HCRX and HP Visualize Device-Dependent Information

The eight-plane HCRX-8[Z], HP [Dual] Visualize-EG and HP Visualize-8 are the first members of the Series 700 graphics family whose overlay planes and image planes are both depth 8.

The default colormap cannot be used with a window in a non-default visual, even one of the same depth as the default visual.

Before trying to use the default colormap in a depth-8 window, verify that the window is in the default visual. If the window is not in the default visual, create a colormap in that visual. This process of creating a non-default colormap is the same as the one used to create windows in depth-12 or depth-24 visuals.

If you have an application that assumes that the default colormap can be used with any depth-8 window (even one in an image-plane visual) specify an image-plane visual as the default.

Unlike the CRX, the HCRX-8[Z]'s default visual the HP [Dual] Visualize-EG's default visual and the HP Visualize-8's default visual do not have fast hardware double-buffering (but the image planes do).

To obtain hardware double-buffering, find a visual in the image planes. The best method is to find all the depth-8 PseudoColor visuals returned by XGetVisualInfo and then eliminate the visuals that are reported in the SERVER_OVERLAY_VISUALS property (discussed below).

If you have an application that assumes the default visual has fast double-buffering, specify an image plane visual as the default.

As on the CRX-24[Z] and CRX-48Z, a property on the root window,SERVER_OVERLAY_VISUALS, is used to describe the visuals that are in the overlay planes.

The HCRX-8[Z], HP [Dual] Visualize-EG and HP Visualize-8 each have one visual in the overlay planes (depth-8 PseudoColor). By default, this overlay visual has no transparent index available to applications for rendering transparency. This means the overlay windows with "floating text" are not supported in the typical X server operation on the HCRX-8[Z], HP [Dual] Visualize-EG or HP Visualize-8.

For applications that require transparent overlay windows on the HCRX-8[Z], HP Visualize-EG(D) or HP Visualize-8, an optional X server mode is available to allow for overlay transparency, but it is restrictive. In this optional mode, overlay colormaps provide a single entry that can be used to render transparency. Only one hardware colormap is available in the overlays (instead of two) and only one hardware colormap is available in the image planes (instead of two).

To activate this optional X server mode to enable transparency, set the EnableOverlayTransparency screen option. You will need to restart the X server for the option to take effect.

With this mode enabled, colormaps created in the default visual have 255 entries; entry 256 is reserved for transparency. As on the CRX-24[Z] and CRX-48Z, the screen option CountTransparentInOverlayVisual can be used to include the transparent index in the colormap size (256 entries instead of 255).

The HCRX-24[Z], HP Visualize-24, and HP Visualize-48[XP] have two visuals in the overlay planes, both depth-8 PseudoColor.

The default overlay visual has 256 entries per colormap and no transparency.

The second overlay visual has 255 entries per colormap and supports transparency in the same way as the CRX-24[Z]. As on the CRX-24[Z] and CRX-48Z, the screen option EnableOverlayTransparency can be used to include the transparent index in the colormap size (256 entries instead of 255).

To allow applications to determine which visuals are in the overlay planes, both overlay visuals are listed in the SERVER_OVERLAY_VISUALS property attached to the root window. The default overlay visual has a transparent type of 0 (None) while the transparent overlay visual has a transparent type of 1 (TransparentPixel).

If you need an overlay colormap that supports transparency, create the colormap using the visual that has transparency in its SERVER_OVERLAY_VISUALS property. To look at the contents of this property, you would use code similar to the following:

{
typedef struct {
    VisualID    overlayVisualID;
    Card32      transparentType;/* None, TransparentPixel, TransparentMask */
    Card32      value;          /* Either pixel value or pixel mask */
    Card32      layer;
} OverlayVisualPropertyRec;
 
OverlayVisualPropertyRec  *pOverlayVisuals, *pOVis;
XVisualInfo               getVis;
XVisualInfo               *pVisuals;
Atom                      overlayVisualsAtom, actualType;
...
    /* Get the visuals for this screen and allocate. */
    getVis.screen = screen;
    pVisuals = XGetVisualInfo(display, VisualScreenMask, &getVis, &nVisuals);
    pOverlayVisuals = (OverlayVisualPropertyRec *)
            malloc ( (size_t)nVisuals * sizeof(OverlayVisualPropertyRec) );
 
    /* Get the overlay visual information for this screen.  Obtain
     * this information from the SERVER_OVERLAY_VISUALS property. */
    overlayVisualsAtom = XInternAtom(display, "SERVER_OVERLAY_VISUALS", True);
    if (overlayVisualsAtom != None)
        {
        /* Since the Atom exists, request the property's contents. */
        bytesAfter = 0;
        numLongs = ( nVisuals * sizeof(OverlayVisualPropertyRec) + 3 ) / 4;
        XGetWindowProperty(display, RootWindow(display, screen),
                               overlayVisualsAtom, 0, numLongs, False,
                               AnyPropertyType, &actualType, &actualFormat,
                               &numLongs, &bytesAfter, &pOverlayVisuals);
        if ( bytesAfter != 0 ) {/* Serious Failure Here */} ;
 
        /* Loop through the pOverlayVisuals array. */
        ...
        nOVisuals = numLongs/sizeof(OverlayVisualPropertyRec);
        pOVis = pOverlayVisuals;
 
        while (nOVisuals >= 0)
            {
            if ( pOVis->transparentType == TransparentPixel )
                {/* Found a transparent overlay visual, set ident. aside. */};
            pOVis++;
            }
        XFree(pOverlayVisuals);
        /* There might be some additional checking of the found
           transparent overlay visuals wanted; e.g., for depth. */
        }
    XFree(pVisuals);
}

This program fragment is not complete; its main purpose is to give the idea of how to find an overlay visual having transparency.

The following information discusses the number of supported colormaps for the HCRX configurations.

The image planes contain the default colormap permanently installed in the hardware plus one other hardware colormap available to applications. No issues involving transparency exist because of the lack of Overlay planes.

When the default visual is in the overlay planes (default location) and the screen option EnableOverlayTransparency is not set, the overlay planes contain the default colormap permanently installed in the hardware, plus one other hardware colormap available to applications. The image planes contain two hardware colormaps each usable by applications.

When the default visual is in the image planes and the screen option EnableOverlayTransparency is not set, the overlay planes contain a single hardware colormap available to applications, plus a colormap reserved by the server (i.e., unavailable to applications) to guarantee the existence of transparency, and the image planes contain the default colormap permanently installed into the hardware, plus one other hardware colormap available to applications.

When the screen option EnableOverlayTransparency is set, both the overlay planes and the image planes have access to one hardware colormap. The default colormap is not permanently installed in the hardware and is in the overlay planes by default, but the Default Visual can be located in the image planes as described in a previous section.

The overlay planes contain the default colormap permanently installed in the hardware, plus one other hardware colormap available to applications. The image planes contain two hardware colormaps, each usable by applications.

Although two hardware colormaps are available to applications in the image planes, a hardware restriction allows only one depth-12 or depth-24 colormap to be installed at any given time. Therefore, if two applications are run simultaneously and use different depth-12 or depth-24 colormaps, the application that has the colormap focus looks correct and the other is technicolored.

The overlay planes contain the default colormap permanently installed in the hardware, plus one other hardware colormap available to applications. The image planes contain four hardware colormaps, each usable by applications.

The four hardware colormaps in the image planes can be treated as depth-8 or depth-24 colormaps. There are no restrictions on the types of colormaps that can be installed in the hardware at any given time. All four colormaps can be used with any visual class.