Re: re-generating a window-configuration by program

[Kevin Rodgers]

Klaus Berndl wrote:

> Is this problem described understandable?
>
> I have already a program which generates the layout above, means it
> splits the frame in the windows A, B, C and E. Now suppose someone
> splits the window E in arbitrary "subwindows"... Then i want to store
> the window-layout of the area E as a window-config like described
> above. Then a special window-deleter restores the layout above
> (i.e. unsplits only area E) and then i want to run the algorithm i
> asked for to restore the splitted layout of area E.

The problem is well-described, but your approach is flawed: your window
configuration data structure describes each window as a component of the
frame (at the same level as the other windows).  But you want to restore
the configuration as if the windows form a hierarchy.  The only way to
do that is to record the chain of events leading to the configuration;
e.g. window F was formed by splitting window E (horizontally or
vertically).  Because of the numerous ways windows can be created,
deleted, and modified, I don't think it is workable to advise the
split-window-*, delete-window, etc. commands; instead, try to use these
(documented in the Window Hooks node of the Emacs Lisp manual):

- Variable: window-size-change-functions
    This variable holds a list of functions to be called if the size
    of any window changes for any reason.  The functions are called
    just once per redisplay, and just once for each frame on which
    size changes have occurred.

    Each function receives the frame as its sole argument.  There is no
    direct way to find out which windows on that frame have changed
    size, or precisely how.  However, if a size-change function
    records, at each call, the existing windows and their sizes, it
    can also compare the present sizes and the previous sizes.

    Creating or deleting windows counts as a size change, and therefore
    causes these functions to be called.  Changing the frame size also
    counts, because it changes the sizes of the existing windows.
...
- Variable: window-configuration-change-hook
    A normal hook that is run every time you change the window
    configuration of an existing frame.  This includes splitting or
    deleting windows, changing the sizes of windows, or displaying a
    different buffer in a window.  The frame whose window
    configuration has changed is the selected frame when this hook
    runs.


--
Kevin Rodgers