NAME¶
X11::Protocol::Ext::DAMAGE - drawing notifications
SYNOPSIS¶
use X11::Protocol;
my $X = X11::Protocol->new;
$X->init_extension('DAMAGE')
or print "DAMAGE extension not available";
my $damage = $X->new_rsrc;
$X->DamageCreate ($damage, $drawable, 'NonEmpty');
sub my_event_handler {
my %h = @_;
if ($h{'name'} eq 'DamageNotify') {
my $drawable = $h{'drawable'};
$X->DamageSubtract ($damage, 'None', $parts_region);
# do something for $parts_region changed in $drawable
}
}
DESCRIPTION¶
The DAMAGE extension lets a client listen for changes to drawables (windows,
pixmaps, etc) due to drawing operations, including drawing into sub-windows
which appears in the parent.
This can be used for various kinds of efficient copying or replicating of window
contents, such as cloning to another screen, showing a magnified view, etc.
The root window can be monitored to get changes on the whole screen.
Content changes due to drawing are conceived as "damage". A
server-side damage object accumulates areas as rectangles to make a
server-side "region" per the XFIXES 2.0 extension (see
X11::Protocol::Ext::XFIXES)
A DamageNotify event is sent from a damage object. A reporting level controls
the level of detail, ranging from just one event on becoming non-empty, up to
an event for every drawing operation affecting the relevant drawable.
Fetching an accumulated damage region (or part of it) is reckoned as a
"repair". It doesn't change any drawables in any way, just fetches
the region from the damage object. This fetch is atomic, so nothing is lost if
the listening client is a bit lagged etc.
See
examples/damage-duplicate.pl in the "X11-Protocol-Other"
sources for one way to use damage to duplicate a window in real-time.
REQUESTS¶
The following requests are made available with an "init_extension()",
as per "EXTENSIONS" in X11::Protocol.
my $is_available = $X->init_extension('DAMAGE');
DAMAGE 1.0¶
- "($server_major, $server_minor) = $X->DamageQueryVersion
($client_major, $client_minor)"
- Negotiate a protocol version with the server. $client_major and
$client_minor is what the client would like, the returned $server_major
and $server_minor is what the server will do, which might be less than
requested (but not more).
The current code supports up to 1.1. If asking for higher then be careful
that it's upwardly compatible. The module code negotiates a version in
"init_extension()" so an explicit
"DamageQueryVersion()" is normally not needed.
- "$X->DamageCreate ($damage, $drawable, $level)"
- Create a new damage object in $damage (a new XID) which monitors changes
to $drawable. If $drawable is a window then changes to its subwindows are
included too.
# listening to every change on the whole screen
my $damage = $X->new_rsrc;
$X->DamageCreate ($damage, $X->root, 'RawRectangles');
$level is an enum string controlling how often "DamageNotify"
events are emitted (see "EVENTS" below).
RawRectangles every change
DeltaRectangles when damage region expands
BoundingBox when damage bounding box expands
NonEmpty when damage first becomes non-empty
- "$X->DamageDestroy ($damage)"
- Destroy $damage.
- "$X->DamageSubtract ($damage, $repair_region,
$parts_region)"
- Move the accumulated region in $damage to $parts_region (a region XID),
and clear it from $damage.
If $parts_region is "None" then $damage is cleared and the region
discarded. This can be used if for example the entire $drawable will be
copied or re-examined, so the exact parts are not needed.
$repair_region is what portion of $damage to consider. "None"
means move and clear everything in $damage. Otherwise $repair_region is a
region XID and the portion of the damage region within $repair_region is
moved and cleared. Anything outside is left in $damage.
If anything is left in $damage then a new "DamageNotify" event is
immediately sent. This can be good for instance if you picked out a
$repair_region corresponding to what you thought was the window size
(perhaps from the "geometry" field of a "DamageNotify"
event), but it has grown in the interim.
Region objects here can be created with the XFIXES 2.0 extension (see
X11::Protocol::Ext::XFIXES). It should be available whenever DAMAGE is
available. If using "None" and "None" to clear and
discard then region objects are not required and there's no need for an
"init_extension('XFIXES')".
DAMAGE 1.1¶
- "$X->DamageAdd ($drawable, $region)"
- Report to any interested damage objects that changes have occurred in
$region (a region XID) of $drawable.
This is used by clients which modify a drawable in ways not seen by the
normal protocol drawing operations. For example an MIT-SHM shared memory
pixmap modified by writing to the memory (see
X11::Protocol::Ext::MIT_SHM), or the various "direct rendering"
to graphics hardware or GL etc.
EVENTS¶
"DamageNotify" events are sent to the client which created the damage
object. These events are always generated, there's nothing to select or
deselect them. The event has the usual fields
name "DamageNotify"
synthetic true if from a SendEvent
code integer opcode
sequence_number integer
and event-specific fields
damage XID, damage object
drawable XID, as from DamageCreate
level enum, as from DamageCreate
more boolean, if more DamageNotify on the way
time integer, server timestamp
area arrayref [$x,$y,$width,$height]
geometry arrayref [$rootx,$rooty,$width,$height]
"drawable" and "level" are as from the
"DamageCreate()" which made the "damage" object.
"more" is true if there's further "DamageNotify" events on
the way for this damage object. This can happen when the "level"
means there's a set of "area" rectangles to report.
"area" is a rectangle within "drawable", as a 4-element
arrayref,
[ $x, $y, $width, $height ]
What it covers depends on the reporting level requested,
- •
- "RawRectangles" -- a rectangle around an arc, line, etc, drawing
operation which changed "drawable".
- •
- "DeltaRectangles" -- an additional rectangle extending the
damage region. Only new rectangles are reported, not any of the existing
damage region. Reporting a region addition may require multiple
"DamageNotify" events.
- •
- "BoundingBox" -- a bounding box around the damage region
accumulated, bigger than previously reported.
- •
- "NonEmpty" -- umm, something, maybe the entire drawable.
"geometry" is the current size and position of the drawable as a
4-element arrayref in root window coordinates. For a pixmap $root_x and
$root_y are 0.
[ $root_x, $root_y, $width, $height ]
ENUM TYPES¶
The reporting level above is type "DamageReportLevel". So for example
(after a successful "$X->init_extension('DAMAGE')"),
$number = $X->num('DamageReportLevel', 'RawRectangles');
$string = $X->interp('DamageReportLevel', 3);
See "SYMBOLIC CONSTANTS" in X11::Protocol.
ERRORS¶
Error type "Damage" is a bad $damage resource XID in a request.
BUGS¶
The server extension version number is queried in the
"init_extension()", but not yet made available as such. The version
determines whether "DamageAdd()" ought to work. Currently that
request is always setup, but presumably generates an Opcode error if the
server doesn't have it.
SEE ALSO¶
X11::Protocol, X11::Protocol::Ext::XFIXES
/usr/share/doc/x11proto-damage-dev/damageproto.txt.gz,
<
http://cgit.freedesktop.org/xorg/proto/damageproto/tree/damageproto.txt>
HOME PAGE¶
<
http://user42.tuxfamily.org/x11-protocol-other/index.html>
LICENSE¶
Copyright 2011, 2012, 2013 Kevin Ryde
X11-Protocol-Other is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later version.
X11-Protocol-Other is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
You should have received a copy of the GNU General Public License along with
X11-Protocol-Other. If not, see <
http://www.gnu.org/licenses/>.