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Chapter 17: Taps, Touches, and Gestures > The Swipes Application

The Swipes Application

The application we're about to build does nothing more than detect swipes, both horizontal and vertical. If you swipe your finger across the screen from left to right, right to left, top to bottom, or bottom to top, the app will display a message across the top of the screen for a few seconds informing you that a swipe was detected (see Figure 17–3).

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Figure 17–3. The Swipes application will detect both vertical and horizontal swipes.

Detecting swipes is relatively easy. We're going to define a minimum gesture length in pixels, which is how far the user needs to swipe before the gesture counts as a swipe. We'll also define a variance, which is how far from a straight line our user can veer and still have the gesture count as a horizontal or vertical swipe. A diagonal line generally won't count as a swipe, but one that's just a little off from horizontal or vertical will.


  

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