desarrollo03tr/splat

A library to make things cross-platform that should be

Splat

Certain types of things are basically impossible to do in cross-platform mobile code today, yet there's no reason why. Writing a ViewModel that handles loading a gallery of pictures from disk will be completely riddled with #ifdefs and basically unreadable.

Splat aims to fix that, by providing a usable leaky abstraction above platform code. It is leaky, because it always provides an extension method ToNative() and FromNative(), which converts the abstraction to the platform-specific version. Load the image in the cross-platform code, then call ToNative() in your view to actually display it.

What does it do?

Splat currently supports:

• Cross-platform image loading/saving
• A port of System.Drawing.Color for portable libraries
• Cross-platform geometry primitives (PointF, SizeF, RectangleF), as well as a bunch of additional extension methods to make using them easier.
• A way to detect whether you're in a Unit Test runner / Design Mode
• A cross-platform logging framework
• Simple yet flexible Service Location

How do I install?

Always Be NuGetting. Package contains binaries for:

• WPF (.NET 4.5)
• Windows Forms
• UWP
• Xamarin (Android, iOS and Mac)
• .NET Standard 1.0 and 2.0

Cross-platform Image Loading

//
// Load an Image
// This code even works in a Portable Library
//

var wc = new WebClient();
byte[] imageBytes = await wc.DownloadDataTaskAsync("http://octodex.github.com/images/Professortocat_v2.png");

// IBitmap is a type that provides basic image information such as dimensions
IBitmap profileImage = await BitmapLoader.Current.Load(imageBytes, null /* Use original width */, null /* Use original height */);

Then later, in your View:

// ToNative always converts an IBitmap into the type that the platform
// uses, such as UIBitmap on iOS or BitmapSource in WPF
ImageView.Source = ViewModel.ProfileImage.ToNative();

Images can also be loaded from a Resource. On Android, this can either be a Resource ID casted to a string, or the name of the resource as as string (optionally including the extension).

var profileImage = await BitmapLoader.Current.LoadFromResource("DefaultAvatar.png", null, null);

Bitmaps can also be created and saved - actually drawing on the image is beyond the scope of this library, you should do this in your view-specific code.

var blankImage = BitmapLoader.Current.Create(512.0f, 512.0f);
await blankImage.Save(CompressedBitmapFormat.Png, 0.0, File.Open("ItsBlank.png"));

Service Location

Splat provides a simple service location implementation that is optimized for Desktop and Mobile applications, while still remaining reasonably flexible. To get a type:

var toaster = Locator.Current.GetService<IToaster>();
var allToasterImpls = Locator.Current.GetServices<IToaster>();

Locator.Current is a static variable that can be set on startup, to adapt Splat to other DI/IoC frameworks. This is usually a bad idea.

The default implementation of Service Location also allows new types to be registered at runtime.

// Create a new Toaster any time someone asks
Locator.CurrentMutable.Register(() => new Toaster(), typeof(IToaster));

// Register a singleton instance
Locator.CurrentMutable.RegisterConstant(new ExtraGoodToaster(), typeof(IToaster));

// Register a singleton which won't get created until the first user accesses it
Locator.CurrentMutable.RegisterLazySingleton(() => new LazyToaster(), typeof(IToaster));

Logging

Splat provides a simple logging proxy for libraries and applications to set up. By default, this logging isn't configured (i.e. it logs to the Null Logger). To set up logging:

1. Register an implementation of ILogger using Service Location.
2. In the class in which you want to log stuff, "implement" the IEnableLogger interface (this is a tag interface, no implementation actually needed).
3. Call the Log method to write log entries:

this.Log().Warn("Something bad happened: {0}", errorMessage);
this.Log().ErrorException("Tried to do a thing and failed", exception);

For static methods, LogHost.Default can be used as the object to write a log entry for.

Using Cross-Platform Colors and Geometry

// This System.Drawing class works, even on WinRT or WP8 where it's not supposed to exist
// Also, this works in a Portable Library, in your ViewModel
ProfileBackgroundAccentColor = new Color(255, 255, 255, 255);

Later, in the view, we can use it:

ImageView.Background = ViewModel.ProfileBackgroundAccentColor.ToNativeBrush();

Detecting whether you're in a unit test runner

// If true, we are running unit tests
ModeDetector.InUnitTestRunner();  

// If true, we are running inside Blend, so don't do anything
ModeDetector.InDesignMode();