From c6a10d47b26de75f85506bde7b60f995a2002c5a Mon Sep 17 00:00:00 2001
From: Frederik Vanrenterghem <frederik@vanrenterghem.biz>
Date: Mon, 6 May 2024 23:00:50 +0800
Subject: [PATCH] Automatically downscale large image attachments in mu4e.

Resize attached images to not exceed 1200x1200.
---
 emacs/.emacs.d/init.el | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/emacs/.emacs.d/init.el b/emacs/.emacs.d/init.el
index 51f86f1..69a744a 100644
--- a/emacs/.emacs.d/init.el
+++ b/emacs/.emacs.d/init.el
@@ -147,6 +147,40 @@
 		   (or (string-join (seq-take (split-string (mu4e-fetch-field msg "X-Spam-Status") " ") 2) " ") "")))))
 (add-to-list 'mu4e-view-fields :spam-status)
 b
+
+;; Resize image attachments when sending email
+(defvar mu4e-resize-image-types '("jpg" "png" "svg" "jpeg")
+  "List of attached image types to resize.")
+
+(defvar mu4e-inhibit-resize nil)
+
+(defun mu4e-resize-image-attachments ()
+  (unless mu4e-inhibit-resize
+    (let (cmds
+      (image-types
+       (mapconcat #'identity mu4e-resize-image-types "\\|")))
+      (save-excursion
+    (message-goto-body-1)
+    (while (re-search-forward 
+        (format "<#part.+\\(filename=\"\\)\\(.+\\(\\.%s\\)\\)\""
+            image-types)
+        nil t)
+      (let* ((infile (match-string-no-properties 2))
+         (outfile (concat (temporary-file-directory)
+                  (file-name-nondirectory infile))))
+        (push (format "convert %s -resize 1200x1200\\> %s"
+              (shell-quote-argument infile)
+              (shell-quote-argument outfile))
+          cmds)
+        (replace-match outfile t t nil 2)))
+    (mapcar #'shell-command cmds)))))
+
+(add-hook 'message-send-hook 'mu4e-resize-image-attachments)
+
+(defun mu4e-inhibit-resize()
+  (interactive)
+  (set (make-local-variable 'mu4e-inhibit-resize) t))
+
 ;; Load configuration for website
 ;(load "mustache-html")
 
-- 
2.39.5