XRANDR(3) Library Functions Manual XRANDR(3)
NAME
Xrandr - X Resize, Rotate and Reflection extension.
SYNTAX
#include <X11/extensions/Xrandr.h>
Bool XRRQueryExtension (Display *dpy,
int *event_base_return, int *error_base_return);
Status XRRQueryVersion (Display *dpy,
int *major_version_return,
int *minor_version_return);
XRRScreenConfiguration *XRRGetScreenInfo (Display *dpy,
Drawable draw);
void XRRFreeScreenConfigInfo (
XRRScreenConfiguration *config);
Status XRRSetScreenConfig (Display *dpy,
XRRScreenConfiguration *config,
Drawable draw,
int size_index,
Rotation rotation,
Time timestamp);
Status XRRSetScreenConfigAndRate (Display *dpy,
XRRScreenConfiguration *config,
Drawable draw,
int size_index,
Rotation rotation,
short rate,
Time timestamp);
Rotation XRRConfigRotations(
XRRScreenConfiguration *config,
Rotation *current_rotation);
Time XRRConfigTimes (
XRRScreenConfiguration *config,
Time *config_timestamp);
XRRScreenSize *XRRConfigSizes(
XRRScreenConfiguration *config,
int *nsizes);
short *XRRConfigRates (
XRRScreenConfiguration *config,
int size_index,
int *nrates);
SizeID XRRConfigCurrentConfiguration (
XRRScreenConfiguration *config,
Rotation *rotation);
short XRRConfigCurrentRate (
XRRScreenConfiguration *config);
int XRRRootToScreen(
Display *dpy,
Window root);
void XRRSelectInput(Display *dpy, Window window, int mask);
/∗
* intended to take RRScreenChangeNotify, or
* ConfigureNotify (on the root window)
* returns 1 if it is an event type it understands, 0 if not
*/
int XRRUpdateConfiguration(XEvent *event);
/∗
* the following are always safe to call, even if RandR is
* not implemented on a screen
*/
Rotation XRRRotations(
Display *dpy, int screen,
Rotation *current_rotation);
XRRScreenSize *XRRSizes(Display *dpy,
int screen, int *nsizes);
short *XRRRates (Display *dpy, int screen,
int size_index, int *nrates);
Time XRRTimes (Display *dpy, int screen, Time *config_timestamp);
ARGUMENTS
display Specifies the connection to the X server.
screen Specifies which screen.
draw Specifies the screen.
rotation Specifies the possible rotations or reflections of the
screen.
current_rotation
Specifies the current rotations and reflection of the screen.
timestamp Specifies the server timestamp.
config_timestamp
Specifies the timestamp when the screen was last (re)config-
ured.
config Specifies the screen configuration being used.
sizes Specifies the array of supported sizes.
rate Specifies the refresh rate in Hz.
DATATYPES
Rotations/Reflections
Can be any of:
#define RR_Rotate_0 1
#define RR_Rotate_90 2
#define RR_Rotate_180 4
#define RR_Rotate_270 8
/∗ new in 1.0 protocol, to allow reflection of screen */
/∗ reflection is applied after rotation */
#define RR_Reflect_X 16
#define RR_Reflect_Y 32
typedef struct {
int width, height;
int mwidth, mheight;
} XRRScreenSize;
typedef struct {
int type; /∗ event base */
unsigned long serial; /∗ # of last request processed by server */
Bool send_event; /∗ true if this came from a SendEvent request */
Display *display; /∗ Display the event was read from */
Window window; /∗ window which selected for this event */
Window root; /∗ Root window for changed screen */
Time timestamp; /∗ when the screen change occurred */
Time config_timestamp; /∗ when the last configuration change */
SizeID size_index;
SubpixelOrder subpixel_order;
Rotation rotation;
int width;
int height;
int mwidth;
int mheight;
} XRRScreenChangeNotifyEvent;
The XRRScreenSize structure contains a possible root size in pixels and
in millimeters.
A XRRScreenChangeNotifyEvent is sent to a client that has requested no-
tification whenever the screen configuration is changed. A client can
perform this request by calling XRRSelectInput, passing the display,
the root window, and the RRScreenChangeNotifyMask mask.
XRRScreenConfiguration is an opaque data type containing the configura-
tion information for a screen.
Timestamps
Time stamps are included and must be used to ensure the client is play-
ing with a full deck: the screen may change properties on the fly and
this ensures its knowledge of the configuration is up to date. This is
to help issues when screens may become hot-pluggable in the future.
DESCRIPTION
Xrandr is a simple library designed to interface the X Resize and Ro-
tate Extension. This allows clients to change the size and rotation of
the root window of a screen, along with the ability to reflect the
screen about either axis (if supported by the implementation). Rota-
tion and reflection may be implemented by software and may result in
slower performance if rotation and reflection are implemented in this
fashion (as are all implementations as of October 2002).
The Xrandr library does some minimal caching to avoid roundtrips to
provide clients frequently used information. See "The X Resize and Ro-
tate Extension" for a detailed description; also note that depth
switching, as described in the document is not implemented, and may (or
may not) ever be implemented, as display memory is growing rapidly, and
toolkits are already beginning to support migration, mitigating the
need for depth switching. If it is implemented in the future, we ex-
pect to do so via an upward compatible extension to the current li-
brary/protocol; functionality described here should continue to work.
Rotation and reflection and how they interact can be confusing. In
Randr, the coordinate system is rotated in a counter-clockwise direc-
tion relative to the normal orientation. Reflection is along the win-
dow system coordinate system, not the physical screen X and Y axis, so
that rotation and reflection do not interact. The other way to con-
sider reflection is to treat it as specified in the "normal" orienta-
tion, before rotation.
The XRRScreenChangeNotify event is sent to clients that ask to be in-
formed whenever the root window configuration changes. Configuration
changes may include resolution, physical size, subpixel order (see
XRender(3)), and rotation. Note that changes to any or all of these
could occur due to external events (user control in the X server, a
different monitor/flat panel display being hot-plugged) and is not only
the result of a protocol/library request to the X server.
Additionally, to eliminate a potential race condition, this event may
be generated immediately upon selecting for notification if the screen
has changed since the client of Xrandr connected to the X server, to
enable reliable screen resolution changing when a user may log in and
change the configuration while one or many clients are starting up.
Xlib notification
Clients must call back into Xlib using XRRUpdateConfiguration when
screen configuration change notify events are generated (or root window
configuration changes occur, to update Xlib's view of the resolution,
size, rotation, reflection or subpixel order. Generally, toolkits will
perform this operation on behalf of applications; we did not want to
change display structure data behind the back of toolkits, as in multi-
threaded clients, various race conditions might occur. Toolkits should
provide clients some mechanism for notification of screen change, of
course.
FUNCTIONS
There are two classes of interfaces: those which can be safely called
even if RandR is not implemented on a screen (to make common idioms not
dependent on the server having support), and those which will return
errors if the extension is not present.
XRRRotations returns both the possible set of rotations/reflections
supported (as a bitmask) as the value of the function, along with the
current rotation/reflection of the screen.
XRRSizes returns the size and a pointer to the current sizes supported
by the specified screen. The first size specified is the default size
of the server. If RandR is not supported, it returns 0 for the number
of sizes.
XRRRates returns a pointer to the rates supported by the specified
size. If RandR is not supported, it returns 0 for the number of rates.
XRRTimes returns the time last reported by the server along with the
timestamp the last configuration changed. If the configuration has
changed since the client last updated its view of the server time, re-
quests to change the configuration will fail until the client has an up
to date timestamp.
XRRRootToScreen returns the screen number given a root window (for ex-
ample, from an XRRScreenChangeNotifyEvent).
The rest of the functions will fail if applied to screens not imple-
menting the RandR extension. XRRSetScreenConfig sets the screen size
and rotation and reflection to the desired values on the screen speci-
fied by draw, or returns a BadValue error. size_index specifies which
size configuration is to be used, rotation specifies which rotation or
reflection is to be used (or a BadValue error is returned). The time-
stamp is used by the server to make sure the client has up to date con-
figuration information. Status is returned to indicate success or fail-
ure; a client must refresh its configuration information if it fails
and try the call again (by calling XRRGetScreenInfo).
XRRSetScreenConfigAndRate is like XRRSetScreenConfig but also sets the
refresh rate. If specified rate is not supported a BadValue error is
returned.
XRRConfigRotations, XRRConfigSizes, XRRConfigCurrentConfiguration, XR-
RConfigTimes, XRRConfigRates, and XRRConfigCurrentRate are used to get
specific configuration information out of a screen configuration.
XRRGetScreenInfo returns a screen configuration for later use; the in-
formation is private to the library. Call XRRFreeScreenConfigInfo to
free this information when you are finished with it. It forces a round
trip to the server.
Other functions include: XRRQueryExtension which returns the event and
error base codes, XRRQueryVersion , which returns the current version
of the extension (this information is cached by the library).
RESTRICTIONS
Xrandr will remain upward compatible after the current 1.0 release.
AUTHOR
Jim Gettys, and Keith Packard, HP.
X Version 11 libXrandr 1.5.2 XRANDR(3)
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