Note 7: Eliminating Excise

Transcription

1 Computer Science and Software Engineering University of Wisconsin - Platteville Note 7: Eliminating Excise Yan Shi Lecture Notes for SE 3330 UW-Platteville Based on About Face 3: Chapter 11 & 16

2 Excise Excise: actions not contributing directly to the goal. Goal: get to the destination car in our garage teleporter Software excise: configuration, backup Excise in UI is a primary cause of user dissatisfaction. Goal: eliminate excise to make users more effective

3 GUI Excise Windows manipulation vs. command line operation GUI helps beginner, intermediate; cmd for expert Solution: provide both GUI and command-line interface can help in testing! Training wheel: should allow easy turning off Better: automatically detect user level!

4 Visual Excise Yale Art School Website:

5 Visual Excise The work a user has to do to decode visual information finding an item in a list figuring out where to begin reading on a screen determining which elements are clickable Metaphors in sovereign application: GOOD? Excessive ornamentation: atmosphere vs. effectiveness

6 Model Excise: Stop the Proceedings Very prevalent excise. Don t stop the proceedings with idiocy! Why can t system fix this? Which one should I save? What does Cancel do? Errors, notifiers, confirmations All are high excise! Don t tell user something they can t fix

7 Navigation All navigation is excise Remember goal: keep user "in the flow" Games may be the biggest exception to this Navigation is also excise in web sites! Navigation through software at multiple levels: among multiple windows, views or pages among panes within a window among tools, commands, or menus within information in one pane/frame (scrolling, zooming, following a link)

8 Navigation Among Windows The most disorienting navigation for users. disrupt a user s flow force him into a new content usually means the contents of the original window are obscured. Navigation Trauma: lost in the interface. Sovereign applications: place all main interactions in a single primary view, which may contain multiple independent panes.

9 Navigation Among Panes What is the problem with this Eclipse UI?

10 Navigation Among Panes Problem: #panes become too numerous sometimes result in visual clutter and confusion crowding forces scrolling solution(??): tabbed panes (e.g., excel) introduce significant navigational excise. appropriate for multiple supporting panes for a primary work area not used at the same time. Good Example: color pane in PowerPoint Bad Example: Notepad++ preference

11 Navigation Among Tools and Menus Goal: minimize mouse movements Cut, Copy, Paste... Tools used frequently: obvious location on toolbar Tools in conjunction with each other grouped together spatially Hierarchy on toolbars is dangerous Photoshop elements & hidden paint bucket Allow toolbars to be reconfigured Standard: add, remove, reorder items All operations must be in menus!

12 Navigation of Information Issue: how to navigate through lots of information? Scrolling: useful tool, but think before using Separate pages: good if appropriate for users mental model do a cluster analysis - keep most related things together Linking: visual context cues paramount hyperlinks usually are underlined, of different font style or color Zooming: for exploring 2D and 3D information

13 Navigation Review Basic principle: navigation is excise Avoid: navigation between windows Manageable: navigation between panes Tools & menus: minimize mouse movements and clicks Information: analyze what s being presented

14 Improving Navigation Reduce # of places to go Provide signposts Provide overviews Map controls to functions carefully Avoid deep hierarchies

15 Reduce # of Places to Go Places: modes, forms, dialogs, pages, windows, screens. Minimize # of windows and views. One full-screen windows with 2 or 3 views is best. Minimize # of dialogs. Minimize # of adjacent panes. 3 maximum for most sovereign applications 2 navigation area and one content area for web Minimize # of controls (clicks) Minimize scrolling and panning

16 Provide Signposts Users navigate by reference to persistent objects. Windows, menu bars, toolbars, status bars, rulers... Help to orient users Visual cues for status, hints on what to do next menus: reliable, consistent way to get operations toolbars: protect against accidental removal web sites: navigation bar remains the same.

17 Provide Overviews Similar purpose as signposts: help to orient users. Graphical: Photoshop Textual: web breadcrumb display Annotated scrollbar: location information Power Point, Word

18 Mapping of Controls to Functions Result: heat a burner Target: which burner? Which enables which? Logical mapping: Sorts Definitely not: sort ascending, sort descending Better: oldest first, smallest first, largest first, etc.

19 Avoid Deep Hierarchy Deeply nested hierarchies intimidates most users Some hierarchy is ok! People understand category & subcategory Problem: circular reasoning behind a directory is a folder with files and other folders in it Solution: Define collections, chose collection first Provide search and access tools

20 Other Common Excise Traps Don t force users to go to another window to perform a function that affects the current window; remember where they put things; resize windows unnecessarily; move windows; reenter their personal setting; fill fields to satisfy some arbitrary measure of completeness(*); confirm their actions. This requires a robust UNDO facility.

21 Users and Undo Computers have no need for undo; human does: user s mental model over implementation model! Traditional view: the rescuer of users in distress Better viewpoint: user tries something, wants to undo it to try something else; a simple trial isn't an error, it's an experiment! Goal of undo: permit exploration, reassure users.

22 Incremental and Procedural Undo Incremental actions: include a data component. cutting, pasting, drawing, typing, deleting Procedural actions: don t change data. formatting a paragraph Most existing undo functions don t discriminate between these two actions.

23 Blind and Explanatory Undo Blind undo: users know that clicking the button undoes the last operation, but have no idea what that operation is. Explanatory undo: let users know what will be undone. more pleasant feature more difficult to implement tooltips for explanations

24 Single and Multiple Undo Single undo: two single undo operations bring back the original status. Assumption: users realize the mistake immediately. Multiple undo: based on stack (LIFO) usually requires a redo function Problem?

25 Undo Solutions Issue: is a stack really the right model? Easier to implement Requires user to undo all intervening actions to recover (say) a deleted paragraph Undo solutions: category-specific undo Deleted data buffer Versioning systems (CVS, Subversion, Google docs etc.) Command pattern the solution you ll use this semester

26 Command Pattern Patterns: solutions to common problems Basic behind command pattern: store commands as objects base class defines abstract execute() subclasses: implement execute()

27 Command Pattern

28 Exercise Restaurant: customer, waiter, cook, different orders Switch to turn on and off a light

29 Command pattern applied Applied to phonebook.java: Handler 1 History 1 1 stack<command> add_entry():void remove_entry():void do_command():void redo():void undo():void Command Entry execute():void unexecute():void name:int phone:int map<string, Entry> 1 1 Phonebook add():void lookup():void remove():void 1 1 AddCommand execute():void unexecute():void RemoveCommand name_to_remove:string execute():void unexecute():void

30 More phonebook details Remove, add: core commands Two lists of commands; clear undone on new cmd Implements GUI/policy/data layers History part of policy layer, encapsulates undo/redo Handler doesn t need to track this! Phonebook: current contents; Map provides lookup Add: points to entry so can redo the add Remove: uses entry in undo Issues to decide What data to store? Have a few intelligent commands, or lots of small ones?

31 Summary Eliminate excise GUI excise Stopping the proceedings navigations Common excise traps Undo Types of undo undo solutions Command Pattern