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bug#53155: Use overlays in hi-lock
From: |
Juri Linkov |
Subject: |
bug#53155: Use overlays in hi-lock |
Date: |
Mon, 10 Jan 2022 10:17:15 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (x86_64-pc-linux-gnu) |
When diff-refine overlays take precedence over hi-lock text properties,
then hi-lock can't be used to review diffs. Hi-lock provides two modes:
font-lock highlighting and highlighting with overlays. Using overlays
solves the problem. But how to decide when overlays should be used?
Detecting whether the buffer is read-only, so no more text is expected
to be added to the buffer? Then add overlays instead of using font-lock?
But this heuristics doesn't work in read-only *vc-change-log* buffers
where expanding commits inserts new text that should be highlighted
with font-lock.
Thus the following patch adds a new variable hi-lock-use-overlays
that can be used like:
#+begin_src emacs-lisp
(add-hook 'diff-mode-hook
(lambda ()
(setq-local hi-lock-use-overlays t)))
#+end_src
diff --git a/lisp/hi-lock.el b/lisp/hi-lock.el
index fbd698e234..99e908ad07 100644
--- a/lisp/hi-lock.el
+++ b/lisp/hi-lock.el
@@ -738,6 +738,17 @@ hi-lock-read-face-name
(add-to-list 'hi-lock-face-defaults face t))
(intern face)))
+(defvar hi-lock-use-overlays nil
+ "Whether to always use overlays instead of font-lock rules.
+When font-lock-mode is enabled and the buffer specifies font-lock rules,
+highlighting is performed by adding new font-lock rules to the existing ones,
+so when new matching strings are added, they are highlighted by font-lock.
+Otherwise, overlays are used, but new highlighting overlays are not added
+when new matching strings are inserted to the buffer.
+However, sometimes overlays are still preferable even in buffers
+where font-lock is enabled, because hi-lock overlays take precedence
+over other overlays in the same buffer, such as diff-refine overlays, etc.")
+
(defun hi-lock-set-pattern (regexp face &optional subexp lighter case-fold
spaces-regexp)
"Highlight SUBEXP of REGEXP with face FACE.
If omitted or nil, SUBEXP defaults to zero, i.e. the entire
@@ -759,7 +770,8 @@ hi-lock-set-pattern
(add-to-list 'hi-lock--unused-faces (face-name face))
(push pattern hi-lock-interactive-patterns)
(push (cons (or lighter regexp) pattern) hi-lock-interactive-lighters)
- (if (and font-lock-mode (font-lock-specified-p major-mode))
+ (if (and font-lock-mode (font-lock-specified-p major-mode)
+ (not hi-lock-use-overlays))
(progn
(font-lock-add-keywords nil (list pattern) t)
(font-lock-flush))
@@ -781,6 +793,7 @@ hi-lock-set-pattern
(match-end subexp))))
(overlay-put overlay 'hi-lock-overlay t)
(overlay-put overlay 'hi-lock-overlay-regexp (or lighter
regexp))
+ (overlay-put overlay 'priority 1)
(overlay-put overlay 'face face))
(goto-char (match-end 0)))
(when no-matches
- bug#53155: Use overlays in hi-lock,
Juri Linkov <=