Re: Best way to intercept terminal escape sequences?

[Ryan Johnson]

 On Fri, 27 Aug 2010 12:36:52 +0200, David Kastrup wrote:
> Ryan Johnson<address@hidden>  writes
> > I tried setting the keyboard-coding-system to iso-latin-1, but no
> > luck.
> You should set it to raw-text, do your mouse code preprocessing, and
> afterwards decode the remainder using the intended coding system.
Like this?

(defun xterm-mouse-event-read ()
  (let ((c (read-char)))
    (cond
     ;; out-of-bounds values come back as zero
     ((eq c 0) #x100)
     ;; 8-bit characters come back weird
     ((> c (unibyte-char-to-multibyte #xff))
      (+ #x80 (logand #xff c)))
     ((> c #xff)
      (multibyte-char-to-unibyte c))
     ;; normal 7-bit character
     (c))))

(defun xterm-mouse-pos-read ()
  (let ((old-coding (keyboard-coding-system)))
    (set-keyboard-coding-system 'raw-text)
    (unwind-protect
        (cons (xterm-mouse-event-read) (xterm-mouse-event-read))
      (set-keyboard-coding-system old-coding))))

That sort of works, but has two major problems:

First, it's unusably slow. The terminal appears to do several full 
redraw operations with every mouse click, which takes several tenths of 
a second.

Second, it's buggy. If I release the mouse button during that 
flickering, there's a very good chance for things to go very wrong. 
Looking at the lossage buffer for a double-click-gone-bad at (235 . 117) 
gave:

ESC [ M SPC \301\253 u
ESC [ M # u
ESC
ESC [ M # u
C-g

That's a mouse-down, followed by part of a mouse-up (missing px), 
followed by a lone ESC, followed by another partial mouse-up, followed 
by the keyboard-quit I sent when I saw this minibuffer prompt:

ESC [ M # u-

In between each line was a raw-text --> utf-8-unix --> raw-text 
transition. Does something fail to release buffered-up characters when 
it gets swapped out? Or might this be related to bug #6920 in some way?

Ryan