Perfect-margin is a global minor mode to auto center windows.

Support using these following modes at the same time:

• linum-mode
• display-line-numbers
• minimap position both 'left 'right
• treemacs position 'left
• org-side-tree position both 'left 'right

You can use treemacs on the left side and minimap on the right side.

minimap window on the right-side has been adviced to be fixed-width.

A picture is more than one thousand words, here is how it looks like.

theme: doom-dracula from beautiful doom-themes

minimap from MELPA

Put perfect-margin under your Emacs load path, and add this to your init.el

(require 'perfect-margin)

Use M-x perfect-margin-mode to turn on/off perfect-margin.

To make it permanent add this to your init.el after require.

(perfect-margin-mode 1)

when using together with minimap or linum, make sure you place config for perfect-margin AFTER minimap and linum.

for doom-emacs users please add this to your config.el file when using minimap on the right side (which is the default value), otherwise the minimap might overlap with the mode line.

(after! doom-modeline
  (setq mode-line-right-align-edge 'right-fringe))

Via M-x customize-group and enter perfect-margin.

Change perfect-margin-visible-width and Apply and Save. That's it.

Or you can change the visible window width by setup perfect-margin-visible-width on the init.el.

(setq perfect-margin-visible-width 128)

By default both left and right margins are set, but in most cases setting only the left margin is sufficient as it allows for more display room on the right. Enable this option to only set the left margin of windows.

(setq perfect-margin-only-set-left-margin t)

perfect-margin by default ignore setting margins for minibuffer window and any window whos name starts with "*". Many of them are for special purpose.

You can change this behavior by setting perfect-margin-ignore-regexps and perfect-margin-ignore-filters.

This behavior might be too conservative, you can

• set perfect-margin-ignore-filters to nil to auto-center minibuffer windows
• set perfect-margin-ignore-regexps to nil to auto-center special windows like the HELM windows
• or simply set both variables to nil to let perfect-margin auto-center all windows no matter what.

(setq perfect-margin-ignore-filters nil)
(setq perfect-margin-ignore-regexps nil)

Default value for these two variables are listed below.

(defcustom perfect-margin-ignore-regexps
  '("^minibuf" "^[[:space:]]*\\*")
  "List of strings to determine if window is ignored.

Each string is used as regular expression to match the window buffer name."
  :group 'perfect-margin)

(defcustom perfect-margin-ignore-filters
  '(window-minibuffer-p)
  "List of functions to determine if window is ignored.

Each function is called with window as its sole arguemnt,
returning a non-nil value indicate to ignore the window."
  :group 'perfect-margin)

perfect-margin by default does not manipulate window fringes.

You can set perfect-margin-hide-fringes to t to tell perfect-margin to set both left and right fringe of all windows to zero, this might be useful in some corner cases where other packages which also manipulate fringes are enabled.

You can place this in your init.el to make mouse wheel scroll on margin area just like it scroll on the visible window.

(dolist (margin '("<left-margin> " "<right-margin> "))
  (global-set-key (kbd (concat margin "<mouse-1>")) 'ignore)
  (global-set-key (kbd (concat margin "<mouse-3>")) 'ignore)
  (dolist (multiple '("" "double-" "triple-"))
      (global-set-key (kbd (concat margin "<" multiple "wheel-up>")) 'mwheel-scroll)
      (global-set-key (kbd (concat margin "<" multiple "wheel-down>")) 'mwheel-scroll)))

(use-package perfect-margin
  :custom
  (perfect-margin-visible-width 128)
  :config
  ;; enable perfect-mode
  (perfect-margin-mode t)
  ;; auto-center minibuffer windows
  (setq perfect-margin-ignore-filters nil)
  ;; auto-center special windows
  (setq perfect-margin-ignore-regexps nil)
  ;; add additinal bding on margin area
  (dolist (margin '("<left-margin> " "<right-margin> "))
  (global-set-key (kbd (concat margin "<mouse-1>")) 'ignore)
  (global-set-key (kbd (concat margin "<mouse-3>")) 'ignore)
  (dolist (multiple '("" "double-" "triple-"))
      (global-set-key (kbd (concat margin "<" multiple "wheel-up>")) 'mwheel-scroll)
      (global-set-key (kbd (concat margin "<" multiple "wheel-down>")) 'mwheel-scroll))))

package.el

(package! perfect-margin)

config.el

(use-package! perfect-margin
  :config
  (after! doom-modeline
    (setq mode-line-right-align-edge 'right-fringe))
  (after! minimap
    ;; if you use (vc-gutter +pretty)
    ;; and theme is causing "Invalid face attribute :foreground nil"
    ;; (setq minimap-highlight-line nil)
    (setq minimap-width-fraction 0.08))
  ;; (setq perfect-margin-only-set-left-margin t)
  (perfect-margin-mode t))