There’s a temptation for mobile developers to include as many features as possible in their apps, and you can see how it might seem like a safe bet. If you give smartphone users everything that’s available to them in their desktop software, how could they ever be disappointed? The problem is that desktop experiences were designed for desktops, and merely cramming them down to fit on tablets and smartphones rarely makes sense.
Snapseed, an acclaimed photo-editing app for iOS and Android, has gracefully avoided this pitfall. Its developers didn’t just point the "Honey, I Shrunk the App" ray at Photoshop, nor did they give users a handful of pre-packaged filters and leave it at that. Instead, they pinpointed what users really needed in mobile photo editor—and what they didn’t need—and built an entirely new UI paradigm to get them there. Some of the app’s smartest touches are photo-specific, but there are still some valuable lessons any mobile developer can take away from its success.
Much of Snapseed’s success can be attributed to its user interface, which was designed from the ground up for touch-screen devices. Getting there wasn’t easy. Nik Software, the company that makes Snapseed (which was recently acquired by Google), started out making image software for professional desktop users, so the designers had to fight the impulse to fall back on familiar interactions and time-tested workflows.
The most noteworthy part of the UI is the single, exceedingly simple gesture that lets users control it all. The app offers users a variety of options for editing photos, from tweaking values like brightness and contrast to applying Instagram-style filters and effects. But every one of them is applied with the same straightforward swipe. No matter which tool you’re using, dragging your finger up and down anywhere on your image lets you choose the value you want to adjust, and dragging your finger sideways applies it in real time. You only have two options: more or less. This brilliantly consistent interaction is one of the first things Josh Haftel, Snapseed’s product manager, points out about the app. "Once they learn that up-down, left-right paradigm, they know how to use the entire application," he says.
Haftel says the team had to constantly remind themselves of this fact. It became routine for the designers to go back and re-establish who, exactly, the app’s target users were, and what it was they wanted. It also meant thinking about what they might not want. "Would adding one thing that solved the needs of 5% hurt the needs of the 95%? That was a constant conversation we had to go through," Haftel says.
Mobile apps don’t just differ from desktop ones in terms of their size, or the types of people using them. There’s also a fundamentally different sense of how interaction should feel. On desktops, we’re always at a remove, mediated by mice and cursors. Mobile apps are intimate and immediate. On touch screens, we directly manipulate the content we’re working with—and that means fluidity is at a premium.
This was particularly important for Snapseed. At some point, the developers made the decision that they wanted users to work directly on their images, instead of manipulating on-screen sliders or dials to change values. But because users didn’t have that slider to give them a feedback on their edits—a sense of how much or how little they were changing the image—it became imperative that the app showed users those adjustments instantaneously.
"In a desktop application you can have the image not updating in real time, as long as the slider updates in real time," Haftel says. "We don’t have that … And we saw that if we ever introduced some kind of a lag between a finger gesture and what you saw on the screen, it completely broke down. People didn’t know what was going on. It feels really disconcerting." We’re used to our desktop software chugging along from time to time. When it happens on our phones and tablets, the whole spell is broken.
There were many advanced features the Snapseed team knew they didn’t want to include from the start. Color curves can be intimidating for any newcomer. But cutting features wasn’t always just a matter of building with the 95% in mind. There’s one feature that the team wanted to include—and seeing its ubiquity in other photo-editing software, perhaps thought they had to include—that didn’t make it in. Zoom.
"People have requested it time and time again," Haftel says. The problem is that whenever the developers tried incorporating it, they had to change their whole processing pipeline, and inevitably they lost that all-important fluidity. So it became a matter of priorities. "We decided it was more important for you to have the ability to make real-time adjustments on the entire image than it was for you to zoom in," Haftel says. The app’s success across platforms suggests that the team was right not to make the compromise.
"I think that we’ve proven that the application can do quite well without zoom. I’m not saying that people haven’t requested it, and I’m not saying that we think it’s not important … But it still has worked without that feature." In some cases, deciding what to leave out of an app can be just as important as figuring out what to put in it.