NonGNU ELPA - visual-fill-column

visual-fill-column

Description
fill-column for visual-line-mode
Latest
visual-fill-column-2.4.tar, 2022-Jan-03, 30.0 KiB
Maintainer
Joost Kremers <joostkremers@fastmail.fm>
Home page
https://codeberg.org/joostkremers/visual-fill-column
Browse ELPA's repository
CGit or Gitweb
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To install this package, run in Emacs:

M-x package-install RET visual-fill-column RET

Full description

Visual Fill Column

visual-fill-column-mode is a small Emacs minor mode that mimics the effect of fill-column in visual-line-mode. Instead of wrapping lines at the window edge, which is the standard behaviour of visual-line-mode, it wraps lines at fill-column. If fill-column is too large for the window, the text is wrapped at the window edge. Told in images, visual-fill-column turns the view on the left into the view on the right, without changing the contents of the file:

Without visual-fill-column | With visual-fill-column --------------------------------- | ------------------------------- screenshot before | screenshot after

Installation

visual-fill-column can be installed via Melpa.

Usage

visual-fill-column-mode is primarily intended to be used alongside visual-line-mode. If this is your desired use-case , the way to activate visual-fill-column-mode depends on how you activate visual-line-mode.

If you activate visual-line-mode by using global-visual-line-mode, you can use global-visual-fill-column-mode (either set the user option through Customize, or call it as a function in your init file). global-visual-fill-column-mode turns on visual-fill-column-mode in every buffer that is visiting a file. (In buffers that do not visit any file, visual-fill-column-mode is mostly useless and sometimes even disruptive.)

visual-fill-column-mode can also be turned on in hooks. For example, if you don't use global-visual-line-mode, but would like to activate visual-fill-column-mode in every buffer that uses visual-line-mode, you can add visual-fill-column-mode to visual-line-mode-hook:

(add-hook 'visual-line-mode-hook #'visual-fill-column-mode)

This method has the effect that visual-fill-column-mode is used in every buffer that uses visual-line-mode. If that's not what you want, you can also use the reverse method: add visual-line-mode to visual-fill-column-mode-hook:

(add-hook 'visual-fill-column-mode-hook #'visual-line-mode)

This way, whenever you activate visual-fill-column-mode (e.g., interactively with M-x visual-fill-column-mode or in a major mode hook), visual-line-mode is also activated, but you can still activate visual-line-mode without using visual-fill-column-mode.

Note that while visual-fill-column-mode was written with the purpose of wrapping text in buffers using visual-line-mode, it is not tied to visual-line-mode: it is perfectly possible to use visual-fill-column-mode on its own.

visual-fill-column-mode works by widening the right window margin. This reduces the area that is available for text display, creating the appearance that the text is wrapped at fill-column. The amount by which the right margin is widened depends on the window width and is automatically adjusted when the window’s width changes (e.g., when the window is split in two side-by-side windows).

In buffers that are explicitly right-to-left (i.e., those where bidi-paragraph-direction is set to right-to-left), the left margin is expanded, so that the text appears at the window’s right side.

Widening the margin normally causes the fringes to be pushed inward. Since this is visually less appealing, the fringes are placed outside the margins. You can undo this by setting the variable visual-fill-column-fringes-outside-margins to nil.

Splitting a Window

Emacs won’t vertically split a window (i.e., into two side-by-side windows) that has wide margins. As a result, displaying buffers such as *Help* buffers, *Completion* buffers, etc., won’t split a window vertically, even if there appears to be enough space for a vertical split. This is technically not problematic, but it may be undesirable from a user's point of view. To remedy this, you can set the option visual-fill-column-enable-sensible-window-split. When this option is set, the variable split-window-preferred-function is set to the function visual-fill-column-split-window-sensibly, which first removes the margins and then calls split-window-sensibly to do the actual splitting.

This option does not affect the ability to split windows manually. Even if you keep visual-fill-column-enable-sensible-window-split unset, you can still split a window into two side-by-side windows by invoking e.g., split-window-right (C-x 3).

Note that this option replaces the option visual-fill-column-inhibit-sensible-window-split. This option was unset by default, causing split-window-preferred-function to be set, which had the unfortunate side effect that it would overwrite a user-defined setting for that variable without warning.

To get the old behaviour back, simply customise the option visual-fill-column-enable-sensible-window-split or set it to t in your init file.

Adjusting Text Size

The width of the margins is adjusted for the text size: larger text size means smaller margins. However, interactive adjustments to the text size (e.g., with text-size-adjust) cannot be detected by visual-fill-column-mode, therefore if you adjust the text size while visual-fill-column-mode is active, the margins won't be adjusted. To remedy this, you can force a redisplay, e.g., by switching buffers, by splitting and unsplitting the window or by calling redraw-display.

Alternatively, you can advise the function text-size-adjust with the function visual-fill-column-adjust:

(advice-add 'text-scale-adjust :after #'visual-fill-column-adjust)

Customisation

The customisation group visual-fill-column has five options (beside global-visual-fill-column-mode) that can be used to customise visual-fill-column:

visual-fill-column-width: column at which to wrap lines. If set to nil (the default), use the value of fill-column instead.

visual-fill-column-center-text: if set to t, centre the text area in the window. By default, the text is displayed at the window’s (left) edge, mimicking the effect of fill-column.

visual-fill-column-extra-text-width: extra columns added to the left and right side of the text area. This should be a cons cell of two integers (<left> . <right>). If visual-fill-column-center-text is t, the text area is centred before the extra columns are added. This is currently used by writeroom-mode to add room for line numbers without shifting the text off-centre.

visual-fill-column-fringes-outside-margins: if set to t, put the fringes outside the margins.

These four options are buffer-local, so the values you set in your init file are default values. They can also be set in mode hooks or directory or file local variables in order to customise particular files or file types.

The fifth option, visual-fill-column-inhibit-sensible-window-split can be set to keep visual-fill-column-mode from setting split-window-preferred-function, as discussed above.

visual-fill-column-mode also binds several mouse events for the left and right margins, so that scrolling or clicking on the margins does what you'd expect (rather than cause an "event not bound" error). If you wish to adjust these bindings, you should do so in visual-fill-column-mode-map.