CS349 - Implementing User Interfaces - Spring 2010

Public Service Annoucements

1. Mid-term: 17 June, 2010, MC4059.

Lecture 21 - Customization

Look-and-feel: customizing components

Customization of component sets is common, especially on major UI projects.

• The usual rule of thumb,
  • `enough', but not `too much', (Albert Einstein famously said, `Make it as simple as possible, but not simpler.' This always appears in quotations; I have never encountered the original. Thus, I am not sure what `it' originally referred to.)

  is not very useful for making practical decisions. On the other hand, it does seem to work pretty well for deciding whether somebody else's work is good or bad.

• Practical questions that need to be asked
  1. What presentation should be a component have?
     • the component's appearance
  2. What affordances should a component have?
     • the component's behaviour

When you are going through this process you are designing a new - or modified - look-and-feel for your interface.

• Why is it sometimes a good thing to give an interface a unique look-and-feel?
• Why is it sometimes a bad thing to give an interface a unique look-and-feel?

(Hints. 1. `Unique' is put in here as a deliberately bad descriptor. 2. The answer should prominentaly include the word `gratuitous'.)

Three questions must be answered.

1. Who does the customization?
2. What is the context of customization?
3. What is the mechanism of customization?

Who does the customization?

1. System programmer/assembler: H/W and OS capabilities
   • Reconfiguration may be available to 2-4
2. Application programmer: look and feel of application
   • Controlled by resource files
   • Preference dialogues allow authors to customize application
3. Designers: [organization-wide] collections of documents
   • Mandated layouts and style sheets
4. Document authors: inidividual documents
   • Customized layouts and style sheets
5. Document user: presentation of current document
   • Proferences in display application

Sometimes there are contradictions and inconsistencies. How do they get sorted out?

• usually by a priority list
  • We would expect lower in the list overrules higher
  • In fact, for CSS we got the priority list
    1. Author: in the html
    2. Reader: user preferences in the browser
    3. Browser: browser defaults
• What if properties are misaligned?
  • Should a treat this element as text or as a header?
  • Elaborate scoping rules, but only authors/designers need to know them

An important special case: Internationalization

Respect for language, culture & politics.

The country-wide context experienced a very large amount of research and attempted innovation during the 1990s. The issue was `internationalization': how do you make an interface that works for groups of peole who come to it from different languages, cultures and political systems.

There is, at present, no acknowledged solution for this problem. There are two practical approaches

1. Open systems (Apple -> Sun)
   • Internationalization is a real problem. Innovate to solve it.
   • LOCALE is the current state of the art,
     • Set at install time
     • It doesn't try to do very much
     • and what it does do is screwed up almost everywhere.
2. Shrink-wrap software
   • A different package for each market
     • Sometimes only the printing on the box
     • Sometimes the tutorial and/or manual
     • Sometimes words that occur in the application
     • Almost never the programmed interface
   • Driven by marketing
3. My way or the highway (Stone age: IBM, then Microsoft)

   Solution by fiat, IBM: `Let them learn EBCDIC', Microsoft: `Let them learn English.' E.g.,

   • Create your own standards.
   • Publish dictionaries

What is the mechanism of customization?

Resources

History

1. Environment variables
2. .rc files
3. Resource forks
4. Resource files: special names, special places

The result: defaults are all-important.

Current Methods

1. BIOS programming/selection
2. Subclassing
3. Style sheets
   • level problems
4. Cascading style sheets
   • what are they? a list of rules
     When a section of a document is an environment labelled by the selectors then the properties listed have the given values

     selector, [selector, ...] {
         property: value;
         [property: value;
          ...]
     }

   • how do they work
   • order of precedence
     1. author
     2. user
     3. browser
   • implementation problems

Return to:

• CS349 - Spring 2010 - Lecture schedule
• CS349 - Spring 2010
• CS349 page
• Bill Cowan's home page.