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fix: stop line highlights bleeding into the text-renderer margin #14

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Merged
chiply merged 1 commit into from
Jul 2, 2026
Merged

fix: stop line highlights bleeding into the text-renderer margin #14

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28 changes: 18 additions & 10 deletions svg-margin.el
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Original file line number Diff line number Diff line change
Expand Up @@ -441,7 +441,8 @@ Its `:text', else the character mapped for its `:shape' in
(defun svg-margin--text-face (ind &optional background)
"Return the face for IND's glyph in `text' mode: its colour, plus BACKGROUND.
Uses IND's `:face' as-is, or an anonymous face from its `:color'; BACKGROUND,
when non-nil, is a colour drawn behind the glyph (the hover highlight).
when non-nil, is a colour drawn behind the glyph (hover highlight, a background
tint, or the neutral cell background).
`:font', `:weight' and `:scale' are honoured only by the `svg' renderer."
(let* ((color (plist-get ind :color))
(base (cond (color (list :foreground color))
Expand All @@ -456,11 +457,18 @@ The string spans RCOLS columns, each `svg-margin-column-width' characters wide;
column 0 is nearest the buffer text. Each occupied cell shows its indicator's
glyph (see `svg-margin--cell-glyph') faced with its colour and tagged -- via a
`svg-margin-cell' help-echo property (BUFFER POS SIDE COLUMN) -- so hover
tracking and per-cell tooltips work; empty cells are spaces. A `:background'
indicator tints the whole string's background. HOVERED-COL, when it is a
cell's column, draws the hover background behind that cell."
tracking and per-cell tooltips work; empty cells are spaces. Every cell paints
an explicit `svg-margin-cell' background so a transient highlight on the
underlying line (show-paren, region, hl-line) does not bleed through the margin;
a `:background' indicator tints the cells instead, and HOVERED-COL draws the
hover background behind its cell."
(let ((w (max 1 svg-margin-column-width))
(bg nil)
;; The margin cell's own background, painted behind every cell so a
;; transient highlight on the underlying line (show-paren, region,
;; hl-line) cannot bleed through an empty or glyph-only cell.
(defbg (let ((c (face-attribute 'svg-margin-cell :background nil t)))
(and (stringp c) c)))
Comment on lines +467 to +471
(cells (make-vector rcols nil))
(parts nil))
(dolist (cell packed)
Expand All @@ -476,8 +484,11 @@ cell's column, draws the hover background behind that cell."
(ind (and cell (plist-get cell :indicator)))
(glyph (if ind (svg-margin--cell-glyph ind) " "))
(hov (and hovered-col (eql col hovered-col) (svg-margin--hover-color)))
(face (if ind (svg-margin--text-face ind hov)
(and hov (list :background hov))))
;; Hover wins, then a background-indicator tint, then the neutral
;; cell background -- so every cell paints an explicit background.
(cellbg (or hov bg defbg))
(face (if ind (svg-margin--text-face ind cellbg)
(and cellbg (list :background cellbg))))
(pad (max 0 (- w (string-width glyph))))
(s (concat glyph (make-string pad ?\s))))
(when face (setq s (propertize s 'face face)))
Expand All @@ -493,10 +504,7 @@ cell's column, draws the hover background behind that cell."
(when (or (plist-get ind :action) (plist-get ind :menu))
(setq s (propertize s 'pointer 'hand)))))
(push s parts)))
(let ((str (apply #'concat (nreverse parts))))
(when bg
(add-face-text-property 0 (length str) (list :background bg) t str))
str)))
(apply #'concat (nreverse parts))))

;;;; Overlays
;; ----------------------------------------------------------------
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24 changes: 24 additions & 0 deletions test/svg-margin-test.el
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Original file line number Diff line number Diff line change
Expand Up @@ -340,6 +340,30 @@
(should (equal "•" (svg-margin--text-margin '((:indicator (:color "#fff") :column 0))
'left 1 1 nil)))))

(ert-deftest svg-margin/text-margin-cell-background ()
"Every text cell paints an explicit background so a highlight on the
underlying line (show-paren, region, hl-line) cannot bleed through the margin.
The neutral background is `svg-margin-cell's; a `:background' indicator tints it."
(let ((svg-margin-column-width 1)
(orig (face-attribute 'svg-margin-cell :background nil nil)))
(unwind-protect
(progn
(set-face-attribute 'svg-margin-cell nil :background "#010203")
;; No tint: empty and glyph cells both carry the neutral cell bg.
(let* ((packed '((:indicator (:color "#ff0000" :text "A") :column 0)))
(str (svg-margin--text-margin packed 'left 2 1 nil))
(empty (get-text-property 0 'face str)) ; leftmost = empty lane 1
(glyph (get-text-property (1- (length str)) 'face str))) ; last = glyph lane 0
(should (equal '(:background "#010203") empty))
(should (member '(:background "#010203") glyph))
(should (member '(:foreground "#ff0000") glyph)))
;; A `:background' indicator tints every cell, overriding the neutral bg.
(let* ((packed '((:indicator (:color "#00ff00"))
(:indicator (:text "A") :column 0)))
(str (svg-margin--text-margin packed 'left 2 1 nil)))
(should (equal '(:background "#00ff00") (get-text-property 0 'face str)))))
(set-face-attribute 'svg-margin-cell nil :background orig))))

(ert-deftest svg-margin/renderer-usable-p ()
"The `text' renderer is usable on any frame; `svg' needs a graphical one.
Runs in batch, where `display-graphic-p' is nil (like a terminal)."
Expand Down
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