Grayhill Multi-Touch Control Wheel - Software Development Kit V3.0 - Manual (Page 17)

Multi-Touch Ring Encoder Software Development Kit User’s Guide v3.0
© 2014 Grayhill, Inc., Confidential and Proprietary Page 17
Tracking Gestures
A Tracking Gesture is not recognized as a single event, but rather, is
reported as a continuous stream of control data for as long as the user
performs the gesture. Tracking Gestures are very useful for viewing and
positioning 2-D and 3-D objects or images, or positioning the view in a field
of text. Pan, Zoom, Rotate and Scroll are examples of Tracking Gestures.
Note that these gestures need not be exclusive (they can all occur
simultaneously) and magnitude and direction information is very important
in providing the most intuitive experience.
The Instinct library can be set to provide tracking data optimized for
controlling/ positioning either 2-D or 3-D objects. Additionally, the 2-D or
3-D tracking data can be reported either in “relative” mode or in “threshold”
mode. The relative mode reports the changes in normalized tracking data
since the last report received from the device. In threshold mode, Instinct
keeps an internal cumulative value of the relative data, but then reports the
number of times this cumulative value is evenly divisible by the specified
threshold value. The internal cumulative value then gets reduced by the
reported multiple of the threshold value.
In the 2-D modes (relative and threshold), Instinct provides the following
tracking data:
• X - average movement of one to five touch positions along the
x-axis
• Y - average movement of one to five touch positions along the
y-axis
• Scale - average change of scale indicated by the relative
expansion (un-pinch) or contraction (pinch) of one to three
touch positions
• Angle - average rotation angle of one to three touch positions
about a point determined by the number of touches
In order to provide the maximum flexibility, Instinct provides full tracking
data for up to three touches. For example; using only the X and Y data:
• A mouse cursor could be moved when only one touch is
present
• An underlying picture could be panned if two touches are used
• The entire picture album could be re-positioned, or a different
one selected, if three touches are used
In this case, the developer simply qualifies the X and Y position data, with
the number of touches, and sends the data to the proper function. Although
some gesture / number of touch combinations are well known, (such as two-
finger “pinch” to control zoom) Instinct gives the flexibility to add many
more dimensions.
In the 3-D modes (relative and threshold), Instinct provides six parameters
corresponding to the six degrees of freedom of movement of any object in
space.