From 98babf12b2d9dbc38250186e0284fad6d937e3f3 Mon Sep 17 00:00:00 2001
From: stardiviner <numbchild@gmail.com>
Date: Tue, 13 Sep 2022 09:04:03 +0800
Subject: [PATCH 2/2] org.el: Add hook function to auto display inline images
 of subtree

* lisp/org.el (org-display-subtree-with-inline-images): Add an option
and hook function to auto display of inline images under current
expanded visible subtree.
---
 lisp/org.el | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/lisp/org.el b/lisp/org.el
index 70333c609..30716c04e 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -1108,6 +1108,13 @@ the following lines anywhere in the buffer:
   :version "24.1"
   :type 'boolean)
 
+(defcustom org-cycle-display-inline-images nil
+  "Non-nil means auto display inline images under subtree when `org-cycle'
+by the function `org-display-subtree-with-inline-images' on hook `org-cycle-hook'."
+  :group 'org-startup
+  :version "24.1"
+  :type 'boolean)
+
 (defcustom org-startup-with-latex-preview nil
   "Non-nil means preview LaTeX fragments when loading a new Org file.
 
@@ -16216,6 +16223,38 @@ buffer boundaries with possible narrowing."
 				(overlay-put ov 'keymap image-map))
 			      (push ov org-inline-image-overlays))))))))))))))))
 
+(defun org-display-subtree-inline-images (&optional state)
+  "Toggle the display of inline images under current expanded visible subtree.
+This hook function will auto display or hide inline images after `org-cycle'.
+It is used to hook on `org-cycle-hook'.
+The function behavior is controlled by `org-cycle-display-inline-images'."
+  (interactive)
+  (when (and org-cycle-display-inline-images
+             ;; not global state change from `org-cycle-global'.
+             (not (memq state '(overview contents all))))
+    (pcase state
+      ('children
+       (save-excursion
+         (save-restriction
+           (org-narrow-to-subtree)
+           ;; If has nested headlines, beg,end only from parent headling
+           ;; to first child headline which reference to upper let-binding
+           ;; `org-next-visible-heading'.
+           (org-display-inline-images t t (point-min) (progn (org-next-visible-heading 1) (point))))))
+      ('subtree
+       (save-excursion
+         (save-restriction
+           (org-narrow-to-subtree)
+           ;; If has nested headlines, also display inline images under all subtrees.
+           (org-display-inline-images t t (point-min) (point-max)))))
+      ('folded
+       (org-narrow-to-subtree)
+       (mapc #'delete-overlay (overlays-in (point-min) (point-max))))
+      ('nil (funcall 'org-toggle-inline-images))
+      (t nil))))
+
+(add-hook 'org-cycle-hook #'org-display-subtree-inline-images)
+
 (defvar visual-fill-column-width) ; Silence compiler warning
 (defun org-display-inline-image--width (link)
   "Determine the display width of the image LINK, in pixels.
-- 
2.37.2