icommand

问题 I'm trying to determine the best way to cause ICommands' CanExecute() to be reflected in the UI. I understand that the Dispatcher is the WPF (engine?) that handles UI drawing, and that by default, the Dispatcher evaluates ICommands' CanExecute() method upon instantiation as well as active user interface (clicking the UI, or keyboard input.) Obviously, this is a problem when CanExecute() on any given ICommand changes, but neither mouse nor keyboard input is provided--and so the UI does not

问题 I have a button control in my wpf-mvvm application. I use an ICommand property (defined in viewmodel) to bind the button click event to viewmodel. I have -> execute and canexecute parameters for my ICommand implementation ( RelayCommand ). Even if CanExecute is false...button is not disabled...WHEN button CONTENT is IMAGE But, when button content is text..enable/disable works fine. <Button DockPanel.Dock="Top" Command="{Binding Path=MoveUpCommand}"> <Button.Content> <Image Source="/Resources

问题 Can Execute of a ICommand while a Context menu open With the continuation of the above query, Still its not able to achieve. Is there any way to raise context menu command's CanExcute while open the context menu. This need to be done in the context menu itself and here am not able to access the viewmodel. Any idea on this? public static BaseCommand SaveCommand { get { if (saveCommand == null) saveCommand = new BaseCommand(OnSaveCommandClicked, OnSaveCommandCanExcute); return saveCommand; } }

问题 Basically, I am creating a portable class library, and creating a bunch of ViewModels: public class CustomerViewModel : ViewModelBase { public string FirstName { ... } // INPC public string LastName { ... } // INPC public string FullName { get { return FirstName + " " + LastName; } } public ICommand DoFooCommand { get; private set; } // DelegateCommand private bool CanDoFoo(object parameter) { ... } private void DoFoo(object parameter) { ... } } This is great if I want for reusability for

问题 This question already has answers here : Closed 6 years ago . Possible Duplicate: How to add a Blend Behavior in a Style Setter when I use an interaction trigger in a style, I am getting the following error, 'triggers is not attachable element of type style'. Any explanation what this error actually means and how to solve it. For reference take a look at MVVM Light toolkit's EventToCommand example. In this particular case, I am using Timeline control from Infragistics which represents events

问题 A Control has its ContextMenu and its MenuItem is bound to an ICommand . ICommand's Can Execute has some code to enable and disable the MenuItem . This hits while loading and checks for Can Execute but it can hit while open the ContexMenu and it need to be hit(Checks) for each time while opening the ContextMenu . <Border> <Border.ContextMenu> <ContextMenu> <MenuItem Command="{Binding SaveCommand, Source={StaticResource vm}}" CommandParameter="{Binding}" Header="Menu1" /> </ContextMenu> <

问题 I'm having a time getting a straight answer on this, I've done a lot of searches and reading, and tried a lot of stuff. It sometimes sounds possible and other times only sounds possible by doing linking and what-not, which is something I'm trying to avoid. I'm a big fan of PCLs. I've created a solution using Visual Studio 2012, Xamarin, and MvvmCross which works great, I can deploy to an iOS device, a Droid device, Windows --- what have you. Visual Studio can build working applications that I

问题 I am busy creating my first MVVM application in WPF. Basically the problem I am having is that I have a TreeView (System.Windows.Controls.TreeView) which I have placed on my WPF Window, I have decide that I will bind to a ReadOnlyCollection of CommandViewModel items, and these items consist of a DisplayString, Tag and a RelayCommand. Now in the XAML, I have my TreeView and I have successfully bound my ReadOnlyCollection to this. I can view this and everything looks fine in the UI. The issue

问题 i want to start a task when a relay command is called, however i want to disable the button as long as that task is running take this example private ICommand update; public ICommand Update { get { if (update == null) { update = new RelayCommand( param => Task.Factory.StartNew(()=> StartUpdate()), param => true); //true means the button will always be enabled } return update; } } what is the best way to check if that task is running? here is my solution but not sure if its the best way class

问题 Let's have a button Command property bound to a custom command. When should I implement ICommand and when derive from RoutedCommand ? I see that RoutedCommand implements ICommand . In which case could I need to iplement an ICommand ? What about MVVM model? Which one suits better for this purpose? 回答1: As you have noticed the RoutedCommand class is an implementation of the ICommand interface, its main distinction if that its function is similar to that of a RoutedEvent : The Execute and