Call Windows Runtime APIs in desktop apps

You can use Universal Windows Platform (UWP) APIs to add modern experiences to your desktop apps that light up for Windows 10 users.

First, set up your project with the required references. Then, call Windows Runtime APIs from your code to add Windows 10 experiences to your desktop app. You can build separately for Windows 10 users or distribute the same binaries to all users regardless of which version of Windows they run.

Some Windows Runtime APIs are supported only in desktop apps that have package identity. For more information, see Available Windows Runtime APIs.

Modify a .NET project to use Windows Runtime APIs

There are several options for .NET projects:

• Starting in .NET 5, you can add a Target Framework Moniker (TFM) to your project file to access WinRT APIs. This option is supported in projects that target Windows 10, version 1809 or later.
• For earlier versions of .NET, you can install the Microsoft.Windows.SDK.Contracts NuGet package to add all necessary references to your project. This option is supported in projects that target Windows 10, version 1803 or later.
• If your project multi-targets .NET 5 (or later) and earlier versions of .NET, you can configure the project file to use both options.

.NET 5: Use the Target Framework Moniker option

This option is only supported in projects that use .NET 5 (or a later release) and target Windows 10, version 1809 or a later OS release. For more background info about this scenario, see this blog post.

With your project open in Visual Studio, right-click your project in Solution Explorer and choose Edit Project File. Your project file should look similar to this.

Replace the value of the TargetFramework element with one of the following strings:

• net5.0-windows10.0.17763.0: Use this value if your app targets Windows 10, version 1809.
• net5.0-windows10.0.18362.0: Use this value if your app targets Windows 10, version 1903.
• net5.0-windows10.0.19041.0: Use this value if your app targets Windows 10, version 2004.

For example, the following element is for a project that targets Windows 10, version 2004.

Save your changes and close the project file.

Earlier versions of .NET: Install the Microsoft.Windows.SDK.Contracts NuGet package

Use this option if your app uses .NET Core 3.x or .NET Framework. This option is supported in projects that target Windows 10, version 1803 or a later OS release.

Make sure package references are enabled:

1. In Visual Studio, click Tools -> NuGet Package Manager -> Package Manager Settings.
2. Make sure PackageReference is selected for Default package management format.

With your project open in Visual Studio, right-click your project in Solution Explorer and choose Manage NuGet Packages.

In the NuGet Package Manager window, select the Browse tab and search for Microsoft.Windows.SDK.Contracts .

After the Microsoft.Windows.SDK.Contracts package is found, in the right pane of the NuGet Package Manager window select the Version of the package you want to install based on the version of Windows 10 you want to target:

• 10.0.19041.xxxx: Choose this for Windows 10, version 2004.
• 10.0.18362.xxxx: Choose this for Windows 10, version 1903.
• 10.0.17763.xxxx: Choose this for Windows 10, version 1809.
• 10.0.17134.xxxx: Choose this for Windows 10, version 1803.

Click Install.

Configure projects that multi-target different versions of .NET

If your project multi-targets .NET 5 (or later) and earlier versions (including .NET Core 3.x and .NET Framework), you can configure the project file to use the Target Framework Moniker to automatically pull in the WinRT API references for .NET 5 and use the Microsoft.Windows.SDK.Contracts NuGet package for earlier versions.

With your project open in Visual Studio, right-click your project in Solution Explorer and choose Edit Project File. The following example demonstrates a project file for an app that uses .NET Core 3.1.

Replace the TargetFramework element in the file with a TargetFrameworks element (note the plural). In this element, specify the Target Framework Monikers for all the versions of .NET you want to target, separated by semi-colons.

• For .NET 5 or later, use one of the following Target Framework Monikers:
  • net5.0-windows10.0.17763.0: Use this value if your app targets Windows 10, version 1809.
  • net5.0-windows10.0.18362.0: Use this value if your app targets Windows 10, version 1903.
  • net5.0-windows10.0.19041.0: Use this value if your app targets Windows 10, version 2004.
• For .NET Core 3.x, use netcoreapp3.0 or netcoreapp3.1.
• For .NET Framework, use net46.

The following example demonstrates how to multi-target .NET Core 3.1 and .NET 5 (for Windows 10, version 2004).

After the PropertyGroup element, add a PackageReference element that includes a conditional statement that installs the Microsoft.Windows.SDK.Contracts NuGet package for any versions of .NET Core 3.x or .NET Framework that your app targets. The PackageReference element must be a child of an ItemGroup element. The following example demonstrates how to do this for .NET Core 3.1.

When you’re done, your project file should look similar to this.

Save your changes and close the project file.

Modify a C++ Win32 project to use Windows Runtime APIs

Use C++/WinRT to consume Windows Runtime APIs. C++/WinRT is an entirely standard modern C++17 language projection for Windows Runtime (WinRT) APIs, implemented as a header-file-based library, and designed to provide you with first-class access to the modern Windows API.

To configure your project for C++/WinRT:

• For new projects, you can install the C++/WinRT Visual Studio Extension (VSIX) and use one of the C++/WinRT project templates included in that extension.
• For existing projects, you can install the Microsoft.Windows.CppWinRT NuGet package in the project.

For more details about these options, see this article.

Add Windows 10 experiences

Now you’re ready to add modern experiences that light up when users run your application on Windows 10. Use this design flow.

вњ… First, decide what experiences you want to add

There’s lots to choose from. For example, you can simplify your purchase order flow by using monetization APIs, or direct attention to your application when you have something interesting to share, such as a new picture that another user has posted.

Even if users ignore or dismiss your message, they can see it again in the action center, and then click on the message to open your app. This increases engagement with your application and has the added bonus of making your application appear deeply integrated with the operating system. We’ll show you the code for that experience a bit later in this article.

Visit the UWP documentation for more ideas.

вњ… Decide whether to enhance or extend

You’ll often hear us use the terms enhance and extend, so we’ll take a moment to explain exactly what each of these terms mean.

We use the term enhance to describe Windows Runtime APIs that you can call directly from your desktop app (whether or not you have chosen to package your application in an MSIX package). When you’ve chosen a Windows 10 experience, identify the APIs that you need to create it, and then see if that API appears in this list. This is a list of APIs that you can call directly from your desktop app. If your API does not appear in this list, that’s because the functionality associated with that API can run only within a UWP process. Often times, these include APIs that render UWP XAML such as a UWP map control or a Windows Hello security prompt.

Although APIs that render UWP XAML typically cannot be called directly from your desktop, you might be able to use alternative approaches. If you want to host UWP XAML controls or other custom visual experiences, you can use XAML Islands (starting in Windows 10, version 1903) and the Visual layer (starting in Windows 10, version 1803). These features can be used in packaged or unpackaged desktop apps.

If you have chosen to package your desktop app in an MSIX package, another option is to extend the application by adding a UWP project to your solution. The desktop project is still the entry point of your application, but the UWP project gives you access to all of the APIs that do not appear in this list. The desktop app can communicate with the UWP process by using a an app service and we have lots of guidance on how to set that up. If you want to add an experience that requires a UWP project, see Extend with UWP components.

вњ… Reference API contracts

If you can call the API directly from your desktop app, open a browser and search for the reference topic for that API. Beneath the summary of the API, you’ll find a table that describes the API contract for that API. Here’s an example of that table:

If you have a .NET-based desktop app, add a reference to that API contract, and then set the Copy Local property of that file to False. If you have a C++-based project, add to your Additional Include Directories, a path to the folder that contains this contract.

вњ… Call the APIs to add your experience

Here’s the code that you’d use to show the notification window that we looked at earlier. These APIs appear in this list so you can add this code to your desktop app and run it right now.

Support Windows XP, Windows Vista, and Windows 7/8 install bases

You can modernize your application for Windows 10 without having to create a new branch and maintain separate code bases.

If you want to build separate binaries for Windows 10 users, use conditional compilation. If you’d prefer to build one set of binaries that you deploy to all Windows users, use runtime checks.

Let’s take a quick look at each option.

Conditional compilation

You can keep one code base and compile a set of binaries just for Windows 10 users.

First, add a new build configuration to your project.

For that build configuration, create a constant that to identify code that calls Windows Runtime APIs.

For .NET-based projects, the constant is called a Conditional Compilation Constant.

For C++-based projects, the constant is called a Preprocessor Definition.

Add that constant before any block of UWP code.

The compiler builds that code only if that constant is defined in your active build configuration.

Runtime checks

You can compile one set of binaries for all of your Windows users regardless of which version of Windows they run. Your application calls Windows Runtime APIs only if the user is runs your application as a packaged application on Windows 10.

The easiest way to add runtime checks to your code is to install this Nuget package: Desktop Bridge Helpers and then use the IsRunningAsUWP() method to gate off all code that calls Windows Runtime APIs. See this blog post for more details: Desktop Bridge — Identify the application’s context.

Related Samples

Find answers to your questions

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What is a Windows API? [closed]

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Closed 3 years ago .

What is a Windows API?

5 Answers 5

It’s a set of functions and data structures that a Windows program can use to ask Windows to do something, like opening a file, displaying a message, etc.

Pretty much everything that a Windows program does involves calling various API functions.

Collectively, all the API functions that Windows makes available are called «The Windows API».

It is not a Windows API, it is the Windows API, and in short it is the set of functions exposed by Windows that allows software to interact with the operating system.

The Windows API (Application Programming Interface) is the complete set of functions (exported by several DLLs) that enables each application to do what it has to do with almost no knowledge about the underlying hardware.

It consists of both functions and data structures (for example, each window has its own data structure).

A big difference between the Windows API and the (venerable) DOS API is that the DOS API only provided the basic OS functions like opening and closing files, and writing to the screen (which was slow, so most programs ignored this). A large portion of the Windows API has to do with Windows and its components (like buttons and edit boxes). That’s why windows applications have a more or less similar look and feel. DOS applications were completely different in appearance.

What is an API call?

Have you ever wondered: What is an API call? It sounds like you’re going to make a telephone call and talk about APIs. Well, if only it were that simple. Read more about APIs and how they unlock success.

API basics

Furthermore, to explain what an API call is, you start at the beginning and discover what an API is for starters. Per Wikipedia, an Application Program Interface (API) is a set of procedures and tools for building software applications.

These processes make it easier for developers to use certain technologies in building applications. APIs are everywhere these days. They are the simplest ways that companies integrate with each other. APIs are the building blocks that make it all come together. Read more about “What is an API” here.

Learn more about AMPLIFY API Management in this video.

With that said, the terminology has branched out for each category, propelling one to ask what’s an API call?

What’s an API call?

Now that you have the gist of what an API does, you must be wondering, what’s an API call? Simply put, whenever you make a call to a server using APIs, this counts as an API call. For example, every time you log in, ask a question on your computer or an app, you’re in fact making an API call.

Are you still confused? Have you ever downloaded an app? Sure, you have! There’s an app for everything from dieting and heart rate to learning a language or banking. I’m certain you may have noticed after you downloaded the app, you probably were asked or prompted to fill in your e-mail or a password, etc. From that point, you go and hit “enter” and your information gets sent to the API. Lo-and-behold, you have made an API call!

It’s that simple! An API call is the process that takes place after the API is set up and ready to go. With your API call, your information is sent and processed back to you.

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