About the Color Picker
This topic covers ways to present users with a standard interface for color
hue/saturation/brightness model of color choice and the red/ green/blue
method. The first is the standard Macintosh model while the second is offered as
a convenience for users such as artists, photographers or printers who may be
more familiar with alternate color selection methods.
Of itself, the Color Picker doesn't alter a monitor's color look-up table and deals only with the application. The application can then apply color changes
that will show up on the screen unless the hardware itself is in less than 4-bit
mode or is a monochrome monitor.
Direct device hardware duplicates color exactly, while fixed devices show an
approximation of the selected colors. On device's with variable color look-up
tables, it is the application that decides how closely the displayed color will
match the requested color.
The GetColor routine, called from an application, shows the user a dialog box in which the user can select which color to modify and what degree of
modification to apply. After the user chooses which color to change, clicking on
a color wheel selects hue and saturation together. Choices range from a
minimum of zero saturation in the middle of the wheel (where the color shows
up as gray) to the outer edge of the wheel where the hues are undiluted with
any gray at all. A vertical scroll bar ranges the brightness of the color from
bight (top) to dim (bottom). The color wheel/ scrollbar set of controls only
relate to the hue/saturation/brightness color model. The red/ green/blue
model is completely controlled by incrementing or decrementing the individual
component's values.