.
private void Button_Click_2(object sender, RoutedEventArgs e)
{
Test t = new Test();
t.NameOfPerson = "Hello Umar";
}
MainPage.xaml look like this
<Page
x:Class="TestApplication.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:TestApplication"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
<Button Content="Button" HorizontalAlignment="Left" Margin="207,187,0,0" VerticalAlignment="Top" Height="80" Width="255" Click="Button_Click_2"/>
<TextBox x:Name="textB" Text="{Binding NameOfPerson}" HorizontalAlignment="Left" Height="80" Margin="730,187,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="307"/>
</Grid>
</Page>
If you are what you are trying to do is having a button refresh your Text, you should look into the MVVM pattern and have the Binding update your UI.
To do this you'll have to create your Object, in this case, let's say a person.
public class Person
{
public string Name { get; set; }
}
Secondly you would want to have a person inside a viewmodel that you'll update using your button. The viewmodel will derive from BindableBase which is a part of Windows Store applications if you would use such thing as Basic Page. The Viewmodel looks like this:
public class MainPageViewModel : BindableBase
{
public MainPageViewModel()
{
}
private Person person;
public Person Person
{
get { return person; }
set { SetProperty(ref person, value); }
}
public void LoadData()
{
Person = new Person() { Name = "Simple name" };
}
public void UpdatePerson()
{
Person.Name = "Updated Name";
OnPropertyChanged("Person");
}
}
and in case you dont have the bindableBase, it looks like this:
[Windows.Foundation.Metadata.WebHostHidden]
public abstract class BindableBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected bool SetProperty<T>(ref T storage, T value, [CallerMemberName] String propertyName = null)
{
if (object.Equals(storage, value)) return false;
storage = value;
this.OnPropertyChanged(propertyName);
return true;
}
protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
var eventHandler = this.PropertyChanged;
if (eventHandler != null)
{
eventHandler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
On your MainPage you create the ViewModel and set the DataContext on your Page. Also you would want to handle your object inside your Viewmodel, so you'll create a update method when clicking the button that will modify your Person object:
public sealed partial class MainPage : Page
{
private readonly MainPageViewModel viewModel;
public MainPage()
{
this.InitializeComponent();
viewModel = new MainPageViewModel();
viewModel.LoadData();
this.DataContext = viewModel;
}
private void Button_Tapped(object sender, TappedRoutedEventArgs e)
{
viewModel.UpdatePerson();
}
}
And finally your TextBox in the UI to point at the Person's name property inside the Viewmodel:
<TextBox
x:Name="textB"
Text="{Binding Person.Name}"
HorizontalAlignment="Left"
Height="80"
Margin="730,187,0,0"
TextWrapping="Wrap"
VerticalAlignment="Top"
Width="307" />
I hope this fulfills your question on how you can have a button updating your UI.