branch: externals/topspace
commit 42353585e048ef2998c5050bc6ffee5e169e6e41
Author: Trevor Pogue <pogu...@mcmaster.ca>
Commit: Trevor Pogue <pogu...@mcmaster.ca>
Minor code improvements from the "low hanging fruit" in initial commit:
- made text start closer to dead centered by changing division constant in
the vcm--center-offset function/property
- simplified the control of vcm-scroll-offset by removing an unnecessary
conditional and making it strictly a variable instead of a property
- rearranged order in which the code sections appear
- added window-resizing hook, but it is not a complete window-resizing
solution because it only works for windows in focus
- removed before-change-functions-hook which is made redundant by
after-change-functions-hook
- added comment clarifications for:
- purpose of variable vcm-first-recenter-done
- fact that the use of term "properties" in this code is inspired
specifically from the definition of properties in Python
---
vertical-center-mode.el | 166 ++++++++++++++++++++++++------------------------
1 file changed, 82 insertions(+), 84 deletions(-)
diff --git a/vertical-center-mode.el b/vertical-center-mode.el
index 650cd7e158..b34cb773aa 100644
--- a/vertical-center-mode.el
+++ b/vertical-center-mode.el
@@ -24,10 +24,11 @@
;;; TODO:
;; - support scrolling above top line with page scrolling as well
+;; - wrapped lines being counted as single lines when centering
;; - cannot scroll above top line if buffer open in multiple windows and
;; one or more windows is scrolled above beginning of buffer
-;; - centering is a bit lower than dead center
-;; - support recentering on window resize
+;; - recentering on window resize only occurs in selected buffer
+;; - issues if enabling when top line in window is > line 1
;; - submit to MELPA? (after optimizing/cleaning up code more)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -69,13 +70,19 @@ another window unless user has previously adjusted its
height with scrolling.
(defun vcm--turn-on ()
(setq-local vcm-on t)
(setq-local vcm-overlay (make-overlay (point-min) (point-max)))
+ ;; vcm-scroll-offset: the overlay portion that the user adjusts with
scrolling
(setq-local vcm-scroll-offset 0)
(setq-local vcm-user-scrolled nil)
(vcm--add-hooks)
(if (not (boundp 'vcm-first-recenter-done))
+ ;; vcm-first-recenter-done is used to block too many recenterings
occuring
+ ;; that are triggered by window-based hooks,
(setq-local vcm-first-recenter-done nil))
- (if vcm-first-recenter-done
- (vcm--recenter-reset-scroll)))
+ ;; Below: let user turn the mode off then on again to recenter while
preventing
+ ;; recentering here on initial mode turn-on. This avoids a bug with buffer
+ ;; not being centered on emacs startup, but need to investigate further to
+ ;; understand the root cause behind this bug/solution relationship.
+ (if vcm-first-recenter-done (vcm--recenter-reset-scroll)))
(defun vcm--turn-off ()
"Delete/unset data structures when the mode is turned off."
@@ -86,7 +93,6 @@ another window unless user has previously adjusted its height
with scrolling.
(makunbound 'vcm-scroll-offset)
(makunbound 'vcm-user-scrolled))
-;; handle insertions into the buffer
(defun vcm--kill-buffer ()
(makunbound 'vcm-first-recenter-done)
(vcm--turn-off))
@@ -95,32 +101,63 @@ another window unless user has previously adjusted its
height with scrolling.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; Hooks
+;;; Properties (inspired specifically by definition of properties from Python)
-(defvar vcm--hook-alist
- '(
- (window-configuration-change-hook . vcm--recenter-reset-scroll-conditional)
- (kill-buffer-hook . vcm--kill-buffer)
- (before-change-functions . vcm--recenter-keep-scroll)
- (after-change-functions . vcm--recenter-keep-scroll)
- (pre-command-hook . vcm--scroll-increase-overlay)
- (post-command-hook . vcm--scroll-decrease-overlay))
- "A list of hooks so they only need to be written in one spot.
-List of cons cells in format (hook-variable . function).")
+(defun vcm--center-offset ()
+ "Portion of the overlay that makes small buffers centered."
+ ;; dividing by slightly less than 2 here made buffers more dead centered
+ (let ((center-offset (/ (* (- (window-height) (vcm--buf-size)) 31) 64)))
+ (when (< center-offset 0) (setq center-offset 0))
+ center-offset)) ; return center-offset
-(defun vcm--add-hooks ()
- "Add hooks defined in variable `vcm-hook-alist'."
- (mapc (lambda (entry) (add-hook (car entry) (cdr entry) t t))
- vcm--hook-alist))
+(defun vcm--add-to-scroll-offset (direction)
+ (let ((pos (+ (- (line-number-at-pos) (vcm--top-line)) (vcm--overlay-size)))
+ (bottom (- (window-height) 5)))
+ ;; avoids a bug with cursor suddenly scrolling up
+ (when (> pos bottom) (previous-line)))
+ ;; only put overlay when top line is 1
+ (when (= (vcm--top-line) 1)
+ ;; block scrolling text fully below bottom of window
+ (unless (and (> direction 0)
+ (>= (vcm--overlay-size) (- (window-height) 5)))
+ (setq vcm-scroll-offset (+ vcm-scroll-offset direction)))))
-(defun vcm--remove-hooks ()
- "Remove hooks defined in variable `vcm-hook-alist'."
- (mapc (lambda (entry) (remove-hook (car entry) (cdr entry) t))
- vcm--hook-alist))
+(defun vcm--overlay-size ()
+ "The total overlay size."
+ (+ vcm-scroll-offset (vcm--center-offset)))
+
+(defun vcm--buf-size ()
+ "Size of the buffer text in lines."
+ (count-lines (point-min) (point-max)))
+
+(defun vcm--top-line ()
+ "Line number of the top line of text shown in the window."
+ (line-number-at-pos (window-start)))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; Scrolling
+;;; Overlay dislaying and recentering hooks
+
+;; the optional unused args in this section are just for hook compatibility
+
+(defun vcm--recenter-keep-scroll (&optional arg0 arg1 arg2)
+ "Use an overlay to display empty lines at the beginning of the buffer.
+This emulates the ability to scroll above the top line."
+ (let ((overlay-size (vcm--overlay-size)))
+ (overlay-put vcm-overlay 'before-string
+ (when (> overlay-size 0) (make-string overlay-size ?\n))))
+ (setq vcm-first-recenter-done t))
+
+(defun vcm--recenter-reset-scroll (&optional arg0 arg1 arg2)
+ (setq vcm-scroll-offset 0)
+ (vcm--recenter-keep-scroll))
+
+(defun vcm--recenter-reset-scroll-conditional (&optional arg0 arg1 arg2)
+ (unless (and vcm-user-scrolled) (vcm--recenter-reset-scroll)))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;;; Scrolling hooks
(defun vcm--scroll (scroll-list ccm-list scroll-direction)
"Emulate scrolling if user command was a scrolling command."
@@ -131,7 +168,7 @@ List of cons cells in format (hook-variable . function).")
(centering-cursor (member this-command ccm-list)))
;; shouldn't scroll from moving cursor unless in centered-cursor-mode
(unless (bound-and-true-p centered-cursor-mode) (setq centering-cursor
nil))
- (when (and (or user-is-scrolling centering-cursor))
+ (when (or user-is-scrolling centering-cursor)
(vcm--add-to-scroll-offset scroll-direction)
(setq vcm-user-scrolled t)
(vcm--recenter-keep-scroll))))
@@ -148,64 +185,25 @@ List of cons cells in format (hook-variable . function).")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; Overlay dislaying and recentering
-
-(defun vcm--recenter-keep-scroll (&optional arg0 arg1 arg2)
- "Use an overlay to display empty lines at the beginning of the buffer.
-This emulates the ability to scroll above the top line."
- (let ((overlay-size (vcm--overlay-size)))
- (overlay-put vcm-overlay 'before-string
- (when (> overlay-size 0) (make-string overlay-size ?\n))))
- (setq vcm-first-recenter-done t))
-
-(defun vcm--recenter-reset-scroll (&optional arg0 arg1 arg2)
- (vcm--reset-scroll)
- (vcm--recenter-keep-scroll))
-
-(defun vcm--recenter-reset-scroll-conditional (&optional arg0 arg1 arg2)
- (unless (and vcm-user-scrolled)
- (vcm--recenter-reset-scroll)))
-
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-
-;;; Properties
-
-(defun vcm--center-offset ()
- "Portion of the overlay that makes small buffer centered."
- (let ((center-offset
- (/ (- (window-height) (vcm--buf-size)) 2)))
- (when (< center-offset 0) (setq center-offset 0))
- center-offset)) ; return center-offset
-
-(defun vcm--scroll-offset ()
- "Portion of the overlay the user adjusts with scrolling."
- (let ((top-line (vcm--top-line)))
- (if (> top-line 2)
- (setq vcm-scroll-offset (- (*(vcm--center-offset) -1) 1))))
- vcm-scroll-offset) ; return vcm-scroll-offset
-
-(defun vcm--add-to-scroll-offset (direction)
- (let ((pos (+ (- (line-number-at-pos) (vcm--top-line)) (vcm--overlay-size)))
- (bottom (- (window-height) 5)))
- ;; avoids a bug with cursor suddenly scrolling up
- (when (> pos bottom) (previous-line)))
- ;; only put overlay when top line is 1
- (when (= (vcm--top-line) 1)
- ;; block scrolling text fully below bottom of window
- (unless (and (> direction 0)
- (>= (vcm--overlay-size) (- (window-height) 5)))
- (setq vcm-scroll-offset (+ (vcm--scroll-offset) direction)))))
-
-(defun vcm--reset-scroll () (setq vcm-scroll-offset 0))
+;;; Hooks
-(defun vcm--overlay-size ()
- "The total overlay size."
- (+ (vcm--scroll-offset) (vcm--center-offset)))
+(defvar vcm--hook-alist
+ '(
+ (window-configuration-change-hook . vcm--recenter-reset-scroll-conditional)
+ (window-size-change-functions . vcm--recenter-reset-scroll)
+ (kill-buffer-hook . vcm--kill-buffer)
+ (after-change-functions . vcm--recenter-keep-scroll)
+ (pre-command-hook . vcm--scroll-increase-overlay)
+ (post-command-hook . vcm--scroll-decrease-overlay))
+ "A list of hooks so they only need to be written in one spot.
+List of cons cells in format (hook-variable . function).")
-(defun vcm--buf-size ()
- "Size of the buffer text in lines."
- (count-lines (point-min) (point-max)))
+(defun vcm--add-hooks ()
+ "Add hooks defined in variable `vcm-hook-alist'."
+ (mapc (lambda (entry) (add-hook (car entry) (cdr entry) t t))
+ vcm--hook-alist))
-(defun vcm--top-line ()
- "Line number of the top line of text shown in the window."
- (line-number-at-pos (window-start)))
+(defun vcm--remove-hooks ()
+ "Remove hooks defined in variable `vcm-hook-alist'."
+ (mapc (lambda (entry) (remove-hook (car entry) (cdr entry) t))
+ vcm--hook-alist))
