About Windows Touch (Windows)

About Windows Touch

This topic gives a brief overview of Windows Touch.

New hardware and API elements in the Windows 7 operating system provide applications the ability to receive input from multiple contacts. This gives such applications the ability to detect and respond to multiple simultaneous touch points on the application's visible surface. Functionality for this feature in Windows 7 is provided by a new message that reports and tracks touches. The new message, WM_TOUCH, reports the action (up, down, move), position, and an identifier for touch points. Windows Touch messages are generated by Windows and are delivered to windows that register for Windows Touch input.

In addition to the new touch input message, gesture messages have been added to the existing list of window messages. Messaging support for gestures is enabled by a single new window message (WM_GESTURE) that is sent or posted to appropriate application windows when user input is recognized as a gesture. Dedicated API functions encapsulate the details for creation and consumption of this message. This is done because the information associated with the message can change in the future without breaking applications that already consume this message.

In addition to gesture messages, specialized interfaces have been added to the Windows SDK. These interfaces enable advanced support for touch input so that application developers can easily create natural user interfaces. The IManipulationProcessor interface interprets WM_TOUCH messages to raise events that contain translation, rotation, and scale information about a collection of touch points. The IInertiaProcessor interface can be used in conjunction with the IManipulationProcessor interface to enable animation and ensure that objects stay on the user's screen when they are moved.

API elements for Windows Touch have some similarities to the Microsoft Surface SDK, but applications targeting Microsoft Surface do not run on Windows Touch computers. Also, applications targeting Windows Touch do not run on Microsoft Surface.

Some of the functionality of Windows Touch is built into the core of Windows 7. This functionality is available to users without the need for developers to explicitly enable support. However, to take full advantage of Windows Touch, developers must use the Windows Touch API. To get started with learning how Windows Touch works, see the Programming Guide or start with Choosing the Right Approach to Windows Touch.

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