(line-move-partial): Rework 2006-09-15 change to use

new window-line-height function.  Further optimize by not calling
pos-visible-in-window-p for window-end when window-line-height
returns useful information.

1 files changed, 45 insertions, 43 deletions

diff --git a/lisp/simple.el b/lisp/simple.el
index 3e089d4e1a8..0a257863a76 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -3487,49 +3487,51 @@ Outline mode sets this."
           (set-window-vscroll nil (- vs (frame-char-height)) t)))
 
     ;; Move forward (down).
-    (let ((wvis (window-line-visibility)))
-      (when (or (null wvis)
-                (and (consp wvis)
-                     (or (>= (car wvis) (frame-char-height))
-                         (>= (cdr wvis) (frame-char-height)))))
-        (let* ((wend (window-end nil t))
-               (evis (or (pos-visible-in-window-p wend nil t)
-                         (pos-visible-in-window-p (1- wend) nil t)))
-               (rbot (nth 3 evis))
-               (vpos (nth 5 evis))
-               ppos py vs)
-          (cond
-           ;; Last window line should be visible - fail if not.
-           ((null evis)
-            nil)
-           ;; If last line of window is fully visible, move forward.
-           ((null rbot)
-            nil)
-           ;; If cursor is not in the bottom scroll margin, move forward.
-           ((< (setq ppos (posn-at-point)
-                     py (cdr (or (posn-actual-col-row ppos)
-                                 (posn-col-row ppos))))
-               (min (- (window-text-height) scroll-margin 1) (1- vpos)))
-            nil)
-           ;; When already vscrolled, we vscroll some more if we can,
-           ;; or clear vscroll and move forward at end of tall image.
-           ((> (setq vs (window-vscroll nil t)) 0)
-            (when (> rbot 0)
-              (set-window-vscroll nil (+ vs (min rbot (frame-char-height))) t)))
-           ;; If cursor just entered the bottom scroll margin, move forward,
-           ;; but also vscroll one line so redisplay wont recenter.
-           ((= py (min (- (window-text-height) scroll-margin 1)
-                       (1- vpos)))
-            (set-window-vscroll nil (frame-char-height) t)
-            (line-move-1 arg noerror to-end)
-            t)
-           ;; If there are lines above the last line, scroll-up one line.
-           ((> vpos 0)
-            (scroll-up 1)
-            t)
-           ;; Finally, start vscroll.
-           (t
-            (set-window-vscroll nil (frame-char-height) t))))))))
+    (let* ((lh (window-line-height -1))
+           (vpos (nth 1 lh))
+           (ypos (nth 2 lh))
+           (rbot (nth 3 lh))
+           ppos py vs)
+      (when (or (null lh)
+                (>= rbot (frame-char-height))
+                (<= ypos (- (frame-char-height))))
+        (unless lh
+          (let* ((wend (window-end nil t))
+                 (evis (or (pos-visible-in-window-p wend nil t)
+                           (pos-visible-in-window-p (1- wend) nil t))))
+            (setq rbot (nth 3 evis)
+                  vpos (nth 5 evis))))
+        (cond
+         ;; If last line of window is fully visible, move forward.
+         ((or (null rbot) (= rbot 0))
+          nil)
+         ;; If cursor is not in the bottom scroll margin, move forward.
+         ((and (> vpos 0)
+               (< (setq ppos (posn-at-point)
+                        py (cdr (or (posn-actual-col-row ppos)
+                                    (posn-col-row ppos))))
+                  (min (- (window-text-height) scroll-margin 1) (1- vpos))))
+          nil)
+         ;; When already vscrolled, we vscroll some more if we can,
+         ;; or clear vscroll and move forward at end of tall image.
+         ((> (setq vs (window-vscroll nil t)) 0)
+          (when (> rbot 0)
+            (set-window-vscroll nil (+ vs (min rbot (frame-char-height))) t)))
+         ;; If cursor just entered the bottom scroll margin, move forward,
+         ;; but also vscroll one line so redisplay wont recenter.
+         ((and (> vpos 0)
+               (= py (min (- (window-text-height) scroll-margin 1)
+                          (1- vpos))))
+          (set-window-vscroll nil (frame-char-height) t)
+          (line-move-1 arg noerror to-end)
+          t)
+         ;; If there are lines above the last line, scroll-up one line.
+         ((> vpos 0)
+          (scroll-up 1)
+          t)
+         ;; Finally, start vscroll.
+         (t
+          (set-window-vscroll nil (frame-char-height) t)))))))
 
 
 ;; This is like line-move-1 except that it also performs