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Chap ter 1
Your Workstation and X
From Apple Macintoshes and 80x86 PCs at the low end to Sun, Hewlett-
Pack ard, IBM, and DEC workstations at the high end, graphics work-
sration~ have changed the way people interact with computers. Built-in'
graphics capabilities have made graphical user interf aces such as the
Macintosh User Interface and Microsoft Windows possible. With these
interfaces, instead of entering commands from the keyboard, you can use
the mouse pointing device to run programs and to edit, copy, and delete
files.Additionally a hical interfaces divide the h sical dis la screen
The difficulty of creating readily transferable appli~tions also plagued
high-end graphics work stations, many of which used to come with built-in proprietary windowing systems that are invariably different"~lii~~
each window s stem can be ro rammed by caHin routines from a
1 r ' ve hen t e same
capability exists on all systems, the routine names usually differ. This situ-
ation has proven troublesome for those who ~ant to write applications
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Chapter 1
Your Workstation and X
From Apple Macintoshes and 80x86 PCs at the low end to Sun, Hewlett-
Packard, IBM, and DEC workstations at the high end, graphics work-
stations have change~ the way people interact with computers. Built-in
graphics capabilities have made graphical user interfaces such as the
Macintosh User Interface and Microsoft Windows possible. With these
interfaces, instead of entering commands from the keyboard, you can use
the mouse pointing device to run programs and to edit, copy, and delete
files.Additionally a hical interfaces divide the h sical dis la screen
The difficulty of creating readily transferable applications also plagued
high-end graphics workstations, many of which used to come with built-
in proprietary windowing systems that are invariably different.
each window s stem can be ro rammed by caHin routines from a
8/7/2019 x Windows 0001
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that work on many different workstation . The X Window S
of the need for a windowin s stem that
Graphics disp~ys have two distinct compOnents:
.• V ideo m onitor, the terminal where the output ~ppears, "
.• Video contro ller , the circuitry that ca~ the output to appear by sending the
appropriate signals to the monitor
r n a bitmapped graphics display) the monitor displays an array of dots (known as pixels)
and ~e appearance of each pixel corresponds to the c09tents of a memory location in t
video' cOntroller. For a black-ana-white display in which each pixd. is either bright or d
_ a single bit of memory can store the'state of a pixel. The term bitrnilppea refers to this
, corresponden~ of each bit in memory to a pixel on the ,screen: '
R aster grap hics is another common name for bitmap~ ~hics 'because the graphi<:s
displa.yappearing on the monitor is consiructedfrom a large num~r, ofhorizoniallines
known as raster lines. Raster lines are generated in the monitor by an decrron beam
-sweepiJ;lgback and forth on a.phosphor<oated screen. Becanse each dot of phosphor.
~nding to a pixel, glows in proportion to1the intensity of the beam, each line of
~ can be generated by controlling the intensity of the beam as it scans acrQSSthe
B y drawing the raster lines repeatedly, die illusion of a sttkdy image is created.
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If this ,summary description of X is too terse for you, don't despair-there is much more to come
This book is designed to help 'Youbecome familiar with X, see how rypical X applications workand learn how to write your own X applications using the C routines in Xlib and other librarie
such asXt and Motif . This chapter introduces you, the prospective X programmer, to the X Win
dow System and gives an overview of its capabilities and benefits. Chapter 2, "Clients, Servers, and
Window Managers," shows how to set up and use X on a workstation and how to run X applica
tions; it also explains {he terminology used to describe the X Window System. Chapter 3, "Explor
ing X Applications," walks you through a number of common X applications to g' e you a feel fo
the windowing system and prepare you to learn how to create similar applications. The final chap
ter in Part One, Chapter 4, "Graphical User Interfaces and X," describes Motif and OPEN LOOK-
two graphical user interfaces built on top ofXlib, the C-callable library of routine~ that represen
Wh
the
basiactcaPlasbiIX"",.OfX. ~
f'~ "1?}~iGOttoV\
. a combination..of-sc, ¥ er thin S' the-X- -ro~ol, X dis la' sety:et..x diems, and Xlib..-routine
Jtsc lemsJlre applic~ons ha: IlseIhework station's displa ¥ ..J,~t's start by taking a 00
picture.