ImagerColorDisplayDoc.tioga
Michael Plass, March 4, 1987 6:36:46 pm PST
ImagerColorDisplay
CEDAR 7.0 — FOR INTERNAL XEROX USE ONLY
ImagerColorDisplay
Michael F. Plass
© Copyright 1987 Xerox Corporation. All rights reserved.
Abstract: This package contains the implementations for various kinds of Imager contexts that can use the color display for output.
Created by: Michael Plass
Maintained by: Michael Plass <Plass.pa>
Keywords: Imager, Color Display, Sampled Images
XEROX Xerox Corporation
Palo Alto Research Center
3333 Coyote Hill Road
Palo Alto, California 94304
For Internal Xerox Use Only
1. Introduction
This is a client package; the color display context implementations register some interesting default display types with ColorDisplayManager in Viewers. Clients may register variations on these that may, for example, use different color maps. The user needs to install the drivers (color display context implementations) for the display types of interest.
Note that these implementations allow output to other rasters as well as to the color display memory. See the interfaces for details.
2. Interfaces (those with
strikeouts are not yet implemented)
ImagerColorMap
Used by various drivers for loading the color map of the color display.
ImagerDitherContext
Does color dithering.
ImagerGrayContext
Monochrome rendering with a gray color map.
ImagerSmoothContext
Monochrome antialiased rendering at low or high resolution,
color antialiased rendering at low resolution only.
ImagerFullColorContext
Color rendering (low resolution color mode only).
3. Color Display Types Registered for various Install files
This section tells which display types are registered by the color display context implementation; these are the atoms you need to pass to ColorDisplayManager.Start to start up the display in the respective modes.
ImagerDither.install
Dither1, Dither2, Dither4, Dither8
note: BlackAndWhite is registered in ColorDisplayManagerImpl, and is considerably faster than Dither1
ImagerGray.install
Gray2, Gray4, Gray8
ImagerSmooth.install
SmoothGray2, SmoothGray4, SmoothGray8, SmoothColor
ImagerFullColor.install
FullColor
4. Turning the Color Display on and off with the Interpreter
This uses an interface provided by Viewers, ColorDisplayManager. For example, to start the display in 8 bit dithered high-resolution mode, you could say (assuming you brought this package into Commands)
PushV Commands; Install ImagerDither; Pop
← ColorDisplayManager.Start[type: $Dither8, side: left]
note: Initalizing the dither table takes time, so be patient
To turn it off, use
← ColorDisplayManager.Stop[]
To find out the currently registered display types, use
← ColorDisplayManager.NextState[].registered
Documentation about a registered display type may be obtained by
← ColorDisplayManager.FetchCreator[$Dither8].documentation
A smoother user interface will surely follow in a separate package, but I'll leave that to someone else.