Subject: [PATCH] Modify the pulsation effect of pulse.el
From: Gautier Ponsinet <[email-masked]>
To: [email-masked]
Cc: Protesilaos Stavrou <[email-masked]>, [email-masked]
Date: Thu, 15 Aug 2024 09:30:35 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Tags: patch

Hello everyone,

CC: Eric M. Ludlam (author of pulse.el) and Protesilaos Stavrou (author
of pulsar.el).

I wanted to use pulse.el without the pulse effect, that is, I have set
the variable pulse-iterations to 1, and I was expecting the pulse
library to simply highlight a region or line for the duration specified
in the variable pulse-delay with the face pulse-highlight-start-face.

It works, except that the face used is not pulse-highlight-start-face.

To reproduce in emacs -Q:
(require 'pulse)
(setopt pulse-iterations 1)
(setopt pulse-delay 5)
(set-face-background 'pulse-highlight-start-face "#ff0000")
(pulse-momentary-highlight-one-line)

Note that the color used by pulse is not pulse-highlight-start-face
(pure red).

If I understand correctly, this behavior comes from the function
pulse-momentary-highlight-overlay. The function
pulse-momentary-highlight-overlay sets an overlay using the face
pulse-highlight-face (reseted to pulse-highlight-start-face by default,
that is, if the argument of pulse-momentary-highlight-overlay is nil),
the function then immediatly starts the pulsation effect. The list of
colors for the pulsation effect is generated by the function
color-gradient, but the documentation of color-gradient says about its
output: "It does not include the START and STOP color in the resulting
list". Thus the first visible color is the first color of the list
returned by color-gradient which is different that the starting face
(pulse-highlight-start-face by default).

A simple solution would be to add the starting color
(pulse-highlight-start-face by default) at the beginning of the list of
colors used for the pulsation effect in
pulse-momentary-highlight-overlay. Please find attached to this mail a
patch for pulse.el which does this modification.

All the best,
Gautier

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From 9def4e3b1536a1eba73adb351954569d396fb164 Mon Sep 17 00:00:00 2001
From: Gautier Ponsinet <[email-masked]>
Date: Thu, 15 Aug 2024 09:17:42 +0200
Subject: [PATCH] Modify the pulsation effect of pulse.el

* lisp/cedet/pulse.el (pulse-momentary-highlight-overlay): Add the start
color to the list of colors used for the pulsation effect.
---
 lisp/cedet/pulse.el | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lisp/cedet/pulse.el b/lisp/cedet/pulse.el
index d9f6a40865a..53256ba3a81 100644
--- a/lisp/cedet/pulse.el
+++ b/lisp/cedet/pulse.el
@@ -158,7 +158,7 @@ ;;; Convenience Functions
                      (face-background 'pulse-highlight-face nil 'default)))
              (stop (color-name-to-rgb (face-background 'default)))
              (colors (mapcar (apply-partially 'apply 'color-rgb-to-hex)
-                             (color-gradient start stop pulse-iterations))))
+                             (cons start (color-gradient start stop (1- pulse-iterations))))))
         (setq pulse-momentary-timer
               (run-with-timer 0 pulse-delay #'pulse-tick
                               colors
-- 
2.46.0