branch: externals/dired-preview
commit 36afd903712042317d0dd4f9034537895e102d7a
Author: Protesilaos Stavrou <i...@protesilaos.com>
Commit: Protesilaos Stavrou <i...@protesilaos.com>
Add initial version of dired-preview
---
.gitignore | 5 +
COPYING | 674 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
README.md | 50 +++++
dired-preview.el | 300 +++++++++++++++++++++++++
4 files changed, 1029 insertions(+)
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000000..0b7f5b7d92
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+*.elc
+*-autoloads.el
+*-pkg.el
+dired-preview.info
+dired-preview.texi
diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000000..fc389822e7
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,674 @@
+ GNU GENERAL PUBLIC LICENSE
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+ IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+ 17. Interpretation of Sections 15 and 16.
+
+ If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+ END OF TERMS AND CONDITIONS
+
+ How to Apply These Terms to Your New Programs
+
+ If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+ <one line to give the program's name and a brief idea of what it does.>
+ Copyright (C) 2023 Protesilaos Stavrou
+
+ 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 <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+ If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+ <program> Copyright (C) 2023 Protesilaos Stavrou
+ This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License. Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+ You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+ The GNU General Public License does not permit incorporating your program
+into proprietary programs. If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library. If this is what you want to do, use the GNU Lesser General
+Public License instead of this License. But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000000..84749d88b1
--- /dev/null
+++ b/README.md
@@ -0,0 +1,50 @@
+# dired-preview for Emacs
+
++ Package name (GNU ELPA): `dired-preview` (⚠️ not available yet;
+ public testing phase as of 2023-06-25)
++ Git repo on SourceHut: <https://git.sr.ht/~protesilaos/dired-preview>
+ - Mirrors:
+ + GitHub: <https://github.com/protesilaos/dired-preview>
+ + GitLab: <https://gitlab.com/protesilaos/dired-preview>
++ Mailing list: <https://lists.sr.ht/~protesilaos/general-issues>
++ Backronym: Directories Invariably Render Everything Decently; PDFs
+ Require Extra Viewing Impediments for Emacs to Work.
+
+* * *
+
+This is a simple package to automatically preview in a side window the
+file at point in Dired buffers. Preview windows are closed when they
+are no longer relevant, while preview buffers are killed if they have
+not been used for other purposes beside previewing.
+
+Enable the `dired-preview-mode` in the current Dired buffer and then
+perform the regular up/down motions (`n` or `p` with default key
+bindings) to call the commands `dired-preview-next-file`,
+`dired-preview-previous-file`. Those will trigger the preview.
+
+The previewed file is displayed in a side window if its size is below
+the number specified in the user option `dired-preview-max-size`.
+Previews are shown subject to a small delay, per ther user option
+`dired-preview-delay`.
+
+Files matching the `dired-preview-ignored-extensions-regexp` are not
+previewed. The default value of that user option includes multimedia,
+PDFs, and EPUBs.
+
+[ In the future, we may find ways to quickly preview any file type
+ without affecting the performance of Emacs. Though `dired-preview`
+ is designed to have no external dependencies, so such an ambition
+ may not be realisable (e.g. produce a thumbnail out of a video). ]
+
+To set up `dired-preview-mode` in every Dired buffer, set it up thus:
+
+```elisp
+(add-hook 'dired-mode-hook #'dired-preview-mode)
+```
+
+I took inspiration for `dired-preview` from the now unmaintained
+`peep-dired` package by Adam Sokolnicki: <https://github.com/asok/peep-dired>.
+My original plan was to volunteer to maintain `peep-dired` but I
+decided to write it my own way: it was easier for me, plus I can
+implement only what I consider necessary without upsetting existing
+users.
diff --git a/dired-preview.el b/dired-preview.el
new file mode 100644
index 0000000000..ebdd171314
--- /dev/null
+++ b/dired-preview.el
@@ -0,0 +1,300 @@
+;;; dired-preview.el --- Automatically preview file at point in Dired -*-
lexical-binding: t -*-
+
+;; Copyright (C) 2023 Free Software Foundation, Inc.
+
+;; Author: Protesilaos Stavrou <i...@protesilaos.com>
+;; URL: https://git.sr.ht/~protesilaos/dired-preview
+;; Mailing-List: https://lists.sr.ht/~protesilaos/general-issues
+;; Version: 0.0.0
+;; Package-Requires: ((emacs "27.1"))
+;; Keywords: files, convenience
+
+;; 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 <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;
+;; This is a simple package to automatically preview in a side window the
+;; file at point in Dired buffers. Preview windows are closed when they
+;; are no longer relevant, while preview buffers are killed if they have
+;; not been used for other purposes beside previewing.
+;;
+;; Enable the `dired-preview-mode' in the current Dired buffer and then
+;; perform the regular up/down motions (`n' or `p' with default key
+;; bindings) to call the commands `dired-preview-next-file',
+;; `dired-preview-previous-file'. Those will trigger the preview.
+;;
+;; The previewed file is displayed in a side window if its size is below
+;; the number specified in the user option `dired-preview-max-size'.
+;; Previews are shown subject to a small delay, per ther user option
+;; `dired-preview-delay'.
+;;
+;; Files matching the `dired-preview-ignored-extensions-regexp' are not
+;; previewed. The default value of that user option includes multimedia,
+;; PDFs, and EPUBs.
+;;
+;; [ In the future, we may find ways to quickly preview any file type
+;; without affecting the performance of Emacs. Though `dired-preview'
+;; is designed to have no external dependencies, so such an ambition
+;; may not be realisable (e.g. produce a thumbnail out of a video). ]
+;;
+;; To set up `dired-preview-mode' in every Dired buffer, set it up thus:
+;;
+;; (add-hook 'dired-mode-hook #'dired-preview-mode)
+;;
+;; I took inspiration for `dired-preview' from the now unmaintained
+;; `peep-dired' package by Adam Sokolnicki:
<https://github.com/asok/peep-dired>.
+;; My original plan was to volunteer to maintain `peep-dired` but I
+;; decided to write it my own way: it was easier for me, plus I can
+;; implement only what I consider necessary without upsetting existing
+;; users.
+
+;;; Code:
+
+(require 'dired)
+
+(defgroup dired-preview nil
+ "Automatically preview file at point in Dired."
+ :group 'dired)
+
+(defcustom dired-preview-ignored-extensions-regexp
+ (concat "\\."
+ "\\(mkv\\|" "webm\\|" "mp4\\|" "mp3\\|" "ogg\\|" "m4a\\|"
+ "gz\\|" "zst\\|" "tar\\|" "xz\\|" "rar\\|" "zip\\|"
+ "iso\\|" "epub\\|" "pdf\\)")
+ "Regular expression of file type extensions to not preview."
+ :group 'dired-preview
+ :type 'string)
+
+(defcustom dired-preview-max-size (expt 2 20)
+ "Files larger than this byte limit are not previewed."
+ :group 'dired-preview
+ :type 'integer)
+
+(defcustom dired-preview-delay 0.7
+ "Time in seconds to wait before previewing."
+ :group 'dired-preview
+ :type 'float)
+
+(defvar dired-preview--buffers nil
+ "List with buffers of previewed files.")
+
+(defun dired-preview--find-file-no-select (file)
+ "Call `find-file-noselect' on FILE with appropriate settings."
+ ;; NOTE: I learnt about `non-essential' and `delay-mode-hooks' from
+ ;; Daniel Mendler's `consult' package, which imnplements a preview
+ ;; functionality as well (more sophisticated than mine):
+ ;; <https://github.com/minad/consult>.
+ (let ((inhibit-message t)
+ (enable-dir-local-variables nil)
+ (enable-local-variables :safe)
+ (non-essential t)
+ (delay-mode-hooks t))
+ (find-file-noselect file :nowarn)))
+
+(defun dired-preview--run-mode-hooks ()
+ "Run mode hooks in current buffer, if `delayed-mode-hooks' is non-nil.
+See `dired-preview--find-file-no-select' for how hooks are
+delayed and `dired-preview--set-up-preview-window' for how this function
+is used."
+ (when (and delay-mode-hooks (current-buffer))
+ (run-mode-hooks delayed-mode-hooks)
+ (set-window-parameter (selected-window) 'dired-preview-window nil)
+ (remove-hook 'post-command-hook #'dired-preview--run-mode-hooks :local)))
+
+(defun dired-preview--add-to-previews (file)
+ "Add FILE to `dired-preview--buffers', if not already in a buffer.
+Always return FILE buffer."
+ (let ((buffer (find-buffer-visiting file)))
+ (if (buffer-live-p buffer)
+ buffer
+ (setq buffer (dired-preview--find-file-no-select file))
+ (add-to-list 'dired-preview--buffers buffer)
+ buffer)))
+
+(defun dired-preview--get-buffers ()
+ "Return buffers that show previews."
+ (seq-filter
+ (lambda (buffer)
+ (when (and (bufferp buffer)
+ (buffer-live-p buffer))
+ buffer))
+ dired-preview--buffers))
+
+(defun dired-preview--get-windows ()
+ "Return windows that show previews."
+ (seq-filter
+ (lambda (window)
+ (when (window-parameter window 'dired-preview-window)
+ window))
+ (window-list)))
+
+(defun dired-preview--preview-p (file)
+ "Return non-nil if FILE can be previewed."
+ (and (not (file-directory-p file))
+ (not (dired-preview--file-ignored-p file))
+ (not (dired-preview--file-large-p file))))
+
+(defun dired-preview--return-preview-buffer (file)
+ "Return buffer to preview FILE in.
+Determine the propriety of this action by checking that FILE
+conforms with `dired-preview--preview-p'."
+ (when (dired-preview--preview-p file)
+ (dired-preview--add-to-previews file)))
+
+(defun dired-preview--file-ignored-p (file)
+ "Return non-nil if FILE extension is among the ignored extensions.
+See user option `dired-preview-ignored-extensions-regexp'."
+ (when-let ((ext (file-name-extension file)))
+ (string-match-p ext dired-preview-ignored-extensions-regexp)))
+
+(defun dired-preview--file-large-p (file)
+ "Return non-nil if FILE exceeds `dired-preview-max-size'."
+ (> (file-attribute-size (file-attributes file)) dired-preview-max-size))
+
+(defun dired-preview--delete-windows ()
+ "Delete preview windows."
+ (mapc
+ (lambda (window)
+ (delete-window window))
+ (dired-preview--get-windows)))
+
+(defun dired-preview--kill-buffers ()
+ "Kill preview buffers."
+ (mapc
+ (lambda (buffer)
+ (when (and (not (eq buffer (current-buffer)))
+ (window-parameter (get-buffer-window buffer)
'dired-preview-window)
+ delayed-mode-hooks)
+ (ignore-errors
+ (kill-buffer-if-not-modified buffer))))
+ (dired-preview--get-buffers)))
+
+(defvar dired-preview--timer nil
+ "Most recent timer object to display a preview.")
+
+(defun dired-preview--close-previews ()
+ "Kill preview buffers and delete their windows."
+ (dired-preview--delete-windows)
+ (dired-preview--kill-buffers))
+
+(defun dired-preview--close-previews-outside-dired ()
+ "Call `dired-preview--close-previews' if BUFFER is not in Dired mode."
+ (when (not (eq major-mode 'dired-mode))
+ (dired-preview--close-previews)))
+
+(defun dired-preview--set-up-preview-window (window &rest _)
+ "Set WINDOW `:preview' parameter."
+ (set-window-parameter window 'dired-preview-window :preview)
+ (with-current-buffer (window-buffer window)
+ (add-hook 'post-command-hook #'dired-preview--close-previews-outside-dired
nil :local)
+ (add-hook 'post-command-hook #'dired-preview--run-mode-hooks nil :local)))
+
+(defvar dired-preview-buffer-name "*dired-preview*"
+ "Name of preview buffer.")
+
+;; TODO 2023-06-13: Determine best way to make the placement of the
+;; preview configurable.
+(defvar dired-preview-display-buffer-side 'right)
+
+(defun dired-preview--display-buffer-action (buffer)
+ "Call `display-buffer' for BUFFER.
+Only do it with the current major mode is Dired."
+ ;; We check for `dired-mode' because we want to avoid the scenario
+ ;; where the user switches to another buffer/window/frame before the
+ ;; timer elapses.
+ (when (eq major-mode 'dired-mode)
+ (display-buffer
+ buffer
+ ;; NOTE 2023-06-13: See TODO above.
+ `((display-buffer-in-side-window)
+ (side . ,dired-preview-display-buffer-side)
+ (slot . -1)
+ (window-width . 0.3)
+ (dedicated . t)
+ (body-function . dired-preview--set-up-preview-window)
+ (window-parameters . ((no-other-window . t)
+ (mode-line-format . ("%e"
+ mode-line-front-space
+
,dired-preview-buffer-name))))))))
+
+(defun dired-preview--cancel-timer ()
+ "Cancel `dired-preview--timer' if it is a timer object."
+ (when (timerp dired-preview--timer)
+ (cancel-timer dired-preview--timer)))
+
+(defun dired-preview--display-buffer-with-delay (buffer)
+ "Display BUFFER with `dired-preview-delay'."
+ (dired-preview--cancel-timer)
+ (setq dired-preview--timer
+ (run-with-timer dired-preview-delay nil
+ #'dired-preview--display-buffer-action buffer)))
+
+(defun dired-preview--display-file (&optional file)
+ "Display preview of file if appropriate.
+
+File is either FILE or the value of `dired-file-name-at-point'.
+
+Return buffer object of displayed buffer."
+ (if-let* ((f (or file (dired-file-name-at-point)))
+ (buffer (dired-preview--return-preview-buffer f)))
+ (dired-preview--display-buffer-with-delay buffer)
+ (dired-preview--close-previews)))
+
+(defun dired-preview-disable-preview ()
+ "Disable preview."
+ (unless (eq major-mode 'dired-mode)
+ (error "Can only use `dired-preview' in Dired"))
+ (dired-preview--close-previews))
+
+(defun dired-preview-enable-preview ()
+ "Enable preview and store window configuration."
+ (unless (eq major-mode 'dired-mode)
+ (error "Can only use `dired-preview' in Dired"))
+ (add-hook 'post-command-hook #'dired-preview--close-previews-outside-dired
nil :local)
+ (dired-preview--display-file))
+
+(defun dired-preview-next-file (number)
+ "Preview next file in Dired.
+With optional numeric argument NUMBER move than many lines. Default is 1."
+ (interactive "^p")
+ (dired-next-line (or number 1))
+ (dired-preview--display-file))
+
+(defun dired-preview-previous-file (number)
+ "Preview previous file in Dired.
+With optional numeric argument NUMBER move than many lines. Default is 1."
+ (interactive "^p")
+ (dired-next-line (- (or number 1)))
+ (dired-preview--display-file))
+
+(defvar dired-preview-mode-map
+ (let ((map (make-sparse-keymap)))
+ (define-key map [remap dired-next-line] #'dired-preview-next-file)
+ (define-key map [remap dired-previous-line] #'dired-preview-previous-file)
+ map)
+ "Keymap for `dired-preview-mode'.")
+
+;;;###autoload
+(define-minor-mode dired-preview-mode
+ "Buffer-local mode to preview file at point in Dired."
+ :global nil
+ :keymap dired-preview-mode-map
+ (if dired-preview-mode
+ (dired-preview-enable-preview)
+ (dired-preview-disable-preview)))
+
+(provide 'dired-preview)
+;;; dired-preview.el ends here
