X11::Protocol::Ext::TOG_CUP(3) colormap utilization policy extension

SYNOPSIS


use X11::Protocol;
my $X = X11::Protocol->new;
$X->init_extension('TOG-CUP')
or print "TOG-CUP extension not available";

DESCRIPTION

The TOG-CUP extension helps applications with private colormaps use the same pixel for the same color in different colormaps.

Using common pixel values, were possible, means that when a private colormap is in use ("$x->InstallColormap()", usually done by the window manager) some of the colours in other windows will still appear correctly.

Note that this extension makes a subtle change to the core "$X->AllocColor()" and "$X->AllocNamedColor()" requests. Normally they allocate the first available pixel, but with TOG-CUP if there's a matching colour in the default colormap and that same pixel in the target colormap is free then that pixel is allocated, thus making that colour the same in the two colormaps.

REQUESTS

The following are made available with an "init_extension()" per ``EXTENSIONS'' in X11::Protocol. 

    my $bool = $X->init_extension('TOG-CUP');
"($server_major, $server_minor) = $X->CupQueryVersion ($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 different.

The current code supports up to 1.0. The intention would be to automatically negotiate in "init_extension()" if necessary, which it's currently not.

"@colors = $X->CupGetReservedColormapEntries ($screen)"
Return a list of reserved colormap entries in the default colormap of screen number $screen (an integer 0 upwards). Each returned element is an arrayref 

    [ $pixel, $red16, $blue16, $green16, $alloc_flags ]

$red16, $blue16 and $green16 are RGB colour components in the range 0 to 65535. $alloc_flags is currently unused.

Reserved colours are pre-allocated and unchanging. The core protocol specifies "$X->{'black_pixel'}" and "$X->{'white_pixel'}" and they're included in the result, plus any further colours which might be reserved.

For example under the MS-DOS graphical overlay manager there's a certain set of ``desktop'' colours which a server on that system might treat as reserved.

"@colors = $X->CupStoreColors ($colormap, [$pixel,$red16,$green16,$blue16],...)"
Allocate read-only colours in $colormap at particular pixels.

Each argument is an arrayref of desired pixel and RGB colour. (A $do_mask parameter can be present at the end too but is unused and can be omitted.) 

    [ $pixel, $red16, $blue16, $green16 ]

The desired colour is allocated shareable read-only (like "$X->AllocColor()") at the given $pixel if possible, or another if necessary. The return is a similar list of arrayref elements, one for each argument 

    [ $pixel, $red16, $blue16, $green16, $alloc_flags ]

The returned $pixel might differ from what was requested. If the requested $pixel is already allocated, and it has a different colour, then another pixel value is chosen.

The returned RGB components are the actual colour shade allocated. This might differ if the visual has limited colour resolution (which is likely).

The returned $alloc_flags has bit 0x08 set if the pixel was successfully allocated, or clear if not. Other bits in $alloc_flags are currently unused.

For example 

    my @ret = $X->CupStoreColors
                ($colormap,
                 [ 2,  65535,0,0],           # red   
                 [ 3,  0,65535,0],           # green
                 [ 4,  16383,16383,16383]);  # grey
    foreach my $elem (@ret) {
      my ($pixel, $red,$green,$blue, $alloc_ok) = @$elem;
      my $ok = ($alloc_ok & 8 ? "allocated" : "oops, not allocated");
      print "at $pixel actual $red,$green,$blue  $ok\n";
    }

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/>.

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