think-cell technical report TC2003/01 A GUI-based Interaction ...

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4.2 Interaction Toolbox INTERACTION CONCEPT induced by a mode switch. Since the think-cell add-in very closely interacts with traditional PowerPoint functionality, frequent mode switches would be required, slowing down the interaction and adding to the confusion on the user’s part. Therefore, I decided to blend in to the existing PowerPoint user interface in the least intrusive way possible. I leave the PowerPoint interface intact and restrict myself to UI components that are not yet used by PowerPoint itself. 4.2.5 General Interaction Patterns In an interactive drawing or layout application, there are few goals that can be reached with one singular command as a button click. Most goals require the sequential combination of several interactions, which I call an interaction pattern. For example, to change an object’s color, it is necessary to select the color feature as well as the object whose color is to be changed. For goals like this, two basic interaction patterns can be found in common software. Choose Tool and Apply. This paradigm requires that the user first decides which tool to use, such as selection or fill color. The tool is then attached to the mouse pointer, often represented by a specific pointer shape. The tool can be applied to the current mouse pointer position with a mouse button click. This pattern is a less obvious variation of a mode switch (Sect. 4.2.4). Select Objects and Modify. The opposite approach requires that the user first selects the objects that she wants to modify. The objects visually reflect their selection state, for example with a highlighted outline. Then, the selected objects can be modified by direct manipulation or with a click on the appropriate toolbar button. In Microsoft PowerPoint, both paradigms are mixed and diluted. To add new drawing objects, PowerPoint uses the choose-tool-and-apply pattern with a non- standard behavior: As soon as the new object is created, the chosen tool is imme- diately released, meaning that multiple inserts require the user to choose the same tool over and over again. On the other hand, for existing objects PowerPoint follows the select-objects-and-modify pattern. During my field study (Chap. 2) I could observe a meta pattern that was followed by most users to insert multiple similar objects: The first object was inserted as the choose-tool-and-apply pattern suggests. This object then served as a master copy: It was brought into shape with some modifications like color, font and shadow. Finally, copy-paste was used to create multiple copies of the master. This meta pattern fits well to the PowerPoint patterns for new objects, modifying objects and duplicating objects. However, it remains unclear if the PowerPoint UI really fits the users’ needs, or if the users chose that meta pattern because it works around the many interactions that would otherwise be required. In order to facilitate the transition from regular PowerPoint to a new environ- ment, for my prototype I decided to stick with the PowerPoint way of inserting 50
4.2 Interaction Toolbox INTERACTION CONCEPT and modifying elements. However, I expect that a future version of the think-cell software, if based on ongoing user studies, will implement more intuitive and less interaction-intensive interaction patterns for the same tasks. 4.2.6 Feedback to the User Besides input from the user, feedback to the user is the other component in human- computer interaction. The challenge of providing good feedback is to give exactly the information required for the user’s task, to prioritize that information to prevent information overload on the user’s part, and to render the information such that it gets as much of the user’s attention as required without unnecessarily distracting the user from her main task. Although in theory input from the computer to the human could use any of the five senses, the only feedback devices available on a standard personal computer are the screen and the speaker. Yet, for the present application I refrain from using audio as a feedback channel, because my study showed that the target user group works in open-plan offices (Sect. 2.1.2). In this situation, audio feedback from various workplaces that are located next to each other would do more harm than good. In effect, the only feedback channel available for my application is the screen. The focus of the application is semiautomatic layout based on implicitly specified constraints. Hence, I must provide enough feedback for the user to understand why a certain layout was chosen and which constraints must be added, removed, or changed in order to achieve the desired layout. The visualization of constraints and their impact on the result plays an important role for the learnability, robustness and efficiency of the system: The user must understand the input-result-relation to make appropriate use of the layout tool. Moreover, some kind of preview that explains what would happen if, for instance, the mouse button was clicked in a certain position, together with instant feedback on user actions, helps the user to avoid or at least to notice erroneous input and to learn the optimal interaction patterns. It might be interesting to incorporate some animation to explain layout changes. In research, animation has been successfully applied in similar settings, where state transitions would otherwise be obscure to the user (e. g., [Gle92]). However, animation requires extra efforts in terms of programming and runtime resources, and it very strongly attracts attention, distracting from anything else the user might be doing. For these reasons, animation must be used with care and I did not use animation at all in the present prototype. Other uses of feedback are understood in recent office software and should be continued in my application. For example, the 3-dimensional appearance of a button conveys the affordance to push it. The shape changes on mouse-over to confirm its responsiveness and on button-click to acknowledge the recognition of a command. Another example is the mouse pointer shape that reflects system state (an hourglass when the system is temporarily not responsive) and input modes (a cross hair for inserting new objects into a slide). The mouse pointer shape is especially 51
Page 1 and 2: think-cell technical report TC2003/
Page 3 and 4: Contents List of Figures 5 1 Introd
Page 5 and 6: List of Figures 1 The consultant’
Page 7 and 8: 1 Introduction INTRODUCTION “Layo
Page 9 and 10: 2 Field Study FIELD STUDY Jeff Hawk
Page 11 and 12: 2.1 Qualitative Aspects FIELD STUDY
Page 19 and 20: 2.2 Quantitative Aspects FIELD STUD
Page 25 and 26: 3 State of the Art STATE OF THE ART
Page 27 and 28: 3.1 User Interfaces for Layout Spec
Page 29 and 30: 3.2 Computer Supported Layout STATE
Page 31 and 32: 3.2 Computer Supported Layout STATE
Page 33 and 34: 3.3 State of the Art - Résumé STA
Page 35 and 36: 4.1 A New Approach to Slide Layout
Page 43 and 44: 4.2 Interaction Toolbox INTERACTION
Page 49: 4.2 Interaction Toolbox INTERACTION
Page 53 and 54: 4.3 Specifying the User Interface I
Page 69 and 70: 5 Implementation IMPLEMENTATION The
Page 71 and 72: 5.1 Program Architecture IMPLEMENTA
Page 77 and 78: 5.2 An Application of Dynamic Progr
Page 83 and 84: 6 Evaluation EVALUATION In this cha
Page 85 and 86: 6.2 Case Study EVALUATION presented
Page 87 and 88: 6.2 Case Study EVALUATION AÖGHKÖ
Page 89 and 90: 7.2 Résumé CONCLUSION User Studie
Page 91 and 92: References REFERENCES [Adoa] Adobe
Page 93 and 94: REFERENCES [Hur78] A. Hurlburt. The

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