Slice images in rss entries for easier scrolling

Can be disabled with +rss-enable-sliced-images.

modules/app/rss/config.el

@@ -11,6 +11,10 @@ absolute paths.")
 (defvar +rss-split-direction 'below
   "What direction to pop up the entry buffer in elfeed.")
 
+(defvar +rss-enable-sliced-images t
+  "Automatically slice images shown in elfeed-show-mode buffers, making them
+easier to scroll through.")
+
 
 ;;
 ;; Packages
@@ -42,6 +46,25 @@ absolute paths.")
   (add-hook! 'elfeed-search-mode-hook
     (add-hook 'kill-buffer-hook #'+rss/quit nil t))
 
+  ;; Large images are annoying to scroll through, because scrolling follows the
+  ;; cursor, so we force shr to insert images in slices.
+  (when +rss-enable-sliced-images
+    (defun +rss-put-image (spec alt &optional flags)
+      (cl-letf (((symbol-function #'insert-image)
+                 (lambda (image &optional alt _area _slice)
+                   (let ((height (cdr (image-size image t))))
+                     (insert-sliced-image image alt nil (max 1 (/ height 20.0)) 1)))))
+        (shr-put-image spec alt flags)))
+    (defun +rss-render-image-tag (dom &optional url)
+      (let ((start (point)))
+        (shr-tag-img dom url)
+        ;; And remove underlines in case images are links, otherwise we get an
+        ;; underline beneath every slice.
+        (put-text-property start (point) 'face '(:underline nil))))
+    (setq-hook! 'elfeed-show-mode-hook
+      shr-put-image-function #'+rss-put-image
+      shr-external-rendering-functions '((img . +rss-render-image-tag))))
+
   ;; Keybindings
   (after! elfeed-show
     (define-key! elfeed-show-mode-map