XSolarisOvlSelectPartner(3) X FUNCTIONS XSolarisOvlSelectPartner(3)

NAME

XSolarisOvlSelectPartner - returns the overlay/underlay visual that
best meets the criteria

SYNOPSIS

#include <X11/extensions/transovl.h>


XSolarisOvlSelectStatus
XSolarisOvlSelectPartner (Display *display, int screen,
VisualID vid, XSolarisOvlSelectType seltype, int numCriteria,
XSolarisOvlVisualCriteria *pCriteria, XVisualInfo
*visinfoReturn, unsigned long *unmetCriteriaReturn)

Arguments
display
Specifies the connection to the X server.

screen An integer specifying the screen for the visual vid.

vid The XID of the visual to find a partner for.

seltype
The type of selection that is to be done.

numCriteria
The number of XSolarisOvlVisualCriteria structures in the
pCriteria array.

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

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

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

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

XSolarisOvlSelectType

An enumeration defining two types of selections that can be done in
XSolarisOvlSelectPartner.
typedef enum {
XSolarisOvlSelectBestOverlay,
XSolarisOvlSelectBestUnderlay,
} XSolarisOvlSelectType;

XSolarisOvlVisualCriteria

A structure defining various criteria to be used during visual
selection, along with indications of the stringency of the criteria.
typedef struct {
unsigned long hardCriteriaMask;
unsigned long softCriteriaMask
int c_class;
unsigned int depth;
unsigned int minColors;
unsigned int minRed;
unsigned int minGreen;
unsigned int minBlue;
unsigned int minBitsPerRGB;
unsigned int minBuffers;
} XSolarisOvlVisualCriteria;

hardCriteriaMask and softCriteriaMask are bitmasks whose values can
be the logical OR of any of the following bitmasks:

#define XSolarisOvlVisualClass (1L<<0)
#define XSolarisOvlDepth (1L<<1)
#define XSolarisOvlMinColors (1L<<2)
#define XSolarisOvlMinRed (1L<<3)
#define XSolarisOvlMinGreen (1L<<4)
#define XSolarisOvlMinBlue (1L<<5)
#define XSolarisOvlMinBitsPerRGB (1L<<6)
#define XSolarisOvlMinBuffers (1L<<7)
#define XSolarisOvlUnsharedPixels (1L<<8)
#define XSolarisOvlUnsharedColors (1L<<9)
#define XSolarisOvlPreferredPartner (1L<<10)

These are described in the XSolarisOvlSelectPartner Description
documentation that follows.

Return Types
XSolarisOvlSelectStatus

A value that indicates whether the routine succeeded in finding a
visual and, if it failed, the reason for the failure. The return
value can be one of:
typedef enum {
XSolarisOvlSuccess,
XSolarisOvlQualifiedSuccess,
XSolarisOvlCriteriaFailure,
XSolarisOvlFailure,
} XSolarisOvlSelectStatus;

XSolarisOvlSuccess is returned if the search is completely successful
in finding a visual that meets all hard and soft criteria of one of
the XSolarisOvlVisualCriteria structure.

XSolarisOvlQualifiedSuccess is returned if the chosen visual
satisfies all hard criteria of one of the XSolarisOvlVisualCriteria
structure, but doesn't meet all soft criteria. In this case,
unmetCriteriaReturn contains the logical OR of the soft criteria that
were not met.

XSolarisOvlCriteriaFailure indicates that no visual could be found
that meets all the hard criteria of any of the
XSolarisOvlVisualCriteria structures. In this case,
unmetCriteriaReturn contains the logical OR of the hard criteria that
were not met for the XSolarisOvlVisualCriteria structure with the
fewest hard criteria not met.

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

DESCRIPTION

Portable applications using overlays may wish to search for an
appropriate overlay visual to use for a given underlay visual, or
vice-versa. Each X screen supporting the overlay extension defines a
set of overlay visuals whose windows are best for use as children of
underlay windows. For each underlay visual, there is a set of
optimal overlay visuals. Together, all combinations of underlay
visuals and their optimal overlay visuals form the set of optimal
overlay/underlay pairs for that screen. The overlay and underlay
visuals of an optimal pair are said to be partners of each other.

XSolarisOvlSelectPartner allows the client to select, given an
underlay visual, an optimal overlay that meets certain criteria.
Inversely, it also allows the client to select an optimal underlay
visual given an overlay visual.

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

This routine searches through the optimal partners of the given
visual, applying the criteria specified in pCriteria. It returns a
success or failure status depending on whether it finds a visual that
meets the criteria.

A criterion can be one of two types:

1. Hard Criterion
A criterion that must be satisfied. Only visuals that meet hard
criteria are candidates for successful matches.

2. Soft Criterion
A desirable criterion, but one which is not required. The visual
that matches all hard criteria and the most soft criteria is
chosen. Its attributes are returned in visinfoReturn. If two or
more visuals are found that meet all of the hard criteria and the
same number of soft criteria, one of them will be chosen and
returned. It is implementation dependent which one is chosen.

XSolarisOvlSelectPartner 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 visual matching the
first criteria set. If a visual is found which meets all of the hard
criteria of the first set, this visual is chosen. If no visual met
all hard criteria of the first set, a search is performed using the
second criteria set. This process continues until either a visual is
found that meets 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 visual as the first
criteria set. Visuals 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 visual with a single subroutine
call.

Any of the possible criteria can be specified either as a hard or
soft criteria for a particular criteria set. For a given set,
hardCriteriaMask is the logical OR of the criteria bitmasks that are
to be applied as hard criteria during the search. Likewise,
softCriteriaMask is the logical OR of the soft criteria bitmasks.

Some criteria have values associated with them. These values are
provided by other data members in the XSolarisOvlVisualCriteria
structure. In the criteria descriptions which follow, these data
members are mentioned where applicable.

XSolarisOvlVisualClass specifies that the client desires the selected
visual to have a specific visual class. The required class is
specified in c_class.

The following criteria interact within one another: XSolarisOvlDepth,
XSolarisOvlMinColors, XSolarisOvlMinRed, XSolarisOvlMinGreen, and
XSolarisOvlMinBlue. Typically, only some subset of these should be
specified. XSolarisOvlDepth specifies that the depth of the selected
visual is to be equal to depth. XSolarisOvlMinColors specifies that
the selected visual is to have at least minColors number of total
displayable colors. XSolarisOvlMinRed, XSolarisOvlMinGreen, and
XSolarisOvlMinBlue can be used to indicate more specific color
requirements for DirectColor or TrueColor visuals. Their
corresponding values are specified in minRed, minGreen, and minBlue,
respectively. These indicate that the selected visual must have at
least the specified number of reds, greens, and/or blues.

XSolarisOvlMinBitsPerRGB specifies that the selected visual is to
have at least minBitsPerRGB of color channel output from colormaps
created on that visual.

XSolarisOvlMinBuffers specifies that the client desires the selected
visual to be able to be assigned at least minBuffers number of
accelerated MBX image buffers.

XSolarisOvlUnsharedPixels selects partner visuals whose window pixels
don't lie in the same drawing plane groups as the window pixels of
the argument visual vid. If a visual uses the same drawing plane
group as the argument visual it is not matched by this criterion.

XSolarisOvlUnsharedColors selects partner visuals whose window pixel
colors can be displayed simultaneously when the overlay/underlay
window pair has the colormap focus. If a visual shares the same
color LUT pool and that pool has only one color LUT in it as the
argument visual it is not matched by this criterion.

If either hardCriteriaMask of a criteria set is to 0, any visual will
match that criteria set with a hard match. Likewise, setting the
softCriteriaMask of a criteria set to 0, is sufficient to guarantee
at least a soft match for that criteria set.

X Version 11 libXext 1.3.6 XSolarisOvlSelectPartner(3)