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;;; calibredb-epub-config --- Functionality for Ebook Management and Display -*- lexical-binding: t; coding: utf-8; -*-
;; author Craig Jennings <c@cjennings.net>
;;; Commentary:
;; This module provides a comprehensive ebook management and reading experience
;; within Emacs, integrating CalibreDB for library management and Nov for EPUB
;; reading.
;;
;; FEATURES:
;; - CalibreDB integration for managing your Calibre ebook library
;; - Nov mode for reading EPUB files with customized typography and layout
;; - Seamless navigation between Nov reading buffers and CalibreDB entries
;; - Image centering in EPUB documents without modifying buffer text
;; - Quick filtering and searching within your ebook library
;;
;; KEY BINDINGS:
;; - M-B: Open CalibreDB library browser
;; - In CalibreDB search mode:
;; - l: Filter by tag
;; - L: Clear all filters
;; - In Nov mode:
;; - z: Open current EPUB in external viewer (zathura)
;; - C-c C-b: Jump to CalibreDB entry for current book
;; - m: Set bookmark
;; - b: List bookmarks
;;
;; WORKFLOW:
;; 1. Press M-B to browse your Calibre library
;; 2. Use filters (l for tags, L to clear) to narrow results
;; 3. Open an EPUB to read it in Nov with optimized typography
;; 4. While reading, use C-c C-b to jump back to the book's metadata
;; 5. Use z to open in external reader when needed
;;
;; CONFIGURATION NOTES:
;; - Prefers EPUB format when available, falls back to PDF
;; - Centers images in EPUB documents using display properties
;; - Applies custom typography with larger fonts for comfortable reading
;; - Uses visual-fill-column for centered text with appropriate margins
;;; Code:
(require 'user-constants) ;; for books-dir
;; Declare functions from lazy-loaded packages
(declare-function calibredb-find-create-search-buffer "calibredb" ())
(declare-function calibredb-search-keyword-filter "calibredb" (keyword))
(declare-function cj/open-file-with-command "system-utils" (command))
(declare-function visual-fill-column-mode "visual-fill-column" (&optional arg))
;; -------------------------- CalibreDB Ebook Manager --------------------------
(use-package calibredb
:defer 1
:commands calibredb
:bind
("M-B" . calibredb)
;; use built-in filter by tag, add clear-filters
(:map calibredb-search-mode-map
("l" . calibredb-filter-by-tag)
("L" . cj/calibredb-clear-filters))
:config
;; basic config
(setq calibredb-root-dir books-dir)
(setq calibredb-db-dir (expand-file-name "metadata.db" calibredb-root-dir))
(setq calibredb-program "/usr/bin/calibredb")
(setq calibredb-preferred-format "epub")
(setq calibredb-search-page-max-rows 20000)
;; search window display
(setq calibredb-size-show nil)
(setq calibredb-order "asc")
(setq calibredb-id-width 7))
(defun cj/calibredb-clear-filters ()
"Clear active filters and show all results."
(interactive)
(setq calibredb-tag-filter-p nil
calibredb-favorite-filter-p nil
calibredb-author-filter-p nil
calibredb-date-filter-p nil
calibredb-format-filter-p nil
calibredb-search-current-page 1)
;; empty string resets keyword filter and refreshes listing
(calibredb-search-keyword-filter ""))
;; ------------------------------ Nov Epub Reader ------------------------------
(use-package nov
:defer .5
:after visual-fill-column
:mode
("\\.epub\\'" . nov-mode)
("\\.epub\\'" . epub-mode)
:hook
(nov-mode . cj/nov-apply-preferences)
(epub-mode . cj/nov-apply-preferences)
:bind
(:map nov-mode-map
("m" . bookmark-set)
("b" . bookmark-bmenu-list)
("r" . nov-render-document)
("l" . recenter-top-bottom)
("d" . sdcv-search-input)
("." . cj/forward-paragraph-and-center)
("<" . nov-history-back)
(">" . nov-history-forward)
("," . backward-paragraph)
;; open current EPUB with zathura (same key in pdf-view)
("z" . (lambda () (interactive) (cj/open-file-with-command "zathura")))
("t" . nov-goto-toc)
("C-c C-b" . cj/nov-jump-to-calibredb)))
(defun cj/forward-paragraph-and-center ()
"Forward one paragraph and center the page."
(interactive)
(forward-paragraph)
(recenter))
(defun cj/nov-apply-preferences ()
"Apply preferences after nov-mode has launched."
(interactive)
(face-remap-add-relative 'variable-pitch :height 180)
(face-remap-add-relative 'fixed-pitch :height 180)
;; Make this buffer-local so other Nov buffers can choose differently
(setq-local nov-text-width 115)
(when (require 'visual-fill-column nil t)
(setq-local visual-fill-column-center-text t
;; small cushion above nov-text-width prevents truncation
visual-fill-column-width (+ nov-text-width 10))
(hl-line-mode)
(visual-fill-column-mode 1))
(nov-render-document))
(defun cj/nov-center-images ()
"Center images in the current Nov buffer without modifying text.
Use `line-prefix' and `wrap-prefix' with a space display property aligned to a
computed column based on the window text area width."
(let ((inhibit-read-only t))
;; Clear any prior centering prefixes first (fresh render usually makes this
;; unnecessary, but it makes the function idempotent).
(remove-text-properties (point-min) (point-max)
'(line-prefix nil wrap-prefix nil))
(save-excursion
(goto-char (point-min))
;; Work in the selected window showing this buffer (if any).
(when-let* ((win (get-buffer-window (current-buffer) t))
(col-width (window-body-width win)) ;; columns
(col-px (* col-width (window-font-width win))))
(while (let ((m (text-property-search-forward
'display nil
(lambda (_ p) (and (consp p) (eq (car-safe p) 'image))))))
(when m
(let* ((img (prop-match-value m))
(img-px (car (image-size img t))) ;; pixel width
;; Convert pixel image width to columns for alignment.
(img-cols (max 1 (ceiling (/ (float img-px)
(max 1 (window-font-width win))))))
(pad-cols (max 0 (/ (- col-width img-cols) 2)))
(prefix (propertize " " 'display `(space :align-to ,pad-cols))))
(save-excursion
(goto-char (prop-match-beginning m))
(beginning-of-line)
(let ((bol (point))
(eol (line-end-position)))
(add-text-properties bol eol
`(line-prefix ,prefix
wrap-prefix ,prefix)))))
t)))))))
(add-hook 'nov-post-html-render-hook #'cj/nov-center-images)
;; Jump from a Nov buffer to the corresponding CalibreDB entry.
(defun cj/nov--metadata-get (key)
"Return a metadata value from nov-metadata trying KEY as symbol and string."
(let* ((v (or (and (boundp 'nov-metadata)
(or (alist-get key nov-metadata nil nil #'equal)
(alist-get (if (symbolp key) (symbol-name key) key)
nov-metadata nil nil #'equal)))
nil)))
(cond
((and (listp v) (= (length v) 1)) (car v))
((stringp v) v)
(t v))))
(defun cj/nov--file-path ()
"Return the current EPUB file path when in nov-mode, or nil."
(when (derived-mode-p 'nov-mode)
;; In nov, the buffer visits the .epub; buffer-file-name is usually the EPUB.
(or buffer-file-name
(and (boundp 'nov-epub-filename) nov-epub-filename)
(and (boundp 'nov-epub-file) nov-epub-file))))
(defun cj/nov-jump-to-calibredb ()
"Open CalibreDB focused on the current EPUB's book entry.
Try to use the Calibre book id from the parent folder name (for example,
\"Title (123)\"). Fall back to a title or author search when no id exists."
(interactive)
(require 'calibredb)
(let* ((file (cj/nov--file-path))
(title (or (cj/nov--metadata-get 'title)
(cj/nov--metadata-get "title")))
(author (or (cj/nov--metadata-get 'creator)
(cj/nov--metadata-get 'author)
(cj/nov--metadata-get "creator")
(cj/nov--metadata-get "author")))
(id (when file
(let* ((parent (file-name-nondirectory
(directory-file-name (file-name-directory file)))))
(when (string-match " (\\([0-9]+\\))\\'" parent)
(match-string 1 parent))))))
(calibredb)
(with-current-buffer (calibredb-find-create-search-buffer)
(setq calibredb-search-current-page 1)
(cond
(id
(calibredb-search-keyword-filter (format "id:%s" id))
(message "CalibreDB: focused by id:%s" id))
((or title author)
(let* ((q (string-join
(delq nil (list (and title (format "title:\"%s\"" title))
(and author (format "authors:\"%s\"" author))))
" and ")))
(calibredb-search-keyword-filter q)
(message "CalibreDB: search %s" (if (string-empty-p q) "<all>" q))))
(t
(calibredb-search-keyword-filter "")
(message "CalibreDB: no metadata; showing all"))))))
(provide 'calibredb-epub-config)
;;; calibredb-epub-config.el ends here
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