Add defcustom to define the cycling order of `recenter-top-bottom'. (Bug#4981)

* window.el (recenter-last-op): Doc fix.
(recenter-positions): New defcustom.
(recenter-top-bottom): Rewrite to use `recenter-positions'.
(move-to-window-line-top-bottom): Rewrite to use `recenter-positions'.

diff --git a/etc/NEWS b/etc/NEWS
index fed8ea18670c81466e9ec5772ffb90c7cf5b2660..9fcea9b23ef70dfbcc143ccdd4b86f7d17aed7b1 100644 (file)
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -159,6 +159,9 @@ operate on several directories (copy, rename, diff).
 ** M-r is bound to the new `move-to-window-line-top-bottom'
 to mirror the new behavior of C-l in Emacs-23.1.
 
+** `recenter-positions' can redefine the default cycling order
+of `recenter-top-bottom'.
+
 \f
 * Changes in Specialized Modes and Packages in Emacs 23.2
 

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 03d63d96b69d6d7b63abdfb5f3f6716f0aab2556..234d50442d477e8594ed219f85165aa1632c94a7 100644 (file)
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,13 @@
+2009-11-29  Juri Linkov  <juri@jurta.org>
+
+       Add defcustom to define the cycling order of `recenter-top-bottom'.
+       (Bug#4981)
+
+       * window.el (recenter-last-op): Doc fix.
+       (recenter-positions): New defcustom.
+       (recenter-top-bottom): Rewrite to use `recenter-positions'.
+       (move-to-window-line-top-bottom): Rewrite to use `recenter-positions'.
+
 2009-11-29  Michael Albinus  <michael.albinus@gmx.de>
 
        Improve integration of Tramp and ange-ftp in eshell.

diff --git a/lisp/window.el b/lisp/window.el
index ed4cfb5653e17bc34298f39ce33310400e9d29b2..e1b2000844c52e3746e4b0276fc7283bc84455d5 100644 (file)
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -1618,38 +1618,59 @@ Otherwise, bury WINDOW's buffer, see `bury-buffer'."
 
 (defvar recenter-last-op nil
   "Indicates the last recenter operation performed.
-Possible values: `top', `middle', `bottom'.")
+Possible values: `top', `middle', `bottom', integer or float numbers.")
+
+(defcustom recenter-positions '(middle top bottom)
+  "Cycling order for `recenter-top-bottom'.
+A list of elements with possible values `top', `middle', `bottom',
+integer or float numbers that define the cycling order for
+the command `recenter-top-bottom'.
+
+Top and bottom destinations are `scroll-margin' lines the from true
+window top and bottom.  Middle redraws the frame and centers point
+vertically within the window.  Integer number moves current line to
+the specified absolute window-line.  Float number between 0.0 and 1.0
+means the percentage of the screen space from the top.  The default
+cycling order is middle -> top -> bottom."
+  :type '(repeat (choice
+                 (const :tag "Top" top)
+                 (const :tag "Middle" middle)
+                 (const :tag "Bottom" bottom)
+                 (integer :tag "Line number")
+                 (float :tag "Percentage")))
+  :version "23.2"
+  :group 'windows)
 
 (defun recenter-top-bottom (&optional arg)
-  "Move current line to window center, top, and bottom, successively.
-With no prefix argument, the first call redraws the frame and
- centers point vertically within the window.  Successive calls
- scroll the window, placing point on the top, bottom, and middle
- consecutively.  The cycling order is middle -> top -> bottom.
+  "Move current buffer line to the specified window line.
+With no prefix argument, successive calls place point according
+to the cycling order defined by `recenter-positions'.
 
 A prefix argument is handled like `recenter':
  With numeric prefix ARG, move current line to window-line ARG.
- With plain `C-u', move current line to window center.
-
-Top and bottom destinations are actually `scroll-margin' lines
- the from true window top and bottom."
+ With plain `C-u', move current line to window center."
   (interactive "P")
   (cond
-   (arg (recenter arg))                 ; Always respect ARG.
-   ((or (not (eq this-command last-command))
-       (eq recenter-last-op 'bottom))
-    (setq recenter-last-op 'middle)
-    (recenter))
+   (arg (recenter arg))                        ; Always respect ARG.
    (t
+    (setq recenter-last-op
+         (if (eq this-command last-command)
+             (car (or (cdr (member recenter-last-op recenter-positions))
+                      recenter-positions))
+           (car recenter-positions)))
     (let ((this-scroll-margin
           (min (max 0 scroll-margin)
                (truncate (/ (window-body-height) 4.0)))))
       (cond ((eq recenter-last-op 'middle)
-            (setq recenter-last-op 'top)
-            (recenter this-scroll-margin))
+            (recenter))
            ((eq recenter-last-op 'top)
-            (setq recenter-last-op 'bottom)
-            (recenter (- -1 this-scroll-margin))))))))
+            (recenter this-scroll-margin))
+           ((eq recenter-last-op 'bottom)
+            (recenter (- -1 this-scroll-margin)))
+           ((integerp recenter-last-op)
+            (recenter recenter-last-op))
+           ((floatp recenter-last-op)
+            (recenter (round (* recenter-last-op (window-height))))))))))
 
 (define-key global-map [?\C-l] 'recenter-top-bottom)
 
@@ -1659,25 +1680,30 @@ Top and bottom destinations are actually `scroll-margin' lines
 With a prefix argument ARG, acts like `move-to-window-line'.
 
 With no argument, positions point at center of window.
-Successive calls position point at the top, the bottom and again
-at the center of the window."
+Successive calls position point at positions defined
+by `recenter-positions'."
   (interactive "P")
   (cond
-   (arg (move-to-window-line arg)) ; Always respect ARG.
-   ((or (not (eq this-command last-command))
-       (eq recenter-last-op 'bottom))
-    (setq recenter-last-op 'middle)
-    (call-interactively 'move-to-window-line))
+   (arg (move-to-window-line arg))     ; Always respect ARG.
    (t
+    (setq recenter-last-op
+         (if (eq this-command last-command)
+             (car (or (cdr (member recenter-last-op recenter-positions))
+                      recenter-positions))
+           (car recenter-positions)))
     (let ((this-scroll-margin
           (min (max 0 scroll-margin)
                (truncate (/ (window-body-height) 4.0)))))
       (cond ((eq recenter-last-op 'middle)
-            (setq recenter-last-op 'top)
-            (move-to-window-line this-scroll-margin))
+            (call-interactively 'move-to-window-line))
            ((eq recenter-last-op 'top)
-            (setq recenter-last-op 'bottom)
-            (move-to-window-line (- -1 this-scroll-margin))))))))
+            (move-to-window-line this-scroll-margin))
+           ((eq recenter-last-op 'bottom)
+            (move-to-window-line (- -1 this-scroll-margin)))
+           ((integerp recenter-last-op)
+            (move-to-window-line recenter-last-op))
+           ((floatp recenter-last-op)
+            (move-to-window-line (round (* recenter-last-op (window-height))))))))))
 
 (define-key global-map [?\M-r] 'move-to-window-line-top-bottom)