Hide drawers if empty.

src/components/drawer.ts

@@ -24,9 +24,18 @@ export class FrigateCardDrawer extends LitElement {
   @property({ type: Boolean, reflect: true, attribute: true })
   public open = false;
 
+  // The 'empty' attribute is used in the styling to change the drawer
+  // visibility and that of all descendants if there is no content. Styling is
+  // used rather than display or hidden in order to ensure the contents continue
+  // to have a measurable size.
+  @property({ type: Boolean, reflect: true, attribute: true })
+  public empty = true;
+
   protected _refDrawer: Ref<HTMLElement & { open: boolean }> = createRef();
   protected _refSlot: Ref<HTMLSlotElement> = createRef();
 
+  protected _resizeObserver = new ResizeObserver(() => this._hideDrawerIfNecessary());
+
   /**
    * Called on the first update.
    * @param changedProps The changed properties.
@@ -42,19 +51,45 @@ export class FrigateCardDrawer extends LitElement {
     this._refDrawer.value?.shadowRoot?.appendChild(style);
   }
 
+  /**
+   * Called when the slotted children in the drawer change.
+   */
   protected _slotChanged(): void {
     const elements = this._refSlot.value?.assignedElements({ flatten: true });
-    if (elements && elements.length && this._refDrawer.value) {
-      // Hide the drawer unless there is content.
-      this._refDrawer.value.hidden = false;
+
+    // Watch all slot children for size changes.
+    this._resizeObserver.disconnect();
+    for (const element of elements ?? []) {
+      this._resizeObserver.observe(element);
     }
+    this._hideDrawerIfNecessary();
+  }
+
+  /**
+   * Hide the drawer if there is nothing to show.
+   * @returns
+   */
+  protected _hideDrawerIfNecessary(): void {
+    if (!this._refDrawer.value) {
+      return;
+    }
+
+    const elements = this._refSlot.value?.assignedElements({ flatten: true });
+    this.empty =
+      !elements ||
+      !elements.length ||
+      // If the element has the special attribute 'empty' also hide it, this is
+      // used to hide carousels that have no actual contents.
+      elements.every((element) => {
+        const box = element.getBoundingClientRect();
+        return !box.width || !box.height;
+      });
   }
 
   protected render(): TemplateResult {
     return html`
       <side-drawer
         ${ref(this._refDrawer)}
-        ?hidden=${true}
         location="${this.location}"
         ?open=${this.open}
       >

src/components/live.ts

@@ -512,7 +512,7 @@ export class FrigateCardLiveCarousel extends FrigateCardMediaCarousel {
   protected render(): TemplateResult | void {
     const [slides, cameraToSlide] = this._getSlides();
     this._cameraToSlide = cameraToSlide;
-    if (!slides || !this.liveConfig || !this.cameras || !this.view) {
+    if (!slides.length || !this.liveConfig || !this.cameras || !this.view) {
       return;
     }
 

src/components/thumbnail-carousel.ts

@@ -5,10 +5,7 @@ import { classMap } from 'lit/directives/class-map.js';
 import { customElement, property, state } from 'lit/decorators.js';
 import { ifDefined } from 'lit/directives/if-defined.js';
 
-import type {
-  FrigateBrowseMediaSource,
-  ThumbnailsControlConfig,
-} from '../types.js';
+import type { FrigateBrowseMediaSource, ThumbnailsControlConfig } from '../types.js';
 import { FrigateCardCarousel } from './carousel.js';
 import { View } from '../view.js';
 import {
@@ -201,7 +198,7 @@ export class FrigateCardThumbnailCarousel extends FrigateCardCarousel {
    */
   protected render(): TemplateResult | void {
     const slides = this._getSlides();
-    if (!slides || !this._config || this._config.mode == 'none') {
+    if (!slides.length || !this._config || this._config.mode == 'none') {
       return;
     }
 

src/components/viewer.ts

@@ -599,7 +599,7 @@ export class FrigateCardViewerCarousel extends FrigateCardMediaCarousel {
   protected _render(): TemplateResult | void {
     const [slides, slideToChild] = this._getSlides();
     this._slideToChild = slideToChild;
-    if (!slides) {
+    if (!slides.length) {
       return;
     }