feat: add image preloading

Author: nicoalee

src/app/pages/tasks/task-playables/face-name-association/face-name-association.component.ts

@@ -150,9 +150,19 @@ export class FaceNameAssociationComponent extends AbstractBaseTaskComponent {
             // store in cache for next block
             this.config.setCacheValue(FaceNameAssociationCache.STIMULI, this.stimuli);
         }
+
+        this.stimuli.forEach((stimulus) => {
+            this.preload(stimulus.imagePath);
+        });
+
         super.start();
     }
 
+    private preload(url: string) {
+        const img = new Image();
+        img.src = url;
+    }
+
     private getActualAnswer(stimulus: FaceNameAssociationStimulus): UserResponse {
         if (this.phase === 'learning-phase') {
             return UserResponse.NA;