Re: posn-at-point get strange info when flycheck enable and (setq truncate-lines t)

["Feng Shu" <tumashu@163.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: "Feng Shu" <tumashu@163.com>
>> Date: Wed, 17 Jan 2018 19:11:44 +0800
>> Cc: "emacs-devel@gnu.org" <emacs-devel@gnu.org>
>> 
>> The problem I faced is that when I use posn-at-point to
>> get buffer POS's pixel position. it will get the picture's pixel position.
>> 
>> The two (X .Y) position is not equal, for example
>> 
>>   (#<window 3 on test.el> 31 (65 . 111) 0 (! . 0) 31 (5 . 3) nil (0 . 24) (13 . 29))
>>   (#<window 3 on test.el> 31 (65 . 87) 0 nil 31 (5 . 3) nil (0 . 0) (13 . 29))
>> 
>> Is it possible force get buffer POS's pixel position?
>
> Is the character at buffer position 32 visible in the window?  Or is
> it "covered" by an overlay or display property?  If it's visible, this
> could be a bug.  Can you prepare a short Lisp fragment that would
> generate the same kind of overlay as flycheck does, and which exhibits
> the same problem with posn-at-point?  Then I could look into fixing
> that if necessary.

#+BEGIN_EXAMPLE
test test

;; Eval the below code, and move point to (point)=5, then run command: `mytest'
;; you will get like:  (#<window 3 on test.el> 5 (48 . 23) 0 (! . 0) 5 (4 . 0) nil (0 . 23) (12 . 28))
;; (remove-overlays 5 10)
;; move point to (point)=5, run `mytest'
;; you will get like: (#<window 3 on test.el> 5 (48 . 0) 0 nil 5 (4 . 0) nil (0 . 0) (12 . 28))

(progn
  (require 'flycheck)
  (setq truncate-lines t)
  (setq overlay (make-overlay 5 10))
  (setf (overlay-get overlay 'before-string)
        (flycheck-error-level-make-fringe-icon
         'error flycheck-indication-mode))
  (defun mytest ()
    (interactive)
    (princ (posn-at-point))))
#+END_EXAMPLE


>
> Btw, note that if you subtract the DX/DY pair from the X/Y coordinates
> in the first position data, you get the X/Y coordinates of the second
> data.  Maybe that's all you need.

Yes, Thanks :-)

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