The Components of Macintosh Graphics
Broadly speaking, a Macintosh graphics system has three parts: QuickDraw, the video card and screen that constitute the display device, and the interface
between them.
QuickDraw comes in three varieties: the original version offered with systems equipped with a 68000 micro processor; the original
part of system software version 7.0.
In general, applications that use the original QuickDraw routines are compatible with all Macintosh systems. Applications using the original
original QuickDraw, nor can applications using direct pixel images run on Note that the original QuickDraw contains a simple eight-color system that is compatible with all machines (although the colors cannot be displayed on
early black-and-white systems), so if your application needs eight colors or
fewer, you can maximize compatibility by using that system, which is
Whenever possible, earlier versions of QuickDraw have been upgraded with later features. For example, later versions of the original QuickDraw can process pictures that include color information. Although such QuickDraw versions cannot display color, they display the best black-and-white
approximation possible.
The Interface
The Monitors control panel lets users arrange their screens in relation to
each other in space (above or below, side by side) and select how many colors,
if any, a device is to display.
with a color-selection dialog box. The Color Picker's wheel and slide controls
let the user preview and select any color the hardware can produce. (The Color
control panel, for example, uses the Color Picker to let the user choose a
highlight color to be used on the desktop.)
that demonstrate an important axiom: the user is in charge. The user can select
any one of trillions of colors through the Color Picker, and that same user may
set the color device to show only black and white pixels.
and control the set of colors needed by your application window. Palettes are
especially important with indexed screen devices, which support only displays
that show a maximum of 256 colors at once. Since all or parts of several
applications and the desktop may be visible on the screen, and they may all
have different color schemes, contention can arise for those 256 table places.
see that the color requirements of the frontmost, or active, window are met
first.
And no matter how wild a neon-blacklit-backlit effect you create, the
terminates.
graphics abilities of the Color Manager to find the best color available when all color table indexes are taken and another color is needed on the screen. The
Color Manager examines the available colors and determines which of them is closest to the requested color. If your application needs to paint a race car
British racing green, for example, you can ask for it by using a
finds available is a close enough match to look good. Or you can ask the Palette Manager for the color and specify how close the match has to be. If no color requested into the color table for the device.
to the video driver and its card. The Slot Manager examines every installed card when the system starts up, and from the information the cards supply,
manages the record that describes the capabilities of the graphics card.