Allow resizing section to span multiple columns (#21742)

* WIP: Allow to resize section

* Use listeners

* Rename variables

* Rename variables

* Remove column min width

* Make column breakpoints optional

* Use old logic to calculate the number of columns

* Remove breakpoints

* Simplify column span

src/data/lovelace/config/section.ts

@@ -5,6 +5,7 @@ import type { LovelaceStrategyConfig } from "./strategy";
 export interface LovelaceBaseSectionConfig {
   title?: string;
   visibility?: Condition[];
+  column_span?: number;
 }
 
 export interface LovelaceSectionConfig extends LovelaceBaseSectionConfig {

src/panels/lovelace/editor/section-editor/hui-section-settings-editor.ts

@@ -13,10 +13,15 @@ const SCHEMA = [
     name: "title",
     selector: { text: {} },
   },
+  {
+    name: "column_span",
+    selector: { number: { min: 1, max: 3 } },
+  },
 ] as const satisfies HaFormSchema[];
 
 type SettingsData = {
   title: string;
+  column_span?: number;
 };
 
 @customElement("hui-section-settings-editor")
@@ -28,6 +33,7 @@ export class HuiDialogEditSection extends LitElement {
   render() {
     const data: SettingsData = {
       title: this.config.title || "",
+      column_span: this.config.column_span || 1,
     };
 
     return html`
@@ -59,6 +65,7 @@ export class HuiDialogEditSection extends LitElement {
     const newConfig: LovelaceSectionRawConfig = {
       ...this.config,
       title: newData.title,
+      column_span: newData.column_span,
     };
 
     if (!newConfig.title) {

src/panels/lovelace/sections/hui-grid-section.ts

@@ -220,8 +220,14 @@ export class GridSection extends LitElement implements LovelaceSectionElement {
           gap: var(--row-gap);
         }
         .container {
+          --grid-column-count: calc(
+            var(--column-count) * var(--column-span, 1)
+          );
           display: grid;
-          grid-template-columns: repeat(var(--column-count), minmax(0, 1fr));
+          grid-template-columns: repeat(
+            var(--grid-column-count),
+            minmax(0, 1fr)
+          );
           grid-auto-rows: minmax(var(--row-height), auto);
           row-gap: var(--row-gap);
           column-gap: var(--column-gap);

src/panels/lovelace/views/hui-sections-view.ts

@@ -1,3 +1,4 @@
+import { ResizeController } from "@lit-labs/observers/resize-controller";
 import { mdiArrowAll, mdiDelete, mdiPencil, mdiViewGridPlus } from "@mdi/js";
 import {
   CSSResultGroup,
@@ -26,6 +27,10 @@ import { showEditSectionDialog } from "../editor/section-editor/show-edit-sectio
 import { HuiSection } from "../sections/hui-section";
 import type { Lovelace } from "../types";
 
+export const DEFAULT_MAX_COLUMNS = 4;
+
+const parsePx = (value: string) => parseInt(value.replace("px", ""));
+
 @customElement("hui-sections-view")
 export class SectionsView extends LitElement implements LovelaceViewElement {
   @property({ attribute: false }) public hass!: HomeAssistant;
@@ -46,6 +51,30 @@ export class SectionsView extends LitElement implements LovelaceViewElement {
 
   @state() _dragging = false;
 
+  private _columnsController = new ResizeController(this, {
+    callback: (entries) => {
+      const totalWidth = entries[0]?.contentRect.width;
+
+      const style = getComputedStyle(this);
+      const container = this.shadowRoot!.querySelector(".container")!;
+      const containerStyle = getComputedStyle(container);
+
+      const paddingLeft = parsePx(containerStyle.paddingLeft);
+      const paddingRight = parsePx(containerStyle.paddingRight);
+      const padding = paddingLeft + paddingRight;
+      const minColumnWidth = parsePx(
+        style.getPropertyValue("--column-min-width")
+      );
+      const columnGap = parsePx(containerStyle.columnGap);
+
+      const columns = Math.floor(
+        (totalWidth - padding + columnGap) / (minColumnWidth + columnGap)
+      );
+      const maxColumns = this._config?.max_columns ?? DEFAULT_MAX_COLUMNS;
+      return Math.max(Math.min(maxColumns, columns), 1);
+    },
+  });
+
   public setConfig(config: LovelaceViewConfig): void {
     this._config = config;
   }
@@ -95,10 +124,11 @@ export class SectionsView extends LitElement implements LovelaceViewElement {
     if (!this.lovelace) return nothing;
 
     const sections = this.sections;
-    const totalCount = this._sectionCount + (this.lovelace?.editMode ? 1 : 0);
+    const totalSectionCount =
+      this._sectionCount + (this.lovelace?.editMode ? 1 : 0);
     const editMode = this.lovelace.editMode;
 
-    const maxColumnsCount = this._config?.max_columns;
+    const maxColumnCount = this._columnsController.value ?? 1;
 
     return html`
       <hui-view-badges
@@ -118,17 +148,29 @@ export class SectionsView extends LitElement implements LovelaceViewElement {
         <div
           class="container"
           style=${styleMap({
-            "--max-columns-count": maxColumnsCount,
+            "--total-section-count": totalSectionCount,
-            "--total-count": totalCount,
+            "--max-column-count": maxColumnCount,
           })}
         >
           ${repeat(
             sections,
             (section) => this._getSectionKey(section),
             (section, idx) => {
+              const sectionConfig = this._config?.sections?.[idx];
+              const columnSpan = Math.min(
+                sectionConfig?.column_span || 1,
+                maxColumnCount
+              );
+
               (section as any).itemPath = [idx];
+
               return html`
-                <div class="section">
+                <div
+                  class="section"
+                  style=${styleMap({
+                    "--column-span": columnSpan,
+                  })}
+                >
                   ${editMode
                     ? html`
                         <div class="section-overlay">
@@ -252,19 +294,19 @@ export class SectionsView extends LitElement implements LovelaceViewElement {
         --row-height: var(--ha-view-sections-row-height, 56px);
         --row-gap: var(--ha-view-sections-row-gap, 8px);
         --column-gap: var(--ha-view-sections-column-gap, 32px);
-        --column-min-width: var(--ha-view-sections-column-min-width, 320px);
         --column-max-width: var(--ha-view-sections-column-max-width, 500px);
+        --column-min-width: var(--ha-view-sections-column-min-width, 320px);
         display: block;
       }
 
       .container > * {
         position: relative;
-        max-width: var(--column-max-width);
         width: 100%;
       }
 
       .section {
         border-radius: var(--ha-card-border-radius, 12px);
+        grid-column: span var(--column-span);
       }
 
       .section:not(:has(> *:not([hidden]))) {
@@ -272,29 +314,22 @@ export class SectionsView extends LitElement implements LovelaceViewElement {
       }
 
       .container {
-        --max-count: min(var(--total-count), var(--max-columns-count, 4));
+        --column-count: min(
-        --max-width: min(
+          var(--max-column-count),
-          calc(
+          var(--total-section-count)
-            (var(--max-count) + 1) * var(--column-min-width) +
-              (var(--max-count) + 2) * var(--column-gap) - 1px
-          ),
-          calc(
-            var(--max-count) * var(--column-max-width) + (var(--max-count) + 1) *
-              var(--column-gap)
-          )
         );
         display: grid;
         align-items: start;
-        justify-items: center;
+        justify-content: center;
-        grid-template-columns: repeat(
+        grid-template-columns: repeat(var(--column-count), 1fr);
-          auto-fit,
-          minmax(min(var(--column-min-width), 100%), 1fr)
-        );
         gap: var(--row-gap) var(--column-gap);
         padding: var(--row-gap) var(--column-gap);
-        box-sizing: border-box;
+        box-sizing: content-box;
-        max-width: var(--max-width);
         margin: 0 auto;
+        max-width: calc(
+          var(--column-count) * var(--column-max-width) +
+            (var(--column-count) - 1) * var(--column-gap)
+        );
       }
 
       @media (max-width: 600px) {