Add snapshot button

src/heyarne/all_my_friends/core.cljs

@@ -21,4 +21,4 @@
   (dom/render [views/app {:on-faces-detected draw-results}]
               (.querySelector js/document "#app")))
 
-(defonce initialize (init))
+(defonce app (init))

src/heyarne/all_my_friends/facemesh.cljs

@@ -34,14 +34,20 @@
                             (resolve result)))))))
 
 ;; this function will be repeatedly called on the video stream to detect faces
+(def request-id (atom nil))
+
 (defn detect-faces [model video on-faces-detected]
   (-> (.estimateFaces model video)
       (.then (fn [predictions]
                (on-faces-detected video predictions))))
-  (js/requestAnimationFrame #(detect-faces model video on-faces-detected)))
+  (reset! request-id (js/requestAnimationFrame #(detect-faces model video on-faces-detected))))
 
 (defn webcam-facemesh [{:keys [on-webcam-rejected
-                               on-faces-detected]}]
+                               on-faces-detected
+                               halt?]}]
+  (let [state (atom {:video nil
+                     :model nil
+                     :ctx nil})]
     (r/create-class
      {:display-name "webcam-facemesh"
 
@@ -51,6 +57,21 @@
          [:canvas#result]
          [:video#capture]])
 
+      :component-did-update
+      (fn [this]
+        ;; this function makes sure to pause the video stream and face prediction
+        ;; when the :halt? property is given
+        (let [{:keys [video model ctx]} @state]
+          (if (:halt? (r/props this))
+            (do
+              (println "Pausing video capture")
+              (.pause video)
+              (js/cancelAnimationFrame @request-id))
+            (do
+              (println "Resuming video capture")
+              (.play video)
+              (detect-faces model video (partial (:on-faces-detected (r/props this)) ctx))))))
+
       :component-did-mount
       (fn [this]
         ;; this function does the following
@@ -75,4 +96,14 @@
                                (set! (.-height canvas) (.-videoHeight video))
                                ;; detect-faces will continously be called via requestAnimationFrame
                                ;; on-faces-detected receives the canvas context as first param and detected predictions as second
-                             (detect-faces model video (partial (:on-faces-detected (r/props this)) ctx)))))))))}))
+                               (detect-faces model video (partial (:on-faces-detected (r/props this)) ctx))))
+                       ;; make the initialized variables available for
+                       ;; component-did-update
+                       (swap! state assoc
+                              :video video
+                              :model model
+                              :ctx ctx))))))
+
+      :component-will-unmount
+      (fn [this]
+        (js/cancelAnimationFrame @request-id))})))

src/heyarne/all_my_friends/views.cljs

@@ -10,9 +10,8 @@
 (def events
   {:welcome/continue (fn [db _]
                        (assoc db :status :running))
-   :running/capture (fn [db _]
-                      (assoc db :current-capture {:img nil
-                                                  :predictions nil}))})
+   :running/snapshot (fn [db result]
+                       (assoc-in db [:snapshots :current] result))})
 
 (defn dispatch [[event data]]
   (when-let [handler (events event)]
@@ -30,26 +29,39 @@ Seit der globalen Covid19-Pandemie sind wir alle dazu gezwungen, auf physischen
    [:p "Ich würde mich freuen, wenn du mir dabei hilfst. Folge dazu einfach den Anweisungen. Das Ergebnis wird hoffentlich eine schöne Sammlung von Webcambildern und 3D-Modellen eurer Köpfe" [:sup "1"] "."]
    [:button {:on-click #(dispatch [:welcome/continue])} "Weiter"]])
 
-(defn running [{on-faces-detected :on-faces-detected}]
+(defn video-snapshot [video-elem]
+  (let [canvas (js/document.createElement "canvas")
+        ctx (.getContext canvas "2d")]
+    (set! (.-width canvas) (.-videoWidth video-elem))
+    (set! (.-height canvas) (.-videoHeight video-elem))
+    (.drawImage ctx video-elem 0 0 (.-width canvas) (.-height canvas))
+    (.getImageData ctx 0 0 (.-width canvas) (.-height canvas))))
+
+
+(defn running [{:keys [on-faces-detected halt?]}]
   (let [result (atom {:video nil
                       :predictions nil})]
-    (fn []
+    (fn [{:keys [on-faces-detected halt?]}]
       [:div.container
        [:p "Tippe auf den Button um mir das untere Bild zu schicken."]
        [webcam-facemesh {:on-faces-detected (fn [ctx video predictions]
                                               (swap! result assoc
                                                      :video video
                                                      :predictions predictions)
-                                              (on-faces-detected ctx video predictions))}]
-       [:button {:on-click #(dispatch [:running/capture @result])} "Tip"]])))
+                                              (on-faces-detected ctx video predictions))
+                         :halt? halt?}]
+       [:button {:on-click #(dispatch [:running/snapshot (update @result :video video-snapshot)])} "Cheese"]])))
 
 (defn app [{:keys [on-faces-detected]}]
-  (let [status (:status @state)]
+  (let [state @state
+        status (:status state)
+        halt? (some? (get-in state [:snapshots :current]))]
     [:<>
      [welcome-message {:hidden? (not= :welcome-message status)}]
      (case status
        :permission-rejected [:div "Sad :("]
-       :running [running {:on-faces-detected on-faces-detected}]
+       :running [running {:on-faces-detected on-faces-detected
+                          :halt? halt?}]
 
        ;; default
        nil)]))