Window controller

This page was written by Pluto and imported with their permission when LinuxMCE branched off in February, 2007. In general any information should apply to LinuxMCE. However, this page should be edited to reflect changes to LinuxMCE and remove old references to Pluto.

Window Controller

Generalities

Only 2 desktops are used:
- desktop 0 is the main desktop, and should be the only one active, at every moment in time
- desktop 1 is used only as a "hidden" desktop, it should never be active

A wrapper for wmctrl was created, and wmctrl commands are used directly in our code.

The wmctrl command-line application is not used, but it can be used for debugging purposes.

Legend (symbols)

Below, the corresponding command-line options are shown for each action.

'*>' is the symbol for corresponding command-line action.

'-x' options for wmctrl means to use the class-name to identify the windows

Window-Controller actions

Action - hide/show window

       windows are not really hidden, they are moved to the desktop 1
       *> wmctrl -x -r xcalc -t 1
       windows are shown by moving them to the desktop 0
       *> wmctrl -x -r xcalc -t 0
 reason:
       when a hide-window command is sent to the wm, the wm unmaps that window,
       and this cause problems with GUI applications that expects their windows to be in a mapped state

Action - changing a window layer (similar, but not always as the same Z-order)

       we use 3 layers: above, below, normal
       wmctrl accepts the following layers: above, below
       These layers are actually properties added for a window.

       layer normal: neither of the "above" and "below" properties is active
       *> wmctrl -x -r xcalc -b remove,below
       *> wmctrl -x -r xcalc -b remove,above
       layer above: only the "above" property should be set
       *> wmctrl -x -r xcalc -b remove,below
       *> wmctrl -x -r xcalc -b add,above
       layer below: only the "below" property should be set
       *> wmctrl -x -r xcalc -b remove,above
       *> wmctrl -x -r xcalc -b add,below

Action - changing a window position and size

       *> wmctrl -x- r xcalc -e 0,100,200,300,400
       (x,y,width,height) = (100,200,300,400)
 note:
       the window must not be maximized, neither in the fullscreen state
       otherwise the command may not succeed

Action - changing the fullscreen state

       In the fullscreen state, the window client area occupy the whole screen.
       *> wmctrl -x -r xcalc -b add,fullscreen
       *> wmctrl -x -r xcalc -b remove,fullscreen

Action - changing the maximized state

       In the fullscreen state, the window area, including the borders and the title, will occupy the whole screen.
       *> wmctrl -x -r xcalc -b add,maximized_horz,maximized_vert
       *> wmctrl -x -r xcalc -b remove,maximized_horz,maximized_vert

Action - activating a window

       That window will be above the other windows which belong to the same layer.
       That window will have the focus.
       If necessary, the window will be moved to the current desktop.
       *> wmctrl -x -R xcalc

Action - list windows

       *> wmctrl -x -p -l -G

Window-Controller Enhancements

When enhancements were added to wmctrl, the compiled executable was renamed to 'xctrl'.

This will allow both application to coexist, without the need put them in separate directories.

These enhancements does not affect the standard wmctrl commands.

New -L option

       list all the properties for every window,
       and will also list extra properties,
       including the layer for every window, as seen by the window-manager
       *> xctrl -L

New -O option

       recursively change the override_redirect property for a window,
       up to the latest parent before the root window
       -O requires a numeric argument, 0 or 1
       *> xctrl -x -O 0 -r xcalc
       *> xctrl -x -O 1 -r xcalc

Original Document

http://svn.plutohome.com/pluto/trunk/src/utilities/linux/window_manager/WINDOW_CONTROLLER.txt