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spacemacs/layers/+distributions/spacemacs-base/local/centered-buffer-mode/centered-buffer-mode.el
Cadel Watson 0f01b0fb59 Change default fringe color for centered-buffer-mode. 
The current default color is "black", which creates ugly bars for many
themes on both sides of the centered buffer. This change sets the fringe
color to the buffer's background color, which blends in nicely.
2016-11-22 20:41:45 -05:00

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;;; centered-buffer-mode.el --- Minor mode for centering buffers.
;; Copyright (C) 2012-2016 Sylvain Benner & Contributors
;;
;; Author: Eugene "JAremko" Yaremenko <w3techplayground@gmail.com>
;; Keywords: centering buffer minor-mode
;; Created: 1 July 2016
;; Version: 1.01
;; Package-Requires: ((emacs "24.4"))
;; URL: https://github.com/syl20bnr/spacemacs
;; This file is not part of GNU Emacs.
;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <http://www.gnu.org/licenses/>.
;;; Code:
(require 'face-remap)
(defgroup spacemacs-centered-buffer-mode nil "Minor mode to center buffer in its window."
:group 'convenience)
(defcustom spacemacs-centered-buffer-mode-min-fringe-width 50
"Minimal fringe width."
:type 'integer
:group 'spacemacs-centered-buffer-mode)
(defcustom spacemacs-centered-buffer-mode-safety-gap-width 20
"Add extra width to the modified buffer to make sure
that differed modifications won't cause an overflow."
:type 'integer
:group 'spacemacs-centered-buffer-mode)
(defcustom spacemacs-centered-buffer-mode-fringe-color (face-background 'default)
"Color of the fringes."
:type 'color
:group 'spacemacs-centered-buffer-mode)
(defvar-local spacemacs--centered-buffer-mode-origin-buffer nil)
(defvar-local spacemacs--centered-buffer-mode-indirect-buffer nil)
(defvar-local spacemacs--centered-buffer-mode-text-pixel-size nil)
(defvar spacemacs-centered-buffer-mode-default-fringe-color (face-background 'fringe))
(defvar spacemacs--centered-buffer-mode-indirect-buffers (list))
(define-minor-mode spacemacs-centered-buffer-mode
"Minor mode to center buffer in its window."
:init-value nil
:group 'spacemacs-centered-buffer-mode
(if spacemacs-centered-buffer-mode
(if (not (window-dedicated-p))
(spacemacs//centered-buffer-mode-enable-branch (called-interactively-p 'any))
(setq spacemacs-centered-buffer-mode nil)
(when (called-interactively-p 'any)
(message "Can't center in dedicated window!")))
(spacemacs//centered-buffer-mode-disable-branch)))
(defun spacemacs//centered-buffer-mode-enable-branch (interact)
"Used it `spacemacs-centered-buffer-mode'.
Assume to be called interactively when INTERACT has non nil value."
;; Mode will be applied to the indirect buffer.
(setq spacemacs-centered-buffer-mode nil)
;; Don't run if the mode is enabled(we are in the indirect buffer).
(unless spacemacs--centered-buffer-mode-origin-buffer
(let* ((window (selected-window))
(origin-buffer (window-buffer window))
(indirect-buffer
(if (buffer-live-p
spacemacs--centered-buffer-mode-indirect-buffer)
spacemacs--centered-buffer-mode-indirect-buffer
(setq spacemacs--centered-buffer-mode-indirect-buffer
(make-indirect-buffer origin-buffer
(format "%s(centered)"
origin-buffer)
t)))))
(spacemacs//centered-buffer-mode-buffer-fringr-color-toggle origin-buffer t)
(setq spacemacs--centered-buffer-mode-indirect-buffer
indirect-buffer
spacemacs-centered-buffer-mode-default-fringe-color
(face-background 'fringe))
(when (derived-mode-p 'org-mode)
(setq-local org-startup-folded nil)
(outline-show-all))
(switch-to-buffer indirect-buffer nil t)
(with-mode-disabled
page-break-lines-mode
(let* ((fringe-w (spacemacs//centered-buffer-calc-fringe
window)))
(if (> fringe-w spacemacs-centered-buffer-mode-min-fringe-width)
(progn
;; Fix visual glitch.
(spacemacs/toggle-line-numbers)
(spacemacs/toggle-line-numbers)
;;
(setq spacemacs--centered-buffer-mode-indirect-buffers
(append (list indirect-buffer)
spacemacs--centered-buffer-mode-indirect-buffers)
spacemacs--centered-buffer-mode-origin-buffer origin-buffer
spacemacs-centered-buffer-mode t
indicate-empty-lines nil
fringes-outside-margins t
left-fringe-width fringe-w
right-fringe-width fringe-w
;; looks better with some margin.
left-margin-width (if (or (not left-margin-width)
(= left-margin-width 0))
1
left-margin-width)
spacemacs--centered-buffer-mode-text-pixel-size
(car (window-text-pixel-size window)))
(face-remap-add-relative 'fringe :background
spacemacs-centered-buffer-mode-fringe-color)
(set-window-buffer window indirect-buffer)
(advice-add 'previous-buffer
:before
#'spacemacs//centered-buffer-mode-prev-next-buffer-advice)
(advice-add 'next-buffer
:before
#'spacemacs//centered-buffer-mode-prev-next-buffer-advice)
(add-hook 'after-change-functions
#'spacemacs//centered-buffer-after-change-function
nil
t)
(add-hook 'buffer-list-update-hook
'spacemacs//centered-buffer-buffer-list-update-fringes)
(add-hook 'window-configuration-change-hook
'spacemacs//centered-buffer-buffer-list-update-fringes))
(setq spacemacs--centered-buffer-mode-origin-buffer nil)
(set-buffer origin-buffer)
(spacemacs//centered-buffer-mode-buffer-fringr-color-toggle origin-buffer nil)
(kill-buffer indirect-buffer)
(setq spacemacs--centered-buffer-mode-indirect-buffer nil)
(when interact
(message "Not enough space to center the buffer!"))))))))
(defun spacemacs//centered-buffer-mode-prev-next-buffer-advice ()
"Disables `spacemacs-centered-buffer-mode' when `spacemacs/previous-buffer'
or `spacemacs/next-buffer' is called."
(when (bound-and-true-p spacemacs-centered-buffer-mode)
(spacemacs-centered-buffer-mode -1)))
(defun spacemacs//centered-buffer-mode-disable-branch ()
"Used in `spacemacs-centered-buffer-mode'."
;; Don't run if the mode is disabled(we are not in the indirect buffer).
(when spacemacs--centered-buffer-mode-origin-buffer
(let* ((window (selected-window))
(origin-buffer spacemacs--centered-buffer-mode-origin-buffer)
(indirect-buffer (window-buffer window)))
(setq spacemacs--centered-buffer-mode-origin-buffer nil)
(switch-to-buffer origin-buffer nil t)
(spacemacs//centered-buffer-mode-buffer-fringr-color-toggle origin-buffer nil)
(setq spacemacs--centered-buffer-mode-indirect-buffer nil)
(when (buffer-live-p indirect-buffer)
(dolist (window (get-buffer-window-list indirect-buffer 2))
(set-window-buffer window origin-buffer))
(kill-buffer indirect-buffer)))))
(defun spacemacs//centered-buffer-mode-buffer-fringr-color-toggle (buffer flag)
"Change fringe color of the BUFFER if FLAG has non-nil value.
Revert changes Otherwise."
(with-current-buffer buffer
(if flag
(face-remap-add-relative 'fringe :background
spacemacs-centered-buffer-mode-fringe-color)
(face-remap-reset-base 'fringe)
(face-remap-add-relative 'fringe
:background
spacemacs-centered-buffer-mode-default-fringe-color))))
(defun spacemacs//centered-buffer-calc-fringe (&optional window text-pixel-size)
"Calculate fringe width for `spacemacs-centered-buffer-mode'.
Uses text-pixel-size if provided, otherwise calculates it with `window-pixel-width'."
(-(/ (- (window-pixel-width window)
(or text-pixel-size
(car (window-text-pixel-size window))))
2)
(if (bound-and-true-p org-indent-mode) 40
spacemacs-centered-buffer-mode-safety-gap-width)))
(defun spacemacs//centered-buffer-buffer-update-window-fringes (window)
"Update fringe width of WINDOW if it displays `centered-buffer-mode' buffer."
(when (and (buffer-local-value 'spacemacs--centered-buffer-mode-origin-buffer
(window-buffer window))
;; Might be needed because
;; (spacemacs-centered-buffer-mode -1) kills buffers.
(buffer-live-p (window-buffer window)))
(let ((fringe-w (spacemacs//centered-buffer-calc-fringe
window
spacemacs--centered-buffer-mode-text-pixel-size)))
(if (> fringe-w spacemacs-centered-buffer-mode-min-fringe-width)
(set-window-fringes window fringe-w fringe-w t)
(spacemacs-centered-buffer-mode -1)
(when spacemacs--centered-buffer-mode-indirect-buffers
(spacemacs//centered-buffer-prune-indirect-buffer-list))))))
(defun spacemacs//centered-buffer-buffer-list-update-fringes ()
"Update fringe width of all `centered-buffer-mode' fringes."
(dolist (frame (frame-list))
(when (frame-live-p frame)
(dolist (window (window-list frame 2))
(spacemacs//centered-buffer-buffer-update-window-fringes window)))))
(defun spacemacs//centered-buffer-after-change-function (begin end length)
"Reduce `centered-buffer-mode' fringe width in case of buffer content overflow."
(dolist (window (get-buffer-window-list (current-buffer) 2 t))
(save-excursion
(let* ((min-pos (progn (goto-char begin)
(point-at-bol)))
(max-pos (progn (goto-char end)
(point-at-eol)))
(updated-segment-max-width (car (window-text-pixel-size window min-pos max-pos))))
(when (> updated-segment-max-width
spacemacs--centered-buffer-mode-text-pixel-size)
(setq spacemacs--centered-buffer-mode-text-pixel-size updated-segment-max-width)
(spacemacs//centered-buffer-buffer-update-window-fringes window))))))
(defun spacemacs//centered-buffer-prune-indirect-buffer-list ()
"Remove indirect buffer from the `spacemacs--centered-buffer-mode-indirect-buffers'
if the buffer hasn't at least one live window. Disables `centered-buffer-mode' hooks
and advices if `spacemacs--centered-buffer-mode-indirect-buffers' has no elements left to
minimize the performance hit when the mode isn't used."
(dolist (buffer spacemacs--centered-buffer-mode-indirect-buffers)
(unless (or (and (buffer-live-p buffer)
(window-live-p (get-buffer-window buffer t)))
(not spacemacs--centered-buffer-mode-indirect-buffers))
(let ((origin-buffer (buffer-local-value
'spacemacs--centered-buffer-mode-origin-buffer
buffer)))
(when (ignore-errors (kill-buffer buffer))
(setq spacemacs--centered-buffer-mode-indirect-buffers
(delete buffer spacemacs--centered-buffer-mode-indirect-buffers))
(when (buffer-live-p origin-buffer)
(spacemacs//centered-buffer-mode-buffer-fringr-color-toggle origin-buffer nil)
(with-current-buffer origin-buffer
(setq spacemacs--centered-buffer-mode-indirect-buffers nil)))))))
;; Remove hooks and advices when they are not needed anymore.
(unless spacemacs--centered-buffer-mode-indirect-buffers
(advice-remove 'previous-buffer
#'spacemacs//centered-buffer-mode-prev-next-buffer-advice)
(advice-remove 'next-buffer
#'spacemacs//centered-buffer-mode-prev-next-buffer-advice)
(remove-hook 'after-change-functions
#'spacemacs//centered-buffer-after-change-function)
(remove-hook 'buffer-list-update-hook
'spacemacs//centered-buffer-buffer-list-update-fringes)
(remove-hook 'window-configuration-change-hook
'spacemacs//centered-buffer-buffer-list-update-fringes)))
(defmacro with-mode-disabled (mode &rest body)
"Evaluate BODY with MODE disabled."
(declare (indent 1) (debug t))
`(if (not (bound-and-true-p ,mode))
(progn ,@body)
(,mode -1)
,@body
(,mode +1)))
(provide 'centered-buffer-mode)
;;; centered-buffer-mode.el ends here
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