One of the difficulties that people who are blind or vision impaired are faced with when using a touchscreen interface is that there must be some form of feedback to replace the visual cues that are necessary to use a touchscreen. Devices such as the Apple iPhone have resolved this by using text-to-speech technology to announce objects on the interface.
For example, you can dial a phone number on the Apple iPhone using the commonly-known standard phone keypad interface. A user who is blind or vision impaired will generally start by placing their finger somewhere on the touch screen and the screen reader software will announce the digit that is underneath your finger (e.g. ‘3’). From there, you can drag your finger around the screen and select the desired digits that make up the phone number you wish to ring. The interface used to dial a phone number remains the same irrespective of whether you are using a screen reader or not.
Project Eyes-Free has taken a different approach which is based on the standard phone keypad layout. Instead of the phone keypad buttons being in a fixed position on the screen like in the iPhone example above, the buttons are positioned relative to your initial touch. So, wherever you first touch the screen, your finger will be on keypad number 5 (the middle number on a standard phone keypad). From there you can stroke up for the number 2, stroke down and right for the number 7 and so on. This is called the Stroke Dialer.
The Stroke Dialer is not only used to dial numbers using the Talking Dialer application, but also as the input method for the Eyes-Free custom-built home screen (The Marvin shell) and as an alternate to the QWERTY keyboard in certain Eyes-Free applications.
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