wcheng81
/
jtBaseApp


			
				
					
						
						
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							/*!
 * All material copyright ESRI, All Rights Reserved, unless otherwise specified.
 * See https://github.com/Esri/calcite-components/blob/master/LICENSE.md for details.
 * v1.0.0-beta.97
 */
import { autoTheme, darkTheme } from "./resources";
/**
 * Emits when the theme is dynamically toggled between light and dark on <body> or in OS preferences.
 */
export function initThemeChangeEvent() {
  const { classList } = document.body;
  const prefersDark = window.matchMedia("(prefers-color-scheme: dark)").matches;
  const getTheme = () => classList.contains(darkTheme) || (classList.contains(autoTheme) && prefersDark) ? "dark" : "light";
  const emitThemeChange = (theme) => document.body.dispatchEvent(new CustomEvent("calciteThemeChange", { bubbles: true, detail: { theme } }));
  const themeChangeHandler = (newTheme) => {
    currentTheme !== newTheme && emitThemeChange(newTheme);
    currentTheme = newTheme;
  };
  let currentTheme = getTheme();
  // emits event on page load
  emitThemeChange(currentTheme);
  // emits event when changing OS theme preferences
  window
    .matchMedia("(prefers-color-scheme: dark)")
    .addEventListener("change", (event) => themeChangeHandler(event.matches ? "dark" : "light"));
  // emits event when toggling between theme classes on <body>
  new MutationObserver(() => themeChangeHandler(getTheme())).observe(document.body, {
    attributes: true,
    attributeFilter: ["class"]
  });
}