Momentum Scrolling and the Infinite Canvas
The idea of treating a computer screen as a window onto content which exists “beyond” the borders of the frame has been one of the fundamental concepts of user interfaces for decades, from command line-based systems, to the graphical user interface, to the way we interact with content we read online. In a way, the endlessly scrolling pictures of Google Images or Pinterest, or the timeline feeds of Twitter or Facebook, are a kind of partial fulfillment of the infinite canvas concept, as they do feel almost literally infinite. They also share another common ancestry—Apple’s implementation of momentum scrolling, as introduced with the iPhone.
Before momentum scrolling, continuous navigation of a document often involved jittery animation, multiple clicks on multiple buttons, and very little in the way of precise control over speed. The multi-touch screen and the iPhone’s OS combined one-to-one motion with some simple simulated physics, and the result was extremely potent—so much so that Apple quickly brought the effect back to their desktop machines, where momentum scrolling soon proved significant in the evolution of digital storytelling, leading to an explosion of vertically scrolling sites like jessandruss.us that integrated parallax and animation into the scrolling effect.
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Another landmark scroller was the much-discussed Snow Fall from the New York Times, which triggers video and animation depending on where in the page the user scrolls, with fluid transitions and clean design that have sparked a whole genre of imitators.
Sites designed for momentum scrolling might seem at first to be purely about space—moving content fluidly through screen. But these sites don’t just push a flat document through a window. These pages are changing, sometimes in unpredictable ways, as they are scrolled. The user’s interaction on one axis is driving change in multiple dimensions, animating not just space, but also time.