NAME¶
X11::Protocol::XSetRoot -- set root window background
SYNOPSIS¶
use X11::Protocol::XSetRoot;
X11::Protocol::XSetRoot->set_background (color => 'green');
# or given $X, but which then can't be used any more
X11::Protocol::XSetRoot->set_background
(X => $X,
pixmap => $pixmap_xid,
pixmap_allocated_colors => 1);
DESCRIPTION¶
This module sets the X root window background in the style of the
"xsetroot" program.
The simplest use is a named colour interpreted by the server's usual
"AllocNamedColor()" or a 1 to 4 digit hex string like
"#RRGGBB" or "#RRRRGGGGBBBB".
X11::Protocol::XSetRoot->set_background
(color => 'green');
X11::Protocol::XSetRoot->set_background
(color => '#FF0000'); # red
A pattern can be set with a pixmap. A pixmap the size of the screen can give a
full background picture.
# draw $pixmap with say $X->black_pixel and $X->white_pixel,
# then set it with
X11::Protocol::XSetRoot->set_background
(X => $X,
pixmap => $pixmap);
"set_background()" takes ownership of the given $pixmap and frees it
with "FreePixmap()" once put into the window background.
Setting the root to a pixmap drawn by a program is the main use for this module.
If you just want a solid colour then that can be done easily enough with the
actual "xsetroot" program.
Retained Resources¶
Allocated pixel colours and any "use_esetroot" preserve pixels and
pixmap with "SetCloseDownMode('RetainPermanent')" and leave root
window properties "_XSETROOT_ID" or "ESETROOT_PMAP_ID"
ready to released by "KillClient()" at a future background change.
In these cases the $X connection cannot be used any more since a further
background change and consequent "KillClient()" could occur at any
time, perhaps immediately.
If a "pixmap" is given then if it contains any allocated pixels
("AllocColor()" etc) then this should be indicated with the
"pixmap_allocated_colors" option. (Allocated pixels are noticed
automatically for "pixel" and "color" options.)
# AllocColor colours, draw $pixmap with them, then
#
X11::Protocol::XSetRoot->set_background
(X => $X,
pixmap => $pixmap,
pixmap_allocated_colors => 1);
# don't use $X any more
The easiest thing is to close an $X connection immediately after a
"set_background()". Perhaps there could be a return value to say
whether a retain was done and so the connection cannot be used again. Or
perhaps if in the future "X11::Protocol" had an explicit
"$X->close()" then that could be done here so a closed connection
would indicate it cannot be used further.
If the root visual is static such as "TrueColor" then there's no
colour allocation as such ("AllocColor()" is just a lookup). In this
case "set_background()" knows there's no need for
"RetainPermanent" for colours, only for pixmaps.
If the "color" or "pixel" options are the screen
"black_pixel" or "white_pixel" then those pixels exist
permanently in the root colormap and "set_background()" knows
there's no need for "RetainPermanent". Similarly if the server has
the TOG-CUP extension (see X11::Protocol::Ext::TOG_CUP) then any reserved
pixels listed there are recognised as permanent.
Virtual Root¶
"XSetRoot" looks for "__SWM_VROOT" using X11::Protocol::WM
"root_to_virtual_root()" and acts on that when applicable. Such a
virtual root is used by "amiwm", "swm" and
"tvtwm" window managers and the "xscreensaver" program.
Alas the enlightenment window manager uses a background window covering the root
window. This stops most root window programs from working, including XSetRoot
here.
Esetroot¶
The "Esetroot" program and various compatible programs such as
"fvwm-root" use different properties than "xsetroot". The
"Esetroot" method records the root pixmap ready for use by programs
such as "Eterm", for example to implement pseudo-transparency
("Eterm --trans", which is what the method was designed for).
The "set_background()" option "use_esetroot" uses the
"Esetroot" style rather than the default "xsetroot" style.
If this is given with "pixel" or "color" options then
"set_background()" makes a 1x1 pixmap to give a solid colour.
"set_background()" always deletes and kills (as appropriate) both the
"xsetroot" and "Esetroot" properties since both are
superseded by a new background.
For reference, to use "Eterm --trans" (as of its version 0.9.6 March
2011) an "Esetroot" background should be present at
"Eterm" startup and should not be removed later (or set to
"None"). It doesn't notice a later "Esetroot" or
re-install. In practice this means "Esetroot" before running
"Eterm" and then all future background changes in
"Esetroot" style.
The advantage of the "Esetroot" method is that the root pixmap is
available for client programs to use in creative ways. If the client draws
some of the root pixmap as its own background then it can appear
semi-transparent without the SHAPE extension, and perhaps do some visual
effects like shading or dithering.
For comparison the "xsetroot" style means the root pixmap is not
available to client programs and therefore in principle allows the server to
apply it to the hardware and never refer to it again. In practice that might
not occur, if for example on multiple console "virtual terminals"
the server must give up the hardware when switched away.
FUNCTIONS¶
- "X11::Protocol::XSetRoot->set_background (key=>value,
...)"
- Set the root window background to a pixmap or colour. The key/value
parameters are
X => X11::Protocol object
display => string ":0.0" etc
screen => integer, eg. 0
root => XID of root window
color => string
pixel => integer pixel value
pixmap => XID of pixmap to display, or "None"
pixmap_allocated_colors => boolean, default false
use_esetroot => boolean, default false
The server is given by an "X" connection object, or a
"display" name to connect to, or the default is the
"DISPLAY" environment variable.
The root window is given by "root" or "screen", or the
default is the default screen in $X either per
"$X->choose_screen()" or the default from the display name.
The background to show is given by a colour name, pixel value, or pixmap.
"color" can be anything understood by the server
"AllocNamedColor()", plus 1 to 4 digit hex
blue named colours
#RGB hex digits
#RRGGBB
#RRRGGGBBB
#RRRRGGGGBBBB
"pixel" is an integer pixel value in the root window colormap.
It's automatically recognised as allocated or not (the screen pre-defined
black or white and TOG-CUP reserved pixels are permanent and so reckoned
not allocated).
"pixmap" is an XID integer. "set_background()" takes
ownership of this pixmap and will "FreePixmap()" once installed.
"None" or 0 means no pixmap, which gives the server's default
root background (usually a black and white weave pattern).
"pixmap_allocated_colors" should be true if any of the pixels in
"pixmap" were allocated with "AllocColor()" etc, as
opposed to just the screen pre-defined black and white pixels (and any
TOG-CUP permanent pixels).
"use_esetroot" means use the root window properties in the style
of "Esetroot". This allows programs such as "Eterm" to
use the root background for "pseudo-transparency" or in other
creative ways.
When an allocated pixel or a pixmap with allocated pixels is set as the
background the "_XSETROOT_ID" mechanism described above means
the $X connection could be killed by another "xsetroot" at any
time, perhaps immediately, and for that reason $X should not be used any
more. The easiest way is to make "set_background()" the last
thing done on $X.
Setting an allocated "pixel" or any "pixmap" can only be
done on a $X connection as such, not with the "display" option.
This is because retaining the colours with the "_XSETROOT_ID"
mechanism can only be done from the client connection which created the
resources, not a new separate client connection.
ROOT WINDOW PROPERTIES¶
- "_XSETROOT_ID"
- For "xsetroot", if colours in the root window background are
allocated by "AllocColor()" etc then "_XSETROOT_ID" is
a pixmap XID which can be killed by "KillClient()" to free those
colours when the root background is replaced. "_XSETROOT_ID" is
only a 1x1 dummy pixmap, it's not the actual root background pixmap.
- "_XROOTPMAP_ID"
- For "Esetroot" style, this is the current root window background
pixmap. It might be set by an "Esetroot" which has run and
exited, or it might be set by a window manager or similar which is still
running.
Client programs can use this to combine the root background into their own
window in interesting ways. Listen to "PropertyNotify" on the
root window for background changes. Note that since this pixmap belongs to
another client it could be freed at any time, so protocol errors when
copying or drawing from it should generally be ignored, or cause a
fallback to some default.
- "ESETROOT_PMAP_ID"
- For "Esetroot" style, this is the same as
"_XROOTPMAP_ID" if that pixmap was created by
"Esetroot" and saved by
"SetCloseDownMode('RetainPermanent')". This should be freed by
"KillClient()" if the background is replaced.
The specification <http://www.eterm.org/docs/view.php?doc=ref#trans>
advises killing "ESETROOT_PMAP_ID" only when equal to
"_XROOTPMAP_ID". Probably it's safer to always kill
"ESETROOT_PMAP_ID" if replacing its value, to be sure of not
leaking resources. But perhaps if both "ESETROOT_PMAP_ID" and
"_XROOTPMAP_ID" exist then they are always equal.
ENVIRONMENT¶
- "DISPLAY"
- The default X server.
FILES¶
/etc/X11/rgb.txt on the server, being the usual colour names database for
the "color" option above.
SEE ALSO¶
X11::Protocol, X11::Protocol::Ext::TOG_CUP
xsetroot(1),
Esetroot(1),
Eterm(1),
fvwm-root(1)
<
http://www.eterm.org/docs/view.php?doc=ref#trans>
<
http://www.eterm.org/doc/Eterm_reference.html#trans>
HOME PAGE¶
<
http://user42.tuxfamily.org/x11-protocol-other/index.html>
LICENSE¶
Copyright 2010, 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/>.