Merge pull request #3188 from crazyserver/MOBILE-3814

Mobile 3814

src/addons/storagemanager/pages/course-storage/course-storage.scss

@@ -26,7 +26,6 @@
             min-height: var(--course-storage-max-activity-height);
             position: absolute;
             @include position(0, 0, null, 0);
-            background: -webkit-linear-gradient(top, rgba(var(--background-gradient-rgb), 0) calc(100% - 30px), rgba(var(--background-gradient-rgb), 1) calc(100% - 20px));
             background: linear-gradient(to bottom, rgba(var(--background-gradient-rgb), 0) calc(100% - 30px), rgba(var(--background-gradient-rgb), 1) calc(100% - 20px));
             z-index: 6;
             pointer-events: none;

src/core/directives/format-text.ts

@@ -90,8 +90,8 @@ export class CoreFormatTextDirective implements OnChanges, OnDestroy, AsyncCompo
 
     protected element: HTMLElement;
     protected emptyText = '';
-    protected contentSpan: HTMLElement;
-    protected domPromise?: CoreCancellablePromise<void>;
+    protected domPromises: CoreCancellablePromise<void>[] = [];
+    protected domElementPromise?: CoreCancellablePromise<void>;
 
     constructor(
         element: ElementRef,
@@ -101,18 +101,10 @@ export class CoreFormatTextDirective implements OnChanges, OnDestroy, AsyncCompo
         CoreComponentsRegistry.register(element.nativeElement, this);
 
         this.element = element.nativeElement;
-        this.element.classList.add('core-format-text-loading'); // Hide contents until they're treated.
-
-        const placeholder = document.createElement('span');
-        placeholder.classList.add('core-format-text-loader');
-        this.element.appendChild(placeholder);
-
-        this.contentSpan = document.createElement('span');
-        this.contentSpan.classList.add('core-format-text-content');
-        this.element.appendChild(this.contentSpan);
+        this.element.classList.add('core-loading'); // Hide contents until they're treated.
 
         this.emptyText = this.hideIfEmpty ? '' : '&nbsp;';
-        this.contentSpan.innerHTML = this.emptyText;
+        this.element.innerHTML = this.emptyText;
 
         this.afterRender = new EventEmitter<void>();
 
@@ -134,14 +126,15 @@ export class CoreFormatTextDirective implements OnChanges, OnDestroy, AsyncCompo
      * @inheritdoc
      */
     ngOnDestroy(): void {
-        this.domPromise?.cancel();
+        this.domElementPromise?.cancel();
+        this.domPromises.forEach((promise) => { promise.cancel();});
     }
 
     /**
      * @inheritdoc
      */
     async ready(): Promise<void> {
-        if (!this.element.classList.contains('core-format-text-loading')) {
+        if (!this.element.classList.contains('core-loading')) {
             return;
         }
 
@@ -229,7 +222,7 @@ export class CoreFormatTextDirective implements OnChanges, OnDestroy, AsyncCompo
      * Add magnifying glass icons to view adapted images at full size.
      */
     async addMagnifyingGlasses(): Promise<void> {
-        const imgs = Array.from(this.contentSpan.querySelectorAll('.core-adapted-img-container > img'));
+        const imgs = Array.from(this.element.querySelectorAll('.core-adapted-img-container > img'));
         if (!imgs.length) {
             return;
         }
@@ -311,7 +304,7 @@ export class CoreFormatTextDirective implements OnChanges, OnDestroy, AsyncCompo
      */
     protected async finishRender(): Promise<void> {
         // Show the element again.
-        this.element.classList.remove('core-format-text-loading');
+        this.element.classList.remove('core-loading');
 
         await CoreUtils.nextTick();
 
@@ -324,7 +317,7 @@ export class CoreFormatTextDirective implements OnChanges, OnDestroy, AsyncCompo
      */
     protected async formatAndRenderContents(): Promise<void> {
         if (!this.text) {
-            this.contentSpan.innerHTML = this.emptyText; // Remove current contents.
+            this.element.innerHTML = this.emptyText; // Remove current contents.
 
             await this.finishRender();
 
@@ -342,10 +335,10 @@ export class CoreFormatTextDirective implements OnChanges, OnDestroy, AsyncCompo
         // Disable media adapt to correctly calculate the height.
         this.element.classList.add('core-disable-media-adapt');
 
-        this.contentSpan.innerHTML = ''; // Remove current contents.
+        this.element.innerHTML = ''; // Remove current contents.
 
         // Move the children to the current element to be able to calculate the height.
-        CoreDomUtils.moveChildren(result.div, this.contentSpan);
+        CoreDomUtils.moveChildren(result.div, this.element);
 
         await CoreUtils.nextTick();
 
@@ -362,7 +355,7 @@ export class CoreFormatTextDirective implements OnChanges, OnDestroy, AsyncCompo
         if (result.options.filter) {
             // Let filters handle HTML. We do it here because we don't want them to block the render of the text.
             CoreFilterDelegate.handleHtml(
-                this.contentSpan,
+                this.element,
                 result.filters,
                 this.viewContainerRef,
                 result.options,
@@ -557,9 +550,10 @@ export class CoreFormatTextDirective implements OnChanges, OnDestroy, AsyncCompo
      * @return The width of the element in pixels.
      */
     protected async getElementWidth(): Promise<number> {
-        this.domPromise = CoreDomUtils.waitToBeInDOM(this.element);
-
-        await this.domPromise;
+        if (!this.domElementPromise) {
+            this.domElementPromise = CoreDomUtils.waitToBeInDOM(this.element);
+        }
+        await this.domElementPromise;
 
         let width = this.element.getBoundingClientRect().width;
         if (!width) {
@@ -709,12 +703,15 @@ export class CoreFormatTextDirective implements OnChanges, OnDestroy, AsyncCompo
                     newUrl += `&h=${privacyHash}`;
                 }
 
+                const domPromise = CoreDomUtils.waitToBeInDOM(iframe);
+                this.domPromises.push(domPromise);
+
+                await domPromise;
+
                 // Width and height are mandatory, we need to calculate them.
                 let width: string | number;
                 let height: string | number;
 
-                await CoreDomUtils.waitToBeInDOM(iframe, 5000);
-
                 if (iframe.width) {
                     width = iframe.width;
                 } else {

src/core/directives/on-appear.ts

@@ -37,7 +37,7 @@ export class CoreOnAppearDirective implements OnInit, OnDestroy {
      * @inheritdoc
      */
     async ngOnInit(): Promise<void> {
-        this.visiblePromise = CoreDomUtils.waitToBeVisible(this.element);
+        this.visiblePromise = CoreDomUtils.waitToBeInViewport(this.element);
 
         await this.visiblePromise;
 

src/core/directives/tests/format-text.test.ts

@@ -58,7 +58,7 @@ describe('CoreFormatTextDirective', () => {
         );
 
         // Assert
-        const text = fixture.nativeElement.querySelector('core-format-text .core-format-text-content');
+        const text = fixture.nativeElement.querySelector('core-format-text');
         expect(text).not.toBeNull();
         expect(text.innerHTML).toEqual(sentence);
     });

src/core/features/course/pages/index/index.html

@@ -29,7 +29,9 @@
         </ng-container>
 
         <ion-label>
-            <h1>{{ title }}</h1>
+            <h1>
+                <core-format-text [text]="title" contextLevel="course" [contextInstanceId]="course?.id"></core-format-text>
+            </h1>
             <div class="core-course-progress" *ngIf="progress !== undefined">
                 <core-progress-bar [progress]="progress" a11yText="core.course.aria:sectionprogress">
                 </core-progress-bar>

src/core/features/editor/components/rich-text-editor/core-editor-rich-text-editor.html

@@ -110,7 +110,7 @@
             </button>
         </ion-slide>
         <ion-slide *ngIf="isPhone">
-            <button [title]="'core.editor.hidetoolbar' | translate" (click)="hideToolbar($event)" (keyup)="hideToolbar($event)"
+            <button [title]="'core.editor.hidetoolbar' | translate" (click)="hideToolbar($event, true)" (keyup)="hideToolbar($event, true)"
                 (mousedown)="downAction($event)" (keydown)="downAction($event)">
                 <ion-icon name="fas-times" aria-hidden="true"></ion-icon>
             </button>

src/core/features/editor/components/rich-text-editor/rich-text-editor.ts

@@ -107,6 +107,7 @@ export class CoreEditorRichTextEditorComponent implements OnInit, AfterContentIn
     protected languageChangedSubscription?: Subscription;
     protected resizeListener?: CoreEventObserver;
     protected domPromise?: CoreCancellablePromise<void>;
+    protected buttonsDomPromise?: CoreCancellablePromise<void>;
 
     rteEnabled = false;
     isPhone = false;
@@ -176,8 +177,6 @@ export class CoreEditorRichTextEditorComponent implements OnInit, AfterContentIn
         this.editorElement.oninput = this.onChange.bind(this);
         this.editorElement.onkeydown = this.moveCursor.bind(this);
 
-        await CoreDomUtils.waitToBeVisible(this.editorElement);
-
         // Use paragraph on enter.
         document.execCommand('DefaultParagraphSeparator', false, 'p');
 
@@ -339,7 +338,7 @@ export class CoreEditorRichTextEditorComponent implements OnInit, AfterContentIn
                 return;
             }
 
-            if (this.isNullOrWhiteSpace(this.editorElement.innerText)) {
+            if (this.isNullOrWhiteSpace(this.editorElement.textContent)) {
                 this.clearText();
             } else {
                 // The textarea and the form control must receive the original URLs.
@@ -718,8 +717,17 @@ export class CoreEditorRichTextEditorComponent implements OnInit, AfterContentIn
 
     /**
      * Hide the toolbar in phone mode.
+     *
+     * @param event Event.
+     * @param force If true it will not check the target of the event.
      */
-    hideToolbar(event: Event): void {
+    hideToolbar(event: Event, force = false): void {
+        if (!force && event.target && this.element.contains(event.target as HTMLElement)) {
+            // Do not hide if clicked inside the editor area, except forced.
+
+            return;
+        }
+
         if (event.type == 'keyup' && !this.isValidKeyboardKey(<KeyboardEvent>event)) {
             return;
         }
@@ -836,7 +844,10 @@ export class CoreEditorRichTextEditorComponent implements OnInit, AfterContentIn
 
         const length = await this.toolbarSlides.length();
 
-        await CoreDomUtils.waitToBeInDOM(this.toolbar.nativeElement, 5000);
+        // Cancel previous one, if any.
+        this.buttonsDomPromise?.cancel();
+        this.buttonsDomPromise = CoreDomUtils.waitToBeInDOM(this.toolbar.nativeElement);
+        await this.buttonsDomPromise;
 
         const width = this.toolbar.nativeElement.getBoundingClientRect().width;
 
@@ -1097,6 +1108,7 @@ export class CoreEditorRichTextEditorComponent implements OnInit, AfterContentIn
         this.labelObserver?.disconnect();
         this.resizeListener?.off();
         this.domPromise?.cancel();
+        this.buttonsDomPromise?.cancel();
     }
 
 }

src/core/services/utils/dom.ts

@@ -97,10 +97,9 @@ export class CoreDomUtilsProvider {
      * Wait an element to be in dom of another element.
      *
      * @param element Element to wait.
-     * @param timeout If defined, timeout to wait before rejecting the promise.
      * @return Cancellable promise.
      */
-    waitToBeInDOM(element: HTMLElement, timeout?: number): CoreCancellablePromise<void> {
+    waitToBeInDOM(element: HTMLElement): CoreCancellablePromise<void> {
         const root = element.getRootNode({ composed: true });
 
         if (root === document) {
@@ -109,33 +108,24 @@ export class CoreDomUtilsProvider {
         }
 
         let observer: MutationObserver;
-        let observerTimeout: number | undefined;
 
         return new CoreCancellablePromise<void>(
-            (resolve, reject) => {
+            (resolve) => {
                 observer = new MutationObserver(() => {
                     const root = element.getRootNode({ composed: true });
 
-                    if (root === document) {
-                        observer?.disconnect();
-                        observerTimeout && clearTimeout(observerTimeout);
-                        resolve();
+                    if (root !== document) {
+                        return;
                     }
+
+                    observer?.disconnect();
+                    resolve();
                 });
 
-                if (timeout) {
-                    observerTimeout = window.setTimeout(() => {
-                        observer?.disconnect();
-
-                        reject(new Error('Waiting for DOM timeout reached'));
-                    }, timeout);
-                }
-
                 observer.observe(document.body, { subtree: true, childList: true });
             },
             () => {
                 observer?.disconnect();
-                observerTimeout && clearTimeout(observerTimeout);
             },
         );
     }
@@ -151,6 +141,7 @@ export class CoreDomUtilsProvider {
 
         let interval: number | undefined;
 
+        // Mutations did not observe for visibility properties.
         return new CoreCancellablePromise<void>(
             async (resolve) => {
                 await domPromise;
@@ -175,6 +166,60 @@ export class CoreDomUtilsProvider {
         );
     }
 
+    /**
+     * Wait an element to be in dom and visible.
+     *
+     * @param element Element to wait.
+     * @param intersectionRatio Intersection ratio (From 0 to 1).
+     * @return Cancellable promise.
+     */
+    waitToBeInViewport(element: HTMLElement, intersectionRatio = 1): CoreCancellablePromise<void> {
+        const visiblePromise = CoreDomUtils.waitToBeVisible(element);
+
+        let intersectionObserver: IntersectionObserver;
+        let interval: number | undefined;
+
+        return new CoreCancellablePromise<void>(
+            async (resolve) => {
+                await visiblePromise;
+
+                if (CoreDomUtils.isElementInViewport(element, intersectionRatio)) {
+
+                    return resolve();
+                }
+
+                if ('IntersectionObserver' in window) {
+                    intersectionObserver = new IntersectionObserver((observerEntries) => {
+                        const isIntersecting = observerEntries
+                            .some((entry) => entry.isIntersecting && entry.intersectionRatio >= intersectionRatio);
+                        if (!isIntersecting) {
+                            return;
+                        }
+
+                        resolve();
+                        intersectionObserver?.disconnect();
+                    });
+
+                    intersectionObserver.observe(element);
+                } else {
+                    interval = window.setInterval(() => {
+                        if (!CoreDomUtils.isElementInViewport(element, intersectionRatio)) {
+                            return;
+                        }
+
+                        resolve();
+                        window.clearInterval(interval);
+                    }, 50);
+                }
+            },
+            () => {
+                visiblePromise.cancel();
+                intersectionObserver?.disconnect();
+                window.clearInterval(interval);
+            },
+        );
+    }
+
     /**
      * Window resize is widely checked and may have many performance issues, debouce usage is needed to avoid calling it too much.
      * This function helps setting up the debounce feature and remove listener easily.
@@ -880,10 +925,21 @@ export class CoreDomUtilsProvider {
         return elementPoint > window.innerHeight || elementPoint < scrollTopPos;
     }
 
+    /**
+     * Check whether an element has been added to the DOM.
+     *
+     * @param element Element.
+     * @return True if element has been added to the DOM, false otherwise.
+     */
+    isElementInDom(element: HTMLElement): boolean {
+        return element.getRootNode({ composed: true }) === document;
+    }
+
     /**
      * Check whether an element is visible or not.
      *
      * @param element Element.
+     * @return True if element is visible inside the DOM.
      */
     isElementVisible(element: HTMLElement): boolean {
         if (element.clientWidth === 0 || element.clientHeight === 0) {
@@ -895,7 +951,35 @@ export class CoreDomUtilsProvider {
             return false;
         }
 
-        return element.offsetParent !== null;
+        return CoreDomUtils.isElementInDom(element);
+    }
+
+    /**
+     * Check whether an element is intersecting the intersectionRatio in viewport.
+     *
+     * @param element
+     * @param intersectionRatio Intersection ratio (From 0 to 1).
+     * @return True if in viewport.
+     */
+    isElementInViewport(element: HTMLElement, intersectionRatio = 1): boolean {
+        const elementRectangle = element.getBoundingClientRect();
+
+        const elementArea = elementRectangle.width * elementRectangle.height;
+        if (elementArea == 0) {
+            return false;
+        }
+
+        const intersectionRectangle = {
+            top: Math.max(0, elementRectangle.top),
+            left: Math.max(0, elementRectangle.left),
+            bottom: Math.min(window.innerHeight, elementRectangle.bottom),
+            right: Math.min(window.innerWidth, elementRectangle.right),
+        };
+
+        const intersectionArea = (intersectionRectangle.right - intersectionRectangle.left) *
+            (intersectionRectangle.bottom - intersectionRectangle.top);
+
+        return intersectionArea / elementArea >= intersectionRatio;
     }
 
     /**

src/core/services/utils/iframe.ts

@@ -51,7 +51,7 @@ export class CoreIframeUtilsProvider {
     protected waitAutoLoginDefer?: PromiseDefer<void>;
 
     constructor() {
-        this.logger = CoreLogger.getInstance('CoreUtilsProvider');
+        this.logger = CoreLogger.getInstance('CoreIframeUtilsProvider');
     }
 
     /**
@@ -237,7 +237,7 @@ export class CoreIframeUtilsProvider {
             contentDocument = 'contentDocument' in element && element.contentDocument
                 ? element.contentDocument
                 : contentWindow && contentWindow.document;
-        } catch (ex) {
+        } catch {
             // Ignore errors.
         }
 
@@ -250,7 +250,7 @@ export class CoreIframeUtilsProvider {
             // It's probably an <embed>. Try to get the window and the document.
             try {
                 contentDocument = element.getSVGDocument();
-            } catch (ex) {
+            } catch {
                 // Ignore errors.
             }
 
@@ -310,10 +310,10 @@ export class CoreIframeUtilsProvider {
             };
         }
 
-        if (contentDocument) {
+        if (contentDocument.body) {
             // Search sub frames.
             CoreIframeUtilsProvider.FRAME_TAGS.forEach((tag) => {
-                const elements = Array.from(contentDocument.querySelectorAll(tag));
+                const elements = Array.from(contentDocument.body.querySelectorAll(tag));
                 elements.forEach((subElement: CoreFrameElement) => {
                     this.treatFrame(subElement, true);
                 });
@@ -333,6 +333,8 @@ export class CoreIframeUtilsProvider {
             return;
         }
 
+        element.classList.add('core-loading');
+
         const treatElement = (sendResizeEvent: boolean = false) => {
             this.checkOnlineFrameInOffline(element, isSubframe);
 
@@ -348,9 +350,12 @@ export class CoreIframeUtilsProvider {
                 this.treatFrameLinks(element, document);
             }
 
+            // Iframe content has been loaded.
             // Send a resize events to the iframe so it calculates the right size if needed.
             if (window && sendResizeEvent) {
-                setTimeout(() => window.dispatchEvent(new Event('resize')), 1000);
+                element.classList.remove('core-loading');
+
+                setTimeout(() => window.dispatchEvent && window.dispatchEvent(new Event('resize')), 1000);
             }
         };
 

src/theme/components/collapsible-item.scss

@@ -75,7 +75,6 @@
                     height: 60px;
                     position: absolute;
                     @include position(null, 0, 0, 0);
-                    background: -webkit-linear-gradient(top, rgba(var(--background-gradient-rgb), 0) calc(100% - var(--gradient-size)), rgba(var(--background-gradient-rgb), 1) calc(100% - 4px));
                     background: linear-gradient(to bottom, rgba(var(--background-gradient-rgb), 0) calc(100% - var(--gradient-size)), rgba(var(--background-gradient-rgb), 1) calc(100% - 4px));
                     z-index: 6;
                 }

src/theme/components/format-text.scss

@@ -5,77 +5,38 @@
 core-format-text {
     --core-format-text-background: var(--background, var(--ion-item-background));
     --core-format-text-viewer-icon-background: rgba(255, 255, 255, .5);
-    --core-format-text-loader-shine: 251,251,251;
 }
 
 body.dark core-format-text {
     --core-format-text-viewer-icon-background: rgba(0, 0, 0, .5);
-    --core-format-text-loader-shine: 90,90,90;
 }
 
 core-format-text {
     display: contents;
+    user-select: text;
+    word-break: break-word;
+    word-wrap: break-word;
 
-    .core-format-text-loader {
-        opacity: 0;
-        @include core-transition(opacity, 200ms);
-        display: contents;
-    }
-
-    &.core-format-text-loading {
-        position: relative;
+    @include core-transition(background-color color, 200ms);
+    &.core-loading {
         width: 100%;
-        height: 100%;
-        opacity: 1;
-        background-color: rgba(0,0,0,.1);
-        overflow: hidden;
-        display: block;
-        border-radius: var(--small-radius);
-
-        .core-format-text-loader {
-            position: absolute;
-            left: -45%;
-            height: 100%;
-            width: 45%;
-            background-image: -webkit-linear-gradient(to left, rgba(var(--core-format-text-loader-shine), .05), rgba(var(--core-format-text-loader-shine), .3), rgba(var(--core-format-text-loader-shine), .6), rgba(var(--core-format-text-loader-shine), .3), rgba(var(--core-format-text-loader-shine), .05));
-            background-image: linear-gradient(to left, rgba(var(--core-format-text-loader-shine), .05), rgba(var(--core-format-text-loader-shine), .3), rgba(var(--core-format-text-loader-shine), .6), rgba(var(--core-format-text-loader-shine), .3), rgba(var(--core-format-text-loader-shine), .05));
-            animation: loading 1s infinite;
-            opacity: 1;
-            display: inline;
-        }
-
-        .core-format-text-content {
+        &:empty:before {
+            content: 'E'; // Set a minimum empty text to have a minimum height of one line.
             opacity: 0;
-            display: inline;
         }
     }
 
-    .core-format-text-content {
-        opacity: 1;
-        @include core-transition(opacity, 200ms);
-
-        display: contents;
-        user-select: text;
-        word-break: break-word;
-        word-wrap: break-word;
-    }
-
     &.collapsible-item {
         display: block;
         // This is to allow clicks in radio/checkbox content.
         cursor: pointer;
         pointer-events: auto;
 
-        .core-format-text-content {
-            display: block;
-        }
-
         &.collapsible-enabled {
-            .core-format-text-content {
-                display: block;
-                max-height: none;
-            }
-            &.collapsible-collapsed .core-format-text-content {
+            display: block;
+            max-height: none;
+
+            &.collapsible-collapsed {
                 overflow: hidden;
             }
         }
@@ -97,7 +58,7 @@ core-format-text {
     }
     &.collapsible-item.inline {
         display: inline-block;
-        &.collapsible-enabled .core-format-text-content {
+        &.collapsible-enabled {
            display: inline-block;
         }
     }
@@ -141,7 +102,7 @@ core-format-text {
     }
 
     // Disable clicks in links inside MathJax equations.
-    .core-format-text-content .filter_mathjaxloader_equation .MathJax_Preview a {
+    .filter_mathjaxloader_equation .MathJax_Preview a {
         pointer-events: none;
     }
 
@@ -243,7 +204,7 @@ core-format-text {
 
 }
 
-core-format-text .core-format-text-content,
+core-format-text,
 core-rich-text-editor .core-rte-editor {
     @include core-headings();
 
@@ -657,14 +618,10 @@ core-rich-text-editor .core-rte-editor {
 
 // h1 is too big and ugly, reduce size when loading.
 ion-header.ios h1 core-format-text {
-    &.core-format-text-loading {
+    &.core-loading {
         max-height: 30px;
         margin-top: 10px;
     }
-    &.core-format-text-content {
-        display: block;
-        margin-top: -10px;
-    }
 }
 
 body.dark core-format-text select,

src/theme/theme.base.scss

@@ -120,15 +120,15 @@ body {
 }
 
 // Correctly inherit ion-text-wrap onto labels.
-.item ion-label core-format-text .core-format-text-content > *,
-.fake-ion-item core-format-text .core-format-text-content > * {
+.item ion-label core-format-text > *,
+.fake-ion-item core-format-text > * {
     white-space: nowrap;
     overflow: hidden;
     text-overflow: ellipsis;
 }
 
-.item.ion-text-wrap > ion-label core-format-text .core-format-text-content > *,
-.fake-ion-item.ion-text-wrap core-format-text .core-format-text-content > * {
+.item.ion-text-wrap > ion-label core-format-text > *,
+.fake-ion-item.ion-text-wrap core-format-text > * {
     white-space: normal;
     overflow: inherit;
 }
@@ -334,7 +334,7 @@ ion-button.button-solid {
     --box-shadow: none;
 }
 
-ion-button core-format-text .core-format-text-content {
+ion-button core-format-text {
     white-space: nowrap;
     overflow: hidden;
     text-overflow: ellipsis;
@@ -350,7 +350,7 @@ ion-button > * {
 
 ion-button.ion-text-wrap {
     white-space: normal;
-    core-format-text .core-format-text-content {
+    core-format-text {
         white-space: normal;
         display: contents;
     }
@@ -1516,3 +1516,36 @@ ion-header.no-title {
         flex-grow: 1;
     }
 }
+
+
+// Loader animation.
+.core-loading {
+    position: relative;
+    background-color: var(--loader-background-color);
+    color: transparent; // Hide contents.
+    overflow: hidden;
+    display: var(--loader-display);
+    border-radius: var(--loader-radius);
+    @include core-transition(all, 200ms);
+    min-height: 8px;
+    min-width: 50px;
+
+    // Hide contents.
+    > * {
+        opacity: 0;
+        @include core-transition(opacity, 200ms);
+    }
+
+    &::after {
+        content: '';
+        position: absolute;
+        left: -45%;
+        height: 100%;
+        width: 45%;
+        background-image: linear-gradient(to left, rgba(var(--loader-shine), .05), rgba(var(--loader-shine), .3), rgba(var(--loader-shine), .6), rgba(var(--loader-shine), .3), rgba(var(--loader-shine), .05));
+        animation: loading 1s infinite;
+        display: block;
+        top: 0;
+        bottom: 0;
+    }
+}

src/theme/theme.dark.scss

@@ -41,6 +41,8 @@
 
     --contrast-background: var(--gray-900);
 
+    --loader-shine: 90, 90, 90;
+
     --drop-shadow-color: 0, 0, 0, 1;
     --drop-shadow-top: 0px 2px 5px rgba(var(--drop-shadow-color));
     --drop-shadow-bottom: 0px -2px 5px rgba(var(--drop-shadow-color));

src/theme/theme.light.scss

@@ -85,6 +85,11 @@
 
     --contrast-background: white;
 
+    --loader-background-color: rgba(0, 0, 0, .1);
+    --loader-shine: 251, 251, 251;
+    --loader-radius: var(--small-radius);
+    --loader-display: block;
+
     --drop-shadow-color: 0, 0, 0, 0.5;
     --drop-shadow-top: 0px 2px 5px rgba(var(--drop-shadow-color));
     --drop-shadow-bottom: 0px -2px 5px rgba(var(--drop-shadow-color));