Re: How to create a small child-frame which only show two lines

[Feng Shu]

Eli Zaretskii <address@hidden> writes:

>> Date: Mon, 11 Dec 2017 16:29:16 +0800 (CST)
>> From: tumashu  <address@hidden>
>> Cc: "address@hidden" <address@hidden>
>> 
>> by the way, does emacs has a function, which can get the point's left-bottom 
>> pixel position,  if not,
>> is it possible to add it to emacs?
>
> Doesn't vertical-motion fit the bill?  If not, why not?

I code the below function with your suggestion, seem to work :-)


(defun my-tooltip-compute-pixel-position (pos tooltip-width tooltip-height)
  "Return bottom-left-corner pixel position of POS in WINDOW.
its returned value is like (X . Y)

If TOOLTIP-WIDTH and TOOLTIP-HEIGHT are given, this function will use
two values to adjust its output position, make sure the *tooltip* at
position not disappear by sticking out of the display."
  (let* ((window (selected-window))
         (frame (window-frame window))
         (xmax (frame-pixel-width frame))
         (ymax (frame-pixel-height frame))
         (posn-top-left (posn-at-point pos window))
         (x (+ (car (window-inside-pixel-edges window))
               (or (car (posn-x-y posn-top-left)) 0)))
         (y-top (+ (cadr (window-pixel-edges window))
                   (or (cdr (posn-x-y posn-top-left)) 0)))
         (posn-next-line-beginning
          (posn-at-point (save-excursion
                           (goto-char pos)
                           (vertical-motion 1)
                           (point))
                         window))
         (y-buttom
          (let ((value (or (cdr (posn-x-y posn-next-line-beginning)) 0)))
            (if (= value y-top)
                ;; FIXME:  If at the end line of buffer, we can not use the 
above
                ;; method to get y-buttom, we just use y-top + 
default-line-height instead.
                (+ y-top (default-line-height))
              value))))
    (cons (max 0 (min x (- xmax (or tooltip-width 0))))
          (max 0 (if (> (+ y-buttom (or tooltip-height 0)) ymax)
                     (- y-top (or tooltip-height 0))
                   y-buttom)))))


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