Stroke Dialler For Android

Video: Stroke Dialer For Android

1 Video: Stroke Dialer For Eyes-Free Keypad Input

Device Used: T-Mobile G1 from HTC

The stroke dialer enables one-handed keypad input using the touch-screen --- and that without having to even look at the screen. Here is how it works --- we start with a brief description of the problem that asks the right question. The answer becomes self-evident as you follow this video.

1.1 The Problem

On-screen keyboards typically show some buttons on the screen that you activate by touching the screen. To activate such buttons, one needs to look at the screen, because the buttons are placed at specific points on the screen, i.e., they are absolutely positioned. So what if you want to activate such buttons without looking at the screen? From the foregoing description, it's clear that the only reason one is forced to look at an on-screen keyboard is because the buttons are absolutely positioned. So let's relax that constraint, let's use relative positioning to place the buttons.

We'll start with a keyboard we're all familiar with, the telephone keypad. Since we're using relative positioning, let's place the center of the keypad wherever you first touch the screen. So, to dial a 5, you just touch the screen.

Now, you know where 5 is --- it's where you first touch down. But look, since you know the layout of a phone keypad, you can now find all the other digits relative to the 5. So for example, 2 is directly above 5 --- so to press 2, you touch down on the screen, and stroke up before lifting your finger. similarly, you stroke down for an 8, or diagonally up for a 1.

In real life, we both hear and feel as we press physical buttons. This form of synchronized auditory and tactile feedback is essential for creating user interfaces that feel realistic. The stroke dialer produces a slight vibration as the finger moves over the various buttons that is synchronized with an auditory tick to achieve this effect. It also produces spoken feedback to indicate the button that was pressed.

To conclude this video, let's dial a few numbers.

Author: T.V Raman <raman@google.com>