Category: C#

Universal Windows Platform Application on Raspberry Pi

Universal Windows Platform (UWP) provides a common app platform on every device that runs Windows 10. The core APIs in UWP are the same on all Windows devices – including Desktop PC, Mobile Phone, XBox, Hololens, IOT devices and others. 

You can target specific device capabilities of a device family with extension SDKs, but you don’t have to do that if you are only using core APIs. Those core APIs include a very impressive set of UI capabilities. What that means is that you can create a UWP application using C# and XAML which will run on an ARM based processor on Raspberry Pi – because Windows 10 IOT Core runs on that.

Universal Windows Platform (UWP) has come a long way. I decided to dust off my good old Raspberry Pi 2B and take it for a spin last weekend.

The goal was simply to create a Hello World UWP application, deploy it on Windows 10 IOT running on Raspberry Pi (RPi), without using any device specific extension SDKs. Here is the stack – 

Create a simple UWP application in Visual Studio 2019. 

Install Windows 10 IOT Core on Raspberry Pi 2B and connect the device to a 50″ screen TV. 

Select ARM in the target platform drop down and Click on Remote Machine to Run/Debug Application on RPi device.

Select RPi device for deployment.

Deployment of UWP on RPi is complete. 

UWP application running on RPi. 

I updated the UWP application to include Syncfusion Chart control. Did you know that you can get a Community License for the entire product line (including Blazor, Xamarin and UWP controls) from Syncfusion?

UWP application is now running on RPi, attached to the Visual Studio debugger running on the development machine (Windows Surface). 

No device specific extension SDKs were referenced, just the core UWP APIs were used.

Code is on github.

Creating Android Apps using C# and Xamarin

You can create native Android and iOS applications using C#, with Xamarin. I explored the capabilities of Xamarin tools and the development experience with Xamarin to create an Android version of CensusMapper. CensusMapper displays U.S. Census data on a Map. I created the original application for Windows 8 (WinRT) using C#. I have since converted it to an MVVM (C#) application, HTML/Javascript (WinJS) version and more recently to a Universal Windows App running on Windows Phone 8.1 and Windows 8.1. In that tradition, now it is faithfully ported to run on Android devices, using C# and Xamarin. CensusMapper is available on Google Play Store.

censusmapper-android-on-nexus5

CensusMapper.Android shows population of each U.S. State. User can tap on a location on the map to show the population (as per 2010 census) of the zip code containing the selected location. User can select a location to view the population compared to the containing geography, as a pie-chart.

This experimental project helped me expand my cross-platform mobile application development skillset in the following areas:

  • Using Xamarin/C# to create an Android app using Xamarin Studio on a PC and a Mac.
  • Structuring C#/.NET source code in a Portable Class Library to allow reuse on Windows, Windows Phone, Android and iOS platforms.
  • Converting the functionality of an existing Windows Universal App (Windows Phone/ WinRT) to an Android app.
  • Using GoogleMaps API (via Google Play Services) to display data retrieved from U.S. Census API.
  • Using Bing Maps API for reverse geocoding in an Android app.
  • Creating custom markers using low-level API in Android.Graphics namespace to display information on the map.
  • Charting with oxyplot cross-platform charting library.
  • Working with Android SDK, AVD Manager as well as developer documentation and resources on Android and Xamarin websites in the development lifecycle of the app.
  • Publishing an app on Google Play Store.

I started with Xamarin.Forms.Maps. It was quick and straight forward to create a Xamarin.Forms app. The tricky part was creating the custom markers (the shape of speech bubble) on the map, instead of using the default push-pin markers . I tried creating a CustomRender to create custom markers and built interactivity with the map elements, but it turned out to be too much hassle. All of that customization would be specific to Android platform only and not reusable on the iOS anyway. So, I decided against using Xamarin.Forms and work directly with Google Maps library. Xamarin.Forms also limits me to Windows Phone 8 compatibility in my PCL. I can’t use Windows Phone 8.1 in any PCL profile compatible with Xamarin.Forms. It also requires a minimum of Android 4.0. The PCL profile # 111 for sharing code between Windows 8, Windows Phone 8.1 as well as Android and iOS, is not compatible with Xamarin.Forms at the time of writing this.

pcl-profile-111

Don’t use the Android emulator for testing. Get a real device. I stopped using the emulator while working on CensusMapper because GooglePlayServices (GPS) dependency was making me jump through way too many hoops. Debugging map functionality on the real device was a much more productive experience. Then I discovered Xamarin’s Android Player. It is awesome. By all means, use it! It is a pleasure to work with, especially on a Mac. Don’t be discouraged by the preview/beta status. It blows the Android SDK virtual devices out of the water, in terms of performance and usability.

I tested on Google Nexus 4 (Android 4.2), Samsung Galaxy SIII (Android 4.3) , BLU Dash JR (Android 4.4) and an older Coby Kyros tablet (Android 2.2). Google Play Services update, required for the app to work, could not be installed on BLU device because of the limited storage space. You must root the device in order to install the GPS updates on an SD card. It is advisable to have a root-friendly device. Google Nexus devices are excellent development devices, allowing you root access and the ability to load custom ROMs. However, it is very important for you to get a few different kinds of devices of various form factors and Android versions/API levels for testing your app’s functional and non-functional aspects.

Android device logs and the IDE build logs are the most important tools you have to resolve problems encountered in the Android app development with Xamarin. These should be the first places to look when troubleshooting issue.

Versions used in this project:
Xamarin 3.8.
Xamarin Studio 5.7
Xamarin Android 4.20.0

Get it on Google Play

Using Layer Diagrams – Keeping your MVVM code from turning into spaghetti

Raleigh Code Camp 2013 is wrapping up this afternoon. The venue and the crowd was phenomenal. I really enjoyed presenting “Using Layer Diagrams – Keeping your MVVM code from turning into spaghetti”. Thanks to everyone who attended the presentation.

John Sonmez, Our Keynote Speaker, made my day by accepting my request to attend my presentation. It was awesome to have him in the audience and to get feedback from him!

I did not get the time to complete the raffle at the end of the presentation. But the folks who won the raffle should be getting an email from me with instructions to download their free license of CodeDemo (Professional).

The presentation slides can be downloaded from here : download.

 

 

Understanding and Using System.Transactions

These are some resources to help grasp System.Transactions functionality and use it effectively in your projects:

Features Provided by System.Transactions
http://msdn.microsoft.com/en-us/library/vstudio/ee818755(v=vs.100).aspx
Implementing an Implicit Transaction using Transaction Scope
http://msdn.microsoft.com/en-us/library/vstudio/ee818746(v=vs.100).aspx
MSDN Articles by John Papa
ADO.NET and System.Transactions
http://msdn.microsoft.com/en-us/magazine/cc163847.aspx
Revisiting System.Transactions
http://msdn.microsoft.com/en-us/magazine/cc163527.aspx
These are specific to TransactionScope (the way to go in most cases)
Here is a practical example of Using TransactionScope :
http://thewayofcode.wordpress.com/2011/12/11/handling-transactions-in-net-using-transactionscope/
This one gets in depth with the way a TransactionScope like functionality can be implemented. Gives you a good understanding of what is happening under the hood when using TransactionScope in some Repository implementations in multi-threaded scenarios.
http://msdn.microsoft.com/en-us/magazine/cc300805.aspx
Here is another example of implementing a transactional repository :
http://www.codeproject.com/Articles/31270/A-Transactional-Repository-Implementation-in-NET
There are excellent tips here about configuring TransactionScope when used with SQL Server:
http://blogs.msdn.com/b/dbrowne/archive/2010/06/03/using-new-transactionscope-considered-harmful.aspx
This is a good resource for CommitableTransaction usage – http://www.codeproject.com/Articles/55472/Committable-Transactions-in-C-SQL
And this one has brilliant under-the-hood coverage – http://www.codeproject.com/Articles/35087/Truly-Understanding-NET-Transactions-and-WCF-Impl

Using Model-View-ViewModel in WPF Applications

I am presenting at SoCalCodeCamp this weekend (January 30th, 2010) – Advanced WPF – Using Model-View-ViewModel in WPF Applications.

tasklist-mockup
tasklist-mockup

Agenda :

1. Roles of the M-V-VM triad
2. Why use M-V-VM ?
3. Characteristics of the ViewModel
4. Build a Sample WPF Application using M-V-VM



Resources :

  1. MSDN Magazine Article and Sample Application Download
  2. Martin Fowler’s description of the ‘Presentation Model ‘
  3. Jeremy Miller’s ‘Build Your Own CAB’ series

Job Opening – Windows GUI Developer

We have a 3-4 month contract position open for a Windows GUI Developer in our group at Calabasas, California:

  • 2+ years experience developing C++/C# Windows thick-client applications
  • Expert in GUI development on Windows
  • Expert in Object Oriented Analysis and Design (OOA/OOD)
  • Deep understanding of client-server software development
  • Experience in multithreading, and thread synchronization
  • Excellent communication skills (written and verbal)
  • Highly organized and detail oriented
  • BSCS/BSEE or equivalent

If you are interested, contact me. The position is available now.