Touch interfaces offer new and exciting ways to provide users with simple and engaging experiences. They also carry unique challenges for the designer. One such challenge is dealing with the “eclipsing” effect. For example, consider the diagram above. When sizing an item on the screen, it’s important to take into account not just the size of a finger but also the area that the finger obscures from vision as it is reaching to touch something. We like to call this the “eclipse” area. One big difference between digital buttons and physical buttons is digital buttons don’t offer any tactile feedback. So, if a finger obscures from vision what it is going to touch before it touches it, sometimes it’s good to compensate in other ways. For example, for small buttons that will get eclipsed be sure not to have any other buttons adjacent or close by. For a slide control, make it evident that the knob has been moved even if you can’t see the knob.
Eclipsing gets most frustrating when small elements are close together and there are frustrating consequences to pressing the wrong item. These situations should be avoided to give your application optimal comfort and ease of use.
