1XEVI(3)                           X FUNCTIONS                          XEVI(3)
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NAME

6       XeviQueryExtension,  XeviQueryVersion,  XeviGetVisualInfo  - X Extended
7       Visual Information functions
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SYNOPSIS

10       #include <X11/extensions/XEVI.h>
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12       Bool XeviQueryExtension (Display *dpy);
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14       Bool XeviQueryVersion (Display *dpy,
15           int *major_version_return,
16           int *minor_version_return);
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18       int XeviGetVisualInfo (Display *dpy, VisualID *visual,
19           int n_visual, ExtendedVisualInfo ** evi_return,
20           int * n_info_return);
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DESCRIPTION

23       The X11 Extended Visual Information extension (EVI) allows a client  to
24       determine  information about core X visuals beyond what the core proto‐
25       col provides.
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27       The  EVI  application  programming  library  contains  the   interfaces
28       described  below.   With the exception of XeviQueryExtension, if any of
29       these routines are called with a display  that  does  not  support  the
30       extension,  the ExtensionErrorHandler (which can be set with XSetExten‐
31       sionErrorHandler and functions the same way as  XSetErrorHandler)  will
32       be called and the function will then return.
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34       XeviQueryExtension  returns  True  if  the  Extended Visual Information
35       extension is available on the given display.  A client must call  Xevi‐
36       QueryExtension  before calling any other EVI function in order to nego‐
37       tiate a compatible protocol version;  otherwise  the  client  will  get
38       undefined behavior (EVI may or may not work).
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40       XeviQueryVersion  returns  True if the request succeeded; the values of
41       the major and minor  protocol  version  supported  by  the  server  are
42       returned in major_version_return and minor_version_return.
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44       XeviGetVisualInfo  returns a list of ExtendedVisualInfo structures that
45       describe visual information beyond that supported by the core protocol.
46       This  includes  layer information relevant for systems supporting over‐
47       lays and/or underlay planes, and information that  allows  applications
48       better  to  determine  the  level of hardware support for multiple col‐
49       ormaps. XeviGetVisualInfo returns Success if successful, or an X  error
50       otherwise.   If  the  argument visual is NULL, then information for all
51       visuals of all screens is returned. Otherwise, it's a pointer to a list
52       of  visuals for which extended visual information is desired.  n_visual
53       is the number of elements in the array visual.   evi_return  returns  a
54       pointer  to  a list of ExtendedVisualInfo. When done, the client should
55       free the list using XFree.  n_info_return returns the  number  of  ele‐
56       ments in the array evi_return.
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58       The ExtendedVisualInfo structure has the following fields:
59            VisualID        core_visual_id
60            int             screen
61            int             level
62            unsigned int    transparency_type
63            unsigned int    transparency_value
64            unsigned int    min_hw_colormaps
65            unsigned int    max_hw_colormaps
66            unsigned int    num_colormap_conflicts
67            VisualID *      colormap_conflicts
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69       The  combination  of  core_visual_id and screen number uniquely specify
70       the visual being described.
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72       level returns the level number for the visual, 0 for normal planes, > 0
73       for overlays, < 0 for underlays.
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75       transparency_type  returns  the  type  of transparency supported by the
76       visual. XEVI_TRANSPARENCY_NONE if  there  are  no  transparent  pixels,
77       XEVI_TRANSPARENCY_PIXEL  if  the  visual  supports a transparent pixel,
78       XEVI_TRANSPARENCY_MASK if the visual supports transparent plane(s).
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80       transparency_value returns the pixel/plane  value  to  set  for  trans‐
81       parency if transparency_type isn't XEVI_TRANSPARENCY_NONE.
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83       min_hw_colormaps  and  max_hw_colormaps  return the minimum and maximum
84       number of hardware colormaps backing up the visual.
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86       num_colormap_conflicts returns the number of elements in  colormap_con‐
87       flicts.   This array returns a list of visuals that may cause conflicts
88       in the use of the hardware colormap. For example, if a 12-bit  hardware
89       colormap  is  overloaded  to support 8-bit colormaps, the corresponding
90       8-bit visuals would conflict with the 12-bit visuals.
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ERRORS

94       XeviGetVisualInfo will return BadValue if passed an illegal visual  ID,
95       BadAccess if the X server does not respond, BadAlloc if there is a mem‐
96       ory allocation failure.
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100X Version 11                     libXext 1.3.4                         XEVI(3)
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