larstvei/center-content-mode
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Optionally use an overlay for vertical margin

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larstvei 2024-09-15 02:46:54 +02:00
parent 21dfc29045
commit 936f79e5db
1 changed files with 28 additions and 1 deletions
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29
center-content.el
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@ -24,6 +24,15 @@
:type 'boolean :type 'boolean
:group 'center-content) :group 'center-content)
(defcustom center-content-vertical-by-overlay nil
"Enable vertical by using overlays.
Using overlays for vertical centering may give some undesirable
effects on the first line. By default, vertical centering is achieved
by using setting `header-line-format'."
:type 'boolean
:group 'center-content)
(defcustom center-content-hide-mode-line t (defcustom center-content-hide-mode-line t
"Hide mode-line when centering." "Hide mode-line when centering."
:type 'boolean :type 'boolean
@ -32,6 +41,9 @@
(defvar-local center-content--horizontal-overlay nil (defvar-local center-content--horizontal-overlay nil
"Overlay used to add left margin for horizontal centering.") "Overlay used to add left margin for horizontal centering.")
(defvar-local center-content--vertical-overlay nil
"Overlay used to add top margin for vertical centering.")
(defvar-local center-content--original-header-line-format header-line-format (defvar-local center-content--original-header-line-format header-line-format
"Stores the original `header-line-format` to restore upon disabling.") "Stores the original `header-line-format` to restore upon disabling.")
@ -73,6 +85,15 @@
(face-remap-add-relative 'header-line 'default)) (face-remap-add-relative 'header-line 'default))
(setq header-line-format (propertize " " 'display `(height ,top-margin))))) (setq header-line-format (propertize " " 'display `(height ,top-margin)))))
(defun center-content--vertical-by-overlay (content-height)
"Add overlay for vertical centering relative to CONTENT-HEIGHT."
(let* ((top-margin (center-content--calculate-top-margin content-height))
(overlay (make-overlay (window-start) (window-start) nil t t))
(space (propertize " " 'display `(space :width 0 :height ,top-margin))))
(overlay-put overlay 'intangible t)
(overlay-put overlay 'before-string space)
(setq center-content--vertical-overlay overlay)))
(defun center-content--enable () (defun center-content--enable ()
"Enable horizontal and vertical centering of content." "Enable horizontal and vertical centering of content."
(setq center-content--original-header-line-format header-line-format) (setq center-content--original-header-line-format header-line-format)
@ -81,7 +102,9 @@
(when center-content-horizontal (when center-content-horizontal
(center-content--horizontal (car content-size))) (center-content--horizontal (car content-size)))
(when center-content-vertical (when center-content-vertical
(center-content--vertical (cdr content-size))) (if center-content-vertical-by-overlay
(center-content--vertical-by-overlay (cdr content-size))
(center-content--vertical (cdr content-size))))
(when center-content-hide-mode-line (when center-content-hide-mode-line
(setq mode-line-format nil)))) (setq mode-line-format nil))))
@ -91,6 +114,10 @@
(when (overlayp center-content--horizontal-overlay) (when (overlayp center-content--horizontal-overlay)
(delete-overlay center-content--horizontal-overlay) (delete-overlay center-content--horizontal-overlay)
(setq center-content--horizontal-overlay nil)) (setq center-content--horizontal-overlay nil))
;; Remove vertical centering overlay
(when (overlayp center-content--vertical-overlay)
(delete-overlay center-content--vertical-overlay)
(setq center-content--horizontal-overlay nil))
;; Restore the header-line face remapping ;; Restore the header-line face remapping
(when center-content--header-line-face-remap-cookie (when center-content--header-line-face-remap-cookie
(face-remap-remove-relative center-content--header-line-face-remap-cookie) (face-remap-remove-relative center-content--header-line-face-remap-cookie)