SketchADoodle: Touch-surface Multi-stroke Gesture Handling by Bézier Curves

Abstract

Touch-surface multi-stroke gestures, as well as freehand drawings, are typically acquired by devices and sensors as a suite of timestamped points on a plane. This Cartesian coordinate system, although useful for computation like complexity analysis, gesture classification and recognition, becomes complex and inefficient when gestures need to be visualized and directly manipulated for editing. To address these challenges, a new mathematical representation of these gestures via a Bézier curve is defined to initiate a model-based approach for gesture direct manipulation (e.g., cut, copy, paste, translate, scale, rotate, deform, crop, compose, decompose). SketchADoodle, an Android-based mobile application for drawing, gesturing, demonstrates how the pseudo-code of the Bézier-based operations are engineered for real-time direct manipulation. We release the programming code for further development of gesture-based user interfaces based on Bézier curves.