I have created an instance of a ToolStripMenuItem and wanted to add it as a submenu to two different menus on my form (to a contextmenu and a menu strip). I know how to get it to work but I am wondering why this doesn't work.
private static string[] parameters = { "itemOne", "itemTwo", "itemThree"};
private void MainForm_Load(object sender, EventArgs e)
{
foreach (string s in parameters)
{
ToolStripMenuItem addThis = new ToolStripMenuItem(s);
existingToolStripMenuItem.DropDownItems.Add(addThis);
existingMenuItem.DropDownItems.Add(addThis);
}
}
I noticed it works fine if I comment out one of the DropDownItems.Add() statements or if I create two separate instances. Why does it do this?
If you learn about the implementation of ToolStripItemCollection.Add, you will find that the second call existingMenuItem.DropDownItems.Add(addThis); removes addThis from existingToolStripMenuItem.DropDownItems.
So learning how to use decompilers such as ILSpy is critical for .NET developers,
http://wiki.sharpdevelop.net/ilspy.ashx
A possible workaround is to create two separate instances as you found out. If you intend to connect the two instances together, you can use ActionList,
http://www.lextm.com/2012/04/packaging-crads-actionlist-for-net-via-nuget/
Related
I am very new to WPF and MVVM Pattern. I even have no experience on windows.
I have Created Simple login window
_ Login.xaml, LoginViewModel.cs
_ Dashboard.xaml, DashboardViewModel.cs
After Login Successfully - ( In Login time we will select Language also )
I am Displaying Username & Selected Language in Dashboard window
I wrote code like this:
public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
try
{
var login = new Login();
var loginVM = new LoginViewModel();
Dashboard main = null;
loginVM.LoginCompleted += (sender, args) =>
{
DashboardViewModel dvModel = new DashboardViewModel(loginVM);
main = new Dashboard();
main.DataContext = dvModel;
main.ShowDialog();
login.Hide();
};
login.DataContext = loginVM;
login.ShowDialog();
}
catch (Exception ex)
{
throw ex;
}
}
In Dashboard Window it is displaying username and Language successfully.
But my problem is those two (Username & Language) properties I want to use in dashboard codebehind for update the layout based on language & other xaml files or other viewmodels . How to do that one ?
Technically I want to use Loginviewmodel object in all viewmodels.
Based on Selected Language I want to update Layout.
Note: Is this login approach good ? Is there any alternative for Globalization in MVVM pattern ?
Using a ViewModel for login is perfectly valid. I would perhaps create a token in your loginVM to pass around the system, depending on your needs. That token should be passed into the constructors of your other viewmodels from your main view model (DashboardViewModel?). This can be resolved using any decent IoC container.
For globalization/localization, I would use resources (in satellite assemblies). We've experimented with various things, and found that we didn't like the WPF UUIDs added everywhere when using LocBaml. And storing translation is a database quickly became a performance hog (even when loading in bulk). This does require you to find your labels etc. to a resource manager, but in my opinion, it is worth it.
Take a look at this article, for a nice extension, that enables you to simply write:
<TextBlock Text="{Resx MyText}"/>
And it will be translated using resource files.
An alterative approach is to simply store the Username and Language is a static property. I know most people don't like globals, but something like this is in nature very global, and you will still be able to inject it in if you so desire. The downside of this approach is that your unit tests would have to setup this static variable first.
EDIT An example of the static approach:
public static class RuntimeInfo {
public static string UserName { get; set; }
public static CultureInfo UserCulture { get; set; }
}
In your loginVM, simply store the necessary values in a static class. This can be accessed anywhere needed. This is not as 'correct' as the previous approach, but it can be more pragmatic than having to pass the username into every single ViewModel in your application.
I still recommend injection through an IoC container though.
I am wondering what might be the best way to use the WeakEventManager (4.5 is fine) together with Events offerring DependencyPropertyChangedEventArgs. These do not derive from EventArgs (for performance reasons) and therefore WeakEventManager does not work out of the Box.
Any guides, links or tips would be highly appreciated!
I'm not sure how using 'PropertyChangedEventManager' would resolve the issue regarding 'WeakEventManager' and binding weak event handlers that use 'DependencyPropertyChangedEventArgs'.
The 'PropertyChangedEventManager' works with instances of 'PropertyChangedEventArgs', which is derived from 'EventArgs', where 'DependencyPropertyChangedEventArgs' does not. This is why standard methods don't work.
In cases like this you can always use a manual approach ('WeakEventHandler' is declared within the scope of the 'MyType' class):
private class WeakEventHandler
{
private readonly System.WeakReference<MyType> m_WeakMyTypeRef;
public WeakEventHandler(MyType myType) => m_WeakMyTypeRef = new System.WeakReference<MyType>(myType);
public void OnClientIsKeyboardFocusWithinChanged(object sender, DependencyPropertyChangedEventArgs args)
{
if (m_WeakMyTypeRef.TryGetTarget(out var myType))
myType.OnClientIsKeyboardFocusWithinChanged(sender, args);
}
}
And code to bind (from within 'MyType' method):
var weakEventHandler = new WeakEventHandler(this);
frameworkElement.IsKeyboardFocusWithinChanged += weakEventHandler.OnClientIsKeyboardFocusWithinChanged;
The downside is that you have to declare a new (private) class although the same class could handle multiple events.
Use the PropertyChangedEventManager built in to .NET.
I'm working on a WinForm application using ninject for dependency injection. My first problem was that the form being instantiated had a parameter (for DI). I added a parameterless constructor thinking this would help. The problem now is that the code inside the constructor with the parameter gets skipped. Here what it looks like:
On my main form:
private void mnuSettings_Click(object sender, System.EventArgs e)
{
frmSettings objForm = new frmSettings();
objForm.Owner=this;
objForm.Show();
}
In the frmSettings form:
private readonly IApplicationPropertiesInterface _applicationProperties;
public frmSettings()
{
InitializeComponent();
}
public frmSettings(IApplicationPropertiesInterface applicationProperties) : this()
{
_applicationProperties = applicationProperties;
}
When I call _applicationProperties.GetExtractFileSaveLocationDirectory() it blows up because the code to set _applicationProperties was never called.
Im wondering if I have structured this incorrectly, and what the best way to achieve this is. My goal is to call the parameterless constructor, but also set _applicationProperties.
Any assistance would be most grateful.
I'm guessing you might be expecting that having Ninject in the building will mena that new will work differently to normal. It doesn't - you need to be doing a kernel.Resolve<Something> for the DI to kick in. Note that most of these pitfalls are covered in detail on the wiki
Can you edit your answer to include details of what you're doing outside of this form please?
In the meantime, here are some previous questions that overlap significantly:-
What is the best practice for WinForms dialogs with ninject?
How to use Ninject in a Windows Forms application?
I asked this question in a similar post but there have been significant updates since then, but still no results so I will try to re-ask the question with the updated information.
Basically I have a pivot view with 4 pivot items. If I create the scenario where I hit the windows key then rapidly press the back key my application will reopen without reconstructing (this is the expected outcome). The functionality of the application is there. I can press application bar buttons etc.
What doesn't work is the pivot items are frozen. If I was on Pivot item A and I press the start and back button quickly I come back to Pivot Item A. If I try to switch Pivot Items, the screen does not update, its "frozen" on Pivot Item A BUT the functionality of Pivot Item B is there. (I know this because the application bar Icons for Pivot Item B are now showing).
I have read many articles on proper tombstoning scenarios and how to approach this problem. My data IS being tombstoned correctly, and upon reactivation the tombstoned data works. No objects are null so I don't have any exceptions being thrown at me.
I check to see if I need to reload the Main ViewModel (I don't need to in this case so the UI elements being created initially are not being re created).
What does fix the problem however is if the application is reconstructed. Lets say I go to the marketplace from my app, let it finish loading and press back, My application will be refreshed and working fine since it properly deactivated and reconstructed istelf. I don't rely on constructors doing all the work so I am not missing any key elements not being set when they aren't fired in the windows/back button scenario.
Does anyone have any idea why my screen would not be updating?
constructor/loaded event/on navigated to event
public MainPage()
{
InitializeComponent();
this.Loaded += new RoutedEventHandler(MainPage_Loaded);
}
private void MainPage_Loaded(object sender, RoutedEventArgs e)
{
if (App.firstTimeLoading == true)
{
App.firstTimeLoading = false;
}
BuildApplicationBar();
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
this.DataContext = App.ViewModel;
App.viewIdentifier = StringResource.MainPageView;
if (!App.ViewModel.IsDataLoaded)
{
App.ViewModel.LoadData();
String bookTitle;
App.Parser.appBookInfoDict.TryGetValue(CPlayerInventoryKeys.kInventoryKeyTitleShortTitle, out bookTitle);
PivotBackground.Title = bookTitle.ToUpper();
CreatePivotItems();
}
if (App.playerController.chapterPlayer.Source == null)
App.restoreStateClass.RestoreState();
//applies the proper background image
if (App.isDarkTheme)
{
BitmapImage bitmapImage = new BitmapImage(new Uri(StringResource.PanoramaBlackImage, UriKind.Relative));
BackgroundImage.ImageSource = bitmapImage;
BackgroundImage.Opacity = .85;
}
else
{
BitmapImage bitmapImage = new BitmapImage(new Uri(StringResource.PanoramaWhiteImage, UriKind.Relative));
BackgroundImage.ImageSource = bitmapImage;
BackgroundImage.Opacity = .5;
}
if (App.firstTimeLoading == false && PivotBackground.SelectedItem != SuggestedPivotItem)
BuildApplicationBar();
else if (PivotBackground.SelectedItem == SuggestedPivotItem)
{
BuildMarketPlaceApplicationBar();
}
base.OnNavigatedTo(e);
}
I found the answer. Since I had a media element open (play/paused) and I was implementing the "non tombstoned" method of hitting windows key and back button very quickly, the media element source was corrupt. Even though I reset this source, apparently it can be ignored and not function properly. All I had to do was add a line of code to the Application Deactivated handler.
private void Application_Deactivated(object sender, DeactivatedEventArgs e)
{
App.MainAudioPlayer.Source = null; //(only showing line added)
}
The behavior you are describing seems to be solely related to the way you are manipulating data internally and constructing your layout. I tested this both in the emulator and on a couple of physical devices, both producing normal output (even when bound to a view model).
Try creating a new Pivot-based application (without all your data - just using the default template) and see if the problem persists. Also worth mentioning - are you testing on a device or in the emulator?
Are you using transitions from the toolkit?
Are they defined in XAML?
If so that could be the issue. There's a bug which is fixed in the next version.
The solution for now is to remove the transitions or define them in code.
I'm pretty new with Prism and after playing a bit around, there a few questions that arise. I'm trying to create a modular application that basically contains a map control in a shell window. The plugin modules offer different tools for interacting with the map. Some of the modules are pretty independent and simply display pins on the map.
1st question: How would RegionManager come into play for the module-specific classes (presenters) that must interact with the main map control? Usually in a RegionManager you register a specific view which is linked to a ViewModel, but in my case there is one single view (the map view) with multiple presenters acting on it.
2nd question: I need to be able to open several windows (shells) -- a bit like an MS Word document -- that should all be extended by the plugin modules. In a single-shell environment, when the module specific classes were instantiated, they could use the Dependency Injection Container to get a reference to the RegionManager or the Shell itself in order to get access to the map control. However with multiple shells, I don't see how to get access to the map control of the right shell. The dependency container has references to object global to the application, not specific for the shell I'm currently working in. Same is true for the EventAggregator.
Any input would be very welcome,
Ed
After hours of reading Prism-related articles and forums I've come across the article "How to build an outlook style application" on Erwin van der Valk's Blog - How to Build an Outlook Style Application.
In one part of the architecture, a Unity Child Container was used to resolve type instances. That's exactly what I needed for the answer to my 2nd question: I needed to have "scoped" (by window) dependency injection (ex: window scoped EventAggregator, Map control, etc.)
Here's how I create a new window:
private IShellWindow CreateNewShell(IRegionManager regionManager)
{
IUnityContainer childContainer = this.Container.CreateChildContainer();
... register types in child container ...
var window = new ShellWindow();
RegionManager.SetRegionManager(window, regionManager);
window.Content = childContainer.Resolve<MapDocumentView>();
return window;
}
So MapDocumentView and all its components will be injected (if needed) window-scoped instances.
Now that I can have scoped injected objects, I can get the window-scoped map in my module-based MapPresenter. To answer my 1st question, I defined an interface IHostApplication which is implemented by the Bootstrapper which has a MapPresenterRegistry property. This interface is added to the main container.
Upon initialization, the modules will register their presenters and upon the window creation, they will be instantiated.
So for the module initialization:
public void Initialize()
{
...
this.hostApplication.MapPresenterRegistry.Add(typeof(ModuleSpecificMapPresenter));
...
}
The code that initializes the map window:
private void View_Loaded(object sender, RoutedEventArgs e)
{
// Register map in the == scoped container ==
container.RegisterInstance<IMap>(this.View.Map);
// Create map presenters
var hostApplication = this.container.Resolve<IHostApplication>();
foreach (var mapPresenterType in hostApplication.MapPresenterRegistry)
{
var mapPresenter = this.container.Resolve(mapPresenterType) as IMapPresenter;
if (mapPresenter != null)
{
this.mapPresenters.Add(mapPresenter);
}
}
}
The module-specific MapPresenter:
public ModuleSpecificMapPresenter(IEventAggregator eventAggregator, IMap map)
{
this.eventAggregator = eventAggregator;
this.map = map;
this.eventAggregator.GetEvent<AWindowSpecificEvent>().Subscribe(this.WindowSpecificEventFired);
// Do stuff on with the map
}
So those are the big lines of my solution. What I don't really like is that I don't take advantage of region management this way. I pretty much have custom code to do the work.
If you have any further thoughts, I would be happy to hear them out.
Eduard
You have one main view and many child views, and child views can be added by different modules.
I'm not sure that the RegionManager class can be applied in this situation, so I would create a separate global class IPinsCollectionState
which must be registered as singleton in the bootstrapper.
public interface IPin
{
Point Coordinates { get; }
IPinView View { get; }
//You can use a view model or a data template instead of the view interface, but this example is the simplest
}
public interface IPinsCollectionState
{
ObservableCollection<IPin> Pins { get; }
}
Your main view model and different modules can receive this interface as a constructor parameter:
public class MapViewModel
{
public MapViewModel(IPinsCollectionState collectionState)
{
foreach (var item in collectionState.Pins)
{ /* Do something */ };
collectionState.Pins.CollectionChanged += (s, e) => {/* Handle added or removed items in the future */};
}
//...
}
Example of a module view model:
public class Module1ViewModel
{
public Module1ViewModel(IPinsCollectionState collectionState)
{
//somewhere in the code
collectionState.Pins.Add(new Module1Pin());
}
}
The second question can be solved in many different ways:
Application.Current.Windows
A global MainViewModel which contains the list of ShellViewModels and if you add new view model it will be displayed in new window. The bootstrapper is single for all windows.
Some kind of shared state which is passed to the constructor of the bootstrapper.
I don't know how these windows are related between themselves, and I don't know which way is the best, maybe it is possible to write an application with separated windows.