larstvei/center-content-mode
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Using overlay at the top

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this is really janky
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larstvei 2024-09-14 02:39:48 +02:00
parent 194631b978
commit 5f4a6580bf
1 changed files with 37 additions and 43 deletions
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center-content.el
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@ -2,29 +2,21 @@
;;; Commentary:
;; This package provides a minor mode `center-content-mode` that centers the visible content
;; of the current buffer both horizontally and vertically. It calculates the necessary margins
;; and applies them using overlays and header line adjustments. The mode line is hidden to
;; provide a clean appearance.
;; This package provides a minor mode `center-content-mode` that centers the content
;; of the current buffer both horizontally and vertically. It calculates the necessary
;; margins and applies them using overlays. The mode line is hidden to provide a clean appearance.
;;; Code:
(defvar-local center-content--horiz-overlay nil
"Overlay used by `center-content-mode` to add left margin for horizontal centering.")
(defvar-local center-content--horizontal-overlay nil
"Overlay used to add left margin for horizontal centering.")
(defvar-local center-content--original-header-line-format nil
"Stores the original `header-line-format` to restore upon disabling.")
(defvar-local center-content--vertical-overlay nil
"Overlay used to add top margin for vertical centering.")
(defvar-local center-content--original-mode-line-format nil
"Stores the original `mode-line-format` to restore upon disabling.")
(defface center-content-header-line
`((t (:inherit default
:background ,(face-background 'default nil t)
:foreground ,(face-foreground 'default nil t))))
"Face for the header line in `center-content-mode`."
:group 'center-content)
(defun center-content--calculate-left-margin ()
"Calculate the left margin needed to center the content horizontally."
(let* ((window (selected-window))
@ -32,15 +24,14 @@
(content-width (car (window-text-pixel-size
window
(window-start window)
(window-end window))))
(space-width (string-pixel-width " "))
(margin (/ (max 0 (- window-width content-width)) (* 2 space-width))))
margin))
(window-end window)))))
(/ (max 0 (- window-width content-width)) 2)))
(defun center-content--calculate-top-margin ()
"Calculate the top margin needed to center the content vertically."
(let* ((window-height (window-pixel-height))
(content-height (cdr (window-text-pixel-size)))
(let* ((window (selected-window))
(window-height (window-pixel-height window))
(content-height (cdr (window-text-pixel-size window)))
(margin (/ (max 0 (- window-height content-height)) 2)))
margin))
@ -49,35 +40,38 @@
(let ((left-margin (center-content--calculate-left-margin))
(top-margin (center-content--calculate-top-margin)))
;; Apply horizontal centering using overlay
(let ((horiz-overlay (make-overlay (point-min) (point-max))))
(overlay-put horiz-overlay 'line-prefix
(propertize " " 'display `(space :width ,left-margin)))
(setq center-content--horiz-overlay horiz-overlay))
;; Save the original header-line-format
(setq center-content--original-header-line-format header-line-format)
;; Apply vertical centering using header-line-format with custom face
(setq header-line-format
(propertize " "
'display `(height ,(max 0 (/ top-margin (frame-char-height))))
'face 'center-content-header-line))
;; Save the original mode-line-format
(let ((horizontal-overlay (make-overlay (point-min) (point-max))))
(overlay-put horizontal-overlay 'line-prefix
(propertize " " 'display `(space :width (,left-margin))))
(setq center-content--horizontal-overlay horizontal-overlay))
;; Apply vertical centering using a before-string overlay
(let ((overlay (make-overlay (point-min) (point-min))))
(overlay-put overlay 'before-string
(propertize "\n" 'display `(space :height (,top-margin))))
;; Set low priority to avoid interfering with line-prefix
(overlay-put overlay 'priority -50)
(setq center-content--vertical-overlay overlay))
;; Save and hide the mode line
(setq center-content--original-mode-line-format mode-line-format)
;; Hide the mode line
(setq mode-line-format nil)))
(setq mode-line-format nil)
;; Force redisplay
(force-mode-line-update)
(redisplay)))
(defun center-content--disable ()
"Disable centering of content."
;; Remove horizontal centering overlay
(when (overlayp center-content--horiz-overlay)
(delete-overlay center-content--horiz-overlay)
(setq center-content--horiz-overlay nil))
;; Restore the original header-line-format
(setq header-line-format center-content--original-header-line-format)
(setq center-content--original-header-line-format nil)
(when (overlayp center-content--horizontal-overlay)
(delete-overlay center-content--horizontal-overlay)
(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--vertical-overlay nil))
;; Restore the original mode-line-format
(setq mode-line-format center-content--original-mode-line-format)
(setq center-content--original-mode-line-format nil)
;; Force redisplay to remove any lingering effects
;; Force redisplay
(force-mode-line-update)
(redisplay))
@ -85,7 +79,7 @@
(define-minor-mode center-content-mode
"Toggle horizontal and vertical centering of buffer content.
When enabled, the visible content of the buffer is centered both
When enabled, the content of the buffer is centered both
horizontally and vertically within the window. The mode line is
hidden for a clean appearance."
:init-value nil