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} 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 segment is not complete; however, its main purpose is to give an idea of how to find an
overlay visual having transparency.
Graphics Administration Guide for HP-UX 10.20
Page 71