Add restoreScroll decorator (#6289)

src/common/decorators/restore-scroll.ts

@@ -0,0 +1,33 @@
+import type { LitElement } from "lit-element";
+import type { ClassElement } from "../../types";
+
+export const restoreScroll = (selector: string): any => {
+  return (element: ClassElement) => ({
+    kind: "method",
+    placement: "prototype",
+    key: element.key,
+    descriptor: {
+      set(this: LitElement, value: number) {
+        this[`__${String(element.key)}`] = value;
+      },
+      get(this: LitElement) {
+        return this[`__${String(element.key)}`];
+      },
+      enumerable: true,
+      configurable: true,
+    },
+    finisher(cls: typeof LitElement) {
+      const connectedCallback = cls.prototype.connectedCallback;
+      cls.prototype.connectedCallback = function () {
+        connectedCallback.call(this);
+        if (this[element.key]) {
+          const target = this.renderRoot.querySelector(selector);
+          if (!target) {
+            return;
+          }
+          target.scrollTop = this[element.key];
+        }
+      };
+    },
+  });
+};

src/components/data-table/ha-data-table.ts

@@ -9,6 +9,8 @@ import {
   PropertyValues,
   query,
   TemplateResult,
+  eventOptions,
+  internalProperty,
 } from "lit-element";
 import { classMap } from "lit-html/directives/class-map";
 import { ifDefined } from "lit-html/directives/if-defined";
@@ -23,6 +25,7 @@ import type { HaCheckbox } from "../ha-checkbox";
 import "../ha-icon";
 import { filterData, sortData } from "./sort-filter";
 import memoizeOne from "memoize-one";
+import { restoreScroll } from "../../common/decorators/restore-scroll";
 
 declare global {
   // for fire event
@@ -96,15 +99,15 @@ export class HaDataTable extends LitElement {
 
   @property({ type: String }) public filter = "";
 
-  @property({ type: Boolean }) private _filterable = false;
+  @internalProperty() private _filterable = false;
 
-  @property({ type: String }) private _filter = "";
+  @internalProperty() private _filter = "";
 
-  @property({ type: String }) private _sortColumn?: string;
+  @internalProperty() private _sortColumn?: string;
 
-  @property({ type: String }) private _sortDirection: SortingDirection = null;
+  @internalProperty() private _sortDirection: SortingDirection = null;
 
-  @property({ type: Array }) private _filteredData: DataTableRowData[] = [];
+  @internalProperty() private _filteredData: DataTableRowData[] = [];
 
   @query("slot[name='header']") private _header!: HTMLSlotElement;
 
@@ -118,6 +121,9 @@ export class HaDataTable extends LitElement {
 
   private curRequest = 0;
 
+  // @ts-ignore
+  @restoreScroll(".scroller") private _savedScrollPos?: number;
+
   private _debounceSearch = debounce(
     (value: string) => {
       this._filter = value;
@@ -286,7 +292,10 @@ export class HaDataTable extends LitElement {
                 </div>
               `
             : html`
-                <div class="mdc-data-table__content scroller">
+                <div
+                  class="mdc-data-table__content scroller"
+                  @scroll=${this._saveScrollPos}
+                >
                   ${scroll({
                     items: !this.hasFab
                       ? this._filteredData
@@ -499,6 +508,11 @@ export class HaDataTable extends LitElement {
     this._table.style.height = `calc(100% - ${this._header.clientHeight}px)`;
   }
 
+  @eventOptions({ passive: true })
+  private _saveScrollPos(e: Event) {
+    this._savedScrollPos = (e.target as HTMLDivElement).scrollTop;
+  }
+
   static get styles(): CSSResult {
     return css`
       /* default mdc styles, colors changed, without checkbox styles */

src/layouts/hass-subpage.ts

@@ -11,6 +11,7 @@ import {
 import { classMap } from "lit-html/directives/class-map";
 import "../components/ha-menu-button";
 import "../components/ha-icon-button-arrow-prev";
+import { restoreScroll } from "../common/decorators/restore-scroll";
 
 @customElement("hass-subpage")
 class HassSubpage extends LitElement {
@@ -23,16 +24,8 @@ class HassSubpage extends LitElement {
   @property({ type: Boolean })
   public hassio = false;
 
-  @property() private _savedScrollPos?: number;
-
-  public connectedCallback() {
-    super.connectedCallback();
-    if (this._savedScrollPos) {
-      (this.shadowRoot!.querySelector(
-        ".content"
-      ) as HTMLDivElement).scrollTop = this._savedScrollPos;
-    }
-  }
+  // @ts-ignore
+  @restoreScroll(".content") private _savedScrollPos?: number;
 
   protected render(): TemplateResult {
     return html`

src/layouts/hass-tabs-subpage.ts

@@ -20,6 +20,7 @@ import { HomeAssistant, Route } from "../types";
 import "../components/ha-svg-icon";
 import "../components/ha-icon";
 import "../components/ha-tab";
+import { restoreScroll } from "../common/decorators/restore-scroll";
 
 export interface PageNavigation {
   path: string;
@@ -53,16 +54,8 @@ class HassTabsSubpage extends LitElement {
 
   @property() private _activeTab?: PageNavigation;
 
-  @property() private _savedScrollPos?: number;
-
-  public connectedCallback() {
-    super.connectedCallback();
-    if (this._savedScrollPos) {
-      (this.shadowRoot!.querySelector(
-        ".content"
-      ) as HTMLDivElement).scrollTop = this._savedScrollPos;
-    }
-  }
+  // @ts-ignore
+  @restoreScroll(".content") private _savedScrollPos?: number;
 
   private _getTabs = memoizeOne(
     (

src/types.ts

@@ -47,6 +47,16 @@ declare global {
 
 export type Constructor<T = {}> = new (...args: any[]) => T;
 
+export interface ClassElement {
+  kind: "field" | "method";
+  key: PropertyKey;
+  placement: "static" | "prototype" | "own";
+  initializer?: Function;
+  extras?: ClassElement[];
+  finisher?: <T>(cls: Constructor<T>) => undefined | Constructor<T>;
+  descriptor?: PropertyDescriptor;
+}
+
 export interface WebhookError {
   code: number;
   message: string;