User Interface Design by Sketching: A Complexity Analysis of Widget Representations

User interface design by sketching, as well as other sketching activities, typically involves sketching objects through representations that should combine meaningfulness for the end users and easiness for the recognition engines. To investigate this relationship, a multi-platform user interface design tool has been developed that enables designers to sketch design ideas in multiple levels of fidelity with multistroke gestures supporting widget representations and commands. A usability analysis of these activities, as they are submitted to a recognition engine, suggests that the level of fidelity, the amount of constraints imposed on the representations, and the visual difference of representations positively impact the sketching activity as a whole. Implications for further sketch representations in user interface design and beyond are provided based on usability guidelines.