Windows Phone

BNS Error: The action request has expired

When using Background Agents in Windows Phone you may experience an InvalidOperationException with the message ‘BNS Error: The action request has expired‘ like so:

BNS Error: The action request has expired

This error means that your background task either threw an exception or failed to call NotifyComplete(). This error will not go away once you’ve fixed the issue – the background task must be removed. You can either do this in code, or uninstall the app and install it again.

Posted by Dan in Windows Phone, 0 comments

InvalidOperationException and FileNotFoundException with Background Tasks in Windows Phone

There are a few Exceptions Windows Phone throws when a Background Task isn’t correctly configured, sadly they’re very misleading. In this blog post I’ll outline some of the common exceptions you’ll get and how to go about fixing them.

Failure to Run

When you call ‘ScheduledActionService.LaunchForTest’ you may get an InvalidOperationException like so:

InvalidOperationException on LaunchForTest

This Exception means you haven’t added the ExtendedTask info in the WMAppManifest.xml file (found in ‘Properties’). Open the file in the XML editor (right-click on it and select ‘Open With’), and make sure you’ve entered the ExtendedTask info:

<Tasks>
  <DefaultTask  Name ="_default" NavigationPage="MainPage.xaml"/>
  <ExtendedTask Name="BackgroundTask">
    <BackgroundServiceAgent Specifier="ScheduledTaskAgent" Name="TileUpdateAgent" Source="WP7LiveTileDemo" Type="WP7LiveTileDemo.Agents.TileUpdateAgent" />
  </ExtendedTask>
</Tasks>

The values are as follows:

  • Specifier – The type of background agent, you can only have one of each type
  • Name – Name for this task, can be anything you like
  • Source – The name of the Assembly (without the .dll extension) that contains the agent. If this is wrong you’ll get both InvalidOperationException and FileNotFoundException exceptions
  • Type – The full class name (ie. must include the namespace path too) of the agent you set up in code. If this is wrong you’ll get an InvalidOperationException

InvalidOperationException and/or FileNotFoundException

If anything is wrong with the ExtendedTask declaration you’ll get InvalidOperationException or FileNotFoundException being thrown from Microsoft.Phone.ni.dll, it’ll look something like this:

InvalidOperationException from a BackgroundTask in WP InvalidOperationException stack trace from a BackgroundTask in WP

Make sure to double-check your ExtendedTask XML is perfect, especially the Source and Type attributes.

Posted by Dan in Windows Phone, 1 comment

Windows Phone app closes as soon as it opens

I was recently having a problem with an app closing as soon as it started, with absolutely no error messages at all. Turns out, the ‘Startup object’ value had been cleared, leaving it at the default ‘not set’. Setting it back to the name of the Application sorted it:

Startup object selection in Visual Studio

Posted by Dan in Programming, Windows Phone, 0 comments

Notify Property Weaver

I’ve found MVVM to require somewhat excessive amounts of boilerplate code, and as far as I’m concerned if you have a lot of boilerplate (aka. repeated) code then you’re doing it wrong. There’s a few articles out there on using a little IL weaving to automatically provide notifications for the INotifyPropertyChanged interface. This dramatically reduces the amount of boilerplate you have to write, and dramatically increases readability. Simon Cropp has released the best solution by far – a NuGet package that you can integrate into your app and forget about.

The solution works with Silverlight 3.5 and .NET 3.5 onwards. Most importantly it works well with Windows Phone 7 – something many other solutions don’t always work particularly well with. The solution even works automatically with dependencies – so if one property changes as a result of another changing, the notifications will automatically be fired for both properties. Very, very clever.

Go give it a go!

Posted by Dan in C#, Windows Phone, 1 comment

I LOVEFiLM Launched

I’ve been holding off talking about my app until I had the free version available on the marketplace… and now it is!

I LOVEFiLM Screenshot

I hope you like it, it’s the product of much work, sweat, blood and tears with a little drop of pixie dust. Obviously you’ll need to have a LOVEFiLM account for the app to actually work for you, but if you do have a LOVEFiLM account I feel this app is the best on the market… because I made it!

No, but seriously this app is fully-featured and should offer everything you need, including:

  • New releases
  • Coming soon
  • Lists (genre, famous actors, famous directors, format, 100 best, language, production year, etc.)
  • Search by keyword
  • Add to default rental list or a specific list
  • Remove from rental list
  • Change title priority
  • Rating
  • Find all of the films / TV shows by your favourite actor, actress, or director
  • Find similar titles to the one you’re currently viewing
  • Play trailer for the title you’re viewing
  • Actor/Director information

But don’t take my word for it, download the free version and see for yourself! If you’re totally confident in my abilities (and who isn’t?!), then use the big banner below to get the full paid version:

Download for Windows Phone 7

Posted by Dan in Windows Phone, 0 comments

Isolated Storage and Multithreading

The documentation is a little weak on thread safety when it comes to Isolated Storage, with just a little message on the subject: “Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.”.

What I’ve found is this: Reading files from Isolated Storage is fine from multiple threads at the same time – obviously if a thread is saving the file then things are a little murkier.

However, writing files is not thread safe. Do not attempt to write two different files at the same time to Isolated Storage, you’ll get an exception sooner or later.

My fix is a little messy, I have a global lock object I use whenever I want to write to Isolated Storage; this means I can only ever save one file at a time.

Posted by Dan in Windows Phone, 0 comments

Deployment Failed – The parameter is incorrect

In your output window you may find something like:

Deploying C:\Users\Username\Documents\Visual Studio 2010\Projects\MyApp\MyApp\Bin\Debug\MyApp.xap…
Deployment of application to device failed.
The parameter is incorrect.

The problem is probably due to the ApplicationIcon.png or Background.png files. These files must be actual files within the project – they can’t be linked to.

Another problem can be an incorrectly formatted WMAppManifest.xml file. Create a dummy project so you can compare your manifest file to the freshly created correct manifest. Pay particular attention to the Genre (must be ‘apps.normal’) and the IconPath and BackgroundImageURI values. Also make sure the DefaultTask’s ‘NavigationPage’ is set correctly.

Posted by Dan in Windows Phone, 1 comment

ID_CAP_LOCATION ‘Location Services’ Incorrectly Detected With WP7Contrib

I had an issue where my app would incorrectly report ‘location services’ when attempting to submit for certification. The problem turned out to be two classes in WP7Contrib using the Microsoft.Phone.Controls.Maps and System.Device.Location namespaces. When the capability detection tool runs, it checks for any use of a namespace, not just methods that actually check the user’s location. Unfortunately you can’t override it in the WMAppManifest.xml file – which begs the question of why even have the flags there if all they do is increase the chances of an exception.

Anyway, to fix the problem you need to comment out two classes in WP7Contrib.Common. In ‘Serialization’ are ‘SerializeGeoCoordinate’ and ‘SerializeLocationRect’. Comment out these classes in their entirety and re-build both WP7Contrib.Common and your app. Your app should no longer be incorrectly detected as using location services.

Posted by Dan in Windows Phone, 0 comments

MSBUILD : error : Xap packaging failed. Object reference not set to an instance of an object.

When you build your WP7 app, you may get the following cryptic error after a successful compilation: MSBUILD : error : Xap packaging failed. Object reference not set to an instance of an object.

This error means one of the core files referenced in the WMAppManifest.xml is missing. This can be either due to the file being renamed or deleted, or just of the wrong build type. Open up your WMAppManifest.xml file in the Properties folder and take a note of the IconPath and BackgroundImageURI values. Make sure the paths are correct and the files are present. Also make sure that if IsResource is set to false, that the graphic has a Build Action of ‘Content’.

Posted by Dan in Windows Phone, 1 comment

WP7Contrib Transitions Part 3 – LongListSelector

Make sure to read parts 1 and 2 first!

By now you’re probably loving the transitions on offer from WP7Contrib, but have found a slight problem in that the Turnstile Feather animation doesn’t work with the LongListSelector as provided by the WP7 Silverlight Toolkit. Fear not! For the opensource nature of WP7Contrib means we can extend the transitions functionality to support the LongListSelector as well as the standard ListBox. It should be noted that these changes aren’t perfect, and are largely a hack to add the functionality in as short a timespan as possible. You can download the demo app here to see the changes in action.

Let’s Have At It

First you need to download the WP7Contrib sourcecode, the code in this example is associated with revision 66430. You can try applying the changes to the latest revision, however note that things have most definitely moved on since 66430.

Open up the solution you’ve downloaded, then expand the ‘WP7Contrib.View.Transitions’ project. Expand ‘Animation’ and open up ‘TurnstileFeatherAnimator.cs’ and add the following properties to the class:

/// <summary>
/// Is BackwardIn or BackwardOut
/// </summary>
protected bool IsBackward { get; set; }

/// <summary>
/// Run the completion action first rather than on completion
/// </summary>
protected bool RunCompletionAnimationFirst { get; set; }

private Action _completionAnimationAction;
private Action _actualBeginAction;
private Action _completionAction;

Change the datatype of the ‘ListBox’ property to ‘Control’, this is so we can use either a ListBox or a LongListSelector without modifying client code.

The IsBackward property tells us if this is a Backward animation, this is required to fix some bugs in the way the LongListSelector handles itself when the page is restored when the user navigates backward.

The RunCompletionAnimationFirst property tells the animator to run the completion animation first or not. This is necessary because I perform a Turnstile animation on the RootElement to complete the feather effect. This turnstile animation needs to run first if the elements are animating in, and last if the elements are animating out.

The three Action properties are necessary to order animations in the correct order, and then perform the actual completion action. These properties will make more sense when you see the implementation details.

Now replace all of the methods in the ‘Public Methods’ region with the following:

/// <summary>
/// The begin.
/// </summary>
/// <param name="completionAction">
/// The completion action.
/// </param>
public override void Begin(Action completionAction)
{
    _completionAction = completionAction;
    completionAction = new Action(AnimationsCompleted);

    if (RunCompletionAnimationFirst)
    {
        _completionAnimationAction = ActualBegin;
        _actualBeginAction = completionAction;

        HideListItems();
        BeginCompletionAnimation();
    }
    else
    {
        _completionAnimationAction = completionAction;
        _actualBeginAction = BeginCompletionAnimation;

        ActualBegin();
    }
}

private void BeginCompletionAnimation()
{
    CompletionAnimation.RootElement = this.RootElement;
    CompletionAnimation.Begin(_completionAnimationAction);
}

private void HideListItems()
{
    if (ListBox is LongListSelector)
    {
        foreach (ContentPresenter li in ((LongListSelector)ListBox).GetItemsWithContainers(false, true).OfType<ContentPresenter>())
            li.Opacity = 0;
    }
    else if (ListBox is ListBox)
    {
        foreach (ContentControl li in ((ListBox)ListBox).GetVisualDescendants().OfType<ListBoxItem>().Where(lbi => IsOnCurrentPage(lbi) && lbi.IsEnabled))
            li.Opacity = 0;
    }
}

private void AnimationsCompleted()
{
    if (!this.IsBackward && ListBox is LongListSelector)
    {
        LongListSelector listBox = (LongListSelector)ListBox;

        listBox.UpdateLayout();
        listBox.SelectedItem = null;
    }

    _completionAction();

    _completionAnimationAction = null;
    _actualBeginAction = null;
    _completionAction = null;
}

private void ActualBegin()
{
    if (ListBox is ListBox)
        ActualBeginListBox();
    else if (ListBox is LongListSelector)
        ActualBeginLongListSelector();
    else
        throw new InvalidOperationException("ListBox must be of type System.Windows.Controls.ListBox or Microsoft.Phone.Controls.LongListSelector");

    base.Begin(_actualBeginAction);
}

private void ActualBeginListBox()
{
    Storyboard = new Storyboard();
    ListBox listBox = (ListBox)ListBox;

    double liCounter = 0;
    var listBoxItems = listBox.GetVisualDescendants().OfType<ListBoxItem>().Where(lbi => IsOnCurrentPage(lbi) && lbi.IsEnabled).ToList();

    if (HoldSelectedItem && Direction == Directions.Out && listBox.SelectedItem != null)
    {
        //move selected container to end
        var selectedContainer = listBox.ItemContainerGenerator.ContainerFromItem(listBox.SelectedItem);
        listBoxItems.Remove(selectedContainer as ListBoxItem);
        listBoxItems.Add(selectedContainer as ListBoxItem);
    }

    foreach (ContentControl li in listBoxItems)
    {
        GeneralTransform gt = li.TransformToVisual(RootElement);
        Point globalCoords = gt.Transform(new Point(0, 0));
        double heightAdjustment = li.Content is FrameworkElement ? ((li.Content as FrameworkElement).ActualHeight / 2) : (li.ActualHeight / 2);
        //double yCoord = globalCoords.Y + ((((System.Windows.FrameworkElement)(((System.Windows.Controls.ContentControl)(li)).Content)).ActualHeight) / 2);
        double yCoord = globalCoords.Y + heightAdjustment;

        double offsetAmount = (RootElement.ActualHeight / 2) - yCoord;

        PlaneProjection pp = new PlaneProjection();
        pp.GlobalOffsetY = offsetAmount * -1;
        pp.CenterOfRotationX = 0;
        li.Projection = pp;

        CompositeTransform ct = new CompositeTransform();
        ct.TranslateY = offsetAmount;
        li.RenderTransform = ct;

        var beginTime = TimeSpan.FromMilliseconds((FeatherDelay * liCounter) + InitialDelay);

        if (Direction == Directions.In)
        {
            li.Opacity = 0;

            DoubleAnimationUsingKeyFrames daukf = new DoubleAnimationUsingKeyFrames();

            EasingDoubleKeyFrame edkf1 = new EasingDoubleKeyFrame();
            edkf1.KeyTime = beginTime;
            edkf1.Value = Angle;
            daukf.KeyFrames.Add(edkf1);

            EasingDoubleKeyFrame edkf2 = new EasingDoubleKeyFrame();
            edkf2.KeyTime = TimeSpan.FromMilliseconds(Duration).Add(beginTime);
            edkf2.Value = 0;

            ExponentialEase ee = new ExponentialEase();
            ee.EasingMode = EasingMode.EaseOut;
            ee.Exponent = 6;

            edkf2.EasingFunction = ee;
            daukf.KeyFrames.Add(edkf2);

            Storyboard.SetTarget(daukf, li);
            Storyboard.SetTargetProperty(daukf, new PropertyPath("(UIElement.Projection).(PlaneProjection.RotationY)"));
            Storyboard.Children.Add(daukf);

            DoubleAnimation da = new DoubleAnimation();
            da.Duration = TimeSpan.FromMilliseconds(0);
            da.BeginTime = beginTime;
            da.To = 1;

            Storyboard.SetTarget(da, li);
            Storyboard.SetTargetProperty(da, new PropertyPath("(UIElement.Opacity)"));
            Storyboard.Children.Add(da);
        }
        else
        {
            li.Opacity = 1;

            DoubleAnimation da = new DoubleAnimation();
            da.BeginTime = beginTime;
            da.Duration = TimeSpan.FromMilliseconds(Duration);
            da.To = Angle;

            ExponentialEase ee = new ExponentialEase();
            ee.EasingMode = EasingMode.EaseIn;
            ee.Exponent = 6;

            da.EasingFunction = ee;

            Storyboard.SetTarget(da, li);
            Storyboard.SetTargetProperty(da, new PropertyPath("(UIElement.Projection).(PlaneProjection.RotationY)"));
            Storyboard.Children.Add(da);

            da = new DoubleAnimation();
            da.Duration = TimeSpan.FromMilliseconds(10);
            da.To = 0;
            da.BeginTime = TimeSpan.FromMilliseconds(Duration).Add(beginTime);

            Storyboard.SetTarget(da, li);
            Storyboard.SetTargetProperty(da, new PropertyPath("(UIElement.Opacity)"));
            Storyboard.Children.Add(da);
        }

        liCounter++;
    }
}

private void ActualBeginLongListSelector()
{
    Storyboard = new Storyboard();
    LongListSelector listBox = (LongListSelector)ListBox;

    double liCounter = 0;
    var listBoxItems = listBox.GetItemsWithContainers(false, true).OfType<ContentPresenter>().ToList();

    if (HoldSelectedItem && Direction == Directions.Out && listBox.SelectedItem != null)
    {
        //move selected container to end
        var listBoxItemsInView = listBox.GetItemsWithContainers(true, true).OfType<ContentPresenter>();
        var selectedContainer = listBoxItemsInView.Where(i => i.Content == listBox.SelectedItem).FirstOrDefault();

        if (selectedContainer != null)
        {
            listBoxItems.Remove(selectedContainer);
            listBoxItems.Add(selectedContainer);
        }
    }

    foreach (ContentPresenter li in listBoxItems)
    {
        GeneralTransform gt = li.TransformToVisual(RootElement);
        Point globalCoords = gt.Transform(new Point(0, 0));
        //double heightAdjustment = li.Content is FrameworkElement ? ((li.Content as FrameworkElement).ActualHeight / 2) : (li.ActualHeight / 2);
        double heightAdjustment = li.ActualHeight / 2;
        //double yCoord = globalCoords.Y + ((((System.Windows.FrameworkElement)(((System.Windows.Controls.ContentControl)(li)).Content)).ActualHeight) / 2);
        double yCoord = globalCoords.Y + heightAdjustment;

        double offsetAmount = (RootElement.ActualHeight / 2) - yCoord;

        PlaneProjection pp = new PlaneProjection();
        pp.GlobalOffsetY = offsetAmount * -1;
        pp.CenterOfRotationX = 0;
        li.Projection = pp;

        CompositeTransform ct = new CompositeTransform();
        ct.TranslateY = offsetAmount;
        li.RenderTransform = ct;

        var beginTime = TimeSpan.FromMilliseconds((FeatherDelay * liCounter) + InitialDelay);

        if (Direction == Directions.In)
        {
            li.Opacity = 0;

            DoubleAnimationUsingKeyFrames daukf = new DoubleAnimationUsingKeyFrames();

            EasingDoubleKeyFrame edkf1 = new EasingDoubleKeyFrame();
            edkf1.KeyTime = beginTime;
            edkf1.Value = Angle;
            daukf.KeyFrames.Add(edkf1);

            EasingDoubleKeyFrame edkf2 = new EasingDoubleKeyFrame();
            edkf2.KeyTime = TimeSpan.FromMilliseconds(Duration).Add(beginTime);
            edkf2.Value = 0;

            ExponentialEase ee = new ExponentialEase();
            ee.EasingMode = EasingMode.EaseOut;
            ee.Exponent = 6;

            edkf2.EasingFunction = ee;
            daukf.KeyFrames.Add(edkf2);

            Storyboard.SetTarget(daukf, li);
            Storyboard.SetTargetProperty(daukf, new PropertyPath("(UIElement.Projection).(PlaneProjection.RotationY)"));
            Storyboard.Children.Add(daukf);

            DoubleAnimation da = new DoubleAnimation();
            da.Duration = TimeSpan.FromMilliseconds(0);
            da.BeginTime = beginTime;
            da.To = 1;

            Storyboard.SetTarget(da, li);
            Storyboard.SetTargetProperty(da, new PropertyPath("(UIElement.Opacity)"));
            Storyboard.Children.Add(da);
        }
        else
        {
            li.Opacity = 1;

            DoubleAnimation da = new DoubleAnimation();
            da.BeginTime = beginTime;
            da.Duration = TimeSpan.FromMilliseconds(Duration);
            da.To = Angle;

            ExponentialEase ee = new ExponentialEase();
            ee.EasingMode = EasingMode.EaseIn;
            ee.Exponent = 6;

            da.EasingFunction = ee;

            Storyboard.SetTarget(da, li);
            Storyboard.SetTargetProperty(da, new PropertyPath("(UIElement.Projection).(PlaneProjection.RotationY)"));
            Storyboard.Children.Add(da);

            da = new DoubleAnimation();
            da.Duration = TimeSpan.FromMilliseconds(10);
            da.To = 0;
            da.BeginTime = TimeSpan.FromMilliseconds(Duration).Add(beginTime);

            Storyboard.SetTarget(da, li);
            Storyboard.SetTargetProperty(da, new PropertyPath("(UIElement.Opacity)"));
            Storyboard.Children.Add(da);
        }

        liCounter++;
    }
}

This is a lot of code! Fortunately this is the only major change to add the functionality we need. In the Begin method we set up our actions mentioned in the properties earlier. The completionAction is the action performed when all animations are completed, just like the original implementation. _actualBeginAction is the action the ActualBegin() method will execute upon completion. This will either be the completionAction, or an action to trigger the completion animation.

The completion animation is badly named, since it can run either at the start or the end of the feather animation.

After the actions are set up, we call the first animation. The first animation will then call the second animation, which will call the completionAction. So as an overview the method calls will be:

Completion animation first: Begin() > BeginCompletionAnimation() > HideListItems() > ActualBegin() > AnimationsCompleted() > CompletionAction()
Completion animation last: Begin() > ActualBegin() > BeginCompletionAnimation() > AnimationsCompleted() > CompletionAction()

We have an additional call to HideListItems() if the completion animation is run first. This is because the screen pivots in and then animates the list. The problem is if the list is visible from the outset you would see the list turnstile-in, then suddenly disappear and animate.

ActualBegin() is where we perform the actual Feather animation. We check the type of control passed in, and trigger the correct animation code. The code is largely the same between the two except for a little setup where we use the methods provided by the LongListSelector to get the containers for the visible elements. This means implementation on the surface is actually easier than with the ListBox where we have to work out which elements are visible.

AnimationsCompleted()

So why do we have an additional method that we run at the end of the animation? This is neccesary to fix a bug in the LongListSelector where the control won’t respond to input from the user after the animation is completed. We call UpdateLayout() to trigger the LongListSelector to sort itself out. Finally we set the SelectedItem to null. This is an implementation detail I’ve found useful for myself – however, you may well want to remove this line. In essence by leaving the item selected, it is the last item to animate off of the list. However, I never want the item to remain selected, so I clear the selection automatically. This isn’t ideal behaviour for a professional control, so don’t go duplicating this kind of hideous hack in your own controls!

Finishing Up

Now we need to tweak the animators themselves to support the new functionality. Update the animators as follows:

public TurnstileFeatherBackwardInAnimator()
{
    this.IsBackward = true;
    this.Duration = 350;
    this.Angle = 50;
    this.FeatherDelay = 50;
    this.Direction = Directions.In;
    this.CompletionAnimation = new TurnstileBackwardInAnimator();
    this.RunCompletionAnimationFirst = true;
}
public TurnstileFeatherBackwardOutAnimator()
{
    this.IsBackward = true;
    this.Duration = 250;
    this.Angle = -80;
    this.FeatherDelay = 50;
    this.Direction = Directions.Out;
    this.CompletionAnimation = new TurnstileBackwardOutAnimator();
}
public TurnstileFeatherForwardInAnimator()
{
    this.Duration = 350;
    this.Angle = -80;
    this.FeatherDelay = 50;
    this.Direction = Directions.In;
    this.CompletionAnimation = new TurnstileForwardInAnimator();
    this.RunCompletionAnimationFirst = true;
}
public TurnstileFeatherForwardOutAnimator()
{
    this.Duration = 250;
    this.Angle = 50;
    this.FeatherDelay = 50;
    this.Direction = Directions.Out;
    this.HoldSelectedItem = true;
    this.CompletionAnimation = new TurnstileForwardOutAnimator();
}

And you’re done!

LongListSelector Scrolling

OK, I may have lied a little about you being done. The LongListSelector has one final issue when we animate, it doesn’t retain its scroll position. The easiest way to solve this is to sub-class AnimatedBasePage and perform the necessary ‘tweaks’ to the selector in the AnimationsComplete() method. But before I show you the code, you’ll need ‘Linq to Visual Tree’ by Colin Eberhardt. The code file is already included in the demo app. Now you’ve got the necessary code, you can add the AnimationsComplete() method to your newly created page class:

public class TransitionPage : AnimatedBasePage
{
    protected override void AnimationsComplete(AnimationType animationType)
    {
        if (animationType == AnimationType.NavigateBackwardIn || animationType == AnimationType.NavigateBackwardOut)
        {
            foreach (LongListSelector listBox in this.Descendants<LongListSelector>())
            {
                listBox.UpdateLayout();

                if (listBox.SelectedItem != null)
                    listBox.ScrollTo(listBox.SelectedItem);
                else
                {
                    object firstObj = listBox.GetItemsInView().Where(i => i != null).FirstOrDefault();

                    if (firstObj != null)
                        listBox.ScrollTo(firstObj);
                }
            }
        }

        base.AnimationsComplete(animationType);
    }
}

This code picks up if the animation is a backward one, and will automatically loop through all of the LongListSelectors (if you have multiple selectors across PivotItems or PanoramaItems they’ll all lose their position) and corrects their position.

Am I actually done now?

Yes, yes you are! It’s been a long road just to add a Feather Turnstile animation to a LongListSelector, but I believe it’s well worth it. The effect looks great and adds a great deal of professionalism to your app.

This concludes the ‘Transitions’ series of blog posts. As always, you can download the sample app here.

Issues

As with all things, there are a few gotchas. The first is the dreaded ‘AG_E_PARSER_BAD_TYPE’ error. This error can occur when you subclass AnimatedBasePage. To this date I still haven’t resolved the issue – it’s very inconsistent and affects some projects but not others. The easiest workaround is to use extension methods and call those from each individual page. It’s far from ideal and a simply hideous hack – but it does work.

The other issue you may get is a page simply refusing to navigate to another. Chances are you’re requesting a navigation too quickly – the page hasn’t finished initialising. The easiest solution in this case is to use the ‘OneShotDispatcherTimer’ from the Kawagoe Toolkit. You can use the timer like so:

OneShotDispatcherTimer timer = new OneShotDispatcherTimer()
{
    Duration = new TimeSpan(0, 0, 1)
};

timer.Fired += (object sender, EventArgs e) => NavigationService.Navigate(new Uri("/NextPage.xaml", UriKind.Relative));
timer.Start();
Posted by Dan in C#, Tutorials, Windows Phone, 0 comments