From 1c5c8bd4df3bd4fd71fad13b2b57e670a4e74355 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Tue, 12 May 2026 06:07:20 -0500 Subject: fix(nov): rework the EPUB reading-width layout MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit `cj/nov--text-width-for-window' computed the target column as a percentage of `(window-body-width)'. But body width is the column count *after* the display margins. `cj/nov-update-layout' runs from `window-configuration-change-hook': it sets `visual-fill-column''s margins, which changes the body width, which fires the hook, which re-runs the layout against the now-narrower body, and so on. It's a shrinking feedback loop that bottoms out at `cj/nov-min-text-width' (40 columns) no matter what `cj/nov-margin-percent' is. That's why the column was a thin strip regardless of the margin setting. The width is now computed from the window's *natural* column count (body width plus any margins already set), so re-running the layout is idempotent. The margin math moved into a pure `cj/nov--text-width' helper, which is what the unit tests drive, and there's a regression test that the result is the same whether or not margins are already in place. Also: - `+'/`=' (`cj/nov-widen-text') and `-'/`_' (`cj/nov-narrow-text') step `cj/nov-margin-percent' by `cj/nov-margin-step' and re-lay-out, reporting the new percentage. `cj/nov-margin-percent' is now clamped to 0..25, so the text column runs from 50% (the floor) to 100% (the full window). - `cj/nov-margin-percent' default is 12 (≈76% text) for a comfortable starting width. - `cj/nov-apply-preferences' re-renders the document at the end again. `b3b537f' removed that on the theory `visual-fill-column' would re-trigger the render. The first page came up off-center until a manual resize, so it's back. - `cj/nov-update-layout' is now a command. The visible result (a ~75% centered column on first open, `+`/`-` to adjust) needs a restart to confirm. The tests cover the width math and clamping, idempotency, the adjust commands and their keybindings, the command status, and the re-render. --- modules/calibredb-epub-config.el | 75 ++++++++++++++++++++++++++++++++-------- 1 file changed, 61 insertions(+), 14 deletions(-) (limited to 'modules') diff --git a/modules/calibredb-epub-config.el b/modules/calibredb-epub-config.el index 43032381..2e02d1a9 100644 --- a/modules/calibredb-epub-config.el +++ b/modules/calibredb-epub-config.el @@ -49,6 +49,7 @@ (declare-function cj/open-file-with-command "system-utils" (command)) (declare-function visual-fill-column-mode "visual-fill-column" (&optional arg)) (declare-function visual-fill-column--adjust-window "visual-fill-column" ()) +(declare-function nov-render-document "nov" ()) ;; -------------------------- CalibreDB Ebook Manager -------------------------- @@ -89,13 +90,18 @@ ;; ------------------------------ Nov Epub Reader ------------------------------ -(defvar cj/nov-margin-percent 25 - "Percentage of window width to use as margins on each side when reading epubs. -For example, 25 means 25% left margin + 25% right margin, with 50% for text.") +(defvar cj/nov-margin-percent 12 + "Percent of the window's natural width used as a margin on each side in epubs. +12 leaves about 76% of the columns for text. Clamped to 0..25, so the text +column runs from 50% (margin 25) to 100% (margin 0) of the window. +Adjust it live with `cj/nov-widen-text' and `cj/nov-narrow-text'.") (defvar cj/nov-min-text-width 40 "Minimum text width in columns for Nov reading buffers.") +(defvar cj/nov-margin-step 2 + "Percentage points each `cj/nov-widen-text'/`cj/nov-narrow-text' press changes.") + ;; Prevent magic-fallback-mode-alist from opening epub as archive-mode ;; Advise set-auto-mode to force nov-mode for .epub files before magic-fallback runs (defun cj/force-nov-mode-for-epub (orig-fun &rest args) @@ -127,21 +133,35 @@ For example, 25 means 25% left margin + 25% right margin, with 50% for text.") (forward-paragraph) (recenter)) +(defun cj/nov--text-width (total-cols) + "Return the Nov text-column width for TOTAL-COLS of usable window width. +`cj/nov-margin-percent' is clamped to 0..25 and taken off each side; the +result is at least `cj/nov-min-text-width'." + (let* ((margin-percent (max 0 (min 25 cj/nov-margin-percent))) + (text-width-ratio (- 1.0 (* 2 (/ margin-percent 100.0))))) + (max cj/nov-min-text-width + (floor (* text-width-ratio total-cols))))) + (defun cj/nov--text-width-for-window (&optional window) "Return preferred Nov text width for WINDOW. -The width uses `cj/nov-margin-percent' while keeping a readable minimum and -clamping excessive margin percentages." +Computed from the window's natural column count -- its current body width +plus any margins already set -- so that re-running `cj/nov-update-layout' is +idempotent: each pass would otherwise shave the column by another margin +fraction, since setting margins narrows the body width." (let* ((window (or window (get-buffer-window (current-buffer) t))) - (window-width (if window (window-body-width window) 80)) - (margin-percent (max 0 (min 45 cj/nov-margin-percent))) - (text-width-ratio (- 1.0 (* 2 (/ margin-percent 100.0))))) - (max cj/nov-min-text-width - (floor (* text-width-ratio window-width))))) + (margins (and window (window-margins window))) + (natural-cols (if window + (+ (window-body-width window) + (or (car margins) 0) + (or (cdr margins) 0)) + 80))) + (cj/nov--text-width natural-cols))) (defun cj/nov-update-layout (&optional _frame) - "Recalculate Nov text layout for the current buffer. -Suitable for `window-configuration-change-hook' or -`window-size-change-functions'." + "Recalculate Nov's centered text column (width + margins) for this buffer. +Also runs from `window-configuration-change-hook' and +`window-size-change-functions' to stay responsive to splits and resizes." + (interactive) (when (derived-mode-p 'nov-mode) (when (require 'visual-fill-column nil t) (setq-local visual-fill-column-center-text t) @@ -150,6 +170,25 @@ Suitable for `window-configuration-change-hook' or (when (bound-and-true-p visual-fill-column-mode) (visual-fill-column--adjust-window))))) +(defun cj/--nov-adjust-margin (delta) + "Add DELTA to `cj/nov-margin-percent' (clamped 0..25), re-lay-out, and report. +A positive DELTA narrows the text column; a negative DELTA widens it." + (setq cj/nov-margin-percent + (max 0 (min 25 (+ cj/nov-margin-percent delta)))) + (cj/nov-update-layout) + (message "EPUB text width: %d%% of the window (margin %d%% each side)" + (- 100 (* 2 cj/nov-margin-percent)) cj/nov-margin-percent)) + +(defun cj/nov-widen-text () + "Give the EPUB text column more of the window, up to the full width." + (interactive) + (cj/--nov-adjust-margin (- cj/nov-margin-step))) + +(defun cj/nov-narrow-text () + "Give the EPUB text column less of the window, down to 50%." + (interactive) + (cj/--nov-adjust-margin cj/nov-margin-step)) + (defun cj/nov-apply-preferences () "Apply preferences after nov-mode has launched." (interactive) @@ -168,7 +207,10 @@ Suitable for `window-configuration-change-hook' or ;; Enable visual-fill-column for centered text with margins (cj/nov-update-layout) ;; Keep centered text width responsive after splits/resizes. - (add-hook 'window-configuration-change-hook #'cj/nov-update-layout nil t)) + (add-hook 'window-configuration-change-hook #'cj/nov-update-layout nil t) + ;; Re-render so the first page is laid out inside the margins just set; + ;; nov-mode's initial render ran before `nov-text-width'/visual-fill-column. + (nov-render-document)) (defun cj/nov-open-external () "Open the current EPUB with zathura." @@ -191,6 +233,11 @@ Suitable for `window-configuration-change-hook' or ("<" . nov-history-back) (">" . nov-history-forward) ("," . backward-paragraph) + ;; +/= widen the text column, -/_ narrow it (50%..100% of the window) + ("+" . cj/nov-widen-text) + ("=" . cj/nov-widen-text) + ("-" . cj/nov-narrow-text) + ("_" . cj/nov-narrow-text) ;; open current EPUB with zathura (same key in pdf-view) ("z" . cj/nov-open-external) ("t" . nov-goto-toc) -- cgit v1.2.3