Software Design See Alan Cooper, The Essentials of User Interface - - PowerPoint PPT Presentation

Duke CPS 108

• 31. 1

Software Design

See Alan Cooper, The Essentials of User Interface Design

• who designs the software?
• Implementation is view of software developer, user’s view is

mental model, software designer has to bridge this gap

➤ Example: copy/move files in a Windows/Mac environment,

what’s the difference in dragging a file/folder between two folders on the same device and dragging between devices, e.g., c: to a:? Is this a problem? To whom?

• Implications in Harpoon? What’s a presentation? A slide?

Implentation model user’s model worse better

Duke CPS 108

• 31. 2

You’re comfortable with technology and mathematics

• “Show me all the first year students who live in Pegram and

in Brown”

➤ what does “and” mean here? Does the average user

understand Boolean? Does the average programmer understand Boolean? Recursion? Threads? Queues?

• How you solve a problem in your program isn’t (necessarily)

how the user solves the problem, keep these distinctions clear

• “Saying that someone is ‘computer literate’ is really a

euphemism meaning he has been indoctrinated and trained in the irrational and counter-intuitive way that file systems work, and once you have been properly subverted into thinking like a computer nerd, the obvious ridiculousness

• f the way the file system presents itself to the user doesn’t

seem so foolish.”

Duke CPS 108

• 31. 3

What’s familiar isn’t necessarily what’s best

• Hierarchical/cascading menus

➤ what’s the purpose ➤ are they good? (“not user

friendly, but very software.dot.dweeb friendly”)

• What’s in the File menu? Why?

➤ Graphics in menus?

• What about redundancies, e.g.,

menu and shortcut and toolbar

➤ users become more expert ➤ pedagogic vector (the program

should instruct)

• What about ‘OK’, ‘Apply’, ‘Cancel’

➤ what do these mean?

Which of these slider interfaces is best? Why?

Copying

Is this a good dialog?

Duke CPS 108

• 31. 4

Issues in Harpoon Outline/Text widget

• What should the outline/text widget do? What should it be

called?

➤ What does user want? ➤ What can programmer do? ➤ How can these be reconciled?

• What are alternatives?

➤ Complete rich-text widget? ➤ Bulleted lines (what’s a bullet, what’s a line)? ➤ What about adding new lines/bullets? ➤ What about font selection?

• Other issues?

➤

Duke CPS 108

• 31. 5

Views and Styles

• What are the potential different views in harpoon

➤ where do you look for ideas?

• Existing programs
• Your own ideas
• focus group/users?

➤ Slide show, creation view, hand-out view, other views?

• What about styles?

➤ Standard presentations, clone a slide and change info ➤ different kinds of slides within a presentation ➤ different kinds of paragraphs/bullet lists within a slide ➤ how to chose, how to create

Duke CPS 108

• 31. 6

Undo/redo and other issues

• Facilitate undo/redo using the Command pattern with

encapsulated state for undo/redo

➤ facilitates multiple levels of undo/redo, not just one ➤ each command encapsulates an action, supports

execute() and unexecute() [see Pixmap]

➤ How is a move undone, what’s the state? ➤ How is a drawing undone, what’s the state?

• Is every command undoable? How can you inform the user

what cannot be undone --- pop up a dialog box on every undoable command (“warning, this command is undoable, cancel or proceed”)