CrossY: A Crossing-Based Drawing Application Georg Apitz & François Guimbretière HCIL, University of Maryland

People, Pens, and Tablet PC The New Yorker Illustration from Ken Hinckley presentation at Stanford

Typical setting for today’s interface Fixed stable environment, with a keyboard, Indirect interaction, High precision, stable pointing system

Typical Tablet PC use Portable, unstable environment, without a keyboard Direct interaction, Low precision aiming

Empirical foundations Use of strokes to cross target is more pen friendly Crossing is as efficient as point-and-click [Accot & Zhai, 2002] The basic interactor How expressive is it? Why crossing?

CrossY video

Previous work Theoretical basis Steering Law, Trajectory-Based Tasks [Accot & Zhai 97-02] Limited scope examples Toggle Map [Baudish 98] Lotus Notes: multiple selection Conceptual design Visual Instruments: [Winograd & Guimbretière 98] Overloading Gedrics: [Geißler 95]

Crossing based buttons Option box: stacked vertical targets Reinforces the idea of mutually exclusive selections Check box: stacked diagonal targets Allow for both single and multiple selections in one stroke

Scrolling Line by line area Page by page area Absolute area

CrossY scrollbar Overloading simplify interactions shorter distances to issue commands not as much precision necessary

CrossY scrollbar Overloading simplify interactions shorter distances to issue commands not as much precision necessary Extending stroke for repeat No need to wait for a timeout

Cursor control Cross to jump to an absolute position

Cursor control Cross to jump to an absolute position

Cursor control Cross to jump to an absolute position Near drag for coarse adjustment

Cursor control Cross to jump to an absolute position Near drag for coarse adjustment

Cursor control Cross to jump to an absolute position Near drag for coarse adjustment Far drag for fine adjustment Similar toFineSlider [Masui 95] But one single stroke

Command composition From stroke-by-stroke interaction borders are used to validate/cancel

Command composition From stroke-by-stroke interaction borders are used to validate/cancel To multi-command stroke

Stroke as a scoping mechanism Stroke “carries” the information StrokeObject find width:med find color:?? find:?? replace?? Replace color:?? replace width:??

Stroke as a scoping mechanism Stroke “carries” the information StrokeObject find width:med find color:red find:?? replace?? Replace color:?? replace width:??

Stroke as a scoping mechanism Stroke “carries” the information StrokeObject find width:med find color:red find:true replace?? Replace color:?? replace width:??

Stroke as a scoping mechanism Stroke “carries” the information No need to travel back to replace button StrokeObject find width:med find color:red find:true replacetrue Replace color:blue replace width:thin

Use of directionality Continuous find and replace

Use of directionality Continuous find and replace Reverse direction for undo

A difficult case

Principles Based Auto-Completion idea Only unique prefixes are presented Selection always at the center

Selecting a file to open Open document /Papers04/ProofRite.pdf In one stroke:

Discussion Space requirements Similar to point-and-click Trade-off with command combination due to sloppiness Overloading vs. easy discovery Consistency helps getting used to it Known in Windowing systems Fluid transition from novice to expert Similar to SHARK: [Zhai et al. 2003] Single commands for novices Command combinations for experts

Discussion Consistency Crossing direction from right to left to avoid occlusion For right handed (90% of users) In File-Open from left to right; based on our writing system Crossing detection: Possibility that widgets miss events because not registered Solution: event dispatch

User feedback / Current study Initial user feedback during Open House at UMD Very positive Liked the easiness Seen as very intuitive How does the layout influence performance Angle of the target is important How do users react to missed crossings

Future Work Find general design rules Do a general performance evaluation Which paths do user travel between crossing targets Several strokes vs. one continuous stroke Toolkit Basic widgets to create crossing-based applications Different feedback Tactile pen

Conclusion Crossing is feasible as sole interaction technique and More flexible Supports command composition Support fluid transition between novice and expert Builds on the advantages of the pen Use strokes Shows what is necessary to built such an application Not limited to tablet PCs or drawing apps

Acknowledgments Microsoft Research Corinna Löckenhoff Anja Szustak Grecia Lapizco-Encinas and Alejandro Rodriguez