Image manager: added ability to trigger load more via scroll

resources/js/components/image-manager.js

@@ -41,6 +41,7 @@ export class ImageManager extends Component {
     }
 
     setupListeners() {
+        // Filter tab click
         onSelect(this.filterTabs, e => {
             this.resetAll();
             this.filter = e.target.dataset.filter;
@@ -48,31 +49,32 @@ export class ImageManager extends Component {
             this.loadGallery();
         });
 
+        // Search submit
         this.searchForm.addEventListener('submit', event => {
             this.resetListView();
             this.loadGallery();
             event.preventDefault();
         });
 
+        // Cancel search button
         onSelect(this.cancelSearch, () => {
             this.resetListView();
             this.resetSearchView();
             this.loadGallery();
         });
 
-        onChildEvent(this.container, '.load-more button', 'click', async event => {
+        // Load more button click
-            const wrapper = event.target.closest('.load-more');
+        onChildEvent(this.container, '.load-more button', 'click', this.runLoadMore.bind(this));
-            showLoading(wrapper);
-            this.page += 1;
-            await this.loadGallery();
-        });
 
+        // Select image event
         this.listContainer.addEventListener('event-emit-select-image', this.onImageSelectEvent.bind(this));
 
+        // Image load error handling
         this.listContainer.addEventListener('error', event => {
             event.target.src = window.baseUrl('loading_error.png');
         }, true);
 
+        // Footer select button click
         onSelect(this.selectButton, () => {
             if (this.callback) {
                 this.callback(this.lastSelected);
@@ -80,17 +82,39 @@ export class ImageManager extends Component {
             this.hide();
         });
 
+        // Delete button click
         onChildEvent(this.formContainer, '#image-manager-delete', 'click', () => {
             if (this.lastSelected) {
                 this.loadImageEditForm(this.lastSelected.id, true);
             }
         });
 
+        // Edit form submit
         this.formContainer.addEventListener('ajax-form-success', () => {
             this.refreshGallery();
             this.resetEditForm();
         });
+
+        // Image upload success
         this.container.addEventListener('dropzone-upload-success', this.refreshGallery.bind(this));
+
+        // Auto load-more on scroll
+        const scrollZone = this.listContainer.parentElement;
+        let scrollEvents = [];
+        scrollZone.addEventListener('wheel', event => {
+            const scrollOffset = Math.ceil(scrollZone.scrollHeight - scrollZone.scrollTop);
+            const bottomedOut = scrollOffset === scrollZone.clientHeight;
+            if (!bottomedOut || event.deltaY < 1) {
+                return;
+            }
+
+            const secondAgo = Date.now() - 1000;
+            scrollEvents.push(Date.now());
+            scrollEvents = scrollEvents.filter(d => d >= secondAgo);
+            if (scrollEvents.length > 5 && this.canLoadMore()) {
+                this.runLoadMore();
+            }
+        });
     }
 
     show(callback, type = 'gallery') {
@@ -232,4 +256,14 @@ export class ImageManager extends Component {
         window.$components.init(this.formContainer);
     }
 
+    runLoadMore() {
+        showLoading(this.loadMore);
+        this.page += 1;
+        this.loadGallery();
+    }
+
+    canLoadMore() {
+        return this.loadMore.querySelector('button') && !this.loadMore.hasAttribute('hidden');
+    }
+
 }