Nearby Color Allocation - Barco Argus X Terminal User Manual

6.2.8 Nearby color allocation

In order to ensure that X X clients can allocate their colors in 8 bit PseudoColor mode even if the color map is al-
ready filled completely the Nearby Color Allocation has been implemented: If an X client requests a shared color
and the X server is not able to allocate this color exactly, it decides to return a color that is »nearby« the re-
quested one.
Nearby Color Allocation can be applied optional, whether by a command line parameter on start up of the
X server (option mode) or by specifying a file with a set of predefined colors (file mode).
Option mode
Nearby Color Allocation is used if the color table is full or if there are more than a given number of colors con-
tained in the color table. The number of colors in the color table up to that colors are allocated by exact match
strategy is set by the following command line parameter:
-nearby <n>
If the color table already contains <n> colors further allocation of shared colors will be carried out using Nearby
Color Allocation strategy. Values between 16 and 256 are allowed.
A certain amount of colors can be reserved as private colors for X clients that are to be started later.
File mode
The environment variable NEARBY_FILE specifies the name of a file that contains the definition of shared col-
ors. The environment variable NEARBY_FILE is only considered if the command line parameter –nearby is not
set. The number of entries in the file specifies the parameter <n> in that case.
If neither –nearby <n> nor NEARBY_FILE is set the X server searches for the file named nearby in the
following directory:
/etc/MMTconfig/nearby.def
If the file nearby.def cannot be found color allocation will be carried out using standard-strategy that means
using exact-matching-strategy.
The nearby configuration file contains in the first line the keyword COLORCELLS separated by a blank from the
number of colors defined in the following lines, e. g.:
COLORCELLS 135
In the following lines the RGB values are defined in hexadecimal notation, separated by blanks and within a
range of 0 to 0xFF. Lines beginning with the character # are considered to be comments. E. g.:
# red:
FF 00 00
# green:
00 FF 00
# blue:
00 00 FF
# grey:
32 32 32
In file mode all specified colors are allocated as shared color cells on start up of the X server. By specifying a
balanced set of colors you can avoid color distortions as they may appear in option mode if e. g. only shades of
blue have been allocated and yellow is requested.
In the file nearby.def a maximum of 256 colors can be specified. If there is a need for private cells, only a
correspondingly smaller number of colors may be defined.
Barco – Argus X Terminal – DOC-3265-2 – user's manual – Revision 04 – May-2004
16 and 256 are allowed.
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6. Advanced configuration
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