Merge pull request #152 from dermotduffy/swipe2

Re-implement the media viewer as a swipe carousel

README.md

@@ -83,7 +83,7 @@ lovelace:
 | `frigate_url` | | The URL of the frigate server. If set, this value will be (exclusively) used for a `Frigate UI` menu button. |
 | `autoplay_clip` | `false` | Whether or not to autoplay clips in the 'clip' [view](#views). Clips manually chosen in the clips gallery will still autoplay.|
 | `live_preload` | `false` | Whether or not to preload the live view. Preloading causes the live view to render in the background so it's instantly available when requested. This consumes additional network/CPU resources continually.|
-
+| `event_viewer.lazy_load` | `true` | Whether or not to lazily load media in the event viewer carousel. Setting this will false will fetch all media immediately which may make the carousel experience smoother at a cost of (potentially) a substantial number of simultaneous media fetches on load. |
 
 #### Live Provider
 

package.json

@@ -19,8 +19,10 @@
     "@material/image-list": "^12.0.0",
     "custom-card-helpers": "^1.8.0",
     "dayjs": "^1.10.7",
+    "embla-carousel": "^5.0.1",
     "home-assistant-js-websocket": "^5.11.1",
     "lit": "^2.0.2",
+    "quick-lru": "github:sindresorhus/quick-lru",
     "screenfull": "^5.1.0",
     "zod": "^3.10.0"
   },

src/card.ts

@@ -51,6 +51,7 @@ import './patches/ha-camera-stream.js';
 import './patches/ha-hls-player.js';
 
 import cardStyle from './scss/card.scss';
+import { ResolvedMediaCache } from './resolved-media.js';
 
 const MEDIA_HEIGHT_CUTOFF = 50;
 const MEDIA_WIDTH_CUTOFF = MEDIA_HEIGHT_CUTOFF;
@@ -133,6 +134,9 @@ export class FrigateCard extends LitElement {
   // Error/info message to render.
   protected _message: Message | null = null;
 
+  // A cache of resolved media URLs/mimetypes for use in the whole card.
+  protected _resolvedMediaCache = new ResolvedMediaCache();
+
   set hass(hass: HomeAssistant & ExtendedHomeAssistant) {
     this._hass = hass;
 
@@ -485,13 +489,19 @@ export class FrigateCard extends LitElement {
     `;
   }
 
-  protected _getBrowseMediaQueryParameters(): BrowseMediaQueryParameters | null {
+  /**
-    if (!this._frigateCameraName) {
+   * Get the parameters to search for media related to the current view.
-      return null;
+   * @returns A BrowseMediaQueryParameters object.
+   */
+  protected _getBrowseMediaQueryParameters(): BrowseMediaQueryParameters | undefined {
+    if (
+      !this._frigateCameraName ||
+      !(this._view.isClipRelatedView() || this._view.isSnapshotRelatedView())
+    ) {
+      return undefined;
     }
-
     return {
-      mediaType: this._view.view == 'clips' ? 'clips' : 'snapshots',
+      mediaType: this._view.isClipRelatedView() ? 'clips' : 'snapshots',
       clientId: this.config.frigate_client_id,
       cameraName: this._frigateCameraName,
       label: this.config.label,
@@ -499,10 +509,16 @@ export class FrigateCard extends LitElement {
     };
   }
 
+  /**
+   * Handler for media play event.
+   */
   protected _playHandler(): void {
     this._mediaPlaying = true;
   }
 
+  /**
+   * Handler for media pause event.
+   */
   protected _pauseHandler(): void {
     this._mediaPlaying = false;
   }
@@ -665,8 +681,10 @@ export class FrigateCard extends LitElement {
   }
 
   protected _render(): TemplateResult | void {
-    const mediaQueryParameters = this._getBrowseMediaQueryParameters();
+    if (!this._hass) {
-    if (!this._hass || !this._frigateCameraName || !mediaQueryParameters) {
+      return html``;
+    }
+    if (!this._frigateCameraName) {
       this._setMessageAndUpdate(
         {
           message: localize('error.no_frigate_camera_name'),
@@ -675,6 +693,7 @@ export class FrigateCard extends LitElement {
         true,
       );
     }
+    const mediaQueryParameters = this._getBrowseMediaQueryParameters();
 
     const pictureElementsClasses = {
       'picture-elements': true,
@@ -724,6 +743,8 @@ export class FrigateCard extends LitElement {
               .browseMediaQueryParameters=${mediaQueryParameters}
               .nextPreviousControlStyle=${this.config.controls?.nextprev ?? 'thumbnails'}
               .autoplayClip=${this.config.autoplay_clip}
+              .resolvedMediaCache=${this._resolvedMediaCache}
+              .lazyLoad=${this.config.event_viewer?.lazy_load ?? true}
               class="${classMap(viewerClasses)}"
               @frigate-card:change-view=${this._changeViewHandler}
               @frigate-card:media-load=${this._mediaLoadHandler}

src/common.ts

@@ -43,6 +43,10 @@ export async function homeAssistantWSRequest<T>(
   return parseResult.data;
 }
 
+export function isTrueMedia(media: BrowseMediaSource): boolean {
+  return !media.can_expand;
+}
+
 // From a BrowseMediaSource item extract the first true media item (i.e. a
 // clip/snapshot, not a folder).
 export function getFirstTrueMediaChildIndex(
@@ -52,7 +56,7 @@ export function getFirstTrueMediaChildIndex(
     return null;
   }
   for (let i = 0; i < media.children.length; i++) {
-    if (!media.children[i].can_expand) {
+    if (isTrueMedia(media.children[i])) {
       return i;
     }
   }

src/components/gallery.ts

@@ -36,7 +36,7 @@ export class FrigateCardGallery extends LitElement {
   protected view!: View;
 
   @property({ attribute: false })
-  protected browseMediaQueryParameters!: BrowseMediaQueryParameters;
+  protected browseMediaQueryParameters?: BrowseMediaQueryParameters;
 
   protected _resizeObserver: ResizeObserver;
 
@@ -72,6 +72,10 @@ export class FrigateCardGallery extends LitElement {
   }
 
   protected async _render(): Promise<TemplateResult | void> {
+    if (!this.browseMediaQueryParameters) {
+      return html``;
+    }
+
     let parent: BrowseMediaSource | null;
     try {
       if (this.view.target) {

src/components/next-prev-control.ts

@@ -2,72 +2,50 @@ import { CSSResultGroup, LitElement, TemplateResult, html, unsafeCSS } from 'lit
 import { customElement, property } from 'lit/decorators.js';
 import { classMap } from 'lit/directives/class-map.js';
 
-import { BrowseMediaSource, NextPreviousControlStyle } from '../types.js';
+import { NextPreviousControlStyle } from '../types.js';
-
-import { View } from '../view.js';
 
 import controlStyle from '../scss/next-previous-control.scss';
 
 @customElement('frigate-card-next-previous-control')
 export class FrigateCardMessage extends LitElement {
   @property({ attribute: false })
-  protected control!: "next" | "previous";
+  protected direction?: 'next' | 'previous';
 
   @property({ attribute: false })
-  protected controlStyle!: NextPreviousControlStyle;
+  protected controlStyle?: NextPreviousControlStyle;
 
   @property({ attribute: false })
-  protected parent!: BrowseMediaSource;
+  protected thumbnail?: string;
 
-  @property({ attribute: false })
+  protected render(): TemplateResult {
-  protected childIndex!: number;
+    if (!this.controlStyle || this.controlStyle == 'none') {
-
-  @property({ attribute: false })
-  protected view!: View;
-
-  protected _changeView(): void {
-    new View({
-      view: this.view.view,
-      target: this.parent,
-      childIndex: this.childIndex,
-    }).dispatchChangeEvent(this);
-  }
-
-  protected render() : TemplateResult {
-    if (this.controlStyle == 'none' || !this.parent.children) {
-      return html``;
-    }
-    const target = this.parent.children[this.childIndex];
-    if (!target) {
       return html``;
     }
 
     const classes = {
       controls: true,
-      previous: this.control == "previous",
+      previous: this.direction == 'previous',
-      next: this.control == "next",
+      next: this.direction == 'next',
-      thumbnails: this.controlStyle == "thumbnails",
+      thumbnails: this.controlStyle == 'thumbnails',
-      chevrons: this.controlStyle == "chevrons",
+      chevrons: this.controlStyle == 'chevrons',
-      button: this.controlStyle == "chevrons",
+      button: this.controlStyle == 'chevrons',
     };
 
-    if (this.controlStyle == "chevrons") {
+    if (this.controlStyle == 'chevrons') {
       return html` <ha-icon-button
-        icon=${this.control == "previous" ? 'mdi:chevron-left' : 'mdi:chevron-right'}
+        icon=${this.direction == 'previous' ? 'mdi:chevron-left' : 'mdi:chevron-right'}
         class="${classMap(classes)}"
-        title=${target.title}
+        title=${this.title}
-        @click=${this._changeView}
       ></ha-icon-button>`;
     }
 
-    if (!target.thumbnail) {
+    if (!this.thumbnail) {
       return html``;
     }
     return html`<img
-      src="${target.thumbnail}"
+      src="${this.thumbnail}"
       class="${classMap(classes)}"
-      title="${target.title}"
+      title="${this.title}"
-      @click=${this._changeView}
     />`;
   }
 

src/components/viewer.ts

@@ -1,20 +1,28 @@
-import { CSSResultGroup, LitElement, TemplateResult, html, unsafeCSS } from 'lit';
+import {
+  CSSResultGroup,
+  LitElement,
+  TemplateResult,
+  html,
+  unsafeCSS,
+  PropertyValues,
+} from 'lit';
+import EmblaCarousel, { EmblaCarouselType } from 'embla-carousel';
+import { HomeAssistant } from 'custom-card-helpers';
 import { customElement, property } from 'lit/decorators.js';
 import { until } from 'lit/directives/until.js';
-import { HomeAssistant } from 'custom-card-helpers';
+import { ifDefined } from 'lit-html/directives/if-defined.js';
 
 import dayjs from 'dayjs';
 import dayjs_custom_parse_format from 'dayjs/plugin/customParseFormat.js';
 
-import { resolvedMediaSchema } from '../types.js';
 import type {
   BrowseMediaNeighbors,
   BrowseMediaQueryParameters,
   BrowseMediaSource,
   ExtendedHomeAssistant,
   NextPreviousControlStyle,
-  ResolvedMedia,
 } from '../types.js';
+import { ResolvedMediaCache, ResolvedMediaUtil } from '../resolved-media.js';
 import { localize } from '../localize/localize.js';
 import {
   browseMediaQuery,
@@ -24,51 +32,224 @@ import {
   dispatchPauseEvent,
   dispatchPlayEvent,
   getFirstTrueMediaChildIndex,
-  homeAssistantWSRequest,
+  isTrueMedia,
 } from '../common.js';
 
 import { View } from '../view.js';
-import {
+import { renderProgressIndicator } from '../components/message.js';
-  renderProgressIndicator,
-} from '../components/message.js';
 
 import './next-prev-control.js';
 
 import viewerStyle from '../scss/viewer.scss';
 
+const IMG_TRANSPARENT_1x1 =
+  'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII=';
+
 // Load dayjs plugin(s).
 dayjs.extend(dayjs_custom_parse_format);
 
 @customElement('frigate-card-viewer')
 export class FrigateCardViewer extends LitElement {
   @property({ attribute: false })
-  protected hass!: HomeAssistant & ExtendedHomeAssistant;
+  protected hass?: HomeAssistant & ExtendedHomeAssistant;
 
   @property({ attribute: false })
-  protected view!: View;
+  protected view?: View;
 
   @property({ attribute: false })
-  protected browseMediaQueryParameters!: BrowseMediaQueryParameters;
+  protected browseMediaQueryParameters?: BrowseMediaQueryParameters;
 
   @property({ attribute: false })
-  protected nextPreviousControlStyle!: NextPreviousControlStyle;
+  protected nextPreviousControlStyle?: NextPreviousControlStyle;
 
   @property({ attribute: false })
-  protected autoplayClip!: boolean;
+  protected autoplayClip?: boolean;
 
-  protected async _resolveMedia(
+  @property({ attribute: false })
-    mediaSource: BrowseMediaSource | null,
+  protected resolvedMediaCache?: ResolvedMediaCache;
-  ): Promise<ResolvedMedia | null> {
+
-    if (!mediaSource) {
+  @property({ attribute: false })
-      return null;
+  protected lazyLoad?: boolean;
-    }
+
-    const request = {
+  protected render(): TemplateResult | void {
-      type: 'media_source/resolve_media',
+    return html`${until(this._render(), renderProgressIndicator())}`;
-      media_content_id: mediaSource.media_content_id,
-    };
-    return homeAssistantWSRequest(this.hass, resolvedMediaSchema, request);
   }
 
+  /**
+   * Resolve all the given media for a target.
+   * @param target The target to resolve media from.
+   * @returns True if the resolutions were all error free.
+   */
+  protected async _resolveAllMediaForTarget(
+    target: BrowseMediaSource,
+  ): Promise<boolean> {
+    if (!this.hass) {
+      return false;
+    }
+
+    let errorFree = true;
+    for (let i = 0; target.children && i < (target.children || []).length; ++i) {
+      if (isTrueMedia(target.children[i])) {
+        errorFree &&= !!(await ResolvedMediaUtil.resolveMedia(
+          this.hass,
+          target.children[i],
+          this.resolvedMediaCache,
+        ));
+      }
+    }
+    return errorFree;
+  }
+
+  /**
+   * Asyncronously render the element.
+   * @returns A template to render.
+   */
+  protected async _render(): Promise<TemplateResult | void> {
+    if (!this.hass || !this.view || !this.browseMediaQueryParameters) {
+      return html``;
+    }
+
+    let autoplay = true;
+    let view = this.view;
+
+    if (!view.target) {
+      let parent: BrowseMediaSource | null = null;
+      try {
+        parent = await browseMediaQuery(this.hass, this.browseMediaQueryParameters);
+      } catch (e) {
+        return dispatchErrorMessageEvent(this, (e as Error).message);
+      }
+      const childIndex = getFirstTrueMediaChildIndex(parent);
+      if (!parent || !parent.children || childIndex == null) {
+        return dispatchMessageEvent(
+          this,
+          this.view.is('clip')
+            ? localize('common.no_clip')
+            : localize('common.no_snapshot'),
+          this.view.is('clip') ? 'mdi:filmstrip-off' : 'mdi:camera-off',
+        );
+      }
+      view = new View({
+        view: this.view.view,
+        target: parent,
+        childIndex: childIndex,
+      });
+
+      // In this block, no clip has been manually selected, so this is loading
+      // the most recent clip on card load. In this mode, autoplay of the clip
+      // may be disabled by configuration. If does not make sense to disable
+      // autoplay when the user has explicitly picked an event to play in the
+      // gallery.
+      autoplay = this.autoplayClip ?? true;
+    }
+
+    if (view.target && !(await this._resolveAllMediaForTarget(view.target))) {
+      return dispatchErrorMessageEvent(this, localize('error.could_not_resolve'));
+    }
+
+    return html` <frigate-card-viewer-core
+      .view=${view}
+      .nextPreviousControlStyle=${this.nextPreviousControlStyle}
+      .resolvedMediaCache=${this.resolvedMediaCache}
+      .autoplayClip=${autoplay}
+      .hass=${this.hass}
+      .browseMediaQueryParameters=${this.browseMediaQueryParameters}
+      .lazyLoad=${this.lazyLoad}
+    >
+    </frigate-card-viewer-core>`;
+  }
+
+  /**
+   * Get element styles.
+   */
+  static get styles(): CSSResultGroup {
+    return unsafeCSS(viewerStyle);
+  }
+}
+
+@customElement('frigate-card-viewer-core')
+export class FrigateCardViewerCore extends LitElement {
+  @property({ attribute: false })
+  protected view?: View;
+
+  @property({ attribute: false })
+  protected nextPreviousControlStyle?: NextPreviousControlStyle;
+
+  @property({ attribute: false })
+  protected resolvedMediaCache?: ResolvedMediaCache;
+
+  @property({ attribute: false })
+  protected autoplayClip?: boolean;
+
+  @property({ attribute: false })
+  protected hass?: HomeAssistant & ExtendedHomeAssistant;
+
+  @property({ attribute: false })
+  protected browseMediaQueryParameters?: BrowseMediaQueryParameters;
+
+  @property({ attribute: false })
+  protected lazyLoad?: boolean;
+
+  // Media carousel object.
+  protected _carousel?: EmblaCarouselType;
+  protected _loadedCarousel = false;
+
+  // Mapping of slide # to BrowseMediaSource child #.
+  // (Folders are not media items that can be rendered).
+  protected _slideToChild: Record<number, number> = {};
+
+  /**
+   * The updated lifecycle callback for this element.
+   * @param changedProperties The properties that were changed in this render.
+   */
+  updated(changedProperties: PropertyValues): void {
+    super.updated(changedProperties);
+
+    if (!this._loadedCarousel) {
+      this.updateComplete.then(() => {
+        this._loadCarousel();
+      });
+    }
+  }
+
+  /**
+   * Load the carousel with "slides" (clips or snapshots).
+   */
+  protected _loadCarousel(): void {
+    const carouselNode = this.renderRoot.querySelector(
+      '.embla__viewport',
+    ) as HTMLElement;
+
+    if (carouselNode) {
+      this._loadedCarousel = true;
+
+      // Start the carousel on the selected child number.
+      const startIndex = Number(
+        Object.keys(this._slideToChild).find(
+          (key) => this._slideToChild[key] === this.view?.childIndex,
+        ),
+      );
+
+      this._carousel = EmblaCarousel(carouselNode, {
+        startIndex: isNaN(startIndex) ? undefined : startIndex,
+      });
+      // Update views based on slide selections.
+      this._carousel.on('select', this._slideSelectHandler.bind(this));
+
+      // Lazily load media that is displayed. These handlers are registered
+      // regardless of the value of this.lazyLoad to allow that value to change
+      // after the carousel has been initialized.
+      this._carousel.on('init', this._lazyLoadMediaHandler.bind(this));
+      this._carousel.on('select', this._lazyLoadMediaHandler.bind(this));
+      this._carousel.on('resize', this._lazyLoadMediaHandler.bind(this));
+    }
+  }
+
+  /**
+   * Get the event start time from a media object.
+   * @param browseMedia The media object to extract the start time from.
+   * @returns The start time in unix/epoch time, or null if it cannot be determined.
+   */
   protected _extractEventStartTimeFromBrowseMedia(
     browseMedia: BrowseMediaSource,
   ): number | null {
@@ -86,20 +267,26 @@ export class FrigateCardViewer extends LitElement {
     return null;
   }
 
-  // Get the previous and next real media items, given the index
+  /**
-  protected _getMediaNeighbors(
+   * Get the previous and next true media items from the current view.
-    parent: BrowseMediaSource,
+   * @returns A BrowseMediaNeighbors with indices and objects of true media
-    index: number | null,
+   * neighbors.
-  ): BrowseMediaNeighbors | null {
+   */
-    if (index == null || !parent.children) {
+  protected _getMediaNeighbors(): BrowseMediaNeighbors | null {
+    if (
+      !this.view ||
+      !this.view.target ||
+      !this.view.target.children ||
+      this.view.childIndex === undefined
+    ) {
       return null;
     }
 
     // Work backwards from the index to get the previous real media.
     let prevIndex: number | null = null;
-    for (let i = index - 1; i >= 0; i--) {
+    for (let i = this.view.childIndex - 1; i >= 0; i--) {
-      const media = parent.children[i];
+      const media = this.view.target.children[i];
-      if (media && !media.can_expand) {
+      if (media && isTrueMedia(media)) {
         prevIndex = i;
         break;
       }
@@ -107,9 +294,9 @@ export class FrigateCardViewer extends LitElement {
 
     // Work forwards from the index to get the next real media.
     let nextIndex: number | null = null;
-    for (let i = index + 1; i < parent.children.length; i++) {
+    for (let i = this.view.childIndex + 1; i < this.view.target.children.length; i++) {
-      const media = parent.children[i];
+      const media = this.view.target.children[i];
-      if (media && !media.can_expand) {
+      if (media && isTrueMedia(media)) {
         nextIndex = i;
         break;
       }
@@ -117,112 +304,274 @@ export class FrigateCardViewer extends LitElement {
 
     return {
       previousIndex: prevIndex,
-      previous: prevIndex != null ? parent.children[prevIndex] : null,
+      previous: prevIndex != null ? this.view.target.children[prevIndex] : null,
       nextIndex: nextIndex,
-      next: nextIndex != null ? parent.children[nextIndex] : null,
+      next: nextIndex != null ? this.view.target.children[nextIndex] : null,
     };
   }
 
-  // Get a clip at the same time as a snapshot.
+  /**
-  protected async _findRelatedClips(
+   * Get a clip view that matches a given snapshot. Includes clips within the
-    snapshot: BrowseMediaSource | null,
+   * same range as the current view.
-  ): Promise<BrowseMediaSource | null> {
+   * @param snapshot The snapshot to find a matching clip for.
-    if (!snapshot) {
+   * @returns The view that would show the matching clip.
+   */
+  protected async _findRelatedClipView(
+    snapshot: BrowseMediaSource,
+  ): Promise<View | null> {
+    if (
+      !this.hass ||
+      !this.view ||
+      !this.view.target ||
+      !this.view.target.children ||
+      !this.view.target.children.length ||
+      !this.browseMediaQueryParameters
+    ) {
       return null;
     }
 
-    const startTime = this._extractEventStartTimeFromBrowseMedia(snapshot);
+    const snapshotStartTime = this._extractEventStartTimeFromBrowseMedia(snapshot);
-    if (startTime) {
+    if (!snapshotStartTime) {
+      return null;
+    }
+
+    // Heuristic: At this point, the user has a particular snapshot that they
+    // are interested in and want to see a related clip, yet the viewer code
+    // does not know the exact search criteria that led to that snapshot (e.g.
+    // it could be a 10-deep folder in the gallery). To give the user to ability
+    // to 'navigate' in the clips view once they change into that mode, this
+    // heuristic finds the earliest and latest snapshot that the user is
+    // currently viewing and mirrors that range into the clips view. Then,
+    // within the results see if there's a clip that matches the same time as
+    // the snapshot.
+    let earliest: number | null = null;
+    let latest: number | null = null;
+    for (let i = 0; i < this.view.target.children.length; i++) {
+      const child = this.view.target.children[i];
+      if (!isTrueMedia(child)) {
+        continue;
+      }
+      const startTime = this._extractEventStartTimeFromBrowseMedia(child);
+
+      if (startTime && (earliest === null || startTime < earliest)) {
+        earliest = startTime;
+      }
+      if (startTime && (latest === null || startTime > latest)) {
+        latest = startTime;
+      }
+    }
+    if (!earliest || !latest) {
+      return null;
+    }
+
+    let clips: BrowseMediaSource | null;
+
     try {
-        // Fetch clips within the same second (same camera/zone/label, etc).
+      clips = await browseMediaQuery(this.hass, {
-        const clipsAtSameTime = await browseMediaQuery(this.hass, {
         ...this.browseMediaQueryParameters,
         mediaType: 'clips',
-          before: startTime + 1,
+        before: latest,
-          after: startTime,
+        after: earliest,
       });
-        if (clipsAtSameTime) {
-          const index = getFirstTrueMediaChildIndex(clipsAtSameTime);
-          if (index != null && clipsAtSameTime.children?.length) {
-            return clipsAtSameTime.children[index];
-          }
-        }
     } catch (e) {
-        // Pass. This is best effort.
+      // This is best effort.
+      return null;
+    }
+
+    if (!clips || !clips.children || !clips.children.length) {
+      return null;
+    }
+
+    for (let i = 0; i < clips.children.length; i++) {
+      const child = clips.children[i];
+      if (!isTrueMedia(child)) {
+        continue;
+      }
+      const clipStartTime = this._extractEventStartTimeFromBrowseMedia(child);
+      if (clipStartTime && clipStartTime === snapshotStartTime) {
+        return new View({
+          view: 'clip',
+          target: clips,
+          childIndex: i,
+          previous: this.view,
+        });
       }
     }
     return null;
   }
 
+  /**
+   * Handle the user selecting a new slide in the carousel.
+   */
+  protected _slideSelectHandler(): void {
+    if (!this._carousel || !this.view) {
+      return;
+    }
+
+    // Update the childIndex in the view (without re-render)
+    const slidesInView = this._carousel.slidesInView(true);
+    if (slidesInView.length) {
+      const childIndex = this._slideToChild[slidesInView[0]];
+      if (childIndex !== undefined) {
+        // Update the currently live view in place.
+        this.view.childIndex = childIndex;
+        this.requestUpdate();
+      }
+    }
+  }
+
+  /**
+   * Handle a next/previous control interaction.
+   * @param direction The direction requested, previous or next.
+   */
+  protected _nextPreviousHandler(direction: 'previous' | 'next'): void {
+    if (direction == 'previous') {
+      this._carousel?.scrollPrev();
+    } else if (direction == 'next') {
+      this._carousel?.scrollNext();
+    }
+  }
+
+  /**
+   * Lazily load media in the carousel.
+   * @param eventName The Embla event name that triggered this load.
+   * // TODO delete eventName above?
+   */
+  protected _lazyLoadMediaHandler(): void {
+    if (!this.lazyLoad || !this._carousel) {
+      return;
+    }
+    const slides = this._carousel.slideNodes();
+    const slidesInView = this._carousel.slidesInView(true);
+    const slidesToLoad = new Set<number>();
+
+    // Lazily load the selected slide and the one on each side of it to improve
+    // the user navigation experience.
+    for (let i = 0; i < slidesInView.length; i++) {
+      const index = slidesInView[i];
+      if (index > 0) {
+        slidesToLoad.add(index - 1);
+      }
+      slidesToLoad.add(index);
+      if (index < slides.length - 1) {
+        slidesToLoad.add(index + 1);
+      }
+    }
+
+    slidesToLoad.forEach((index) => {
+      const slide = slides[index];
+
+      // Snapshots.
+      const img = slide.querySelector('img');
+
+      // Frigate >= 0.9.0+ clips.
+      const hls_player = slide.querySelector(
+        'frigate-card-ha-hls-player',
+      ) as HTMLElement & { url: string };
+
+      // Frigate < 0.9.0 clips. frigate-card-ha-hls-player will also have a
+      // video source element, so search for that first.
+      const video_source = slide.querySelector('video source') as HTMLElement & {
+        src: string;
+      };
+
+      if (img) {
+        img.src = img.getAttribute('data-src') || img.src;
+      } else if (hls_player) {
+        hls_player.url = hls_player.getAttribute('data-url') || hls_player.url;
+      } else if (video_source) {
+        video_source.src = video_source.getAttribute('data-src') || video_source.src;
+      }
+    });
+  }
+
+  /**
+   * Render the element.
+   * @returns A template to display to the user.
+   */
   protected render(): TemplateResult | void {
-    return html`${until(this._render(), renderProgressIndicator())}`;
+    if (
+      !this.view ||
+      !this.view.target ||
+      !this.view.target.children ||
+      !this.view.target.children.length ||
+      this.view.childIndex === undefined ||
+      !this.resolvedMediaCache
+    ) {
+      return html``;
     }
 
-  protected async _render(): Promise<TemplateResult | void> {
+    const slides: TemplateResult[] = [];
-    let autoplay = true;
+    this._slideToChild = {};
 
-    let parent: BrowseMediaSource | null = null;
+    for (let i = 0; i < this.view.target.children?.length; ++i) {
-    let childIndex: number | null = null;
+      const slide = this._renderMediaItem(this.view.target.children[i]);
-    let mediaToRender: BrowseMediaSource | null = null;
+      if (slide) {
-
+        this._slideToChild[slides.length] = i;
-    if (this.view.target) {
+        slides.push(slide);
-      parent = this.view.target;
-      childIndex = this.view.childIndex ?? null;
-      mediaToRender = this.view.media ?? null;
-    } else {
-      try {
-        parent = await browseMediaQuery(this.hass, this.browseMediaQueryParameters);
-      } catch (e) {
-        return dispatchErrorMessageEvent(this, (e as Error).message);
       }
-      childIndex = getFirstTrueMediaChildIndex(parent);
-      if (!parent || !parent.children || childIndex == null) {
-        return dispatchMessageEvent(
-          this,
-          this.view.is('clip')
-            ? localize('common.no_clip')
-            : localize('common.no_snapshot'),
-          this.view.is('clip') ? 'mdi:filmstrip-off' : 'mdi:camera-off',
-        );
-      }
-      mediaToRender = parent.children[childIndex];
-
-      // In this block, no clip has been manually selected, so this is loading
-      // the most recent clip on card load. In this mode, autoplay of the clip
-      // may be disabled by configuration. If does not make sense to disable
-      // autoplay when the user has explicitly picked an event to play in the
-      // gallery.
-      autoplay = this.autoplayClip;
-    }
-    const resolvedMedia = await this._resolveMedia(mediaToRender);
-    if (!mediaToRender || !resolvedMedia) {
-      // Home Assistant could not resolve media item.
-      return dispatchErrorMessageEvent(this, localize('error.could_not_resolve'));
     }
 
-    const neighbors = this._getMediaNeighbors(parent, childIndex);
+    const neighbors = this._getMediaNeighbors();
 
-    return html` <div>
+    return html`<div class="container">
-      ${neighbors?.previousIndex != null
+      ${neighbors && neighbors.previous
         ? html`<frigate-card-next-previous-control
-            .control=${'previous'}
+            .direction=${'previous'}
             .controlStyle=${this.nextPreviousControlStyle}
-            .parent=${parent}
+            .thumbnail=${neighbors.previous.thumbnail}
-            .childIndex=${neighbors.previousIndex}
+            .title=${neighbors.previous.title}
-            .view=${this.view}
+            @click=${() => this._nextPreviousHandler('previous')}
           ></frigate-card-next-previous-control>`
         : ``}
+      <div class="embla">
+        <div class="embla__viewport">
+          <div class="embla__container">${slides}</div>
+        </div>
+      </div>
+      ${neighbors && neighbors.next
+        ? html`<frigate-card-next-previous-control
+            .direction=${'next'}
+            .controlStyle=${this.nextPreviousControlStyle}
+            .thumbnail=${neighbors.next.thumbnail}
+            .title=${neighbors.next.title}
+            @click=${() => this._nextPreviousHandler('next')}
+          ></frigate-card-next-previous-control>`
+        : ``}
+    </div>`;
+  }
+
+  /**
+   * Render a given media item.
+   * @param mediaToRender The media item to render.
+   * @returns A template or void if the item could not be rendered.
+   */
+  protected _renderMediaItem(mediaToRender: BrowseMediaSource): TemplateResult | void {
+    // media that can be expanded (folders) cannot be resolved to a single media
+    // item, skip them.
+    if (!this.view || !isTrueMedia(mediaToRender)) {
+      return;
+    }
+
+    const resolvedMedia = this.resolvedMediaCache?.get(mediaToRender.media_content_id);
+    if (!resolvedMedia) {
+      return;
+    }
+
+    return html`
+      <div class="embla__slide">
         ${this.view.is('clip')
           ? resolvedMedia?.mime_type.toLowerCase() == 'application/x-mpegurl'
             ? html`<frigate-card-ha-hls-player
                 .hass=${this.hass}
-              .url=${resolvedMedia.url}
+                url=${ifDefined(this.lazyLoad ? undefined : resolvedMedia.url)}
+                data-url=${ifDefined(this.lazyLoad ? resolvedMedia.url : undefined)}
                 title="${mediaToRender.title}"
                 muted
                 controls
                 playsinline
                 allow-exoplayer
-              ?autoplay="${autoplay}"
+                ?autoplay="${this.autoplayClip}"
               >
               </frigate-card-ha-hls-player>`
             : html`<video
@@ -230,43 +579,41 @@ export class FrigateCardViewer extends LitElement {
                 muted
                 controls
                 playsinline
-              ?autoplay="${autoplay}"
+                ?autoplay="${this.autoplayClip}"
-              @loadedmetadata=${(e) => dispatchMediaLoadEvent(this, e)}a
+                @loadedmetadata="${(e) => dispatchMediaLoadEvent(this, e)}"
                 @play=${() => dispatchPlayEvent(this)}
                 @pause=${() => dispatchPauseEvent(this)}
               >
-              <source src="${resolvedMedia.url}" type="${resolvedMedia.mime_type}" />
+                <source
+                  src=${ifDefined(this.lazyLoad ? undefined : resolvedMedia.url)}
+                  data-src=${ifDefined(this.lazyLoad ? resolvedMedia.url : undefined)}
+                  type="${resolvedMedia.mime_type}"
+                />
               </video>`
           : html`<img
-            src=${resolvedMedia.url}
+              src=${ifDefined(this.lazyLoad ? IMG_TRANSPARENT_1x1 : resolvedMedia.url)}
+              data-src=${ifDefined(this.lazyLoad ? resolvedMedia.url : undefined)}
               title="${mediaToRender.title}"
               @click=${() => {
-              // Get clips potentially related to this snapshot.
+                if (this._carousel?.clickAllowed()) {
-              this._findRelatedClips(mediaToRender).then((relatedClip) => {
+                  this._findRelatedClipView(mediaToRender).then((view) => {
-                if (relatedClip) {
+                    if (view) {
-                  new View({
+                      view.dispatchChangeEvent(this);
-                    view: 'clip',
-                    target: relatedClip,
-                  }).dispatchChangeEvent(this);
                     }
                   });
+                }
               }}
               @load=${(e) => {
                 dispatchMediaLoadEvent(this, e);
               }}
             />`}
-      ${neighbors?.nextIndex != null
+      </div>
-        ? html`<frigate-card-next-previous-control
+    `;
-            .control=${'next'}
-            .controlStyle=${this.nextPreviousControlStyle}
-            .parent=${parent}
-            .childIndex=${neighbors.nextIndex}
-            .view=${this.view}
-          ></frigate-card-next-previous-control>`
-        : ``}
-    </div>`;
   }
 
+  /**
+   * Get element styles.
+   */
   static get styles(): CSSResultGroup {
     return unsafeCSS(viewerStyle);
   }

src/editor.ts

@@ -263,6 +263,13 @@ export class FrigateCardEditor extends LitElement implements LovelaceCardEditor
                   @change=${this._valueChanged}
                 ></ha-switch>
               </ha-formfield>
+              <ha-formfield .label=${localize('editor.lazy_load')}>
+                <ha-switch
+                  .checked=${this._config?.event_viewer?.lazy_load !== false}
+                  .configValue=${'event_viewer.lazy_load'}
+                  @change=${this._valueChanged}
+                ></ha-switch>
+              </ha-formfield>
             </div>`
           : ''}
         <div class="option" @click=${this._toggleOption} .option=${'appearance'}>

src/localize/languages/en.json

@@ -34,7 +34,8 @@
     "label": "Frigate label/object filter (Optional)",
     "live_provider": "Live view provider (Optional)",
     "live_preload": "Preload live view",
-    "image": "Static image URL for image view (Optional)"
+    "image": "Static image URL for image view (Optional)",
+    "lazy_load": "Lazily load event media"
   },
   "menu": {
     "frigate": "Frigate Menu / Default View",

src/resolved-media.ts

@@ -0,0 +1,66 @@
+import { HomeAssistant } from 'custom-card-helpers';
+import { homeAssistantWSRequest } from './common.js';
+import {
+  BrowseMediaSource,
+  ExtendedHomeAssistant,
+  ResolvedMedia,
+  resolvedMediaSchema,
+} from './types.js';
+import QuickLRU from 'quick-lru';
+
+// It's important the cache size be at least as large as the largest likely
+// media query or media items will from a given query will be evicted for other
+// items in the same query (which would result in only partial results being
+// returned to the user).
+// Note: Each entry is about 400 bytes. 
+
+const RESOLVED_MEDIA_CACHE_SIZE = 1000; 
+
+export class ResolvedMediaCache {
+  protected _cache: QuickLRU<string, ResolvedMedia>;
+
+  constructor() {
+    this._cache = new QuickLRU({maxSize: RESOLVED_MEDIA_CACHE_SIZE});
+  }
+
+  public has(id: string): boolean {
+    return this._cache.has(id);
+  }
+
+  public get(id: string): ResolvedMedia | undefined {
+    return this._cache.get(id);
+  }
+
+  public set(id: string, resolvedMedia: ResolvedMedia): void {
+    this._cache.set(id, resolvedMedia);
+  }
+}
+
+export class ResolvedMediaUtil {
+  static async resolveMedia(
+    hass: HomeAssistant & ExtendedHomeAssistant,
+    mediaSource?: BrowseMediaSource,
+    cache?: ResolvedMediaCache,
+  ): Promise<ResolvedMedia | null> {
+    if (!mediaSource) {
+      return null;
+    }
+    const cachedValue = cache ? cache.get(mediaSource.media_content_id) : undefined;
+    if (cachedValue) {
+      return cachedValue;
+    }
+    const request = {
+      type: 'media_source/resolve_media',
+      media_content_id: mediaSource.media_content_id,
+    };
+    const resolvedMedia = await homeAssistantWSRequest(
+      hass,
+      resolvedMediaSchema,
+      request,
+    );
+    if (cache && resolvedMedia) {
+      cache.set(mediaSource.media_content_id, resolvedMedia);
+    }
+    return resolvedMedia;
+  }
+}

src/scss/viewer.scss

@@ -6,7 +6,44 @@ img,video {
   height: 100%;
   display: block;
 }
-div {
+
+div.container {
   // Keep the controls positioned relative to the video.
   position: relative;
 }
+
+.embla {
+  position: relative;
+  margin-left: auto;
+  margin-right: auto;
+}
+
+.embla__viewport {
+  overflow: hidden;
+  width: 100%;
+}
+
+.embla__container {
+  display: flex;
+  user-select: none;
+  -webkit-touch-callout: none;
+  -khtml-user-select: none;
+  -webkit-tap-highlight-color: transparent;
+}
+
+.embla__viewport.is-draggable {
+  cursor: move;
+  cursor: grab;
+}
+
+.embla__viewport.is-dragging {
+  cursor: grabbing;
+}
+
+.embla__slide {
+  position: relative;
+  min-width: 100%;
+  max-width: 100%;
+  margin-right: 10px;
+  overflow: hidden;
+}

src/types.ts

@@ -283,6 +283,9 @@ export const frigateCardConfigSchema = z.object({
   label: z.string().optional(),
   zone: z.string().optional(),
   autoplay_clip: z.boolean().default(false),
+  event_viewer: z.object({
+    lazy_load: z.boolean().default(true),
+  }).optional(),
   menu_mode: z.enum(FRIGATE_MENU_MODES).optional().default('hidden-top'),
   menu_buttons: z
     .object({

src/view.ts

@@ -24,14 +24,37 @@ export class View {
     return this.view == name;
   }
 
+  /**
+   * Determine if a view is a gallery.
+   */
   public isGalleryView(): boolean {
     return this.view == 'clips' || this.view == 'snapshots';
   }
 
+  /**
+   * Determine if a view is of a piece of media (i.e. not the gallery).
+   */
   public isMediaView(): boolean {
     return !this.isGalleryView();
   }
 
+  /**
+   * Determine if a view is related to a clip or clips.
+   */
+  public isClipRelatedView(): boolean {
+    return ['clip', 'clips'].includes(this.view);
+  }
+
+  /**
+   * Determine if a view is related to a snapshot or snapshots.
+   */
+  public isSnapshotRelatedView(): boolean {
+    return ['snapshot', 'snapshots'].includes(this.view);
+  }
+
+  /**
+   *  Get the media item that should be played.
+   **/
   get media(): BrowseMediaSource | undefined {
     if (this.target) {
       if (this.target.children && this.childIndex !== undefined) {
@@ -42,6 +65,10 @@ export class View {
     return undefined;
   }
 
+  /**
+   * Dispatch an event to request a view change.
+   * @param node The element dispatching the event.
+   */
   public dispatchChangeEvent(node: HTMLElement): void {
     node.dispatchEvent(
       new CustomEvent<View>('frigate-card:change-view', {