Segue Icon in TextBlock with Data Binding

Segue Icon in TextBlock with Data Binding - c#

I am trying to make a Grid with an Icon in it. I am storing the string representation of the icon in a database, and trying to display these icons in a GridHub by binding to the Icon property (a string) on my viewmodel.
When I use this xaml, I get the actual text displayed in the grid
<TextBlock Text="{Binding Icon}"
FontFamily="Segoe UI Symbol"
FontSize="100"
TextAlignment="Center"
VerticalAlignment="Top"
Foreground="DarkGray"
AutomationProperties.Name="Some Label"/>
But this displays the icon as expected
<TextBlock Text=""
FontFamily="Segoe UI Symbol"
FontSize="100"
TextAlignment="Center"
VerticalAlignment="Top"
Foreground="DarkGray"
AutomationProperties.Name="Some Label"/>
My Model looks like:
public class PermissionGroup
{
/// <summary>
/// The unique identifier for the group.
/// </summary>
public string PermissionGroupId { get; set; }
/// <summary>
/// The name of the group
/// </summary>
public string Name { get; set; }
/// <summary>
/// The page associated with the permission group
/// </summary>
public string PageName { get; set; }
/// <summary>
/// The icon that will be shown on the PermissionHub page
/// </summary>
public string Icon { get; set; }
/// <summary>
/// A description of the permissions in the group
/// </summary>
public string Description { get; set; }
/// <summary>
/// The permissions associated with this permission group
/// </summary>
public List<Permission> Permissions { get; set; }
}
and my viewmodel just contains a list of these objects.
In my database I have tried storing the following:

\uE1D4 (has to be escaped to get in the db)
57812 (the result of char.Parse("\uE1D4"))
and none of these has resulted in the icon being displayed correctly!
The output of first XAML example

You have to decode the html encoded string. For instance you can try this very rough example:
public class ViewModel
{
public PermissionGroup PG {get; set;}
public ViewModel()
{
PG = new PermissionGroup();
PG.Icon= System.Net.WebUtility.HtmlDecode("");
}
}
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
this.DataContext = new ViewModel();
}
}
<TextBlock Text="{Binding Path=PG.Icon}" FontFamily="Segoe UI Symbol"/>
or
<Style x:Key="Segoe">
<Setter x:Name="Segoe" Property="TextElement.FontFamily" Value="Resources/#Segoe UI Symbol" />
</Style>
<TextBlock Text="{Binding PG.Icon}"
Style="{DynamicResource Segoe}"
A font viewer is available here, in case you need one.
EDIT: anyway the unicode escape sequence should work better than the html encoding, that's why I'm suggesting to double check with a font viewer and to link the font ttf as a resource.
You can also add a button to analyse the unicode conversion of your xaml text, when directly entered without binding. Something like this
private void Button_Click(object sender, RoutedEventArgs e)
{
byte[] stringBytes = Encoding.Unicode.GetBytes(txname.Text);
char[] stringChars = Encoding.Unicode.GetChars(stringBytes);
StringBuilder builder = new StringBuilder();
Array.ForEach<char>(stringChars, c => builder.AppendFormat("\\u{0:X}", (int)c));
Debug.WriteLine(builder);
}

Related

Avalonia UI Error in binding "Could not find CLR property"

I am trying to create an MVVM application which pulls data from an API and puts the data into lists which are used to navigate the program.
The issue I'm having is that the list produces this error and I cannot figure out why:
Binding: Error in binding to "Avalonia.Controls.TextBlock"."Text":
"Could not find CLR property 'name' on 'attributes'"
For context, the 'attributes' class contains the 'name' variable and I have confirmed that the name variable is populated beforehand (the program printed the name variable before I moved onto trying to form a list).
XAML code (MainWindow.xaml):
<Window xmlns="https://github.com/avaloniaui"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vm="clr-namespace:RT_Stream_App.ViewModels;assembly=RT_Stream_App"
Icon="resm:RT_Stream_App.Assets.avalonia-logo.ico"
Title="RT Stream App">
<Design.DataContext>
<vm:MainWindowViewModel/>
</Design.DataContext>
<ListBox Items="{Binding CompanyList}" HorizontalAlignment="Left" Width="512" Height="512" Margin="20,20,0,10" VerticalAlignment="Top">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel DataContext="attributes">
<TextBlock Text="{Binding name}" TextAlignment="Center" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<!-- <TextBlock Text="{Binding Greeting}" HorizontalAlignment="Center" VerticalAlignment="Center"/> -->
</Window>
MainWindowViewModel.cs
namespace RT_Stream_App.ViewModels
{
public class MainWindowViewModel : ViewModelBase
{
// use => instead of = for assigning
// public string Greeting => "I am testing!";
public companies.APIData siteList => loadCompanies();
//public string Greeting => TestLoop(siteList);
public ObservableCollection<companies.companyData> CompanyList => siteList.data;
public companies.APIData loadCompanies()
{
// This takes the API data for companies and converts it into a useable class
companies.APIData toReturn = JsonConvert.DeserializeObject<companies.APIData>(new WebClient().DownloadString("https://svod-be.roosterteeth.com/api/v1/channels"));
return toReturn;
}
}
}
Class data (companies.cs):
namespace RT_Stream_App.Classes
{
public class companies
{
/// <summary>
/// Root of the JSON
/// </summary>
public class APIData
{
public ObservableCollection<companyData> data = new ObservableCollection<companyData>();
}
/// <summary>
/// A class that holds the data for each company (Name and link mostly)
/// </summary>
public class companyData
{
public attributeData attributes = new attributeData();
public linkData links = new linkData();
}
/// <summary>
/// Contains the company name
/// </summary>
public class attributeData
{
public string name { get; set; }
}
/// <summary>
/// Contains link data for the next step
/// </summary>
public class linkData
{
public string shows { get; set; }
}
}
}
What am I doing wrong and what needs to be changed?
Update: I have tried changing the DataTemplate in the XAML to the following:
<DataTemplate>
<StackPanel>
<TextBlock Text="{Binding attributes.name}" TextAlignment="Center" />
</StackPanel>
</DataTemplate>
Which produces this error:
Binding: Error in binding to "Avalonia.Controls.TextBlock"."Text":
"Could not find CLR property 'attributes'
<DataTemplate>
<StackPanel DataContext="{Binding attributes}">
<TextBlock Text="{Binding name}" TextAlignment="Center" />
</StackPanel>
</DataTemplate>
Produces this error:
Binding: Error in binding to
"Avalonia.Controls.StackPanel"."DataContext": "Could not find CLR
property 'attributes'
Fix update: From Kekekeks answer, I figured out why my program wasn't working and now lists load. Due to using JSON.NET, I was worried about using constructors but I made the following change to all of my classes and the program displays the intended list
Class data (companies.cs) Updated:
public class APIData
{
public APIData()
{
this.data = new ObservableCollection<companyData>();
}
public ObservableCollection<companyData> data {
get;
set;
}
}

You are setting a string "attributes" as your DataContext. Then Binding can't find the property "name" on System.String.
Remove DataContext="attributes" and replace your binding with Text="{Binding attributes.name}"

CarouselView in XamarinForms

I'm trying to use the CarouselView in the Xamarin project. But I can’t do it. Here are the installed packages:
Here is the xaml code:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:FlowersStore"
xmlns:cv="clr-namespace:Xamarin.Forms;assembly=Xamarin.Forms.CarouselView"
x:Class="FlowersStore.MainPage">
<StackLayout>
<Grid RowSpacing="0">
<Grid.RowDefinitions>
<RowDefinition Height=".3*"/>
<RowDefinition Height=".7*"/>
</Grid.RowDefinitions>
<cv:CarouselView ItemsSource="{Binding Zoos}" x:Name="CarouselZoos">
<cv:CarouselView.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Image Grid.RowSpan="2" Aspect="AspectFill" Source="{Binding ImageUrl}"/>
<StackLayout Grid.Row="1" BackgroundColor="#80000000" Padding="12">
<Label TextColor="White" Text="{Binding Name}" FontSize="16" HorizontalOptions="Center" VerticalOptions="CenterAndExpand"/>
</StackLayout>
</Grid>
</DataTemplate>
</cv:CarouselView.ItemTemplate>
</cv:CarouselView>
</Grid>
</StackLayout>
And here is the c # code:
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using Xamarin.Forms;
namespace FlowersStore
{
public class Zoo
{
public string ImageUrl { get; set; }
public string Name { get; set; }
}
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
LoadDataCatouselView();
}
public void LoadDataCatouselView()
{
ObservableCollection<Zoo> Zoos = new ObservableCollection<Zoo>
{
new Zoo
{
ImageUrl = "http://content.screencast.com/users/JamesMontemagno/folders/Jing/media/23c1dd13-333a-459e-9e23-c3784e7cb434/2016-06-02_1049.png",
Name = "Woodland Park Zoo"
},
new Zoo
{
ImageUrl = "http://content.screencast.com/users/JamesMontemagno/folders/Jing/media/6b60d27e-c1ec-4fe6-bebe-7386d545bb62/2016-06-02_1051.png",
Name = "Cleveland Zoo"
},
new Zoo
{
ImageUrl = "http://content.screencast.com/users/JamesMontemagno/folders/Jing/media/e8179889-8189-4acb-bac5-812611199a03/2016-06-02_1053.png",
Name = "Phoenix Zoo"
}
};
CarouselZoos.ItemsSource = Zoos;
}
}
}
I use Xamarin Live Player for debugging. The log on the mobile phone displays the following message:
[LogEntry: Time=19.11.2018 14:54:54 +03:00, Level=Error, Title=Visualization Error, Message=The given key was not present in the dictionary. (KeyNotFoundException)]
How to fix it? Thanks.
Update 1:
I replaced the code based on your advice. I used your advice. I tried to run the application on:
Androind version: 7.1
Emulator: Genymotion Galaxy S7 7.1.0 API 25
And got this error:
What it? :(

The problem is with the long path.
An easy solution is to move the entire project solution to a shorter path like C:\
Here's an explanation from microsoft:
Path Too Long Exception

In your XAML you have the following line:
<cv:CarouselView ItemsSource="{Binding Zoos}" x:Name="CarouselZoos">
This means that the code is looking to bind a property named Zoos to the ItemsSource property of the CarouselView. You will need to create a property of type List<View> and implement the INotifyPropertyChanged structure to update the view. You'll also need to assign the content page's BindingContext to itself (BindingContext = this;).
You may also find that you cannot simply bind a URL to the Image source, and expect the image to appear.

Add the BindingContext=this; after the InitializeComponent(); or else add CarouselZoos.ItemsSource = Zoos; in OnAppearing() method

Try this
First add this class, for property binding and implement the INotifyPropertyChanged structure to update the view.
public class ViewModelBase : INotifyPropertyChanged
{
string title = string.Empty;
/// <summary>
/// Gets or sets the title.
/// </summary>
/// <value>The title.</value>
public string Title
{
get { return title; }
set { SetProperty(ref title, value); }
}
string icon = string.Empty;
/// <summary>
/// Gets or sets the icon.
/// </summary>
/// <value>The icon.</value>
public string Icon
{
get { return icon; }
set { SetProperty(ref icon, value); }
}
bool isBusy;
/// <summary>
/// Gets or sets a value indicating whether this instance is busy.
/// </summary>
/// <value><c>true</c> if this instance is busy; otherwise, <c>false</c>.</value>
public bool IsBusy
{
get { return isBusy; }
set
{
SetProperty(ref isBusy, value);
}
}
/// <summary>
/// Sets the property.
/// </summary>
/// <returns><c>true</c>, if property was set, <c>false</c> otherwise.</returns>
/// <param name="backingStore">Backing store.</param>
/// <param name="value">Value.</param>
/// <param name="propertyName">Property name.</param>
/// <param name="onChanged">On changed.</param>
/// <typeparam name="T">The 1st type parameter.</typeparam>
protected bool SetProperty<T>(
ref T backingStore, T value,
[CallerMemberName]string propertyName = "",
Action onChanged = null)
{
if (EqualityComparer<T>.Default.Equals(backingStore, value))
return false;
backingStore = value;
onChanged?.Invoke();
OnPropertyChanged(propertyName);
return true;
}
/// <summary>
/// Occurs when property changed.
/// </summary>
public event PropertyChangedEventHandler PropertyChanged;
/// <summary>
/// Raises the property changed event.
/// </summary>
/// <param name="propertyName">Property name.</param>
protected void OnPropertyChanged([CallerMemberName]string propertyName = "") => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
Now when you got the base class for bind properties you can add a view model class for bind the properties and follow the MVVM pattern. I think this is the most property way to manipulate the data.
public class Zoo
{
public string ImageUrl { get; set; }
public string Name { get; set; }
}
public class CarouselViewModel : ViewModelBase
{
private ObservableCollection<Zoo> zoos;
public ObservableCollection<Zoo> Zoos
{
get => zoos; set => SetProperty(ref zoos, value);
}
public CarouselViewModel()
{
zoos = new ObservableCollection<Zoo>
{
new Zoo
{
ImageUrl = "http://content.screencast.com/users/JamesMontemagno/folders/Jing/media/23c1dd13-333a-459e-9e23-c3784e7cb434/2016-06-02_1049.png",
Name = "Woodland Park Zoo"
},
new Zoo
{
ImageUrl = "http://content.screencast.com/users/JamesMontemagno/folders/Jing/media/6b60d27e-c1ec-4fe6-bebe-7386d545bb62/2016-06-02_1051.png",
Name = "Cleveland Zoo"
},
new Zoo
{
ImageUrl = "http://content.screencast.com/users/JamesMontemagno/folders/Jing/media/e8179889-8189-4acb-bac5-812611199a03/2016-06-02_1053.png",
Name = "Phoenix Zoo"
}
};
}
}
public partial class MainPage : ContentPage
{
public CarouselViewModel viewModel;
public MainPage()
{
InitializeComponent();
this.BindingContext = viewModel = new CarouselViewModel();
}
}

Binding text file to a XAML ListBox control

How do I bind a Text File name, to a ListBox control in a Windows Metro style application using C#?
Or:
How do I bind a Dictionary() to a XAML ListBox control?

After what seemed to be endless hours of reading through documentation, searching, and asking questions; I managed to figure this out for myself.
Below is the code that works just as I need it to in my situation:
XAML:
<ListBox Name="NotesList">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Filename}" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Code-behind:
public class NoteView
{
public string Filename { get; set; }
public string Contents { get; set; }
}
/// <summary>
/// Invoked when this page is about to be displayed in a Frame.
/// </summary>
/// <param name="e">Event data that describes how this page was reached. The Parameter
/// property is typically used to configure the page.</param>
protected override void OnNavigatedTo(NavigationEventArgs e)
{
var noteList = new ObservableCollection<NoteView>();
for (int i = 0; i < 10; i++)
{
noteList.Add(new NoteView { Filename = "Sample note " + i });
}
NotesList.ItemsSource = noteList;
}

Listbox items are placed ontop of each other

I can't seem to figure out why the listbox items are place ontop of each other... they should be below one another. Heres some markup and code.
<ListBox x:Name="DeviceList" Background="#ff4c4c4c" BorderThickness="0" ScrollViewer.CanContentScroll="False" MouseEnter="DeviceList_MouseEnter" MouseLeave="DeviceList_MouseLeave"
ManipulationBoundaryFeedback="DeviceList_ManipulationBoundaryFeedback" ItemContainerStyle="{DynamicResource ResourceKey=ListBoxItemStyle}" PreviewMouseDown="DeviceList_PreviewMouseDown"
PreviewMouseMove="DeviceList_PreviewMouseMove" PreviewMouseUp="DeviceList_PreviewMouseUp" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" DockPanel.Dock="Bottom">
<ListBox.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="..\Utilities\Resources\Themes\Slider.xaml"></ResourceDictionary>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</ListBox.Resources>
</ListBox>
#region Constructors
/// <summary>
/// Constructor.
/// </summary>
public ConfiguratorView()
{
InitializeComponent();
foreach (Device device in (Application.Current.Windows[1].DataContext as ConfiguratorViewModel).AvailableDevices)
{
devices.Add(AddDevice(device.Icon + "_def", device.Description));
}
DeviceList.ItemsSource = devices;
}
#endregion
#region Internal Members
/// <summary>
/// Add the device to the list of devices.
/// </summary>
/// <param name="icon"></param>
/// <param name="description"></param>
/// <returns></returns>
private Canvas AddDevice(string icon, string description)
{
Canvas canvas = new Canvas();
canvas.Name = icon;
ContentControl backgroundContent = new ContentControl();
Label label = new Label();
backgroundContent.Template = Application.Current.FindResource(icon) as ControlTemplate;
label.Content = description;
canvas.Children.Add(backgroundContent);
canvas.Children.Add(label);
return canvas;
}
The device list adds the canvas as the item... and then i set the ItemsSource to the List. Loading it shows all icons right on top of the last one. Any thoughts?

Everything will appear on top of each other because Canvas.Top defaults to NaN.
You could manually calculate the appropriate Canvas.Top values, but I would suggest:
Keeping the Device object simple with a property for Description and icon
Creating a DataTemplate for the ListBox items to display those properties.
EDIT:
For example (I haven't tested this)
Say your Device class looks something like this:
public class Device
{
public string Description { get; set; }
public object Icon { get; set; }
}
And then your datatemplete for the ListBox could look like this:
<ListBox ItemsSource="{Binding Devices}">
<ListBox.ItemsTemplate>
<DataTemplate>
<Canvas>
<!-- add items here -->
<TextBlock Text="{Binding Description}" Canvas.Top="5" />
<Canvas>
</DataTemplate>
</ListBox.ItemsTemplate>
</ListBox>

WPF MVVM Modal Overlay Dialog only over a View (not Window)

I'm pretty much new to the MVVM architecture design...
I was struggling lately to find a suitable control already written for such a purpose but had no luck, so I reused parts of XAML from another similar control and got make my own.
What I want to achieve is:
Have a reusable View (usercontrol) + viewmodel (to bind to) to be able to use inside other views as a modal overlay showing a dialog that disables the rest of the view, and shows a dialog over the it.
How I wanted to implement it:
create a viewmodel that takes string(message) and action+string collection(buttons)
viewmodel creates a collection of ICommands that call those actions
dialog view binds to the its viewmodel that will be exposed as property of another viewmodel (parent)
dialog view is put into the xaml of the parent like this:
pseudoXAML:
<usercontrol /customerview/ ...>
<grid>
<grid x:Name="content">
<various form content />
</grid>
<ctrl:Dialog DataContext="{Binding DialogModel}" Message="{Binding Message}" Commands="{Binding Commands}" IsShown="{Binding IsShown}" BlockedUI="{Binding ElementName=content}" />
</grid>
</usercontrol>
So here the modal dialog gets the datacontext from the DialogModel property of the Customer viewmodel, and binds commands and message. It would be also bound to some other element (here 'content') that needs to be disabled when the dialog shows (binding to IsShown). When you click some button in the dialog the associated command is called that simply calls the associated action that was passed in the constructor of the viewmodel.
This way I would be able to call Show() and Hide() of the dialog on the dialog viewmodel from inside the Customer viewmodel and alter the dialog viewmodel as needed.
It would give me only one dialog at a time but that is fine.
I also think that the dialog viewmodel would remain unittestable, since the unittests would cover the calling of the commands that ought to be created after it being created with Actions in the constructor. There would be a few lines of codebehind for the dialog view, but very little and pretty dumb (setters getters, with almost no code).
What concerns me is:
Is this ok?
Are there any problems I could get into?
Does this break some MVVM principles?
Thanks a lot!
EDIT: I posted my complete solution so you can have a better look. Any architectural comments welcome. If you see some syntax that can be corrected the post is flagged as community wiki.

Well not exactly an answer to my question, but here is the result of doing this dialog, complete with code so you can use it if you wish - free as in free speech and beer:
XAML Usage in another view (here CustomerView):
<UserControl
x:Class="DemoApp.View.CustomerView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:controls="clr-namespace:DemoApp.View"
>
<Grid>
<Grid Margin="4" x:Name="ModalDialogParent">
<put all view content here/>
</Grid>
<controls:ModalDialog DataContext="{Binding Dialog}" OverlayOn="{Binding ElementName=ModalDialogParent, Mode=OneWay}" IsShown="{Binding Path=DialogShown}"/>
</Grid>
</UserControl>
Triggering from parent ViewModel (here CustomerViewModel):
public ModalDialogViewModel Dialog // dialog view binds to this
{
get
{
return _dialog;
}
set
{
_dialog = value;
base.OnPropertyChanged("Dialog");
}
}
public void AskSave()
{
Action OkCallback = () =>
{
if (Dialog != null) Dialog.Hide();
Save();
};
if (Email.Length < 10)
{
Dialog = new ModalDialogViewModel("This email seems a bit too short, are you sure you want to continue saving?",
ModalDialogViewModel.DialogButtons.Ok,
ModalDialogViewModel.CreateCommands(new Action[] { OkCallback }));
Dialog.Show();
return;
}
if (LastName.Length < 2)
{
Dialog = new ModalDialogViewModel("The Lastname seems short. Are you sure that you want to save this Customer?",
ModalDialogViewModel.CreateButtons(ModalDialogViewModel.DialogMode.TwoButton,
new string[] {"Of Course!", "NoWay!"},
OkCallback,
() => Dialog.Hide()));
Dialog.Show();
return;
}
Save(); // if we got here we can save directly
}
Here is the code:
ModalDialogView XAML:
<UserControl x:Class="DemoApp.View.ModalDialog"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Name="root">
<UserControl.Resources>
<ResourceDictionary Source="../MainWindowResources.xaml" />
</UserControl.Resources>
<Grid>
<Border Background="#90000000" Visibility="{Binding Visibility}">
<Border BorderBrush="Black" BorderThickness="1" Background="AliceBlue"
CornerRadius="10,0,10,0" VerticalAlignment="Center"
HorizontalAlignment="Center">
<Border.BitmapEffect>
<DropShadowBitmapEffect Color="Black" Opacity="0.5" Direction="270" ShadowDepth="0.7" />
</Border.BitmapEffect>
<Grid Margin="10">
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<TextBlock Style="{StaticResource ModalDialogHeader}" Text="{Binding DialogHeader}" Grid.Row="0"/>
<TextBlock Text="{Binding DialogMessage}" Grid.Row="1" TextWrapping="Wrap" Margin="5" />
<StackPanel HorizontalAlignment="Stretch" VerticalAlignment="Bottom" Grid.Row="2">
<ContentControl HorizontalAlignment="Stretch"
DataContext="{Binding Commands}"
Content="{Binding}"
ContentTemplate="{StaticResource ButtonCommandsTemplate}"
/>
</StackPanel>
</Grid>
</Border>
</Border>
</Grid>
</UserControl>
ModalDialogView code behind:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
namespace DemoApp.View
{
/// <summary>
/// Interaction logic for ModalDialog.xaml
/// </summary>
public partial class ModalDialog : UserControl
{
public ModalDialog()
{
InitializeComponent();
Visibility = Visibility.Hidden;
}
private bool _parentWasEnabled = true;
public bool IsShown
{
get { return (bool)GetValue(IsShownProperty); }
set { SetValue(IsShownProperty, value); }
}
// Using a DependencyProperty as the backing store for IsShown. This enables animation, styling, binding, etc...
public static readonly DependencyProperty IsShownProperty =
DependencyProperty.Register("IsShown", typeof(bool), typeof(ModalDialog), new UIPropertyMetadata(false, IsShownChangedCallback));
public static void IsShownChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if ((bool)e.NewValue == true)
{
ModalDialog dlg = (ModalDialog)d;
dlg.Show();
}
else
{
ModalDialog dlg = (ModalDialog)d;
dlg.Hide();
}
}
#region OverlayOn
public UIElement OverlayOn
{
get { return (UIElement)GetValue(OverlayOnProperty); }
set { SetValue(OverlayOnProperty, value); }
}
// Using a DependencyProperty as the backing store for Parent. This enables animation, styling, binding, etc...
public static readonly DependencyProperty OverlayOnProperty =
DependencyProperty.Register("OverlayOn", typeof(UIElement), typeof(ModalDialog), new UIPropertyMetadata(null));
#endregion
public void Show()
{
// Force recalculate binding since Show can be called before binding are calculated
BindingExpression expressionOverlayParent = this.GetBindingExpression(OverlayOnProperty);
if (expressionOverlayParent != null)
{
expressionOverlayParent.UpdateTarget();
}
if (OverlayOn == null)
{
throw new InvalidOperationException("Required properties are not bound to the model.");
}
Visibility = System.Windows.Visibility.Visible;
_parentWasEnabled = OverlayOn.IsEnabled;
OverlayOn.IsEnabled = false;
}
private void Hide()
{
Visibility = Visibility.Hidden;
OverlayOn.IsEnabled = _parentWasEnabled;
}
}
}
ModalDialogViewModel:
using System;
using System.Windows.Input;
using System.Collections.ObjectModel;
using System.Collections.Generic;
using System.Windows;
using System.Linq;
namespace DemoApp.ViewModel
{
/// <summary>
/// Represents an actionable item displayed by a View (DialogView).
/// </summary>
public class ModalDialogViewModel : ViewModelBase
{
#region Nested types
/// <summary>
/// Nested enum symbolizing the types of default buttons used in the dialog -> you can localize those with Localize(DialogMode, string[])
/// </summary>
public enum DialogMode
{
/// <summary>
/// Single button in the View (default: OK)
/// </summary>
OneButton = 1,
/// <summary>
/// Two buttons in the View (default: YesNo)
/// </summary>
TwoButton,
/// <summary>
/// Three buttons in the View (default: AbortRetryIgnore)
/// </summary>
TreeButton,
/// <summary>
/// Four buttons in the View (no default translations, use Translate)
/// </summary>
FourButton,
/// <summary>
/// Five buttons in the View (no default translations, use Translate)
/// </summary>
FiveButton
}
/// <summary>
/// Provides some default button combinations
/// </summary>
public enum DialogButtons
{
/// <summary>
/// As System.Window.Forms.MessageBoxButtons Enumeration Ok
/// </summary>
Ok,
/// <summary>
/// As System.Window.Forms.MessageBoxButtons Enumeration OkCancel
/// </summary>
OkCancel,
/// <summary>
/// As System.Window.Forms.MessageBoxButtons Enumeration YesNo
/// </summary>
YesNo,
/// <summary>
/// As System.Window.Forms.MessageBoxButtons Enumeration YesNoCancel
/// </summary>
YesNoCancel,
/// <summary>
/// As System.Window.Forms.MessageBoxButtons Enumeration AbortRetryIgnore
/// </summary>
AbortRetryIgnore,
/// <summary>
/// As System.Window.Forms.MessageBoxButtons Enumeration RetryCancel
/// </summary>
RetryCancel
}
#endregion
#region Members
private static Dictionary<DialogMode, string[]> _translations = null;
private bool _dialogShown;
private ReadOnlyCollection<CommandViewModel> _commands;
private string _dialogMessage;
private string _dialogHeader;
#endregion
#region Class static methods and constructor
/// <summary>
/// Creates a dictionary symbolizing buttons for given dialog mode and buttons names with actions to berform on each
/// </summary>
/// <param name="mode">Mode that tells how many buttons are in the dialog</param>
/// <param name="names">Names of buttons in sequential order</param>
/// <param name="callbacks">Callbacks for given buttons</param>
/// <returns></returns>
public static Dictionary<string, Action> CreateButtons(DialogMode mode, string[] names, params Action[] callbacks)
{
int modeNumButtons = (int)mode;
if (names.Length != modeNumButtons)
throw new ArgumentException("The selected mode needs a different number of button names", "names");
if (callbacks.Length != modeNumButtons)
throw new ArgumentException("The selected mode needs a different number of callbacks", "callbacks");
Dictionary<string, Action> buttons = new Dictionary<string, Action>();
for (int i = 0; i < names.Length; i++)
{
buttons.Add(names[i], callbacks[i]);
}
return buttons;
}
/// <summary>
/// Static contructor for all DialogViewModels, runs once
/// </summary>
static ModalDialogViewModel()
{
InitTranslations();
}
/// <summary>
/// Fills the default translations for all modes that we support (use only from static constructor (not thread safe per se))
/// </summary>
private static void InitTranslations()
{
_translations = new Dictionary<DialogMode, string[]>();
foreach (DialogMode mode in Enum.GetValues(typeof(DialogMode)))
{
_translations.Add(mode, GetDefaultTranslations(mode));
}
}
/// <summary>
/// Creates Commands for given enumeration of Actions
/// </summary>
/// <param name="actions">Actions to create commands from</param>
/// <returns>Array of commands for given actions</returns>
public static ICommand[] CreateCommands(IEnumerable<Action> actions)
{
List<ICommand> commands = new List<ICommand>();
Action[] actionArray = actions.ToArray();
foreach (var action in actionArray)
{
//RelayExecuteWrapper rxw = new RelayExecuteWrapper(action);
Action act = action;
commands.Add(new RelayCommand(x => act()));
}
return commands.ToArray();
}
/// <summary>
/// Creates string for some predefined buttons (English)
/// </summary>
/// <param name="buttons">DialogButtons enumeration value</param>
/// <returns>String array for desired buttons</returns>
public static string[] GetButtonDefaultStrings(DialogButtons buttons)
{
switch (buttons)
{
case DialogButtons.Ok:
return new string[] { "Ok" };
case DialogButtons.OkCancel:
return new string[] { "Ok", "Cancel" };
case DialogButtons.YesNo:
return new string[] { "Yes", "No" };
case DialogButtons.YesNoCancel:
return new string[] { "Yes", "No", "Cancel" };
case DialogButtons.RetryCancel:
return new string[] { "Retry", "Cancel" };
case DialogButtons.AbortRetryIgnore:
return new string[] { "Abort", "Retry", "Ignore" };
default:
throw new InvalidOperationException("There are no default string translations for this button configuration.");
}
}
private static string[] GetDefaultTranslations(DialogMode mode)
{
string[] translated = null;
switch (mode)
{
case DialogMode.OneButton:
translated = GetButtonDefaultStrings(DialogButtons.Ok);
break;
case DialogMode.TwoButton:
translated = GetButtonDefaultStrings(DialogButtons.YesNo);
break;
case DialogMode.TreeButton:
translated = GetButtonDefaultStrings(DialogButtons.YesNoCancel);
break;
default:
translated = null; // you should use Translate() for this combination (ie. there is no default for four or more buttons)
break;
}
return translated;
}
/// <summary>
/// Translates all the Dialogs with specified mode
/// </summary>
/// <param name="mode">Dialog mode/type</param>
/// <param name="translations">Array of translations matching the buttons in the mode</param>
public static void Translate(DialogMode mode, string[] translations)
{
lock (_translations)
{
if (translations.Length != (int)mode)
throw new ArgumentException("Wrong number of translations for selected mode");
if (_translations.ContainsKey(mode))
{
_translations.Remove(mode);
}
_translations.Add(mode, translations);
}
}
#endregion
#region Constructors and initialization
public ModalDialogViewModel(string message, DialogMode mode, params ICommand[] commands)
{
Init(message, Application.Current.MainWindow.GetType().Assembly.GetName().Name, _translations[mode], commands);
}
public ModalDialogViewModel(string message, DialogMode mode, params Action[] callbacks)
{
Init(message, Application.Current.MainWindow.GetType().Assembly.GetName().Name, _translations[mode], CreateCommands(callbacks));
}
public ModalDialogViewModel(string message, Dictionary<string, Action> buttons)
{
Init(message, Application.Current.MainWindow.GetType().Assembly.GetName().Name, buttons.Keys.ToArray(), CreateCommands(buttons.Values.ToArray()));
}
public ModalDialogViewModel(string message, string header, Dictionary<string, Action> buttons)
{
if (buttons == null)
throw new ArgumentNullException("buttons");
ICommand[] commands = CreateCommands(buttons.Values.ToArray<Action>());
Init(message, header, buttons.Keys.ToArray<string>(), commands);
}
public ModalDialogViewModel(string message, DialogButtons buttons, params ICommand[] commands)
{
Init(message, Application.Current.MainWindow.GetType().Assembly.GetName().Name, ModalDialogViewModel.GetButtonDefaultStrings(buttons), commands);
}
public ModalDialogViewModel(string message, string header, DialogButtons buttons, params ICommand[] commands)
{
Init(message, header, ModalDialogViewModel.GetButtonDefaultStrings(buttons), commands);
}
public ModalDialogViewModel(string message, string header, string[] buttons, params ICommand[] commands)
{
Init(message, header, buttons, commands);
}
private void Init(string message, string header, string[] buttons, ICommand[] commands)
{
if (message == null)
throw new ArgumentNullException("message");
if (buttons.Length != commands.Length)
throw new ArgumentException("Same number of buttons and commands expected");
base.DisplayName = "ModalDialog";
this.DialogMessage = message;
this.DialogHeader = header;
List<CommandViewModel> commandModels = new List<CommandViewModel>();
// create commands viewmodel for buttons in the view
for (int i = 0; i < buttons.Length; i++)
{
commandModels.Add(new CommandViewModel(buttons[i], commands[i]));
}
this.Commands = new ReadOnlyCollection<CommandViewModel>(commandModels);
}
#endregion
#region Properties
/// <summary>
/// Checks if the dialog is visible, use Show() Hide() methods to set this
/// </summary>
public bool DialogShown
{
get
{
return _dialogShown;
}
private set
{
_dialogShown = value;
base.OnPropertyChanged("DialogShown");
}
}
/// <summary>
/// The message shown in the dialog
/// </summary>
public string DialogMessage
{
get
{
return _dialogMessage;
}
private set
{
_dialogMessage = value;
base.OnPropertyChanged("DialogMessage");
}
}
/// <summary>
/// The header (title) of the dialog
/// </summary>
public string DialogHeader
{
get
{
return _dialogHeader;
}
private set
{
_dialogHeader = value;
base.OnPropertyChanged("DialogHeader");
}
}
/// <summary>
/// Commands this dialog calls (the models that it binds to)
/// </summary>
public ReadOnlyCollection<CommandViewModel> Commands
{
get
{
return _commands;
}
private set
{
_commands = value;
base.OnPropertyChanged("Commands");
}
}
#endregion
#region Methods
public void Show()
{
this.DialogShown = true;
}
public void Hide()
{
this._dialogMessage = String.Empty;
this.DialogShown = false;
}
#endregion
}
}
ViewModelBase has :
public virtual string DisplayName { get; protected set; }
and implements INotifyPropertyChanged
Some resources to put in the resource dictionary:
<!--
This style gives look to the dialog head (used in the modal dialog)
-->
<Style x:Key="ModalDialogHeader" TargetType="{x:Type TextBlock}">
<Setter Property="Background" Value="{StaticResource Brush_HeaderBackground}" />
<Setter Property="Foreground" Value="White" />
<Setter Property="Padding" Value="4" />
<Setter Property="HorizontalAlignment" Value="Stretch" />
<Setter Property="Margin" Value="5" />
<Setter Property="TextWrapping" Value="NoWrap" />
</Style>
<!--
This template explains how to render the list of commands as buttons (used in the modal dialog)
-->
<DataTemplate x:Key="ButtonCommandsTemplate">
<ItemsControl IsTabStop="False" ItemsSource="{Binding}" Margin="6,2">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button MinWidth="75" Command="{Binding Path=Command}" Margin="4" HorizontalAlignment="Right">
<TextBlock Text="{Binding Path=DisplayName}" Margin="2"></TextBlock>
</Button>
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
</DataTemplate>

I have a custom open source FrameworkElement on my GitHub page that allows you to display modal content over the primary content.
The control can be used like this:
<c:ModalContentPresenter IsModal="{Binding DialogIsVisible}">
<TabControl Margin="5">
<Button Margin="55"
Padding="10"
Command="{Binding ShowModalContentCommand}">
This is the primary Content
</Button>
</TabItem>
</TabControl>
<c:ModalContentPresenter.ModalContent>
<Button Margin="75"
Padding="50"
Command="{Binding HideModalContentCommand}">
This is the modal content
</Button>
</c:ModalContentPresenter.ModalContent>
</c:ModalContentPresenter>
Features:
Displays arbitrary content.
Does not disable the primary content whilst the modal content is being displayed.
Disables mouse and keyboard access to the primary content whilst the modal content is displayed.
Is only modal to the content it is covering, not the entire application.
can be used in an MVVM friendly way by binding to the IsModal property.

I would approach this as a service that gets injected into your ViewModel, along the lines of the sample code below. To the extent what you want to do is in fact message box behavior, I would have my service implementation use a MessageBox!
I am using KISS here in order to present the concept. No code behind, and completely unit testable as shown.
As an aside, that Josh Smith example you are working off of was incredibly helpful to me also, even if it doesn't cover everything
HTH,
Berry
/// <summary>
/// Simple interface for visually confirming a question to the user
/// </summary>
public interface IConfirmer
{
bool Confirm(string message, string caption);
}
public class WPFMessageBoxConfirmer : IConfirmer
{
#region Implementation of IConfirmer
public bool Confirm(string message, string caption) {
return MessageBox.Show(message, caption, MessageBoxButton.YesNo) == MessageBoxResult.Yes;
}
#endregion
}
// SomeViewModel uses an IConfirmer
public class SomeViewModel
{
public ShellViewModel(ISomeRepository repository, IConfirmer confirmer)
{
if (confirmer == null) throw new ArgumentNullException("confirmer");
_confirmer = confirmer;
...
}
...
private void _delete()
{
var someVm = _masterVm.SelectedItem;
Check.RequireNotNull(someVm);
if (detailVm.Model.IsPersistent()) {
var msg = string.Format(GlobalCommandStrings.ConfirmDeletion, someVm.DisplayName);
if(_confirmer.Confirm(msg, GlobalCommandStrings.ConfirmDeletionCaption)) {
_doDelete(someVm);
}
}
else {
_doDelete(someVm);
}
}
...
}
// usage in the Production code
var vm = new SomeViewModel(new WPFMessageBoxConfirmer());
// usage in a unit test
[Test]
public void DeleteCommand_OnExecute_IfUserConfirmsDeletion_RemovesSelectedItemFrom_Workspaces() {
var confirmerMock = MockRepository.GenerateStub<IConfirmer>();
confirmerMock.Stub(x => x.Confirm(Arg<string>.Is.Anything, Arg<string>.Is.Anything)).Return(true);
var vm = new ShellViewModel(_repository, _crudConverter, _masterVm, confirmerMock, _validator);
vm.EditCommand.Execute(null);
Assert.That(vm.Workspaces, Has.Member(_masterVm.SelectedItem));
Assert.That(vm.Workspaces, Is.Not.Empty);
vm.DeleteCommand.Execute(null);
Assert.That(vm.Workspaces, Has.No.Member(_masterVm.SelectedItem));
Assert.That(vm.Workspaces, Is.Empty);
}

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