Gestures are a special type of a touch screen event. The term gesture is used for a variety of things in Android, from a simple touch sequence like a fling or a pinch to the formal Gesture class that we’re going to talk about later in this section. Flings, pinches, long presses, and scrolls have expected behaviors with expected triggers. That is, it is pretty clear to most people that a fling is a gesture where a finger touches the screen, drags somewhat quickly off in a single direction, and then lifts up. For example, when someone use a fling in the Gallery application (the one that shows images in a left-to-right chain), the images will move sideways to show new images to the user.

The first gesture we want to cover is the pinch. ...

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