XSolarisOvlSelectPair(3) X FUNCTIONS XSolarisOvlSelectPair(3)

NAME

XSolarisOvlSelectPair - selects an optimal overlay/underlay visual
pair that best meets the criteria

SYNOPSIS

#include <X11/extensions/transovl.h>


XSolarisOvlSelectStatus
XSolarisOvlSelectPair (Display *display, int screen, int
numCriteria, XSolarisOvlPairCriteria *pCriteria, XVisualInfo
*ovVisinfoReturn, XVisualInfo *unVisinfoReturn, unsigned long
*unmetOvCriteriaReturn, unsigned long *unmetUnCriteriaReturn)

Arguments
display
Specifies the connection to the X server.

screen An integer specifying the screen on which the visuals are to
be searched.

numCriteria
The number of XSolarisOvlPairCriteria structures in the
pCriteria array.

pCriteria
An array of pair criteria structures in priority order from
high to low specifying the criteria to be used in selecting
the pair.

ovVisinfoReturn
A pointer to a caller provided XVisualInfo structure. On
successful return, this structure contains a description of
the chosen overlay visual.

unVisinfoReturn
A pointer to a caller provided XVisualInfo structure. On
successful return, this structure contains a description of
the chosen underlay visual.

unmetOvCriteriaReturn
A pointer to a bitmask that describes the criteria that were
not satisfied for the overlay visual. This return argument is
only meaningful when the routine returns a value of
XSolarisOvlQualifiedSuccess, or XSolarisOvlCriteriaFailure.

unmetUnCriteriaReturn
A pointer to a bitmask that describes the criteria that were
not satisfied for the underlay visual. This return argument
is only meaningful when the routine returns a value of
XSolarisOvlQualifiedSuccess, or XSolarisOvlCriteriaFailure.

Argument Types
See the Description section for a full description of how these types
should be used.

XSolarisOvlPairCriteria
A structure defining various criteria to be used during visual
selection, along with indications of the stringency of the
criteria.

typedef struct {
XSolarisOvlVisualCriteriaoverlayCriteria;
XSolarisOvlVisualCriteriaunderlayCriteria;
} XSolarisOvlPairCriteria;

XSolarisOvlVisualCriteria is defined in the specification of
XSolarisOvlSelectPartner(3).

Return Types
XSolarisOvlSelectStatus
Refer to the specification of XSolarisOvlSelectPartner(3) for
the definition of this type.

XSolarisOvlSuccess is returned if the search is completely successful
in finding a pair that meets all hard and soft criteria of one of the
XSolarisOvlPairCriteria structures.

XSolarisOvlQualifiedSuccess is returned if the chosen pair satisfies
all hard criteria of one of the XSolarisOvlPairCriteria structures,
but doesn't meet all soft criteria. In this case,
unmetOvCriteriaReturn and unmetUnCriteriaReturn contains the logical
OR of the soft criteria that were not met for the overlay and
underlay, respectively.

XSolarisOvlCriteriaFailure indicates that no pair could be found that
meets all the hard criteria of any of the XSolarisOvlPairCriteria
structures. In this case, unmetOvCriteriaReturn and
unmetUnCriteriaReturn contains the logical OR of the hard criteria
that were not met by the XSolarisOvlPairCriteria structure with the
fewest hard failures, for the overlay and underlay, respectively.

XSolarisOvlFailure is returned if some other error is encountered
besides criteria match failure.

DESCRIPTION

This routine is similar to XSolarisOvlSelectPartner(3). However,
instead of selecting a partner visual given another visual, this
routine simultaneously selects both the overlay and underlay visual
from the set of all visual pairs for the given screen. The pair
selected will be the one that best matches the given criteria.

The client is assured that, short of X errors not related to
overlays, it can successfully create windows with the returned
visuals.

This routine searches through all optimal visual pairs for a given
screen, and then through all pairs of visuals (optimal and non-
optimal), applying the specified criteria. These criteria are
specified in pCriteria. Each element of pCriteria specifies criteria
for both the overlay and underlay. It returns a success or failure
status depending on whether it finds a pair that meets all the given
criteria.

The selected pair will have an overlay that satisfies all the hard
criteria specified for the overlay. The pair will have an underlay
visual that satisfies all the hard criteria for the underlay. The
attributes of the overlay visual are returned in ovVisinfoReturn.
Likewise, the attributes of the underlay visual are specified in
unVisinfoReturn. If two or more pairs are found that meet all of the
hard criteria (both overlay and underlay) and the same number of soft
criteria (either overlay or underlay), one of them will be chosen and
returned. It is implementation dependent which one is chosen.

Like XSolarisOvlSelectPartner(3), XSolarisOvlSelectPair supports a
degradation sequence of criteria sets. This means that multiple
criteria sets can be specified in a single call. First, an attempt
is made to find a pair matching the first criteria set for both the
overlay and the underlay. If a pair is found which meets all of the
hard criteria of the first set, this pair is chosen. If no pair
meets all hard criteria of the first set, a search is performed using
the second criteria set. This process continues until either a pair
is found that meets the all of the hard criteria of some criteria
set, or all sets have been used to search. This degradation sequence
allows clients to specify the criteria for the most preferred pair as
the first criteria set. Pairs that are acceptable but which are less
desirable can be specified in criteria sets following the first.
This allows the search to proceed through a progressive relaxation in
the client's requirements for the pair with a single subroutine call.

The criteria masks that can be specified are described in the
specification of XSolarisOvlSelectPartner(3).

X Version 11 libXext 1.3.6 XSolarisOvlSelectPair(3)