Consider this simple ViewModel:
public class AboutViewModel
: MvxViewModel
{
private readonly IMvxWebBrowserTask _webBrowserTask;
public AboutViewModel(IMvxWebBrowserTask webBrowserTask) { _webBrowserTask = webBrowserTask; }
private MvxCommand<string> _showInStoreCommand;
public ICommand ShowInStoreCommand
{
get
{
_showInStoreCommand = _showInStoreCommand ?? new MvxCommand<string>(DoShowInStoreCommand);
return _showInStoreCommand;
}
}
private void DoShowInStoreCommand(string url)
{
_webBrowserTask.ShowWebPage(url);
}
public string Wp8StoreUrl
{
get { return "http://windowsphone.com/s?appId=myappid"; }
}
public string AndroidStoreUrl
{
get { return "https://play.google.com/store/apps/details?id=mypackagename"; }
}
public string TouchStoreUrl
{
get { return "http://itunes.com"; }
}
}
Which I want to bind in a MvxDialogViewController and I write something like this:
Root = new RootElement
{
new Section()
{
new StringElement("Show in App Store").Bind(bindings, e => e.SelectedCommand, vm => vm.ShowInStoreCommand, new MvxCommandParameterValueConverter(), ViewModel.TouchStoreUrl),
}
}
Why does this always give me null in the DoShowInStoreCommand's url argument? How do I use Command Parameters when binding Elements?
EDIT:
I tried the following, as what Slodge wrote in his answer does not match any of the Extension method signatures, but it is giving me errors when it tries to bind:
new StringElement("Show in App Store")
.Bind(bindings, "SelectedCommand CommandParameter(ShowInStoreCommand, TouchStoreUrl)")
error:
MvxBind: Error: 2.37 Problem parsing Lang binding MvxException: Must follow binding option CommandParameter with an '=' in SelectedCommand CommandParameter(ShowInStoreCommand, TouchStoreUrl)
at Cirrious.MvvmCross.Binding.Parse.Binding.MvxBindingParser.ParseEquals (System.String block) [0x0003c] in c:\Projects\Misc\MVVMCROSS\Cirrious\Cirrious.MvvmCross.Binding\Parse\Binding\MvxBindingParser.cs:83
at Cirrious.MvvmCross.Binding.Parse.Binding.Swiss.MvxSwissBindingParser.ParseNextBindingDescriptionOptionInto (Cirrious.MvvmCross.Binding.Parse.Binding.MvxSerializableBindingDescription description) [0x0019a] in c:\Projects\Misc\MVVMCROSS\Cirrious\Cirrious.MvvmCross.Binding\Parse\Binding\Swiss\MvxSwissBindingParser.cs:56
at Cirrious.MvvmCross.Binding.Parse.Binding.Tibet.MvxTibetBindingParser.ParseNextBindingDescriptionOptionInto (Cirriou
s.MvvmCross.Binding.Parse.Binding.MvxSerializableBindingDescription description) [0x00033] in c:\Projects\Misc\MVVMCROSS\Cirrious\Cirrious.MvvmCross.Binding\Parse\Binding\Tibet\MvxTibetBindingParser.cs:49
at Cirrious.MvvmCross.Binding.Parse.Binding.Swiss.MvxSwissBindingParser.ParseBindingDescription (ParentIsLookingForComma parentIsLookingForComma) [0x00014] in c:\Projects\Misc\MVVMCROSS\Cirrious\Cirrious.MvvmCross.Binding\Parse\Binding\Swiss\MvxSwissBindingParser.cs:176
at Cirrious.MvvmCross.Binding.Parse.Binding.Swiss.MvxSwissBindingParser.ParseBindingDescription () [0x00001] in c:\Projects\Misc\MVVMCROSS\Cirrious\Cirrious.MvvmCross.Binding\Parse\Binding\Swiss\MvxSwissBindingParser.cs:159
at Cirrious.MvvmCross.Binding.Parse.Binding.MvxBindingParser.ParseTargetPropertyNameAndDescription () [0x0000f] in c:\Projects\Misc\MVVMCROSS\Cirrious\Cirrious.MvvmCross.Binding\Parse\Binding\MvxBindingParser.cs:72
at Cirrious.MvvmCross.Binding.Parse.Binding.MvxBindingParser.TryParseBindingSpecification (System
.String text, Cirrious.MvvmCross.Binding.Parse.Binding.MvxSerializableBindingSpecification& requestedBindings) [0x0001a] in c:\Projects\Misc\MVVMCROSS\Cirrious\Cirrious.MvvmCross.Binding\Parse\Binding\MvxBindingParser.cs:51
The binding you've created in:
new StringElement("Show in App Store").Bind(
bindings,
e => e.SelectedCommand,
vm => vm.ShowInStoreCommand,
new MvxCommandParameterValueConverter(), ViewModel.TouchStoreUrl),
is a binding to the expression vm => vm.ShowInStoreCommand on the ViewModel, but it captures the current value of ViewModel.TouchStoreUrl
If you want to use MultiBinding in MvvmCross, then you can do this using the Tibet extensions (see https://github.com/MvvmCross/MvvmCross/wiki/Databinding) - but these are not easily accessible in the fluent Expression syntax - instead you have to use the string based syntax instead.
So this binding could be achieved using something like:
new StringElement("Show in App Store").Bind(
bindings,
e => e.SelectedCommand,
"CommandParameter(ShowInStoreCommand, TouchStoreUrl)")
Related
The following line throws a runtime exception:
Accept = ReactiveCommand.Create(this.WhenAnyValue(x => x.Canexecute()));
Here's the code:
public class InstructionsViewModel : ReactiveObject
{
public InstructionsViewModel()
{
Accept = ReactiveCommand.Create(this.WhenAnyValue(x => x.CanExecute));
Accept.Subscribe(x =>
{
Debug.Write("Hello World");
});
}
public ReactiveCommand<object> Accept { get; }
bool _canExecute;
public bool CanExecute { get { return _canExecute; } set { this.RaiseAndSetIfChanged(ref _canExecute, value); } }
}
Error:
Cannot convert lambda expression to type 'IObserver' because
it is not a delegate type
I've also tried the following:
public InstructionsViewModel()
{
Accept = ReactiveCommand.Create(this.WhenAnyValue(x => x.Canexecute()));
Accept.Subscribe(x =>
{
Debug.Write("Hello World");
});
}
public ReactiveCommand<object> Accept { get; }
public bool Canexecute() => true;
I receive the following error:
An exception of type 'System.NotSupportedException' occurred in
ReactiveUI.dll but was not handled in user code
Additional information: Index expressions are only supported with
constants.
Is this even supported on Windows Phone 10?
I guess that your problem is not with ReactiveCommand, but with WhenAnyValue.
WhenAnyValue accepts a property, while you feed it with a method, which causes run time exception (see the sourcecode).
Check if this works (I changed CanExecute to be a property instead of a method):
public InstructionsViewModel()
{
Accept = ReactiveCommand.Create(this.WhenAnyValue(x => x.CanExecute));
Accept.Subscribe(x =>
{
Debug.Write("Hello World");
});
}
public ReactiveCommand<object> Accept { get; }
private bool _canExecute;
public bool CanExecute { get { return _canExecute; } set { this.RaiseAndSetIfChanged(ref _canExecute, value); } }
Also, as a general advice - do not nest your calls, this makes debugging harder. You should split creating command into two lines:
var canExecute = this.WhenAnyValue(x => x.CanExecute)
Accept = ReactiveCommand.Create(canExecute);
I'm currently trying to bind two images to an iOS ImageView via MvvmCross.
One should be displayed when the ImageView is in 'default' state, the other one when the ImageView is highlighted.
By the following code I can bind the Image for the default state. But how do I bind the one for 'highlighted' state?
public CategoryCell(IntPtr handle): base(string.Empty, handle)
{
_imageViewLoader = new MvxImageViewLoader(() => this.imageView);
this.DelayBind(() =>
{
var set = this.CreateBindingSet<CategoryCell, MaterialCategory>();
set.Bind(titleLabel).To(materialCategory => materialCategory.Label);
set.Bind(_imageViewLoader).To(materialCategory => materialCategory.ImageActiveUri);
set.Bind(this).For(cell => cell.Selected).To(materialCategory => materialCategory.IsSelected);
set.Apply();
});
}
Another approach if you do not need image loading i.e. for lots of static UX.
You can set up as follows -
_imageView = new UIImageView(UIImage.FromFile("some/image/off.png"))
{
HighlightedImage = UIImage.FromFile("some/image/on.png")
};
And bind it e.g. an "Enabled" Property -
this.DelayBind(() =>
{
var set = this.CreateBindingSet<SomeView, SomeViewModel>();
set.Bind(_imageView).For(v => v.Highlighted).To(vm => vm.Enabled);
set.Apply();
});
And don't forget to add Highlighted to your LinkerPleaseInclude.cs.
Hope this helps
I think the best solution is to introduce an extra property ImageUri. In the setter of your IsSelected you set the ImageUri dependend on the selection state.
ViewModel:
public class MaterialCategory : MvxViewModel
{
//...
public string ImageActiveUri { ... } // call UpdateImageUri() here, too
public string ImageInactiveUri { ... } // call UpdateImageUri() here, too
public string ImageUri { ... }
public bool IsSelected
{
get { return _isSelected; }
set
{
_isSelected = value;
UpdateImageUri();
RaisePropertyChanged(() => IsSelected);
}
}
private void UpdateImageUri()
{
ImageUri = IsSelected ? ImageActiveUri : ImageInactiveUri;
}
}
Binding:
set.Bind(_imageViewLoader).To(materialCategory => materialCategory.ImageUri);
// instead of:
// set.Bind(_imageViewLoader).To(materialCategory => materialCategory.ImageActiveUri);
I am just following the code examples of a Beginning SilverLight book and here is part of the code about user controls and Dependeny Property that I have typed from the book into my IDE:
public class CoolDownButtonControl: Control
{
public static readonly DependencyProperty CoolDownSecondsProperty =
DependencyProperty.Register(
"CoolDownSeconds",
typeof(int),
typeof(CoolDownButtonControl),
new PropertyMetadata(
new PropertyChangedCallback(
CoolDownButtonControl.OnCoolDownSecondsPropertyChanged
)
)
);
public int CoolDownSeconds
{
get
{
return (int)GetValue(CoolDownSecondsProperty);
}
set
{
SetValue(CoolDownSecondsProperty, value);
}
}
private static void OnCoolDownSecondsPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
CoolDownButtonControl cdBuutton = d as CoolDownButtonControl;
cdBuutton.OnCoolDownButtonChange(null);
}
}
The problem is that IDE highlights the line of cdBuutton.OnCoolDownButtonChange(null); complaining about
CoolDownButtonControl does not contain a definition for
OnCoolDownButtonChange
As I am new to this and hoping to learn it from this example I couldn't figure out what is wrong and how to fix it?
You should add that method too, something like this:
protected virtual void OnCoolDownButtonChange(RoutedEventArgs e)
{
}
I'm creating my own IntelliSense Presenter, since Visual Studio2012 support change theme, so I want my background color of the presenter can be auto-changed when the theme been changed. Is there a way to track the theme changes event, or get the current color theme of the Visual Studio?
Yes, this is possible. I had to solve a similiar issue with one of my extensions...
The current theme is stored in the Windows Registry; so I implemented the following utility class.
public enum VsTheme
{
Unknown = 0,
Light,
Dark,
Blue
}
public class ThemeUtil
{
private static readonly IDictionary<string, VsTheme> Themes = new Dictionary<string, VsTheme>()
{
{ "de3dbbcd-f642-433c-8353-8f1df4370aba", VsTheme.Light },
{ "1ded0138-47ce-435e-84ef-9ec1f439b749", VsTheme.Dark },
{ "a4d6a176-b948-4b29-8c66-53c97a1ed7d0", VsTheme.Blue }
};
public static VsTheme GetCurrentTheme()
{
string themeId = GetThemeId();
if (string.IsNullOrWhiteSpace(themeId) == false)
{
VsTheme theme;
if (Themes.TryGetValue(themeId, out theme))
{
return theme;
}
}
return VsTheme.Unknown;
}
public static string GetThemeId()
{
const string CategoryName = "General";
const string ThemePropertyName = "CurrentTheme";
string keyName = string.Format(#"Software\Microsoft\VisualStudio\11.0\{0}", CategoryName);
using (RegistryKey key = Registry.CurrentUser.OpenSubKey(keyName))
{
if (key != null)
{
return (string)key.GetValue(ThemePropertyName, string.Empty);
}
}
return null;
}
}
Okay; this just helps to figur out the current settings... listening for the theme changed notification is a bit trickier. After your package is loaded, you must obtain an IVsShell instance via the DTE; once you have this object you can utilize the AdviceBroadcastMessages method to subscribe for event notifications. You have to provide an object whose type implements the IVsBroadcastMessageEvents interface...
I don´t want to post the whole implementation, but the following lines might illustrate the key scenario...
class VsBroadcastMessageEvents : IVsBroadcastMessageEvent
{
int IVsBroadcastMessageEvent.OnBroadcastMessage(uint msg, IntPtr wParam, IntPtr lParam)
{
const uint WM_SYSCOLORCHANGE = 0x15;
if (msg == WM_SYSCOLORCHANGE)
{
// obtain current theme from the Registry and update any UI...
}
}
}
Consider implementing IDisposable on that type as well, in order to be able to unsubscribe from the event source, when the package gets unloaded.
This is how I subscribe for event notifications...
class ShellService
{
private readonly IVsShell shell;
private bool advised;
public ShellService(IVsShell shellInstance)
{
this.shell = shellInstance;
}
public void AdviseBroadcastMessages(IVsBroadcastMessageEvents broadcastMessageEvents, out uint cookie)
{
cookie = 0;
try
{
int r = this.shell.AdviseBroadcastMessages(broadcastMessageEvents, out cookie);
this.advised = (r == VSConstants.S_OK);
}
catch (COMException) { }
catch (InvalidComObjectException) { }
}
public void UnadviseBroadcastMessages(uint cookie)
{
...
}
}
Keep the value of the cookie parameter; you´ll need it to successfully unsubscribe.
Hope that helps (-:
Just wanted to put an update just in case anyone else comes along.. #Matze and #Frank are totally right.. However in VS 2015.. they added a easy way to detect the theme change. So you need to include PlatformUI an dyou get a super easy event
using Microsoft.VisualStudio.PlatformUI;
....
//Then you get an event
VSColorTheme.ThemeChanged += VSColorTheme_ThemeChanged;
You should make sure your control is disposable so you can unsubscribe from the event...
BONUS!
It also give you easy access to the colors.. even if the user has changed them from the default .. so you can do stuff like this in when set your colors
var defaultBackground = VSColorTheme.GetThemedColor(EnvironmentColors.ToolWindowBackgroundColorKey);
var defaultForeground = VSColorTheme.GetThemedColor(EnvironmentColors.ToolWindowTextColorKey);
For VS 2015 this has changed, the solution #Matze has still works but you need to update the GetThemeId() function to check for the version and if it's 14.0 (VS2015) look in a different place in the registry. The way the value is stored has changed also, it's still a string but now contains other values seperated by a '*'. The theme guid is the last value in the list.
if (version == "14.0")
{
string keyName = string.Format(#"Software\Microsoft\VisualStudio\{0}\ApplicationPrivateSettings\Microsoft\VisualStudio", version);
using (RegistryKey key = Registry.CurrentUser.OpenSubKey(keyName))
{
if (key != null)
{
var keyText = (string)key.GetValue("ColorTheme", string.Empty);
if (!string.IsNullOrEmpty(keyText))
{
var keyTextValues = keyText.Split('*');
if (keyTextValues.Length > 2)
{
return keyTextValues[2];
}
}
}
}
return null;
}
I'm trying to get windows workflows working, and I've become a little stumped.
I've gotten a single workflow working, but now I am trying to do something a little more complex: start a workflow, where each activity itself contains a workflow. (Picture something like the main program starts the activities "Input, logic, and output", and then each of those have additional activities like "prompt user, get input, etc.")
I've had it working fine, with the example from here (http://msdn.microsoft.com/en-us/magazine/gg535667.aspx), when I am not passing any parameters from the main program to the activites. My question is, how exactly does the 'Variables' and 'metadata.SetVariablesCollection' work in the NativeActivity, and how to I get the parameters to the low level activities?
This is what I am currently trying:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Activities;
using System.Collections.ObjectModel;
using System.Activities.Statements;
namespace Project1
{
internal class MainProgram
{
internal static void Main(string[] args)
{
try
{
var act = new SimpleSequence();
act.Activities.Add((Activity)(new WriteSomeText()));
act.Activities.Add((Activity)(new WriteSomeText()));
act.Activities.Add((Activity)(new WriteSomeText()));
act.Variables.Add(new Variable<string> ("stringArg", "TEXT"));
WorkflowInvoker.Invoke(act);
}
catch (Exception ex)
{
System.Console.WriteLine("EXCEPTION: {0}", ex);
}
}
public class WriteSomeText : CodeActivity
{
[RequiredArgument]
public InArgument<string> stringArg { get; set; }
protected override void Execute(CodeActivityContext context)
{
string output = context.GetValue(stringArg);
System.Console.WriteLine(output);
}
}
public class SimpleSequence : NativeActivity
{
Collection<Activity> activities;
Collection<Variable> variables;
Variable<int> current = new Variable<int> { Default = 0 };
public Collection<Activity> Activities
{
get
{
if (this.activities == null)
this.activities = new Collection<Activity>();
return this.activities;
}
set
{
this.activities = value;
}
}
public Collection<Variable> Variables
{
get
{
if (this.variables == null)
this.variables = new Collection<Variable>();
return this.variables;
}
set
{
this.variables = value;
}
}
protected override void CacheMetadata(NativeActivityMetadata metadata)
{
metadata.SetChildrenCollection(this.activities);
metadata.SetVariablesCollection(this.variables);
metadata.AddImplementationVariable(this.current);
}
protected override void Execute(NativeActivityContext context)
{
if (this.Activities.Count > 0)
context.ScheduleActivity(this.Activities[0], onChildComplete);
}
void onChildComplete(NativeActivityContext context, ActivityInstance completed)
{
int currentExecutingActivity = this.current.Get(context);
int next = currentExecutingActivity + 1;
if (next < this.Activities.Count)
{
context.ScheduleActivity(this.Activities[next], this.onChildComplete);
this.current.Set(context, next);
}
}
}
}
}
This ends up throwing the following exception:
EXCEPTION: System.Activities.InvalidWorkflowException: The following errors were encountered while processing the workflow tree:
'WriteSomeText': Value for a required activity argument 'stringArg' was not supplied.
'WriteSomeText': Value for a required activity argument 'stringArg' was not supplied.
'WriteSomeText': Value for a required activity argument 'stringArg' was not supplied.
at System.Activities.Validation.ActivityValidationServices.ThrowIfViolationsExist(IList`1 validationErrors)
at System.Activities.Hosting.WorkflowInstance.ValidateWorkflow(WorkflowInstanceExtensionManager extensionManager)
at System.Activities.Hosting.WorkflowInstance.RegisterExtensionManager(WorkflowInstanceExtensionManager extensionManager)
at System.Activities.WorkflowApplication.EnsureInitialized()
at System.Activities.WorkflowApplication.RunInstance(WorkflowApplication instance)
at System.Activities.WorkflowApplication.Invoke(Activity activity, IDictionary`2 inputs, WorkflowInstanceExtensionManager extensions, TimeSpan timeout)
at System.Activities.WorkflowInvoker.Invoke(Activity workflow, TimeSpan timeout, WorkflowInstanceExtensionManager extensions)
at System.Activities.WorkflowInvoker.Invoke(Activity workflow)
at Project1.MainProgram.Main(String[] args) in c:\users\user\documents\visual studio 2010\Projects\ModelingProject1\Project1\MainProgram.cs:line 25
I know, I only pass 1 parameter, but the exception still says that I am missing 3 parameters. I am missing something as to how to do this properly.
You're correctly declaring stringArg as an InArgument but you're not passing any value to it when calling it inside SimpleSequence.
You can pass something using the constructor, while constructing the all activity itself, like this:
public class WriteSomeText : CodeActivity
{
[RequiredArgument]
public InArgument<string> stringArg { get; set; }
public WriteSomeText(string stringArg)
{
this.stringArg = stringArg;
}
protected override void Execute(CodeActivityContext context
{
string output = context.GetValue(stringArg);
System.Console.WriteLine(output);
}
}
// Calling the activity like this:
internal static void Main(string[] args)
{
var act = new SimpleSequence()
{
Activities =
{
new WriteSomeText("hello"),
new WriteSomeText("world"),
new WriteSomeText("!")
}
};
WorkflowInvoker.Invoke(act);
Console.WriteLine("Press any key to exit");
Console.ReadKey();
}
Also notice that is a best practice to use the constructor to initialize collections:
public SimpleSequence()
{
activities = new Collection<Activity>();
variables = new Collection<Variable>();
}
This way is even more intuitive to initialize the activity:
var act = new SimpleSequence()
{
Activities =
{
new WriteSomeText("hello"),
new WriteSomeText("world"),
new WriteSomeText("!")
},
Variables =
{
new Variable<int>("myNewIntVar", 10),
// ....
}
};
EDIT:
There are a couple of other ways to approach the problem. This is your best friend while starting in the WF4 world.
Check WF\Basic\CustomActivities\Code-Bodied for a little push with this particular case.