Xamarin.Forms: sharing resources in XAML using Styles

Previously, I’ve blogged about creating a custom Behavior in Xamarin.Forms. The sample published on GitHub initially used the default template available in Visual Studio which instantiates the Application singleton from C# using the following App class:

This is a great approach, however very often it is useful to define common resources in XAML and reuse them across the application using Styles.

To achieve this, It’s possible to transform the App class in a partial one and add a new App.xaml source file containing a resource dictionary to be shared:

In this code, I’ve defined a new resource with a specific Padding to be applied only on iOS via the OnPlatform class, and an explicit style named PageStyle targeting ContentPage types.

The modified code behind is now taking care of parsing/loading the XAML (via the InitializeComponent() call) and then creates an instance of SamplePage:

The page can now consume the new style specifying Style=”{StaticResource PageStyle}” (dynamic resources are also supported):

This is a basic example of using styles in Xamarin.Forms: a complete coverage of the various options is available on the Xamarin official documentation.

The source code is available for download here.

Xamarin.Forms: using the PanGestureRecognizer

Recently I’ve blogged about Xamarin.Forms and how to create a XAML Behavior for enabling Multi-Touch gestures to generic elements and implementing a scale / pinch functionality.

Fortunately the framework provides three types of recognizer that greatly simplify the implementation:

  • PinchGestureRecognizer allows user interactions for zoom / scale functionalities;
  • PanGestureRecognizer enables pan / translate transformations;
  • TapGestureRecognizer detects tap events.

Yesterday I decided to try the PanGestureRecognizer for extending the capabilities of the Behavior described in the previous post.

First of all, I added two Bindable properties in order to permit activation / deactivation of individual gestures (Bindable properties are equivalent to Dependency ones in UWP XAML)

In this way we can specify in our XAML what gestures are enabled:

Then I initialised the GestureRecognizers adding a new PanGestureRecognizer to the recognizers list:

And subscribed to the PanUpdated event in order to apply the translate transform:

The implementation of this event handler permits to update the X and Y coordinates of the element when a Pan gesture is detected:

Here we go: the sample app can now be deployed to the emulators and iOS / Android / Windows devices.

Just a couple of notes:

  • deployment to iOS required this workaround to work properly since the new sample app uses different assemblies;
  • Tap gestures on Android requires Xamarin.Forms – minimum version v2.1.0.6501-pre1 as pointed by the official documentation.

As usual, the latest source code is available for download on GitHub.

Having fun with Xamarin.Forms and Multi-Touch Behaviors

Recently Xamarin has released preview support for the Universal Windows Platform in their Xamarin.Forms framework so I have been playing around with version 2.0 for testing its features and verify how easy is to target multiple platforms (iOS, Android, Windows 10 UWP, Windows Phone, Windows 8.1) with a single codebase.

One of the experiments I have done is related to custom multi-touch gestures: the idea to use a XAML Behavior is a common scenario to write well structured code so I started creating a new Cross-Platform Xamarin.Forms Portable project and upgraded the NuGet packages to the latest stable version of the framework (currently v2.0.1.6505).

I have then read the official documentation and analysed the samples available on GitHub: a very good example is the PinchGesture one so, starting from it, I created a new MultiTouchBehavior implementing this gesture and attached the same Behavior to an Image object added to a sample ContentPage, as described below in this lovely cross-platform XAML 🙂

The BindingContext=”{Binding}” is used to trigger the BindingContextChanged event and initialise correctly the GestureRecognizers  for the parent object since the AssociatedObject.Parent is set to null when the Behavior.OnAttachedTo() is called (I suppose that the XAML tree is not yet completely created when the behavior is attached in Xamarin.Forms):

Here is the project deployed to the Android, iOS and Windows 10 emulators:

MultiTouch_Android_Emulator   Simulator Screen Shot 14 Feb 2016, 18.25.00   MultiTouch_Windows10_Emulator

I’ve been particularly impressed by Xamarin.Forms: the possibility to target so many platforms using the same code is a killer feature and the development environment is also very comfortable to use.

The sample code used in this post is available on GitHub, I’m planning to add more functionalities in the future with particular regard to other common multi-touch gestures using Xamarin.Forms and XAML.

XAML Behaviors, Windows 10 UWP and Open-Source

I’ve always been a great fan of XAML Behaviors: they help following good coding practices and keeping separation of concerns in your code. Ah, did I also mention that they help to write elegant code? 😉

Good news is that XAML Behaviors have been Open-Sourced and are available for download and contributions on GitHub: more information available in the official announcement here.

I already had fun submitting a couple of Pull Requests: head over to GitHub and enjoy!

NDepend v6 available

Version 6 of NDepend is now available for download from the official site.

New features include:

  • enhanced Visual Studio integration;
  • support for Visual Studio 2015;
  • rule files shareable amongst projects;
  • default rules description and HowToFix;
  • default rules less false positives;
  • colored code metric view;
  • intuitive display of code coverage percentage;
  • compiler generated code removal;
  • async support;
  • analysis enhancements;
  • support for Visual Studio Blue, Dark, Light themes;
  • support for high DPI resolution;
  • integration with TFS, SonarQube and TeamCity.

A detailed description of the new capabilities is available here.

Windows 10 UWP: Using PlayReady content protection with live DASH

I’ve recently blogged about using PlayReady content protection with Smooth Streaming on Windows 10 UWP by initialising a MediaProtectionManager object in the player element.

Since PlayReady is a technology for handling protected media content, it is possible to use it with different stream formats like Dynamic Adaptive Streaming over HTTP (DASH).

In the previous days, I have been exploring the live DASH sample available in the Universal Windows Platform repository on GitHub: the example enables playback of streams containing the profile “urn:mpeg:dash:profile:isoff-live:2011“.

It is possible to just add PlayReady content protection to this live player by initialising the MediaExtensionManager and then handling the MediaProtectionManager setup / ServiceRequested event:

The updated Visual Studio solution is available here on GitHub.

Smooth Streaming PlayReady samples for Windows 10 UWP available on GitHub

Lately I have been investigating PlayReady support available in the new Windows 10 Universal Windows Platform and found that the additional SDK necessary for Windows 8.1 Universal apps is not required for UWP since PlayReady Client is now part of the platform as described in this MSDN documentation.

When migrating Windows 8.1 apps to UWP, the key is to change the namespace from Microsoft.Media.PlayReadyClient to Windows.Media.Protection.PlayReady:

I have just pushed two samples on GitHub (C# and JavaScript) which also require the Universal Smooth Streaming SDK.

NDepend v5.0 available

I’ve just received my copy of NDepend v5.0: this new version adds several great features to the product including

  • Support for Visual Studio 2013 (yeah!)
  • New Dashboard Panel
  • Focusing on Recent Rules violation
  • UI Enhancements
  • Trend Monitoring
  • Churning Rules and Queries
  • Report Enhancements

Click here to read a detailed description of the new capabilities and access the download links (14 days trial available).

Happy coding!

Microsoft Patterns & Practices: Prism for the Windows Runtime – My favourite resources

As you may know, the Microsoft Patterns & Practices team has recently released the final version of  “Prism for Windows Runtime“, available for download here on CodePlex.

Prism for Windows Runtime

This project contains a complete guidance for building Windows Store apps using C# and XAML and includes the following resources:

Big kudos to all the p & p team: they did an amazing job and I personally felt honored to have the possibility of providing feedback whilst the project was in development.

This is really a great guidance for building Windows Store applications that can be easily tested, maintained and extended: every developer building complex apps will benefit from it.

Other useful links:

Happy coding everyone!

Using the Multi-Touch Behavior in a Windows Phone 7 Multi-Page application

In these days I’m receiving several questions in the Multi-Touch Behaviors forums about enabling Multi-Touch manipulations in Windows Phone applications composed by more than one page.

Today I’ve modified the available sample inserting an additional page containing an image enabled for translation, rotation, zoom and inertia via the usual “MultiTouchBehavior“:


Starting from release 0.6.1 it’s now possible to use the Behavior in different pages of the application, in this way enabling multi-touch in different elements of a Windows Phone 7 application.

As usually the sample code is available for download on http://multitouch.codeplex.com, check out the Visual Studio solution “SilverlightWP7MultiTouch.sln” which contains all necessary libraries.

Happy Silverlighting!