Images and Scaling with Windows Runtime #WinRT #WPDev #Windev

With the advent of Windows Phone 8.1, developers have the option of using WinRT native XAML stack as opposed to the Silverlight XAML the only option with early Windows Phone iterations.

One of the differences between WinRT XAML and Silverlight XAML is scaling and like with fonts, & images, scaling can have a significant effect on the look and feel of an app.

The default behavior with Windows Phone 8 was the inherent Silverlight behavior of scaling the image to fit. This meant that unless a high-resolution image was used, the image would end up looking blurred. Windows Runtime takes a different approach.

Windows 8x supports multitudes of screen sizes, resolutions and DPI. Windows Phone now supports 4 resolutions. The way Windows Runtime deals with this is by allowing developer to specify multiple images to match certain scale factors.

Windows Store Apps Windows Phone Store Apps
1.0 (100% no scaling) 1.0 (100% no scaling)
1.4 (140% scaling) 1.4 (140% scaling)
1.8 (180% scaling) 2.4 (240% scaling)

The runtime would determine the scaling factor to use depending upon the screen size, resolution, DPI and the form factor of device in question. The developer is required to supply images for scaling 1; the other scale factors are optional. If they are supplied, they will be used if necessary.

There are two ways of supplying images to support multi-scaling support.

  • Specify image scale within the file name e.g. Image.scale-100.png or Image.scale-140.png
  • Create direct for each image scale and place images inside without specifying scaling like in 1. E.g. scale-100/Image.png or scale-140/Image.png

The attached project includes examples of both ways.

To use this and enable auto-scaling support, you specify the image as specified below

<Image Source="Assets/Iris.png" />
<Image Source="Assets/Iris2.png" />

Occasionally it is necessary to set the images from code. In those instances, one should query the windows runtime to determine the current scaling factor and return appropriate image resource.

var uri = new System.Uri("ms-appx:///Assets/Iris.png");
var file = await StorageFile.GetFileFromApplicationUriAsync(uri);

This will correctly detect the scaling factor and get appropriate file.

Alternatively, for Windows 8x, we can use DisplayProperties.ResolutionScale to determine current scaling and for Windows Phone, we can use DisplayInformation.RawPixelsPerViewPixel.

Uri uri = null;
#if WINDOWS_PHONE_APP
    var rawpixelperview = Windows.Graphics.Display.DisplayInformation.GetForCurrentView().RawPixelsPerViewPixel; 

    var Width = Convert.ToInt32(Window.Current.Bounds.Width * rawpixelperview); 
    var Height = Convert.ToInt32(Window.Current.Bounds.Height * rawpixelperview); 

    if(Width == 480 && Height == 800)
    {
        uri2 = new System.Uri("ms-appx:///Assets/scale-100/Iris2.png");
    }
    else if((Width == 720 && Height == 1280 ) || (Width == 768 && Height == 1280))
    {
        uri2 = new System.Uri("ms-appx:///Assets/scale-140/Iris2.png");
    }
    else
    {
        uri2 = new System.Uri("ms-appx:///Assets/scale-240/Iris2.png");
    }
#else
    switch (DisplayProperties.ResolutionScale)
    {
        case ResolutionScale.Scale100Percent:
            uri2 = new System.Uri("ms-appx:///Assets/scale-100/Iris2.png");
            break;

        case ResolutionScale.Scale140Percent:
            uri2 = new System.Uri("ms-appx:///Assets/scale-140/Iris2.png");
            break;

        case ResolutionScale.Scale180Percent:
            uri2 = new System.Uri("ms-appx:///Assets/scale-180/Iris2.png");
            break;
    }
#endif

var file = await StorageFile.GetFileFromApplicationUriAsync(uri);

It worth noting that images set in xaml and those done codebehind behave differently at least as far as size on screen is concerned. The only way to achieve correct size as visible in xaml is to set size to that of scale 1.0 image.

Supporting Accessibility

Windows Store apps support high contrast mode. The two available options are

  • Black background and white foreground
  • White background and black foreground.

To additionally support these two accessible image formats, you need to provide scale factor 1 images named / placed appropriately. I have excluded the high contrast images from sample as windows phone was using that by default.

Assets/Iris.scale-100_contrast-black.png

Assets/Iris.scale-100_contrast-white.png

or

Assets/scale-100_contrast-black/Iris2.png

Assets/scale-100_contrast-white/Iris2.png

Downloadable sample code can be downloaded here

Color Picker for #win8dev

I use colour picker across multiple projects on both windows phone and windows 8. Allowing users a choice of colour is a good thing from experience perspective. Whilst I found a number of solutions for Windows Phone, I never really found much for Windows 8.

Last year I ported the Coding4Fun ColorHexagonPicker to use with my TableClock app.Recenly working on Scribble I needed a broader range of colours and I decided to create an appbar control that conveniently lives in AppBar.

I have uploaded the source to Github. Feel free to fork and extent.

Screenshot (1)

 

WinRT and pointer manipulation #win8dev #winrtdev

We all know how Windows 8 introduced touch as a first class member in user input. If you have used Windows 8 it feels intuitive to touch.. hell I used to touch my non-touch laptop occasionally and not because I wanted to fondle it :)

Rewinding a bit.. in Silverlight and Windows Phone, we had a nice historic Touch.FrameReported event. This was the fastest way to detect pointer / touch interaction on the screen. It also supported multi-touch detection by means of exposing TouchFrameEventArges.GetTouchPoints.

We also know how famously .NET components were sliced and diced (lets leave it for some other time when I have had a drink or two). So its only natural that WinRT 1.0 native XAML didn’t have Touch.FrameReported.

The other high level mechanism for touch event detection was the set of manipulation events
* UIElement.ManipulationStarted
* UIElement.ManipulationDelta and
* UIElement.ManipulationCompleted

These made it to WinRT 1.0 XAML.. However there were changes. Now it comes armed with ManipulationMode.

The MEME RTFM definitely applies to me – I never read the manual… When we had proper MSDN lib for documentation it was all good.. now documentation is all over the place.. (Damn it… need to focus more… another thing to talk over a drink).

So what happened.. why trying to detect touch / pointer events, I started using Manipulation events but hell no.. the event’s just wouldn’t get called.. The mode has tons of options but to handle it yourself you need to set the ManipulationMode to All. Someone remind me something.. If I declare a bleeding event handler.. isn’t my intention already pretty clear ? (Something every logical from .NET lost in translation on its way to WinRT design).

So eventually I got that to work by setting ManipulationMode to All. Surprise surprise, the manipulation event args only expose a few things like Position and PointerType…So this definitely can’t do multi-touch.. sure it will detect all the touch inputs but it can’t tell the difference the two fingers!!

Time to give it the middle one and start looking at alternatives. Previously in WPF / Silverlight we had Mice events
* UIElement.MouseLeftButtonDown
* UIElement.MouseLeftButtonUp
* UIElement.MouseMove

Those didn’t directly made it. WinRT merged Mice and Touch events into Pointer events. So now we have
* UIElement.PointerPressed
* UIElement.PointerReleased
* UIElement.PointerMoved

The PointerRoutedEventArgs that are passed to the event handers not only give you current position and intermediate positions, they also give you access to Pointer associated with the event. Each touch point / mice button gets a unique id. This way you can detect activity of each touch points over the screen.

The post is very verbose and lot of gibberish.. let me throw some code snippet to lighten it up :)

private void LayoutRoot_PointerMoved(object sender, PointerRoutedEventArgs e)
{
    Point position2 = e.GetCurrentPoint(this.LayoutRoot).Position;
    Pointer pointer2 = e.Pointer;
    FreeSketch(position2, pointer2);
}

private void FreeSketch(Point position2, Pointer pointer2)
{
    if (bDraw && pointer1.PointerId == pointer2.PointerId)
    {
        Line l = new Line()
        {
            X1 = position1.X,
            Y1 = position1.Y,
            X2 = position2.X,
            Y2 = position2.Y,
            StrokeThickness = 5,
            Stroke = new SolidColorBrush(Colors.Blue),
            Fill = new SolidColorBrush(Colors.Blue)
        };
        this.LayoutRoot.Children.Add(l); // adding to canvas
        this.position1 = position2;
    }
}

Happy coding

Search charm and user input gotchas #win8dev #winrtdev

A while back I implemented external and in-app search using search charm. This means that from anywhere in the app or even from main metro start screen, the user can start typing (which causes search to popup) and assuming they choose Cineworld, the search is passed off to my app.

Fast forward about 2 months back when I was implementing user submitted reviews for films and cinemas. I realised that the text input wouldn’t accept a single character – instead would keep showing the search charm….

aayyee.. that’s the search implementation… so I needed to selectively disable it depending upon where user is and what the user is up to.. trying to implement something meant going to layoutaware page so I don’t have to keep doing this.. whilst I was trying to figure out what to do next, I came across AllowSearch method.. strange.. then it occurred to me that I had added that while I was implementing search

 

protected void AllowSearch(bool bAllowed)
{
    SearchPane.GetForCurrentView().ShowOnKeyboardInput = bAllowed;
}

 
so I went about calling this.AllowSearch(false); in pages where I didn’t want search enabled.

Fast forward a bit closer, last week, I was using WebView allow ticket purchase in-app.. I tried clicks etc but not the full login etc as I know that already works and that’s implemented by Cineworld themselves.. I submit that app and a user contacts me saying.. they can’t book tickets.. search charm keeps popping up…

Damn it.. I had totally forgotten about AllowSearh method. Lets hope this serves as a reminder to myself to remember this in future.
Happy coding

WebView and working with C# and XAML #win8dev

Many of my Cineworld app users whether its Windows Phone or Windows 8 complain about lack of in-app ticketing. In fact I would personally as a user prefer otherwise – Use tried and trusted website for ticketing as opposed to an app – sure my app might be good enough to be an official app but that’s a different issue.

So what did I do, well for Windows Phone 7 and 8, I used WebBrowser control and added in-app use of Cineworld mobile website. Most users are happy – can’t please everyone. I do remember that WebBrowser control offered many more events for management in Windows Phone 8 than in Windows Phone 7. So how about Windows 8 ?

Well Windows 8 / WinRT 1.0 ships with WebView control. This is similar is many ways to Windows Phone 7 WebBrowser control. Why do I say that ? Well, it contains LoadCompleted event to inform about page loaded but no loading event. Doesn’t expose the internal navigation stack and is substantially more painful than Windows Phone 7 Browser Control :|

I am also aware that Windows 8.1 / WinRT 1.1 (??) ships with much improved WebView that exposes all the relevant event without hacks

Navigating Event: A quick search on the net found me Limitations of the WebView in Windows 8 Metro Apps. The post along side How to emulate Navigating event in the WebView turned out to be very useful. I used the WebViewWrapper to add Navigating event.

LoadCompleted Event: This event was exposed by the WebView and I used both maintain NavigationStack and toggle progress ring visibility

Progress Ring: Nothing can sit on top of WebView – no matter what order you define the elements in XAML. One needs to set WebView to collapsed visibility to show any other xaml content. I tend to toggle opacity to 0.5 and then show progress ring however this was a kill-joy till I found this “How to put a ProgressRing over a WebView” – easy peasy.. use WebViewBrush and paint a rectangle and hide the webview.. user cant really tell :)

Navigation Stack: Most pages in a Windows 8 apps expose back button. By default the back button calls GoBack defined in LayoutAwarePage.cs. It is however overrideable. So what should be behaviour be ? Well if you have been browsing a few pages, backbutton should ideally unwind that stack. Since WebView doesn’t really expose Nav Stack (just like Windows Phone 7 API), we need to do the dirty work. Use Completed to push the Uri. On Back button press pop the Uri. Apart from that, we just use InvokeScript to use browser’s internal nav stack using javascript.

<Grid Background="#FF231F20">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>

    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="Auto"/>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>

    <WebView Grid.Row="0" Grid.RowSpan="2" Grid.Column="1" x:Name="wbCineworld" />
    <Rectangle Grid.Row="0" Grid.RowSpan="2" Grid.Column="1" Name="MaskRectangle"/>

    <Grid x:Name="gProgress" Grid.Row="0" Grid.RowSpan="2" Grid.Column="0" Grid.ColumnSpan="2" HorizontalAlignment="Stretch" VerticalAlignment="Center" Height="100" Background="White" Visibility="Collapsed">
        <ProgressRing x:Name="prProgress" HorizontalAlignment="Center" VerticalAlignment="Center" IsActive="True" Height="80" Width="80" Foreground="#FFB51C10"/>
    </Grid>

    <Button x:Name="backButton" Click="GoBack" IsEnabled="{Binding Frame.CanGoBack, ElementName=pageRoot}" Style="{StaticResource BackButtonStyle}"/>
    <Button Grid.Column="0" Grid.Row="1" VerticalAlignment="Bottom" x:Name="btnExitTicketing" Style="{StaticResource DeleteAppBarButtonStyle}" AutomationProperties.Name="Exit ticketing" Click="btnExitTicketing_Click" />
</Grid>
public sealed partial class InAppBrowser : Cineworld.Common.LayoutAwarePage
{
    public InAppBrowser()
    {
        this.InitializeComponent();

        var wrapper = new WebViewWrapper(this.wbCineworld);
        wrapper.Navigating += WrapperNavigating;
    }

    void WrapperNavigating(object sender, NavigatingEventArgs e)
    {
        this.SpinAndWait(true);
    }

    private Stack<Uri> NavigationStack = new Stack<Uri>();
    public static Uri NavigationUri { get; set; }

    private void SpinAndWait(bool bNewVal)
    {
        WebViewBrush brush = new WebViewBrush();
        brush.SourceName = "wbCineworld";
        brush.Redraw();
        MaskRectangle.Fill = brush;

        this.wbCineworld.Visibility = bNewVal ? Windows.UI.Xaml.Visibility.Collapsed : Windows.UI.Xaml.Visibility.Visible;
        this.MaskRectangle.Opacity = bNewVal ? 0.5 : 1;

        this.MaskRectangle.Visibility = bNewVal ? Windows.UI.Xaml.Visibility.Visible : Windows.UI.Xaml.Visibility.Collapsed;

        this.gProgress.Visibility = bNewVal ? Windows.UI.Xaml.Visibility.Visible : Windows.UI.Xaml.Visibility.Collapsed;
        this.prProgress.IsActive = bNewVal;
    }

    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        base.OnNavigatedTo(e);

        this.wbCineworld.LoadCompleted += wbCineworld_LoadCompleted;

        this.wbCineworld.Navigate(NavigationUri);

        this.SpinAndWait(true);
    }

    void wbCineworld_LoadCompleted(object sender, NavigationEventArgs e)
    {
        this.SpinAndWait(false);
        NavigationStack.Push(e.Uri);
    }

    protected override void GoBack(object sender, RoutedEventArgs e)
    {
        if (this.NavigationStack.Count > 1)
        {
            this.wbCineworld.InvokeScript("eval", new string[1] { "history.go(-1)" });

            // note that this is another Pop - as when the navigate occurs a Push() will happen
            NavigationStack.Pop();
        }
        else
            base.GoBack(sender, e);
    }

    private void btnExitTicketing_Click(object sender, RoutedEventArgs e)
    {
        base.GoBack(sender, e);
    }
}

Let me just reiterate – I haven’t found something new, I have just found a few bits and have put them together. Happy coding.

Note: Meant to post this earlier.. I am checking NavigationStack.Count and ideally the check should be > 0 but in my case, there was an additional redirection and hence I am using Count > 1.

Persistent Thread like behavior with #win8dev

As you might have gathered, I
* like writing bad code
* doing things that people frown upon (like writing bad code)

Ever since I started Windows 8 Development, I miss Threads in all their glory. Sure Async Task is mostly fine but its not the same. Earlier today, Arafat asked a question about truly async logging mechanism. I suggested hacking Async Task into a thread like behaviour :) – actually it just gets you a threadpool thread :)

Task.Run provides a mechanism to queue given code on a ThreadPool for parallel execution. What happens when you refuse to return the method ? well you get the ThreadPool thread as your personal bitch :)

CancellationTokenSource CancellationSource = null;
CancellationToken TaskCancellationToken;

private async void AlwaysOnLoggingAsyncTask()
{
     while (!this.TaskCancellationToken.IsCancellationRequested)
     {
          // do something.. actually do anything
          // in the sample I was mucking around with StorageFile
          // hence the async void 

          await Task.Delay(1000); // don't kill the PC by running a tight loop.
     }
}

private async void btnStart_Click(object sender, RoutedEventArgs e)
{
     CancellationSource = new CancellationTokenSource();
     this.TaskCancellationToken = CancellationSource.Token;
     Task.Run(() => this.AlwaysOnLoggingAsyncTask(), TaskCancellationToken);
}

private void btnStop_Click(object sender, RoutedEventArgs e)
{
     CancellationSource.Cancel();
}

Here’s a dummy sample logging project that incorporates this bad code :)

Update: since I was writing really bad code, I deliberately forgot to add Task.Delay. If you prefer to not write code that makes system a bit less miserable, consider adding a Task.Delay of about 1000 (1 second)

Update 2: Jarno pointed out that I am writing really really bad code – mechanism dating pre-Task era – which is correct. Old habits die hard. Well I’ve update the blog plus source :P to use Task Cancellation Token

Changes to Windows Azure Mobile Service and what they mean

Just over a month and half back, Windows Azure team released the Mobile Services. In addition to announcing paid services, they severely restricted the Free tier to the extent that it was not usable. The initial statement I got from them was that Free tier was meant for Testing. So what happened next ? I got it all up in my head and started a user voice. I talked to as many Windows Phone and Windows 8 developers as I could to tell them about it and to ask for their votes.

While I was vote gathering, I was also talking to Azure team and we discussed some stats on what is acceptable for free tier. We discussed the fact that 100 devices a month wasn’t really well thought-out idea and that it needed change. They agreed to increase the number and took on my suggestion of a daily device count as opposed to monthly device count.

The reasoning behind this is simple. If a user downloads your app, plays with it for 5 minutes but never ever uses your app, the user would have impacted the limited device count for whole month. With a daily limit, the new installs only impact for 24 hours not 30 days.

Last night Dinesh Kulkarni a Program Manager at WAMS acknowledged the user voice, closed it and updated the WAMS pricing document to reflect the changes that were in plan for good part of last month.

So what do we get now ?
Instead of 100 unique devices a month, we get 500 unique devices per day.

It is also worth noting Free tier isn’t covered by SLA and that its not monitored. Azure team will fix any issues on the Free tier (when identified) however Free tier services aren’t actively monitored – unlike the Standard and Premium tier that feature active monitoring to meet the SLA.

Additionally the 500 devices a day for Free tier are applicable across all your mobile services – not one. If you have 1 WAMS, you get 500 devices a day, if you have 10, you still only get 500 a day between all 10 services.

And finally what happens when your service registers 500 devices and additional devices keep coming ?
Well the service will stop servicing requests (not sure whether its for additional devices or across all) and will become available after 24hour device count reset.
The service would otherwise be untouched.

I think this is a satisfactory conditions imposed on Free tier. WAMS team would like to be cost neutral and for popular high device count / high volume app, they would like you to use paid SLA driven tiers.

I’d like to thank the Windows Azure Mobile Services team Josh Twist, Kirill Gavrylyuk and Dinesh Kulkarni for being open to the suggestion and of course all the Windows Phone and Windows 8 developers who took time to vote on the user voice. Without the developers, my whinging would have gone unheard. Thank you