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Longhorn Pillars: Avalon


Microsoft’s aim for Longhorn is to make Windows a personal operating system that takes the experiences of users and their PC to a whole new level. With Longhorn, Microsoft is looking to new ways of utilizing the potential of your computer, and to make your computer be on the same level in terms of meeting the demands of your passion. Most of the experiences have to be realized visually in what the company describes as the "Visualize and Organize" part of their Longhorn strategy. Areas in central and graphical processing power from the CPU and GPU are critical when it comes to realizing the benefits of Longhorn.

Avalon, the presentation services for presenting information and media technologies in Windows Longhorn, also the engine for driving the graphics subsystem, which will be primarily supplied by the Video Graphics Card or Graphics Processing Unit (GPU), which is also responsible for redrawing Longhorn’s interface. Avalon represents a significant evolution of presentation technology, with the goal of allowing developers to easily build rich and compelling user interfaces that seamlessly integrate high-quality document and multimedia content.

The presentation technologies in “Longhorn” allows developers to deliver an exciting and compelling user experience by providing a full set of the pre-packaged UI components, multimedia support, and smooth integration of applications into the user interface. “Avalon” is designed to take advantage of the capabilities of specific hardware components, so that all applications use the power of the Graphics-Processing Unit, rendering high quality, next generation user interfaces.

Avalon is exposed mainly through managed code, so for the developer the architecture itself allows you to customize the API (Application Programming Interface) controls through inheritance. This allows a developer to maintain control of appearance and input functionality without rewriting code; for example, the keyboard is simply available without the developer having to program any part of its infrastructure. For Layout and Localization, Avalon allows you to resize the layout to accommodate localized content. New styles also allow you to give your applications a consistent look and feel.

Existing Win32 based applications should continue to work normally in Longhorn, but they will not be able to take advantage of the new features without some degree of adaptation to the new programming model.

Here are some scenarios where a Developer utilizing Avalon can enhance an existing Win32 based application, these include:

  • Using the “Avalon” user interface (UI) for dialog boxes of wizards.
  • Hosting the Avalon UI as a child of a Win32 window.
  • Redesigning the appearance of existing applications so that they resemble the Avalon UI.
  • Hosting a Win32 window as an element in the Avalon UI.
  • Hosting an ActiveX control as an Avalon element.
  • Replacing Win32 menus and toolbars with their Avalon equivalents.
  • Integrating Avalon command with Win32 commands.
  • Using drag-and-drop across Avalon and Win32.

Finally, Avalon graphics-rendering layer contributes new drawing and animation features to Longhorn. These features were previously provided by using specialized libraries, specifically the Windows Graphics Device Interface (GDI) and Windows GDI+. To accommodate developers working with existing unmanaged applications, Avalon’s Visual API provides limited interoperability between the Avalon Graphics System and GDI-based rendering services.


This feature information was obtained partially or in full from Microsoft at and are provided by for your convenience. For the most accurate information please visit the official site. Microsoft retains all intellectual property rights.


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