include image caching

Author: borkdude

src/nextjournal/clerk.clj

@@ -596,7 +596,7 @@
   * a symbol representing the var name (qualified or not)
   * the form of an anonymous expression"
   ([]
-   (swap! webserver/!doc dissoc :blob->result)
+   (swap! webserver/!doc dissoc :blob->result ::webserver/presentation-cache)
    (if (fs/exists? config/cache-dir)
      (do (fs/delete-tree config/cache-dir)
          (prn :cache-dir/deleted config/cache-dir))

src/nextjournal/clerk/viewer.cljc

@@ -552,7 +552,8 @@
         {:as to-present :nextjournal/keys [auto-expand-results?]} (merge (dissoc (->opts wrapped-value) :!budget :nextjournal/budget)
                                                                          (dissoc cell :result ::doc) ;; TODO: reintroduce doc once we know why it OOMs the static build on CI (some walk issue probably)
                                                                          opts-from-block
-                                                                         (ensure-wrapped-with-viewers (or viewers (get-viewers (get-*ns*))) value))
+                                                                         (ensure-wrapped-with-viewers (or viewers (get-viewers (get-*ns*))) value)
+                                                                         (when blob-id {:nextjournal/blob-id blob-id}))
         presented-result (-> (present to-present)
                              (update :nextjournal/render-opts
                                      (fn [{:as opts existing-id :id}]
@@ -939,14 +940,14 @@
 
 (defn ->opts [wrapped-value]
   (select-keys wrapped-value [:nextjournal/budget :nextjournal/css-class :nextjournal/width :nextjournal/render-opts
-                              :nextjournal/render-evaluator
-                              :!budget :store!-wrapped-value :store!-viewer
+                              :nextjournal/render-evaluator :nextjournal/blob-id
+                              :!budget :store!-wrapped-value :store!-viewer :presentation-cache
                               :present-elision-fn :path :offset]))
 
 (defn inherit-opts [{:as wrapped-value :nextjournal/keys [viewers]} value path-segment]
   (-> (ensure-wrapped-with-viewers viewers value)
-      (merge (select-keys (->opts wrapped-value) [:!budget :store!-wrapped-value :store!-viewer
-                                                  :present-elision-fn :nextjournal/budget :path]))
+      (merge (select-keys (->opts wrapped-value) [:!budget :store!-wrapped-value :store!-viewer :presentation-cache
+                                                  :present-elision-fn :nextjournal/budget :path :nextjournal/blob-id]))
       (update :path (fnil conj []) path-segment)))
 
 (defn present-ex-data [parent throwable-map]
@@ -996,11 +997,21 @@
 (def image-viewer
   {#?@(:bb []
        :clj [:pred #(instance? BufferedImage %)
-             :transform-fn (fn [{image :nextjournal/value}]
-                             (-> {:nextjournal/value (buffered-image->bytes image)
-                                  :nextjournal/content-type "image/png"
-                                  :nextjournal/width (image-width image)}
-                                 mark-presented))])
+             :transform-fn (fn [{image :nextjournal/value
+                                 blob-id :nextjournal/blob-id
+                                 :keys [presentation-cache]
+                                 :as wrapped-value}]
+                             (let [cache-path [blob-id (:path wrapped-value)]
+                                   bytes (or (when presentation-cache
+                                               (get-in @presentation-cache cache-path))
+                                             (let [b (buffered-image->bytes image)]
+                                               (when (and presentation-cache blob-id)
+                                                 (swap! presentation-cache assoc-in cache-path b))
+                                               b))]
+                               (-> {:nextjournal/value bytes
+                                    :nextjournal/content-type "image/png"
+                                    :nextjournal/width (image-width image)}
+                                   mark-presented)))])
    :name `image-viewer
    :render-fn '(fn [blob-or-url] [:div.flex.flex-col.items-center.not-prose
                                   [:img {:src #?(:clj  (nextjournal.clerk.render/url-for blob-or-url)

src/nextjournal/clerk/webserver.clj

@@ -146,15 +146,17 @@
     (future-cancel scheduled-send-status-future)))
 
 (defn present+reset! [doc]
-  (let [presented (view/doc->viewer doc)
+  (let [!presentation-cache (or (::presentation-cache @!doc) (atom {}))
+        presented (view/doc->viewer {:presentation-cache !presentation-cache} doc)
         sync-vars-old (v/extract-sync-atom-vars @!doc)
         sync-vars (v/extract-sync-atom-vars doc)]
+    (swap! !presentation-cache select-keys (keys (:blob->result doc)))
     (doseq [sync-var (set/difference sync-vars sync-vars-old)]
       (add-watch @sync-var (symbol sync-var) sync-atom-changed))
     (doseq [sync-var (set/difference sync-vars-old sync-vars)]
       (remove-watch @sync-var (symbol sync-var)))
     (maybe-cancel-send-status-future @!doc)
-    (reset! !doc (with-meta doc presented))
+    (reset! !doc (with-meta (assoc doc ::presentation-cache !presentation-cache) presented))
     presented))
 
 (defn update-doc! [{:as doc :keys [nav-path fragment skip-history?]}]
@@ -327,7 +329,7 @@
                    nil)))
           {:status 200
            :headers {"Content-Type" "text/html" "Cache-Control" "no-store"}
-           :body (view/->html {:doc (view/doc->viewer @!doc)
+           :body (view/->html {:doc (view/doc->viewer {:presentation-cache (::presentation-cache @!doc)} @!doc)
                                :resource->url @config/!resource->url
                                :render-router :serve
                                :conn-ws? true})})