---
name: "Xevi"
section: "3"
platform: "linux"
package: "libxext"
version: "1.3.7-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Xevi"
---

# Xevi(3)

X Extended Visual Information functions

## NAME

XeviQueryExtension, XeviQueryVersion, XeviGetVisualInfo - X Extended Visual Information functions

## SYNOPSIS

```
#include <X11/extensions/XEVI.h>

Bool
XeviQueryExtension (Display *dpy);

Bool
XeviQueryVersion (Display *dpy,
    int *major_version_return,
    int *minor_version_return);

int
XeviGetVisualInfo (Display *dpy, VisualID *visual,
    int n_visual, ExtendedVisualInfo **evi_return,
    int *n_info_return);
```

## DESCRIPTION

**The** **X11 Extended Visual Information extension (EVI) allows a client to determine** **information about core X visuals beyond what the core protocol provides.**

**The EVI application programming library contains the interfaces described below.** **With the exception of** **XeviQueryExtension**, **if any of these routines are** **called with a display that does not support the extension,** **the ExtensionErrorHandler (which can be set with** **XSetExtensionErrorHandler** **and functions the same way as** **XSetErrorHandler**) **will be called and the function will then return.**

**XeviQueryExtension** **returns** **True** **if the Extended Visual Information extension is available on the given display.** **A client must call** **XeviQueryExtension** **before calling any other EVI** **function in order to negotiate a compatible protocol version;** **otherwise the client will get undefined behavior** **(EVI may or may not work).**

**XeviQueryVersion** **returns** **True** **if the request succeeded; the values of the major and minor protocol** **version supported by the server are returned in** *major\_version\_return* **and** *minor\_version\_return*.

**XeviGetVisualInfo** **returns a list of ExtendedVisualInfo structures that describe** **visual information beyond that supported by the core protocol.** **This includes layer information relevant for systems** **supporting overlays and/or underlay planes,** **and information that allows applications better to determine the level** **of hardware support for multiple colormaps.** **XeviGetVisualInfo returns** **Success** **if successful, or an X error otherwise.** **If the argument** *visual* **is NULL, then information for all visuals of all** **screens is returned.** **Otherwise, it's a pointer to a list of visuals for which** **extended visual information is desired.** *n\_visual* **is the number of elements in the array visual.** *evi\_return* **returns a pointer to a list of ExtendedVisualInfo.** **When done, the client** **should free the list using XFree.** *n\_info\_return* **returns the number of elements in the array evi\_return.**

**The** **ExtendedVisualInfo** **structure has the following fields:**

```
VisualID	core_visual_id
int 	screen
int 	level
unsigned int	transparency_type
unsigned int	transparency_value
unsigned int	min_hw_colormaps
unsigned int	max_hw_colormaps
unsigned int	num_colormap_conflicts
VisualID *  	colormap_conflicts
```

The combination of *core\_visual\_id* and *screen* number uniquely specify the visual being described.

*level* returns the level number for the visual, 0 for normal planes, \> 0 for overlays, \< 0 for underlays.

*transparency\_type* returns the type of transparency supported by the visual. XEVI\_TRANSPARENCY\_NONE if there are no transparent pixels, XEVI\_TRANSPARENCY\_PIXEL if the visual supports a transparent pixel, XEVI\_TRANSPARENCY\_MASK if the visual supports transparent plane(s).

*transparency\_value* returns the pixel/plane value to set for transparency if transparency\_type isn't XEVI\_TRANSPARENCY\_NONE.

*min\_hw\_colormaps* and *max\_hw\_colormaps* return the minimum and maximum number of hardware colormaps backing up the visual.

*num\_colormap\_conflicts* returns the number of elements in *colormap\_conflicts*. This array returns a list of visuals that may cause conflicts in the use of the hardware colormap. For example, if a 12-bit hardware colormap is overloaded to support 8-bit colormaps, the corresponding 8-bit visuals would conflict with the 12-bit visuals.

## ERRORS

**XeviGetVisualInfo** will return *BadValue* if passed an invalid visual ID, *BadAccess* if the X server does not respond, *BadAlloc* if there is a memory allocation failure.