"The primary goal of our touch language is to promote ease of use and ensure user confidence," said Jerry Koh and Jeff Piira, managers on Microsoft's Human Interaction Platform team, in a co-authored blog post.
Koh and Pirra said that, while Windows 8 will run reasonably well on touch computers built for Windows 7, Windows 8's unique characteristics mean that, new, Windows 8-specific hardware is required to experience the full potential of touch on the new operating system.
Most significantly, Windows 8 running in the Metro interface mode dispenses with the familiar Start button, and instead gives users access to key functions through what Microsoft calls the Charms bar. To access Charms, which presents options for Share, Search, Settings, Start, and Devices, users need to swipe the right edge of the screen.
"The edge swipe required to reveal charms and app bars fundamentally changes all the assumptions made on touch hardware," said Koh and Pirra. "Traditionally, the edges of the screen are where touch sensitivity drops off, and it's a place that hardware manufacturers have traditionally not placed much emphasis on. The center of the screen received all the innovation, while the edges have suffered. If you have seen or experienced the Windows 8 user experience, the edge swipe is a critical part of using Windows."
[ Buy a new iPad now, or wait for a Windows 8 tablet later this year? New iPad Vs. Windows 8 Tablets: 8 Considerations. ]
To ensure that hardware makers deliver Windows 8 PCs and tablets that offer consistent, edge-to-edge touch performance, Microsoft is vetting all OEMs' hardware designs before they are approved for sale as a Windows 8 device. "We worked closely with our hardware partners to figure out a design that will allow all pixels on a touch screen to be accurate and perform well," said Koh and Pirra.
They noted that on Windows 8 systems, full-screen apps will be able to take advantage of all pixels while still allowing users to trigger the Charms bar with an edge swipe. With Windows 7, by contrast, Microsoft created a 20-pixel buffer for edge swipes that was not available to apps. "There were many challenges here, but we were able to deliver on the promise of Windows 8 PCs that have the ability to trigger the edge swipe without taking any pixels from applications," said Koh and Pirra.
Also, Windows 8 will offer more touch points than Windows 7, which should be a boon to both developers and users. Most basic functions can be performed on a Windows 7 or Windows 8 device with just two fingers, but Windows 8 can support gestures that use five fingers. "This unlocks opportunities for developers to push the envelope with multi-touch applications," said the bloggers.
Microsoft has not confirmed a date for Windows 8's release, but some hardware makers have hinted that they may have Windows 8 systems for sale as soon as October.
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