The Overlay Plane Color Map Management Scheme

Many applications use the default X11 color map. A technicolor effect (color flashing) in the windows using the default color map occurs when a non-default color map is downloaded into the hardware color map that had previously contained the default X11 color map.

Because so many applications use the default X11 color map, and because the HP Visualize-FX devices have two hardware color maps in the overlay planes, the behavior on these devices is to dedicate (that is, lock) one overlay hardware color map to always hold the default X11 color map. This means that the assigned default overlay hardware color map cannot have another color map downloaded to it. The other overlay hardware color map is available to applications that use color maps other than the default.

The following section describes the default frame buffer configuration for the HP Visualize-FX devices.

The default visual configuration is:
- overlay planes
- depth 8
- PseudoColor
- opaque (no transparency)
with 256 color map entries. Note that when using the default X server mode of the HP Visualize-FX devices, if you query the X server for the number of entries in the default color map, the server will reply that there are 256 entries available. Although these entries are available, the X server reserves the last entry (index 255). So, that entry is not writable and should not be used.
The default X11 color map is locked into one of the hardware color maps in the overlay planes. For a description of how to move the default visual to images planes, read the section "Moving the Default Visual to the Images Planes" in this chapter.

The Overlay Plane Color Map Management Scheme

Technical documentation

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