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Pace 64

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K > of Applications,

OOP s Intuitive Interface W idens Ran ge of Applications

t kadi Snovi j Po Li. naj ite ii Kovine a i

a -bo: jheet. h bb; rič uh techriigues.i, '!; MacPaint. Many more o£ he programs. |

This is the zmoinnnlinem fora fri ses, Usin ohikorent rei pri dih have been developed, and the most so"; |

third in a series — ' User interfaces based on object-orleni: . styles are organized ln 4 Hierarchy: The, ,.: phisticated dre using object-oriented | |
of articles on ob- ' ed technigues enable users to explore:: ij | attributes of each style sheet are set at' 4 technigues to make it ii to create, |

ject-oriented. | and experiment witli a new enviroti' £; / the appropriate level in the hierarchy. complex drawings. | sti ki
technigues, a — ment. Many programs čan be learned, / ji; Lower-level styleš inherit attributes "| As shown in the figure, a bali or |
new technology X with little or no training. Once Usersi/ (17 ' from higher levels, ind only definitions; draw program provides the user with Wi
that's changing 1; learn the functions of d word processor;'" that are new, Ads need tobe j ij an empty window bordered by a num- [E
the way pro |.or prograni editor, they then can trans; (//, specified."" osel MOM IM ber of icons that represent Various li

; |

grammers and .. 'fer that fm ti to othet products "jiv" For Pene, the basic text style in a drawing tools. These include line-widthi
i , document might define the margins, font | ; drawing tools; paint patterns; brush
compulters. technigues. ili and padragraph style: A heading style; HI ' shapes; erasers; tools to draw boxes, cir.
There are a ' Thus, PN eta help," would be ii subclass of the basic text ';.//' cles, polygons; and other special oflecta. |
number of appli- — the user to grasp and work with the ' si style: It would'retain the font and mar! || The mouse and a pointer are then used | l
cations today complex computer environment. Users | gins, biit change the font size and add X (to put the shapes or drawings on the '
that make use of, ; learning to operate a windowed intersii V the bold attribute. A programming book "screen. These programs all tise the basic.
object-oriented face do so in a fraction of the time it." might have a different style for code ex- |; object-oriented user interface and em-
programming. There are varying SEO. jploy icons to represent various options.
to which the concepts are used, but in, In contrast, conventional paint pro-
all cases, object oriented technigues al: " How Word- Processing Style Sheets Use / grams view the picture as a large bit

low the user to deal with a complex en- bi | map. For Sak jale box is nodi
vironment in a straightforward manner; witl a conventional paint program, the |
OI a v enteg Frogrammine a
with an object-orieni ace, while - on. ;
others give users the ability to oeganize Styles Are O: ganized bene - ze | secting the box, some more bits are ; |
and create objects as well. i Hi In a Hierareh y 2; NE | turned on. The program only has

This week, we'l look at three exam- s s ' 'knowledge" of the on and off bits. Af'

ples of object-oriented programming: 4 ter the initial drawing, the program has;
€ Window:-based user interfaces: These Level l: no control over the circle and sguare

are the emerging standard for comput- ... Basic Style | 'andi can only add or erase bits. There |,
ers, including workstations, Macintoshes - Aitributes (are copy and duplicate functions, but ''

and now PCs, with Presentation Manag-': s h h € these work with areas of bits and not a
er (PM) and Microsoft Windows. '' 3% v IS z . with objects jin the in : ;

€ Word processors: Powerful style (ie še HOBIJE Ji
sheets let the user create complex docu: :: j/One Shape at a Time . is]

ment formats with little effort. 4 %Y oa! S b  Inan object-oriented drawing pro- ' ' is
' Graphics programs: The creation of ,. sz N gram, the shapes are remembered by | .://
complex drawings is easier with object" ' the program as individual objects. They

oriented technigues. Level il: N sš si m can be šelected and modified once
The most noticeable effect of object; Level | Style Plus 55 h : | drawn. They can be moved about the |
oriented programming can be seen in :

v Bcreen, copied or deleted without. dis-

the windowing user interfaces that we Additional Attrib utes — -k | turbing the objects they overlap. " H tudiki
first popularized on the Macintosh. » Heading —— - Z % Objects cari be combined into more HU |

'These technigues' are now becoming '
available on PCs with Microsoft Win-
dows and IBM's PM. The style of inte;

" complex objects, which cari then be ma-' H |
| nipulated as single objects. Complex ob-' | [E
jects can be duplicated and moved, al- |

face was first developed for Digitalk |; Level Ill; za - J z ej lowing the user to work with the draw: | (| i
S Provan the first pure object-ori: Level ll Style Plus ž - be UE] s! j | |: bi
The user benefits from the more intu-" Additional Attributes pie < line means changing its end points. The ' | H H
itive interface provided by object-orient- » Subheading —— same edit message can be sent to d rect, (|
|

ed technigues. The windowing interface
is organized like objects in an office. The
user can move the objects: open win-
dows, close windows, pull down menus, '
select items. The effect is the same as

: angle, but with different results: The ;.' |!
edit. will change both the rectangle's H
heken . height and width. Each object. responds ' | Kai
to set attribute messages, but, the IE,

GAJA ; pesi no j —— izlo | | |, attributes affect each object differently.
opening wers, selecting objects . 5 po pi ; i : '! For simple drawings, the conventional
in the drawer, moving a coffee cup and. USinuy object-oriented. technigues, styles are organized in a hi bit-mapped paint programs are ade- ||

drinking the coffee. Various icons repre- mi attributes. each priat ' guate, but for more complex drawings, |
senting objects are used to send mes- :'" ; erarchy. The of. style are at the ab, Di o, e |; the object-oriented approach is recom- |
sages to the object. The user simply mended. The use of object-oriented tech-
elicks on the icori to obtain the desired ': |, higues simplifies the user interface and |
result. For example, to seroll a opera " helps the user to manage complexity. |
the user points the mouse to the scroll

; beti Ne Hi IE Next week, iti the fourti and final ar.
bar and clicks it. To close a window, the '— would take them to learn i a oouvenunai,  omoleš in which day the font is." ticle in this serles, we will look.at the

i

mouse is elicked in the "go away" box | al PC interface, because the windowing Ji changed. All of these substyles intierit J growing use of object-oriented tech- |
on-screen. technigues help manage and control.the:, attributes from the basic style, so the | nigues to implement CASE tools and

Visual clues are used wherever possi-:  complexity of the environment. ' 4%/: user has to specify only what, is differ- ' | databases.a
ble to indicate the behaviors of an ob- One of the more dramatic recent uses.  ent for the styles lower ini the hierarchy.,. ———————<—<5<—
ject or identify the object. There are of object-oriented technigues is in the |! ' This use of objeciorlented technigues H Pag he remijo zem
icons for the controls on a window and. . definition of style sheets in some word-,,. for style definitions resultš in d very  %: these articles, please call The »James
icons used to identify the applications processing programs. The style sheet de: | easy-to-use interface for developing come , Martin Report, an information service
and documents in the system. For exam-  fines attributes, such as page layout, plex documents. The levels of abstrač- ' a A EO MSO
ple, different icons are used for pictures ' font type and text format; for some por'"' tion and inneritance mike it tasy to? st | /' For information on seminars, please |
and text documents. Similar icons and tion of the document. A complex docu- |., work with and control documents that | |; contact (in the United States and. Gra

messages are used across multiple appli- | ment might have styles for regular text, (have a complex K ozeRa Ami oe ada) Technology
cations. Open, close and save operations  bulleted text, i d, ted h ei | |;741 10th St, Santa Monica, Calif.

- always appear in the same place on the sm bi ti ij 90402 (213) 394-8305. Ii Europe, con.
screen, whether the application Isa tai " There are numerouš programs for Za | tact Savant, 2 New St, Carnforih,
Word processor, draw program or pro- ' [Hi ne pictures on di computer, begin Janes LAS 9BX United Kingdom
Bram-development environment. The go- t se Vovtu Compu KA 0624). soka ga NUK)

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