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racket-show-pseudo-tooltip: Show after end of same line if possible
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Show the tooltip after end of the same line if there is room to do so.
Otherwise follow the previous strategies, including trying to show on
the next line (which, although most similar to a GUI tooltip, has a
tendency to obscure something interesting on the next line -- unlike
GUI tooltips, ours don't automatically disappear because that can be
its own annoyance).
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@greghendershott
greghendershott committed May 8, 2023
1 parent c2fe266 commit c6dbe02
Showing 1 changed file with 76 additions and 68 deletions.
144 changes: 76 additions & 68 deletions racket-show.el
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Original file line number Diff line number Diff line change
Expand Up @@ -126,74 +126,82 @@ any border."
(ov (make-overlay eol (1+ eol))))
(overlay-put ov 'after-string text)
(list ov))
;; Otherwise we simulate a tooltip displayed one line below pos,
;; and one column right (although it might start further left
;; depending on window-width) "over" any existing text.
(pcase-let*
((text (propertize (concat " " text " ")
'face
`(:inherit default
:foreground ,(face-foreground 'tooltip)
:background ,(face-background 'tooltip)
:box (:line-width -1))))
(text-len (length text))
(bol (racket--bol pos))
(eol (racket--eol pos))
;; Position the tooltip on the next line, indented to `pos'
;; -- but not so far it ends off right edge.
(indent (max 0 (min (- pos bol)
(- (window-width) (string-width text) 2))))
(beg (+ eol indent 1))
(next-eol (racket--eol (1+ eol))))
;; If the tip starts before next-eol, create an overlay with the
;; 'display property, covering the span of the tooltip text but
;; not beyond next-eol.
;;
;; As a further wrinkle, when the overlay does not cover the
;; entire rest of the line, our new text might not be exactly
;; the same pixel width as the text we replace -- causing the
;; remaining text to shift. This can happen e.g. due to Unicode
;; characters like λ. Furthermore, our replacement text can be
;; two pixels wider because :box (:line-width -1) doesn't seem
;; to work as advertised.
;;
;; To avoid this, we add _another_ overlay simply to replace the
;; character following our tooltip with a space of the necessary
;; pixel width to keep things aligned. Although covering the
;; character with a space isn't great -- even if you justify it
;; as a sort of "shadow" (?) -- it's better than having the
;; remainder of the line jiggle as the tooltip apears and
;; disappears.
(if (< beg next-eol)
(cl-flet ((text-pixel-width
(beg end)
(car (window-text-pixel-size nil beg end))))
(let* ((end (min next-eol (+ beg text-len)))
(ov (make-overlay beg end))
(old (text-pixel-width (1+ eol) end))
(_ (overlay-put ov 'display text))
(new (text-pixel-width (1+ eol) end))
(diff (- new old)))
(cons
ov
(when (and (not (zerop diff))
(< end next-eol))
(let* ((ov-spacer (make-overlay end (1+ end)))
(width (text-pixel-width end (1+ end)))
(space-width (abs (- width diff))))
(overlay-put ov-spacer
'display
`(space
:width (,space-width)))
(list ov-spacer))))))
;; Else the tip starts after next-eol. So, create an overlay
;; on the newline, and use an after-string, where we prefix
;; enough blank spaces before the tooltip text itself to get
;; the desired indent.
(let* ((ov (make-overlay (1- next-eol) next-eol))
(blanks (make-string (- beg next-eol) 32)))
(overlay-put ov 'after-string (concat blanks text))
(list ov))))))
;; Else we simulate a tooltip. The only question is where, and the
;; overlay(s) necessary to achieve that.
(let*
((text (propertize (concat " " text " ")
'face
`(:inherit default
:foreground ,(face-foreground 'tooltip)
:background ,(face-background 'tooltip)
:box (:line-width -1))))
(text-width (string-width text))
(bol (racket--bol pos))
(eol (racket--eol pos)))
;; If there is room after end of same line, show there.
(if (< (+ text-width 1) (- (window-width) (- eol bol)))
(let ((ov (make-overlay (1- eol) eol)))
(overlay-put ov 'after-string (concat " " text))
(list ov))
;; Otherwise we simulate a tooltip displayed one line below
;; pos, and one column right (although it might start further
;; left depending on window-width) "over" any existing text.
(let*
(;; Position the tooltip on the next line, indented to `pos'
;; -- but not so far it ends off right edge.
(indent (max 0 (min (- pos bol)
(- (window-width) text-width 2))))
(beg (+ eol indent 1))
(next-eol (racket--eol (1+ eol))))
;; If the tip starts before next-eol, create an overlay with
;; the 'display property, covering the span of the tooltip
;; text but not beyond next-eol.
;;
;; As a further wrinkle, when the overlay does not cover the
;; entire rest of the line, our new text might not be
;; exactly the same pixel width as the text we replace --
;; causing the remaining text to shift. This can happen e.g.
;; due to Unicode characters like λ. Furthermore, our
;; replacement text can be two pixels wider because :box
;; (:line-width -1) doesn't seem to work as advertised.
;;
;; To avoid this, we add _another_ overlay simply to replace
;; the character following our tooltip with a space of the
;; necessary pixel width to keep things aligned. Although
;; covering the character with a space isn't great -- even
;; if you justify it as a sort of "shadow" (?) -- it's
;; better than having the remainder of the line jiggle as
;; the tooltip apears and disappears.
(if (< beg next-eol)
(cl-flet ((text-pixel-width
(beg end)
(car (window-text-pixel-size nil beg end))))
(let* ((end (min next-eol (+ beg text-width)))
(ov (make-overlay beg end))
(old (text-pixel-width (1+ eol) end))
(_ (overlay-put ov 'display text))
(new (text-pixel-width (1+ eol) end))
(diff (- new old)))
(cons
ov
(when (and (not (zerop diff))
(< end next-eol))
(let* ((ov-spacer (make-overlay end (1+ end)))
(width (text-pixel-width end (1+ end)))
(space-width (abs (- width diff))))
(overlay-put ov-spacer
'display
`(space
:width (,space-width)))
(list ov-spacer))))))
;; Else the tip starts after next-eol. So, create an overlay
;; on the newline, and use an after-string, where we prefix
;; enough blank spaces before the tooltip text itself to get
;; the desired indent.
(let* ((ov (make-overlay (1- next-eol) next-eol))
(blanks (make-string (- beg next-eol) 32)))
(overlay-put ov 'after-string (concat blanks text))
(list ov))))))))

(defun racket--bol (pos)
"Given POS return line beginning position."
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