24 Editing Pictures
If you want to create a picture made out of text characters (for
example, a picture of the division of a register into fields, as a
comment in a program), use the command `edit-picture' to enter Picture
In Picture mode, editing is based on the "quarter-plane" model of
text. In this model, the text characters lie studded on an area that
stretches infinitely far to the right and downward. The concept of the
end of a line does not exist in this model; the most you can say is
where the last non-blank character on the line is found.
Of course, Emacs really always considers text as a sequence of
characters, and lines really do have ends. But in Picture mode most
frequently-used keys are rebound to commands that simulate the
quarter-plane model of text. They do this by inserting spaces or by
converting tabs to spaces.
Most of the basic editing commands of Emacs are redefined by Picture
mode to do essentially the same thing but in a quarter-plane way. In
addition, Picture mode defines various keys starting with the `C-c'
prefix to run special picture editing commands.
One of these keys, `C-c C-c', is pretty important. Often a picture
is part of a larger file that is usually edited in some other major
mode. `M-x edit-picture' records the name of the previous major mode.
You can then use the `C-c C-c' command (`picture-mode-exit') to restore
that mode. `C-c C-c' also deletes spaces from the ends of lines,
unless you give it a numeric argument.
The commands used in Picture mode all work in other modes (provided
the `picture' library is loaded), but are only bound to keys in
Picture mode. Note that the descriptions below talk of moving "one
column" and so on, but all the picture mode commands handle numeric
arguments as their normal equivalents do.
Turning on Picture mode calls the value of the variable
`picture-mode-hook' as a function, with no arguments, if that value
exists and is non-`nil'.
- Basic Picture
- Basic concepts and simple commands of Picture Mode.
- Insert in Picture
- Controlling direction of cursor motion
after "self-inserting" characters.
- Tabs in Picture
- Various features for tab stops and indentation.
- Rectangles in Picture
- Clearing and superimposing rectangles.
automatically generated by info2www version 188.8.131.52