master bb67924415: Run newsticker's ticker only periodically (bug#59856)

[Ulf Jasper]

branch: master
commit bb679244152dddd9949ca065aa6617457f7a7144
Author: Alex Bochannek <alex@bochannek.com>
Commit: Ulf Jasper <ulf.jasper@web.de>

    Run newsticker's ticker only periodically (bug#59856)
    
    * doc/misc/newsticker.texi (Frontends, Configuration): Add
    newsticker-ticker-period
    * lisp/net/newst-ticker.el (newsticker--ticker-period-timer): New.
    (newsticker--ticker-timer): Modify doc string.
    (newsticker-ticker-interval): Modify doc string.
    (newsticker-ticker-period): New
    (newsticker--display-tick, newsticker--display-jump)
    (newsticker--display-scroll, newsticker-start-ticker)
    (newsticker-stop-ticker): Use newsticker--ticker-timer and
    newsticker--ticker-period-timer.
---
 doc/misc/newsticker.texi |  9 ++++++-
 lisp/net/newst-ticker.el | 69 +++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 61 insertions(+), 17 deletions(-)

diff --git a/doc/misc/newsticker.texi b/doc/misc/newsticker.texi
index d71895da5d..4a0311cad4 100644
--- a/doc/misc/newsticker.texi
+++ b/doc/misc/newsticker.texi
@@ -307,11 +307,16 @@ news ticker.
 
 @findex newsticker-start-ticker
 @findex newsticker-stop-ticker
+@vindex newsticker-ticker-period
 Headlines can be displayed in the echo area, either scrolling like
 messages in a stock-quote ticker, or just changing.  This can be
 started with the command @code{newsticker-start-ticker}.  It can be
 stopped with @code{newsticker-stop-ticker}.
 
+The ticker by default runs continuously.  To only run it once, at a
+specific time interval, set the @code{newsticker-ticker-period}
+variable.
+
 
 @node Navigation
 @section Navigation
@@ -542,8 +547,10 @@ are shown in the echo area, i.e., the ``ticker''.
 @itemize
 @item
 @vindex newsticker-display-interval
+@vindex newsticker-ticker-period
 @vindex newsticker-scroll-smoothly
-@code{newsticker-ticker-interval} and
+@code{newsticker-ticker-interval},
+@code{newsticker-ticker-period}, and
 @code{newsticker-scroll-smoothly} define how headlines are shown in
 the echo area.
 @end itemize
diff --git a/lisp/net/newst-ticker.el b/lisp/net/newst-ticker.el
index 5477ad946b..064b72f02c 100644
--- a/lisp/net/newst-ticker.el
+++ b/lisp/net/newst-ticker.el
@@ -44,8 +44,10 @@
   "Last message that the newsticker displayed.")
 (defvar newsticker--scrollable-text ""
   "The text which is scrolled smoothly in the echo area.")
+(defvar newsticker--ticker-period-timer nil
+  "Timer for newsticker ticker display.")
 (defvar newsticker--ticker-timer nil
-  "Timer for newsticker ticker.")
+  "Timer for newsticker ticker scrolling.")
 
 ;;;###autoload
 (defun newsticker-ticker-running-p ()
@@ -77,7 +79,7 @@ value effective."
 
 (defcustom newsticker-ticker-interval
   0.3
-  "Time interval for displaying news items in the echo area (seconds).
+  "Time interval for scrolling news items in the echo area (seconds).
 If equal or less than 0 no messages are shown in the echo area.  For
 smooth display (see `newsticker-scroll-smoothly') a value of 0.3 seems
 reasonable.  For non-smooth display a value of 10 is a good starting
@@ -86,6 +88,17 @@ point."
   :set #'newsticker--set-customvar-ticker
   :group 'newsticker-ticker)
 
+(defcustom newsticker-ticker-period
+  0
+  "Time interval for displaying news items in the echo area (seconds).
+If equal or less than 0 messages are shown continuously.  In order not
+to miss new items, a value of equal or less than the shortest feed
+retrieval interval (or the global `newsticker-retrieval-interval`) is
+recommended."
+  :type 'number
+  :set #'newsticker--set-customvar-ticker
+  :group 'newsticker-ticker)
+
 (defcustom newsticker-scroll-smoothly
   t
   "Decides whether to flash or scroll news items.
@@ -129,9 +142,16 @@ If t the echo area will not show obsolete items.  See also
   "Called from the display timer.
 This function calls a display function, according to the variable
 `newsticker-scroll-smoothly'."
-  (if newsticker-scroll-smoothly
-      (newsticker--display-scroll)
-    (newsticker--display-jump)))
+  (when (not newsticker--ticker-timer)
+      (if newsticker-scroll-smoothly
+       (setq newsticker--ticker-timer
+             (run-at-time 1
+                          newsticker-ticker-interval
+                          #'newsticker--display-scroll))
+     (setq newsticker--ticker-timer
+           (run-at-time nil
+                        newsticker-ticker-interval
+                        #'newsticker--display-jump)))))
 
 (defsubst newsticker--echo-area-clean-p ()
   "Check whether somebody is using the echo area / minibuffer.
@@ -149,7 +169,12 @@ there is another message displayed or the minibuffer is 
active."
     (when (newsticker--echo-area-clean-p)
       (setq newsticker--item-position (1+ newsticker--item-position))
       (when (>= newsticker--item-position (length newsticker--item-list))
-        (setq newsticker--item-position 0))
+        (setq newsticker--item-position 0)
+        (when (> newsticker-ticker-period 0)
+          (cancel-timer newsticker--ticker-timer)
+          (setq newsticker--ticker-timer nil)
+          (run-at-time newsticker-ticker-interval nil
+                       (lambda () (message "")))))
       (setq newsticker--prev-message
             (nth newsticker--item-position newsticker--item-list))
       (message "%s" newsticker--prev-message))))
@@ -192,7 +217,12 @@ there is another message displayed or the minibuffer is 
active."
         (setq newsticker--prev-message subtext)
         (setq newsticker--item-position (1+ i))
         (when (>= newsticker--item-position l)
-          (setq newsticker--item-position 0))))))
+          (setq newsticker--item-position 0)
+          (when (> newsticker-ticker-period 0)
+            (cancel-timer newsticker--ticker-timer)
+            (setq newsticker--ticker-timer nil)
+            (run-at-time newsticker-ticker-interval nil
+                         (lambda () (message "")))))))))
 
 ;;;###autoload
 (defun newsticker-start-ticker ()
@@ -200,19 +230,26 @@ there is another message displayed or the minibuffer is 
active."
 Start display timer for the actual ticker if wanted and not
 running already."
   (interactive)
-  (if (and (> newsticker-ticker-interval 0)
-           (not newsticker--ticker-timer))
-      (setq newsticker--ticker-timer
-            (run-at-time newsticker-ticker-interval
-                         newsticker-ticker-interval
-                         #'newsticker--display-tick))))
+  (when (and (> newsticker-ticker-interval 0)
+             (not newsticker--ticker-period-timer)
+             (not newsticker--ticker-timer))
+      (if (> newsticker-ticker-period 0)
+          (setq newsticker--ticker-period-timer
+                (run-at-time nil
+                             newsticker-ticker-period
+                             #'newsticker--display-tick))
+        (newsticker--display-tick))))
 
 (defun newsticker-stop-ticker ()
   "Stop newsticker's ticker (but not the news retrieval)."
   (interactive)
-  (when newsticker--ticker-timer
-    (cancel-timer newsticker--ticker-timer)
-    (setq newsticker--ticker-timer nil)))
+  (progn
+    (when newsticker--ticker-timer
+      (cancel-timer newsticker--ticker-timer)
+      (setq newsticker--ticker-timer nil))
+    (when newsticker--ticker-period-timer
+      (cancel-timer newsticker--ticker-period-timer)
+      (setq newsticker--ticker-period-timer nil))))
 
 ;; ======================================================================
 ;;; Manipulation of ticker text