X11::Protocol::Ext::MIT_SCREEN_SAVER - external screen saver support
use X11::Protocol; my $X = X11::Protocol->new; $X->init_extension('MIT-SCREEN-SAVER') or print "MIT-SCREEN-SAVER extension not available";
The MIT-SCREEN-SAVER extension allows a client screen saver program to draw a screen saver. Any client can listen for screen saver activation too.
A screen saver program registers itself and desired window attributes with
MitScreenSaverSetAttributes() and selects saver notify events with
MitScreenSaverSelectInput(). There can only be one external saver program at any one time.
See examples/mit-screen-saver-external.pl in the X11-Protocol-Other sources for a complete screen saver program.
See the core
SetScreenSaver() for the usual screen idle timeout, saver cycle period, and the "Blank" or "Internal" builtin saver styles. And see the core
ForceScreenSaver() to forcibly turn on the screen saver.
The following requests are made available with an
init_extension() per "EXTENSIONS" in X11::Protocol.
my $bool = $X->init_extension('MIT-SCREEN-SAVER');
($server_major, $server_minor) = $X->MitScreenSaverQueryVersion ($client_major, $client_minor)
Negotiate a protocol version with the server.
$client_minor is what the client would like, the returned
$server_minor is what the server will do, which will be the closest to the client requested version that the server supports.
The code in this module supports 1.0. The intention would be to automatically negotiate within
init_extension() if/when necessary.
($state, $window, $til_or_since, $idle, $event_mask, $kind) = $X->MitScreenSaverQueryInfo ($drawable)
Return information about the screen saver on the screen of
$drawable (an integer XID).
$state is an enum string "Off", "On", or "Disabled".
$window is the screen saver window, or "None". The server creates this as an override-redirect child of the root window but it doesn't appear in the
QueryTree() children of the root. The window might not exist until required for an activated External saver.
$til_or_since is a period in milliseconds. If
$state is "Off" then it's how long until the saver will be activated due to idle. If
$state is "On" then it's how long in milliseconds since the saver was activated. But see "BUGS" below.
$idle is how long in milliseconds the screen has been idle.
$event_mask is the current client's mask as set by
$kind is an enum string for how the saver is being done now or how it will be done when next activated,
"Blanked" video output turned off "Internal" server builtin saver "External" external saver client
$X->MitScreenSaverSelectInput ($drawable, $event_mask)
MitScreenSaverNotify events from the screen of
$drawable (an XID).
$event_mask has two bits,
bitpos bitval NotifyMask 0 0x01 CycleMask 1 0x02
There's no pack function for these yet, so just give the integer bitvals, for example 0x03 for both.
$X->MitScreenSaverSetAttributes ($drawable, $class, $depth, $visual, $x, $y, $width, $height, $border_width, key => value, ...)
Setup the screen saver window on the screen of
$drawable (an XID).
The arguments are the same as the core
CreateWindow(), except there's no new XID to create and the parent window is always the root window on the screen of
$drawable could be the root window already).
This setup makes the saver "External" kind on its next activation. If the saver is currently active then it's not changed. The client can listen for
MitScreenSaverNotify (see "EVENTS" below) to know when the saver is activated. The saver window XID is reported in that Notify and exposures etc can be selected on it at that time to know when to drawn, unless perhaps a background pixel or pixmap in this
MitScreenSaverSetAttributes() is enough.
Only one client at a time can setup a saver window like this. If another has done so then an Access error results.
Unset the screen saver window. If the client did not set the window then do nothing.
This changes the saver from "External" kind back to the server builtin. If the screen saver is currently active then that happens immediately.
At client shutdown an Unset is done automatically, unless
RetainPermanent closedown mode.
MitScreenSaverNotify events are sent to the client when selected by
MitScreenSaverSelectInput() above. It reports when the screen saver state changes. The event has the usual fields
name "MitScreenSaverNotify" synthetic true if from a SendEvent code integer opcode sequence_number integer
and event-specific fields
state "Off", "On", "Cycle" time server timestamp (integer) root root window of affected screen (XID) window the screen saver window (XID) kind "Blanked", "Internal", "External" forced integer 0 or 1
state is "Off" if the saver has turned off or "On" if it turned on.
forced is 1 if the change was due to a
ForceScreenSaver() request rather than user activity/inactivity. On/Off events are selected by NotifyMask to
state is "Cycle" if the saver cycling period has expired, which means it's time to show something different. This is selected by CycleMask to
kind is the current saver kind, as described under
In XFree86 and X.org servers through to circa X.org 1.10, if the screen saver is activated with a
ForceScreenSaver() request then the
MitScreenSaverQueryInfo() is a big number, apparently being a negative for the future time when it would have activated due to idle. There's no attempt to do anything about that here.
In these servers when the saver is "On" the idle timeout apparently continues to fire too, so the "since" of
$til_or_since is only since the last firing, as if screen saver was re-activated, not the time since first activated, or something like that.
xset(1), for setting the core screen saver parameters from the command line.
Copyright 2011, 2012 Kevin Ryde
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