Use gradient based on min/max color temp for tile card feature (#17612)

src/common/color/convert-light-color.ts

@@ -1,7 +1,7 @@
 import { clamp } from "../number/clamp";
 
-const DEFAULT_MIN_KELVIN = 2700;
-const DEFAULT_MAX_KELVIN = 6500;
+export const DEFAULT_MIN_KELVIN = 2700;
+export const DEFAULT_MAX_KELVIN = 6500;
 
 export const temperature2rgb = (
   temperature: number

src/components/ha-temp-color-picker.ts

@@ -1,10 +1,14 @@
 import { DIRECTION_ALL, Manager, Pan, Tap } from "@egjs/hammerjs";
-import { css, html, LitElement, PropertyValues, svg } from "lit";
+import { LitElement, PropertyValues, css, html, svg } from "lit";
 import { customElement, property, query, state } from "lit/decorators";
 import { classMap } from "lit/directives/class-map";
 import { styleMap } from "lit/directives/style-map";
 import { rgb2hex } from "../common/color/convert-color";
-import { temperature2rgb } from "../common/color/convert-light-color";
+import {
+  DEFAULT_MAX_KELVIN,
+  DEFAULT_MIN_KELVIN,
+  temperature2rgb,
+} from "../common/color/convert-light-color";
 import { fireEvent } from "../common/dom/fire_event";
 
 const SAFE_ZONE_FACTOR = 0.9;
@@ -79,10 +83,10 @@ class HaTempColorPicker extends LitElement {
   public value?: number;
 
   @property({ type: Number })
-  public min = 2000;
+  public min = DEFAULT_MIN_KELVIN;
 
   @property({ type: Number })
-  public max = 10000;
+  public max = DEFAULT_MAX_KELVIN;
 
   @query("#canvas") private _canvas!: HTMLCanvasElement;
 

src/dialogs/more-info/components/lights/light-color-temp-picker.ts

@@ -16,6 +16,10 @@ import {
   LightEntity,
 } from "../../../../data/light";
 import { HomeAssistant } from "../../../../types";
+import {
+  DEFAULT_MAX_KELVIN,
+  DEFAULT_MIN_KELVIN,
+} from "../../../../common/color/convert-light-color";
 
 declare global {
   interface HASSDomEvents {
@@ -37,12 +41,17 @@ class LightColorTempPicker extends LitElement {
       return nothing;
     }
 
+    const minKelvin =
+      this.stateObj.attributes.min_color_temp_kelvin ?? DEFAULT_MIN_KELVIN;
+    const maxKelvin =
+      this.stateObj.attributes.max_color_temp_kelvin ?? DEFAULT_MAX_KELVIN;
+
     return html`
       <ha-temp-color-picker
         @value-changed=${this._ctColorChanged}
         @cursor-moved=${this._ctColorCursorMoved}
-        .min=${this.stateObj.attributes.min_color_temp_kelvin!}
-        .max=${this.stateObj.attributes.max_color_temp_kelvin!}
+        .min=${minKelvin}
+        .max=${maxKelvin}
         .value=${this._ctPickerValue}
       >
       </ha-temp-color-picker>

src/panels/lovelace/tile-features/hui-light-color-temp-tile-feature.ts

@@ -1,6 +1,14 @@
 import { HassEntity } from "home-assistant-js-websocket";
 import { css, html, LitElement, nothing } from "lit";
 import { customElement, property, state } from "lit/decorators";
+import { styleMap } from "lit/directives/style-map";
+import memoizeOne from "memoize-one";
+import { rgb2hex } from "../../../common/color/convert-color";
+import {
+  DEFAULT_MAX_KELVIN,
+  DEFAULT_MIN_KELVIN,
+  temperature2rgb,
+} from "../../../common/color/convert-light-color";
 import { computeDomain } from "../../../common/entity/compute_domain";
 import { stateActive } from "../../../common/entity/state_active";
 import "../../../components/ha-control-slider";
@@ -57,6 +65,13 @@ class HuiLightColorTempTileFeature
         ? this.stateObj.attributes.color_temp_kelvin
         : undefined;
 
+    const minKelvin =
+      this.stateObj.attributes.min_color_temp_kelvin ?? DEFAULT_MIN_KELVIN;
+    const maxKelvin =
+      this.stateObj.attributes.max_color_temp_kelvin ?? DEFAULT_MAX_KELVIN;
+
+    const gradient = this.generateTemperatureGradient(minKelvin!, maxKelvin);
+
     return html`
       <div class="container">
         <ha-control-slider
@@ -66,13 +81,38 @@ class HuiLightColorTempTileFeature
           .disabled=${this.stateObj!.state === UNAVAILABLE}
           @value-changed=${this._valueChanged}
           .label=${this.hass.localize("ui.card.light.color_temperature")}
-          .min=${this.stateObj.attributes.min_color_temp_kelvin!}
-          .max=${this.stateObj.attributes.max_color_temp_kelvin!}
+          .min=${minKelvin}
+          .max=${maxKelvin}
+          style=${styleMap({
+            "--gradient": gradient,
+          })}
         ></ha-control-slider>
       </div>
     `;
   }
 
+  private generateTemperatureGradient = memoizeOne(
+    (min: number, max: number) => {
+      const count = 10;
+
+      const gradient: [number, string][] = [];
+
+      const step = (max - min) / count;
+      const percentageStep = 1 / count;
+
+      for (let i = 0; i < count + 1; i++) {
+        const value = min + step * i;
+
+        const hex = rgb2hex(temperature2rgb(value));
+        gradient.push([percentageStep * i, hex]);
+      }
+
+      return gradient
+        .map(([stop, color]) => `${color} ${(stop as number) * 100}%`)
+        .join(", ");
+    }
+  );
+
   private _valueChanged(ev: CustomEvent) {
     ev.stopPropagation();
     const value = ev.detail.value;
@@ -86,11 +126,10 @@ class HuiLightColorTempTileFeature
   static get styles() {
     return css`
       ha-control-slider {
+        --control-slider-color: var(--tile-color);
         --control-slider-background: -webkit-linear-gradient(
           left,
-          rgb(255, 160, 0) 0%,
-          white 50%,
-          rgb(166, 209, 255) 100%
+          var(--gradient)
         );
         --control-slider-background-opacity: 1;
         --control-slider-thickness: 40px;