Haijun Xia

NanoStylus: Enhancing Input on Ultra-Small Displays with a Finger-Mounted Stylus

Due to their limited input area, ultra-small devices, such as smartwatches, are even more prone to occlusion or the fat finger problem, than their larger counterparts, such as smart phones, tablets, and tabletop displays. We present NanoStylus -- a finger-mounted fine-tip stylus that enables fast and accurate pointing on a smartwatch with almost no occlusion. The NanoStylus is built from the circuitry of an active capacitive stylus, and mounted within a custom 3D-printed thimble-shaped housing unit. A sensor strip is mounted on each side of the device to enable additional gestures. A user study shows that NanoStylus reduces error rate by 80%, compared to traditional touch interaction and by 45%, compared to a traditional stylus. This high precision pointing capability, coupled with the implemented gesture sensing, gives us the opportunity to explore a rich set of interactive applications on a smartwatch form factor.

Object-Oriented Drawing

We present Object-Oriented Drawing, which replaces most WIMP UI with Attribute Objects. Attribute Objects embody the attributes of digital content as UI objects that can be manipulated through direct touch gestures. In the paper, the fundamental UI concepts are presented, including Attribute Objects, which may be moved, cloned, linked, and freely associated with drawing objects. Other functionalities, such as attribute-level blending and undo, are also demonstrated. We developed a drawing application based on the presented concepts with simultaneous touch and pen input. An expert assessment of our application shows that direct physical manipulation of Attribute Objects enables a user to quickly perform interactions which were previously tedious, or even impossible, with a coherent and consistent interaction experience throughout the entire interface.

Collection Objects: Enabling Fluid Formation and Manipulation of Aggregate Selections

Despite the long development of Graphical User Interfaces, working with multiple graphical objects remains a challenge, due to the difficulties of forming complex selections, ambiguities of operations, and tediousness of repetitively unselect-reselect or ungroup-regroup objects. Instead of tackling them as individual problems, we attribute it to the lack of system support to the general selection-action cycles. We propose Collection Objects to not only support a single fast selection-action cycle but also allow multiple cycles to be chained together into a fluid workflow. Collection Objects unifies selection, grouping, and manipulation of aggregate selections into a single object, with which selection can be composed with various techniques, modified for later actions, grouped with objects inside still directly accessible, and quasi-moded for less context switching. We implemented Collection Object in the context of a vector drawing application with simultaneous pen and touch input. Results of an expert evaluation show that Collection Objects holds considerable promises for fluid interaction with multiple objects.

You Watch, You Give, and You Engage: A Study of Live Streaming Practices in China

Despite gaining traction in North America, live streaming has not reached the popularity it has in China, where live- streaming has a tremendous impact on the social behaviors of users. To better understand this socio-technological phenomenon, we conducted a mixed methods study of live streaming practices in China. We present the results of an online survey of 527 live streaming users, focusing on their broadcasting or viewing practices and the experiences they find most engaging. We also interviewed 14 active users to explore their motivations and experiences. Our data revealed the different categories of content that was broadcasted and how varying aspects of this content engaged viewers. We also gained insight into the role reward systems and fan group-chat play in engaging users, while also finding evidence that both viewers and streamers desire deeper channels and mechanisms for interaction in addition to the commenting, gifting, and fan groups that are available today.

DataInk: Direct and Creative Data-Oriented Drawing

Creating whimsical, personal data visualizations remains a challenge due to a lack of tools that enable for creative visual expression while providing support to bind graphical content to data. Many data analysis and visualization creation tools target the quick generation of visual representations, but lack the functionality necessary for graphics design. Toolkits and charting libraries offer more expressive power, but require expert programming skills to achieve custom designs. In contrast, sketching affords fluid experimentation with visual shapes and layouts in a free-form manner, but requires one to manually draw every single data point. We aim to bridge the gap between these extremes. We propose DataInk, a system supports the creation of expressive data visualizations with rigorous direct manipulation via direct pen and touch input. Leveraging our commonly held skills, coupled with a novel graphical user interface, DataInk enables direct, fluid, and flexible authoring of creative data visualizations.

Object-Oriented Interaction: Enabling Direct Physical Manipulation of Abstract Content via Objectification

Touch input promises intuitive interactions with digital content as it employs our experience of manipulating physical objects: digital content can be rotated, scaled, and translated using direct manipulation gestures. However, the reliance on analog also confines the scope of direct physical manipulation: the physical world provides no mechanism to interact with digital abstract content. As such, applications on touchscreen devices either only include limited functionalities or fallback on the traditional form-filling paradigm, which is tedious, slow, and error prone for touch input. My research focuses on designing a new UI framework to enable complex functionalities on touch screen devices by expanding direct physical manipulation to abstract content via objectification. I present two research projects, objectification of attributes and selection, which demonstrate considerable promises.