[elpa] master ddcd8e6 4/8: Merge pull request #16 from tsdh/master

[Artur Malabarba]

branch: master
commit ddcd8e6bb4a27a17862726cd7d3955df274c19be
Merge: 3c14fa3 ff1f8d2
Author: Artur Malabarba <address@hidden>
Commit: Artur Malabarba <address@hidden>

    Merge pull request #16 from tsdh/master
    
    Speed up beacon--movement->
---
 beacon.el |   23 ++++++++++++++++++++---
 1 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/beacon.el b/beacon.el
index 66853ca..138c3ba 100644
--- a/beacon.el
+++ b/beacon.el
@@ -264,6 +264,11 @@ Only returns `beacon-size' elements."
 (defvar beacon--previous-mark-head nil)
 (defvar beacon--previous-window nil)
 
+(defun beacon--pos-on-current-line-p (pos)
+  "Return non-nil if POS is on the current line."
+  (and (<= (save-excursion (beginning-of-line) (point)) pos)
+       (<= pos (save-excursion (end-of-line) (point)))))
+
 (defun beacon--movement-> (delta)
   "Return non-nil if latest point movement is > DELTA.
 If DELTA is nil, return nil."
@@ -273,9 +278,21 @@ If DELTA is nil, return nil."
               (current-buffer))
        (> (abs (- (point) beacon--previous-place))
           delta)
-       (> (count-screen-lines (min (point) beacon--previous-place)
-                              (max (point) beacon--previous-place))
-          delta)))
+       ;; Check if the movement was larger than DELTA lines by testing if
+       ;; `point' is still on the same line or on any line DELTA lines up or
+       ;; down.  This is much cheaper than computing the actual number of lines
+       ;; moved using `count-screen-lines'.
+       (let ((prev-pos (marker-position beacon--previous-place)))
+        (catch 'movement
+          (when (beacon--pos-on-current-line-p prev-pos)
+            (throw 'movement nil))
+          (dolist (inc '(1 -1))
+            (save-excursion
+              (dotimes (i delta)
+                (vertical-motion inc)
+                (when (beacon--pos-on-current-line-p prev-pos)
+                  (throw 'movement nil)))))
+          (throw 'movement t)))))
 
 (defun beacon--maybe-push-mark ()
   "Push mark if it seems to be safe."