Fetch thumbnails for next/previous controls.

src/components/live.ts

@@ -585,6 +585,7 @@ export class FrigateCardLiveCarousel extends LitElement {
       >
         <frigate-card-next-previous-control
           slot="previous"
+          .hass=${this.hass}
           .direction=${'previous'}
           .controlConfig=${config.controls.next_previous}
           .label=${getCameraTitle(this.hass, prev)}
@@ -601,6 +602,7 @@ export class FrigateCardLiveCarousel extends LitElement {
         ${slides}
         <frigate-card-next-previous-control
           slot="next"
+          .hass=${this.hass}
           .direction=${'next'}
           .controlConfig=${config.controls.next_previous}
           .label=${getCameraTitle(this.hass, next)}

src/components/next-prev-control.ts

@@ -5,6 +5,10 @@ import { classMap } from 'lit/directives/class-map.js';
 import { NextPreviousControlConfig } from '../types.js';
 
 import controlStyle from '../scss/next-previous-control.scss';
+import { createFetchThumbnailTask } from '../utils/thumbnail.js';
+import { HomeAssistant } from 'custom-card-helpers';
+import { dispatchFrigateCardErrorEvent } from './message.js';
+import { errorToConsole } from '../utils/basic.js';
 
 @customElement('frigate-card-next-previous-control')
 export class FrigateCardNextPreviousControl extends LitElement {
@@ -18,6 +22,9 @@ export class FrigateCardNextPreviousControl extends LitElement {
     this._controlConfig = controlConfig;
   }
 
+  @property({ attribute: false })
+  public hass?: HomeAssistant;
+
   @state()
   protected _controlConfig?: NextPreviousControlConfig;
 
@@ -33,6 +40,12 @@ export class FrigateCardNextPreviousControl extends LitElement {
   // Label that is used for ARIA support and as tooltip.
   @property() label = '';
 
+  protected _embedThumbnailTask = createFetchThumbnailTask(
+    this,
+    () => this.hass,
+    () => this.thumbnail,
+  );
+
   protected render(): TemplateResult {
     if (this.disabled || !this._controlConfig || this._controlConfig.style == 'none') {
       return html``;
@@ -66,12 +79,30 @@ export class FrigateCardNextPreviousControl extends LitElement {
     if (!this.thumbnail) {
       return html``;
     }
-    return html`<img
+
-      src="${this.thumbnail}"
+    const renderControlInProgress = (): TemplateResult => {
-      class="${classMap(classes)}"
+      // Just render an 'empty' thumbnail control until the thumbnail loads.
-      title="${this.label}"
+      return html`<div class=${classMap(classes)}></div>`;
-      aria-label="${this.label}"
+    };
-    />`;
+
+    return html`${this._embedThumbnailTask.render({
+      initial: () => renderControlInProgress(),
+      pending: () => renderControlInProgress(),
+      error: (e: unknown) => {
+        errorToConsole(e as Error);
+        dispatchFrigateCardErrorEvent(this, e as Error);
+      },
+      complete: (embeddedThumbnail: string | null) => {
+        return embeddedThumbnail
+          ? html`<img
+              src="${embeddedThumbnail}"
+              class="${classMap(classes)}"
+              title="${this.label}"
+              aria-label="${this.label}"
+            />`
+          : html``;
+      },
+    })}`;
   }
 
   static get styles(): CSSResultGroup {
@@ -80,7 +111,7 @@ export class FrigateCardNextPreviousControl extends LitElement {
 }
 
 declare global {
-	interface HTMLElementTagNameMap {
+  interface HTMLElementTagNameMap {
-		"frigate-card-next-previous-control": FrigateCardNextPreviousControl
+    'frigate-card-next-previous-control': FrigateCardNextPreviousControl;
-	}
+  }
 }

src/components/thumbnail.ts

@@ -1,4 +1,3 @@
-import { Task } from '@lit-labs/task/task.js';
 import { format, fromUnixTime } from 'date-fns';
 import { CSSResult, html, LitElement, TemplateResult, unsafeCSS } from 'lit';
 import { customElement, property } from 'lit/decorators.js';
@@ -18,6 +17,7 @@ import { stopEventFromActivatingCardWideActions } from '../utils/action.js';
 import { errorToConsole, prettifyTitle } from '../utils/basic.js';
 import { retainEvent } from '../utils/frigate.js';
 import { getEventDurationString } from '../utils/ha/browse-media.js';
+import { createFetchThumbnailTask } from '../utils/thumbnail.js';
 import { View } from '../view.js';
 import { dispatchFrigateCardErrorEvent, renderProgressIndicator } from './message.js';
 
@@ -32,52 +32,12 @@ export class FrigateCardThumbnailFeatureEvent extends LitElement {
   @property({ attribute: false })
   public hass?: ExtendedHomeAssistant;
 
-  protected _embedThumbnailTask = new Task(
+  protected _embedThumbnailTask = createFetchThumbnailTask(
     this,
-    this._embedThumbnail.bind(this),
+    () => this.hass,
-    // Do not re-run the task if hass changes, unless it was previously undefined.
+    () => this.thumbnail,
-    (): [boolean, string | undefined] => [!!this.hass, this.thumbnail],
   );
 
-  /**
-   * Sign a thumbnail URL if necessary. May throw.
-   * @param param0 A list of lit-task dependencies.
-   * @returns A signed URL or null.
-   */
-  protected async _embedThumbnail([haveHASS, thumbnail]: [
-    boolean,
-    string | undefined,
-  ]): Promise<string | null> {
-    if (!haveHASS || !this.hass || !thumbnail) {
-      return null;
-    }
-    if (this.thumbnail?.startsWith('data:')) {
-      return this.thumbnail;
-    }
-    return new Promise((resolve, reject) => {
-      if (!this.hass) {
-        reject();
-        return;
-      }
-      this.hass
-        .fetchWithAuth(thumbnail)
-        // Since we are fetching with an authorization header, we cannot just put the
-        // URL directly into the document; we need to embed the image. We could do this
-        // using blob URLs, but then we would need to keep track of them in order to
-        // release them properly. Instead, we embed the thumbnail using base64.
-        .then((response) => response.blob())
-        .then((blob) => {
-          const reader = new FileReader();
-          reader.onload = () => {
-            const result = reader.result;
-            resolve(typeof result === 'string' ? result : null);
-          };
-          reader.onerror = (e) => reject(e);
-          reader.readAsDataURL(blob);
-        });
-    });
-  }
-
   protected render(): TemplateResult | void {
     return html`
       ${this.thumbnail

src/components/viewer.ts

@@ -627,6 +627,7 @@ export class FrigateCardViewerCarousel extends LitElement {
     >
       <frigate-card-next-previous-control
         slot="previous"
+        .hass=${this.hass}
         .direction=${'previous'}
         .controlConfig=${this.viewerConfig?.controls.next_previous}
         .thumbnail=${prev && prev.thumbnail ? prev.thumbnail : undefined}
@@ -640,6 +641,7 @@ export class FrigateCardViewerCarousel extends LitElement {
       ${slides}
       <frigate-card-next-previous-control
         slot="next"
+        .hass=${this.hass}
         .direction=${'next'}
         .controlConfig=${this.viewerConfig?.controls.next_previous}
         .thumbnail=${next && next.thumbnail ? next.thumbnail : undefined}

src/utils/thumbnail.ts

@@ -0,0 +1,71 @@
+import { Task } from '@lit-labs/task';
+import { ReactiveControllerHost } from '@lit/reactive-element';
+import { HomeAssistant } from 'custom-card-helpers';
+
+/**
+ * Fetch a thumbnail URL and return a data URL.
+ * @param hass Home Assistant object.
+ * @param thumbnailURL The thumbnail URL.
+ * @returns A base64 encoded data URL for the thumbnail.
+ */
+export const fetchThumbnail = async (
+  hass: HomeAssistant,
+  thumbnailURL: string,
+): Promise<string | null> => {
+  if (!hass) {
+    return null;
+  }
+  if (thumbnailURL?.startsWith('data:')) {
+    return thumbnailURL;
+  }
+  return new Promise((resolve, reject) => {
+    if (!hass) {
+      reject();
+      return;
+    }
+    hass
+      .fetchWithAuth(thumbnailURL)
+      // Since we are fetching with an authorization header, we cannot just put the
+      // URL directly into the document; we need to embed the image. We could do this
+      // using blob URLs, but then we would need to keep track of them in order to
+      // release them properly. Instead, we embed the thumbnail using base64.
+      .then((response) => response.blob())
+      .then((blob) => {
+        const reader = new FileReader();
+        reader.onload = () => {
+          const result = reader.result;
+          resolve(typeof result === 'string' ? result : null);
+        };
+        reader.onerror = (e) => reject(e);
+        reader.readAsDataURL(blob);
+      });
+  });
+};
+
+/**
+ * Create a Lit task to fetch a thumbnail.
+ * @param host The Lit Element.
+ * @param getHASS A function to get the Home Assistant object.
+ * @param getThumbnail A function to get the Thumbnail URL.
+ * @returns A new Lit Task.
+ */
+export const createFetchThumbnailTask = (
+  host: ReactiveControllerHost,
+  getHASS: () => HomeAssistant | undefined,
+  getThumbnailURL: () => string | undefined,
+): Task => {
+  return new Task(
+    host,
+    async ([haveHASS, thumbnailURL]: [boolean, string | undefined]): Promise<
+      string | null
+    > => {
+      const hass = getHASS();
+      if (!haveHASS || !hass || !thumbnailURL) {
+        return null;
+      }
+      return fetchThumbnail(hass, thumbnailURL);
+    },
+    // Do not re-run the task if hass changes, unless it was previously undefined.
+    (): [boolean, string | undefined] => [!!getHASS(), getThumbnailURL()],
+  );
+};