From 65c986aa9470183c3a546b21dbd1d14eae109626 Mon Sep 17 00:00:00 2001 From: Stefan Monnier Date: Mon, 7 Aug 2006 17:47:55 +0000 Subject: [PATCH] (font-lock-extend-jit-lock-region-after-change): Add docstring. --- lisp/font-lock.el | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/lisp/font-lock.el b/lisp/font-lock.el index 3496560cc71..ab80316ae6a 100644 --- a/lisp/font-lock.el +++ b/lisp/font-lock.el @@ -1173,6 +1173,13 @@ what properties to clear before refontifying a region.") (defvar jit-lock-start) (defvar jit-lock-end) (defun font-lock-extend-jit-lock-region-after-change (beg end old-len) + "Function meant for `jit-lock-after-change-extend-region-functions'. +This function does 2 things: +- extend the region so that it not only includes the part that was modified + but also the surrounding text whose highlighting may change as a consequence. +- anticipate (part of) the region extension that will happen later in + `font-lock-default-fontify-region', in order to avoid the need for + double-redisplay in `jit-lock-fontify-now'." (save-excursion ;; First extend the region as font-lock-after-change-function would. (let ((region (if font-lock-extend-after-change-region-function @@ -1198,8 +1205,11 @@ what properties to clear before refontifying a region.") 'font-lock-multiline nil) (point-max))) ;; Finally, pre-enlarge the region to a whole number of lines, to try - ;; and predict what font-lock-default-fontify-region will do, so as to + ;; and anticipate what font-lock-default-fontify-region will do, so as to ;; avoid double-redisplay. + ;; We could just run `font-lock-extend-region-functions', but since + ;; the only purpose is to avoid the double-redisplay, we prefer to + ;; do here only the part that is cheap and most likely to be useful. (when (memq 'font-lock-extend-region-wholelines font-lock-extend-region-functions) (goto-char beg) -- 2.39.2