We've Come a Long Way Baby - WriteableBitmapEx now on GitHub

The WriteableBitmapEx project is now 6 years old and times have changed since all began. It all started with Silverlight and more XAML flavors were added over time until all XAML flavors were supported including Windows Phone, WPF, WinRT Windows Store XAML, (Windows 10) UWP and still Silverlight.

The version control system and open source services landscape has changed as well and the CodePlex infrastructure has not been too reliable recently. That's why I finally took the time to move the WriteableBitmapEx source code from CodePlex' SVN bridge to Git and make it available on GitHub: https://github.com/teichgraf/WriteableBitmapEx
Additionally was the open source license changed from Ms-PL to MIT which should simplify the usage as well. See the Codeplex Issue Tracker for a list of features that will be added in the future. Please use the GitHub Issues functionality to add new issues which are not already reported. Of course the latest binaries will continue to be distributed via NuGet.

Breakdown of Windows Phone App Download Statistics

Line Graph by Scott Lewis, Noun

In this blog post I want to share the download graph of my quite successful Windows Phone app Pictures Lab and my conclusions. Some of you might have seen a similar graph already on Twitter or on Facebook, but I thought an update and a bit more explanation might probably make sense.





The graph below shows the download statistics of my Pictures Lab app during the last 9 months. The green line represents the daily downloads and the orange are the accumulated downloads. I blurred the numbers at the scales, since I don't release the download number for various reasons. Please note, Pictures Lab offers a trial mode which means users can try the app for free. Therefore the download numbers aren't equal to the number of sold licenses! Although the app has a pretty good conversion rate from trial-to-paid of ~32% worldwide average and in December it even was 97% in Norway! I noticed that all the Scandinavian countries seem to have a great conversion rate in general. Worst seems to be Hong Kong, but that's a story for a different blog post. Just to be clear, Pictures Lab provides me with a solid extra income each month and the trend is positive, but it's not enough to make a living out of that yet.
The absolute download numbers actually don't matter that much for this blog post. The important part of the graph are the text labels I manually added. Those labels mark events I tracked and noted at that time and are usually followed by a download peak.

Pictures Lab download graph from 04-01-2011 to 01-07-2012 (click on the image for the original size).

My conclusions

1. Steadily releasing updates with new functionality and being featured at the Windows Phone sites has a big impact on the downloads. Keep in mind the major Pictures Lab updates were featured at least at 3-5 of the top Windows Phone sites.
2. Being featured at the Marketplace also has a significant positive impact on downloads. Of course this depends on how big the local Marketplace is. Unfortunately does the AppHub not provide the information when an app has been featured. There is the Distimo service which tracks that too, but that service needs your live id credentials and I won't give a 3rd party site my live id to store it in their database. Fortunately some of my friends ping me when they see my apps being featured in their local marketplace. I think it's pretty much safe to say that all the graph peaks without a label nearby are related to a Marketplace feature.  
3. The base line increased not only after the 3.0, but also after the peak of the 4.0 update. The 4.0 update brought the multi-language support with 10 languages. The steady download jump after 4.0 is a pretty good indication that localization can help to increase downloads.
4. The price drop to $0.99 was followed by the highest peak in the graph, but after that it went down pretty quickly. I think the price point is the hardest thing to get right and it largely varies for different kind of apps, so the above Pictures Lab pricing information shouldn't be generalized.   
5. Of course Christmas, the holidays and New Year also resulted in nice peaks. Customers have time to browse the marketplace or just want to fill up their brand new Windows Phones with some apps.

What about the Windows Phone 7.5?
The first Windows Phone 7.5 (previously known as Mango) devices and Nokia hit the market in October and November 2011. This fact also needs to be considered when interpreting the graph. Although from looking at the statistics of my other apps I see that Windows Phone 7.5 didn't have such a huge impact like the updates had. The downloads definitely increased due to the Windows Phone 7.5 launch, but the tracked events align very well with the peaks in the graph and the increase of the base line after.
Let me try to clarify this and my conclusion #3 with the graphs of my successful Helium Voice Free app and my not so successful Benchmark Free app.

Helium Voice Free got a nice update in November, but I didn't inform the Windows Phone sites, so there are no peaks in the graph. You can see that the release of Windows Phone 7.5 slightly increased the downloads and the downward trend turned into an upward trend.

Helium Voice Free graph from 04-01-2011 to 01-07-2012 (click on the image for the original size to see numbers).

In the Benchmark Free download graph there's also this small increase of the average downloads around the Windows Phone 7.5 device launch, but it's not as much as after the updates of Pictures Lab.

Benchmark Free graph from 04-01-2011 to 01-07-2012 (click on the image for the original size).

Considering all that information, I think this means the Windows Phone 7.5 launch of course raised the downloads base line, but the Pictures Lab updates had a bigger impact on the downloads and it's not only the Windows Phone 7.5 launch which raised the average downloads of Pictures Lab.
Keep in mind that such a statistical analysis isn't bullet-proof at all, esp. when there's not all the information available like the date of all marketplace features and more. Please also note not all apps are the same and things that work for Pictures Lab or Helium Voice Free don't necessarily need to be valid for other apps.

Makes sense?
What are your conclusions?

What is your experience?

Thank you!

I would like to thank all the users of the app, the great group of translators who helped me to translate Pictures Lab, the beta testers and not at last all the great Windows Phone sites which keep us informed about all the things happening around Windows Phone and help us developers by informing the world about our apps. Keep it up!

Let me out - Facebook Logout in a Windows Phone App

A while ago I implemented the Facebook photo endpoint into my Windows Phone Pictures Lab app. The implementation of the login was quite straightforward thanks to OAuth 2.0. Only the logout was way harder than one might expect. This post describes how to logout from Facebook using the Facebook API.






In my Pictures Lab app you can edit photos, make them look awesome and then save or share those with your friends at Twitter or Facebook. The Windows Phone Mango API provides the ShareLinkTask and the ShareStatusTask which can be used by an app to share an URL or text using the social services the user has connected the device to. Unfortunately there's no built-in SharePhotoTask to share a photo using the services the user has already authorized. That's why I had to implement it in a custom way where the user has to authorize again. This blog post by my mate Nick Randolph describes very well how to login to Facebook from a Windows Phone app.

For some situations it might make sense to allow the user to logout from within the app. One might think this can't be hard and in most cases it's pretty easy. Logging out from Twitter is very easy for example. You just have to start the authorization process again. However, logging out from Facebook is way harder since they store a cookie and the WebBrowser control doesn't provide a way to clear the cookies, so just starting the authorization process again doesn't work.
One way to log out from Facebook uses a special Uri that contains a part of the access token which was queried during the app authorization process.

Here's the snippet I use in Pictures Lab to split the access token to get the session key which is then used to build the custom Uri:

public Uri GetLogoutUri(FacebookCredentials credentials)
{
   var sessionkey = ExtractSessionKeyFromAccessToken(credentials.AccessToken);
   var url = String.Format("http://facebook.com/logout.php?app_key={0}&session_key={1}&next={2}", EndpointData.FacebookAppId, sessionkey, EndpointData.FacebookLogoutCallbackUrl);
   return new Uri(url);
}

private static string ExtractSessionKeyFromAccessToken(string accessToken)
{
   if (!String.IsNullOrEmpty(accessToken))
   {
      var parts = accessToken.Split('|');
      if (parts.Length > 2)
      { 
         return parts[1];
      }
   }
   return String.Empty;
}

That logout Uri is then used to navigate the WebBrowser control to it which then correctly triggers the log out process.

Browser.Navigate(FacebookService.GetLogoutUri(EndpointData.Settings.Facebook));

That's it. You just have to know their trick. Hope this helps.

SLARToolkit Samples Updated

The samples of my open source Windows Phone and Silverlight Augmented Reality Toolkit were updated to the latest version of the WP 7.1 and Silverlight 5 SDKs.
Please note the changed security model in Silverlight 5, which is a big bummer. My Silverlight MVP friend Morten wrote a few true words about it here.
As usual you can find a list of the samples on the project site and also get the code there.

Welcome to Zombieland, the Metro Style Land of WinRT and the Undead

Silverlight is dead! WPF is dead! .NET is dead! Hey, they didn't talk about SharePoint or SQL Server at the BUILD conference, those must be dead too. Welcome our new Metro-id overlords!
We read such FUD everywhere these days. Actually none of these technologies are dead for the next several years! And you'll probably agree if you know the facts and not the FUD. So here are my thoughts based only on the facts I got from watching BUILD sessions, reading posts that stick to the facts and not listening to people who obviously didn't inform themselves, but nevertheless spread FUD around.

What happened
Microsoft announced the new version of Windows at the BUILD conference and the new Windows 8 runtime called WinRT, which is used to develop Metro style Apps. Metro style Apps are primarily focused on consumers, designed touch first and therefore perfect for modern multi-touch devices like tablets.
The good ol' desktop is still there and the usual Windows applications are now called Desktop Apps.
There's a lot confusion out there at the moment and many think only Metro style Apps are the future. Actually both models can exist side-by-side and I'm sure the mainly used UI will be the classic desktop for the usual business client. Metro is for tablets, maybe later for the phone. Desktop Apps will still work better for the classic business PC scenario in an office.
After trying Windows 8 I don't see myself using Metro style Apps a lot on my PC when I work at the desk. However, I will love to use it when I'm hanging out on my couch with a tablet. The good news is, both models are supported by Windows 8 and therefore can run on one device, including ARM hardware. Awesome!

WinRT

First and foremost, .NET plays a significant role in both development models and is not only used for Desktop Apps. I guess the FUD comes from the architectural picture above, where .NET and Silverlight are only represented by a small box in the lower right corner. Of course Microsoft wants to push the new Metro style Apps, the WinRT model and wants to get web developers into the boat, so they adjusted the graphic and marketing message accordingly.
WinRT is actually a new native COM library, plus some extra infrastructure. Therefore an app developer has not to deal with the COM stuff directly, instead you get a thin / fast projection layer (binding) for each of the supported programming languages. This projection layer is automatically built using WinMD metadata and provides projections for JavaScript, .NET (C# / VB) or C / C++. The UI can be designed with XAML or HTML / CSS in case of JavaScript.
The rendering is completely done using DirectX 11.1 (Direct2D) which results in great performance. In Windows 8 the rendering job is finally fully executed by the right processor. This architecture makes it also possible to implement the complete UI just with DirectX, which will usually be done by games. At the moment it's not possible in the Windows 8 Developer Preview to mix a XAML app with DirectX, which doesn't make much sense since the XAML rendering is done by DirectX. Fortunately all hints that it'll be possible in a later version of Windows 8, maybe in the beta.

The below picture by Doug Seven is a way more accurate picture of the Windows 8 platform architecture.

There are a few good, unbiased posts about WinRT out there, which stick to the facts:
WinRT: An Object Orientated Replacement for Win32
WinRT, the C++ Component Extensions
WinRT demystified 
A bad picture is worth a thousand long discussions.
WinRT reference with all namespaces at the unbiased MSDN, where JaveScript is just another language one can use for Metro style Apps.

WinRT and .NET
From what I have seen so far, coding Metro style Apps using C# / .NET seems pretty straightforward if you've done Silverlight, WPF or esp. Windows Phone development before. The BCL used by .NET WinRT is not the full Desktop version of .NET 4.5, it's a reduced set similar to the Silverlight types.
The design of the native WinRT COM library was heavily influenced by .NET. You see it everywhere. Type names, Properties, Events... Even WinMD is the .NET assembly metadata format.
WinRT types map to .NET types and copying of data structures at the boundaries is avoided by the projection layer to get the best performance. Only two types need to be converted using built-in extension methods. The System.IO.Stream can't be mapped to the WinRT stream, so there's an extension method. A Byte[] to WinRT IBuffer conversion is the other extension method.
You can even write your own, custom WinRT components in C# without decorating the classes with ugly COM attributes. Those components are then automatically exposed to the other languages using the generic WinMD metadata. So you can write a component in C++ or in C# and use it from a JavaScript WinRT project. Pretty cool concept if you ask me.
Many WinRT classes look like their origin is .NET / Silverlight and the WinRT WriteableBitmap is also very similar to Silverlight's implementation. So expect a WinRT version of my open source WriteableBitmapEx library in a few weeks when I'm done with the Mango updates for all my Windows Phone apps. After that I will probably port / rewrite some of my WP7 apps for WinRT.

The lifecycle of a WinRT app should  be quite familiar for a WP7 developer, since it's similar to the WP 7.5 Mango Fast App Switching. The lifecycle states are: Running > Suspended in RAM > Terminated. Apps get an event for suspending, not for terminate, so the state has to be saved during suspending. Of course an app should only be resurrected from the tombstone state if the app was launched, not when resumed. Apps get 5s for suspending and need to launch within 15s. Unfortunately we don't know the reference machine where those values are measured. Probably the low end configuration.
By the way, the Windows Store will be the better version of the WP7 Marketplace. It will include In-App offers, time limited trials and a very nice dashboard with a lot of analytic capabilities and insights.
In general should a WP7 developer feel most familiar with WinRT. Many concepts made it into WinRT and were improved and actually cleaned up.
My Silverlight MVP friend Morten Nielsen started a blog post series about how to port Silverlight / WPF apps to WinRT.
You should also read this post: WinRT and .NET and watch the ton of great BUILD sessions.

Conclusion

I welcome the new possibilities and great performance we get in Windows 8 with the WinRT. I'm sure Windows 8 will be an awesome tablet OS.
XAML has become a first class citizen and .NET is now installed with Windows 8. Microsoft is also working on a next version of .NET. Version 4.5 of .NET will bring better performance for WPF's ItemsControl for example. Seems not very dead to me. In fact, a Silverlight / WPF / WP7 developer's knowledge of XAML and the Silverlight runtime is more valuable than ever before with WinRT.
Silverlight 5 is still in development and wasn't even released. We don't know if it will be the last version or if Silverlight 6 will see the light of the day. For now I'm quite happy with all the features of Silverlight 5 and we can develop a ton of applications for our customers for the next several years.

One should also not forget how long it will take until Windows 8 is finally out and reached a critical mass. A lot of machines out there still run Windows XP. Windows 7 is way better and I guess the transition to Windows 8 will take even longer. Windows 8 will probably mainly pushed by non-PC multi-touch consumer devices in the near future.

This flowchart by the Telerik guys sums it up pretty nicely.

So get yourself informed and start coding away. Don't give FUD a chance!

Imagine Cup 2011 Worldwide Finals

The Imagine Cup is one of the world's premier student tech competitions. Students compete in different categories like Software Design, Game Design, Windows Phone 7 and more. The competitions begin each year with local events in over 100 countries. The best of the best will then participate in the worldwide final.  The 2011 Imagine Cup Worldwide Finals will be held from 8 - 13 July in New York City, USA.

I'm very honored to take part in the Imagine Cup 2011 Worldwide Finals as a judge in the Windows Phone category. The Windows Phone judges consist of two community members and two Microsoft employees.

People's Choice Award
There's also a People's Choice Award where everyone can vote for their favorite team.

Can you say no if Eva Longoria asks you to vote?

You can find a list of all the Windows Phone finalist teams here. All the teams have built great solutions around the theme for 2011  Imagine a world where technology helps solve the toughest problems.
There's no filter for a category at the People's Choice Award website, that's why I made a list of all the Windows Phone finalists entries:

• DREGON by team "Digitron-WP7" from Belgium.
• Peekaboo by team "HOMERUN" from Korea.
• Hot Potato by team "Zipi Zigi" from Korea.
• Recyclocator by team "Code Instincts" from Singapore.
• Lifelens by team "The LifeLens Project" from USA.

Please cast your vote.

Nodo vs Mango - Windows Phone ListBox Performance Improvements in Action

There were quite a few complaints about the Windows Phone's ListBox scrolling performance in the past. The Windows Phone team obviously heard it and heavily worked on the performance and responsiveness of the whole platform and the ListBox in particular. The touch input processing was loaded off from the UI thread to a new separate thread. Additionally the BitmapImage doesn't load the data on the UI thread anymore. I'm sure lots of other tweaks were implemented to increase the performance and the responsiveness of the platform. I think the Windows Phone team did a very good job!

Showdown

The video below shows a side-by-side comparison of a Nodo device with build 7392 and a prototype device with a Mango prebuild. The Nodo device on the left side is a Samsung Omnia 7, the Mango device on the right side is the ASUS prototype.

For comparison I use the official Twitter app build against 7.0 and in the second half of the video I show the effects preview list of my Pictures Lab app. This effects pivot item only uses a ListBox with a DataTemplate that contains an Image control with a fixed size and a TextBox for each item. So there's no background image loading being performed or any other heavy computing, just a static list with a lot of redrawing.

Background music is Taiga by SMILETRON

As you can see, it's quite a huge difference and even this Mango prebuild  runs very smooth on this rather old ASUS hardware. There's still some room left for more improvement, like the rasterizer, but imagine the boost on production devices with the final Mango version.

MANGO, MANGO, MANGO!

I don't have a deal with Microsoft or are paid to blog or tweet this. I'm just exited about all the goodies that are coming with Mango. Good times.