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Re: Best way to intercept terminal escape sequences?

From: Ryan Johnson
Subject: Re: Best way to intercept terminal escape sequences?
Date: Fri, 27 Aug 2010 15:56:14 +0200
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv: Gecko/20100802 Lightning/1.0b2 Thunderbird/3.1.2

 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
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)))
     ;; 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

(defun xterm-mouse-pos-read ()
  (let ((old-coding (keyboard-coding-system)))
    (set-keyboard-coding-system 'raw-text)
        (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 [ M # u

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?


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