excalidraw/src/components/LibraryUnit.tsx

import React, { useRef, useEffect, useState } from "react";
import { exportToSvg } from "../scene/export";
import { close } from "../components/icons";

import "./LibraryUnit.scss";
import { t } from "../i18n";
import useIsMobile from "../is-mobile";
import { LibraryItem } from "../types";

// fa-plus
const PLUS_ICON = (
  <svg viewBox="0 0 1792 1792">
    <path d="M1600 736v192q0 40-28 68t-68 28h-416v416q0 40-28 68t-68 28h-192q-40 0-68-28t-28-68v-416h-416q-40 0-68-28t-28-68v-192q0-40 28-68t68-28h416v-416q0-40 28-68t68-28h192q40 0 68 28t28 68v416h416q40 0 68 28t28 68z" />
  </svg>
);

export const LibraryUnit = ({
  elements,
  pendingElements,
  onRemoveFromLibrary,
  onClick,
}: {
  elements?: LibraryItem;
  pendingElements?: LibraryItem;
  onRemoveFromLibrary: () => void;
  onClick: () => void;
}) => {
  const ref = useRef<HTMLDivElement | null>(null);
  useEffect(() => {
    const elementsToRender = elements || pendingElements;
    if (!elementsToRender) {
      return;
    }
    const svg = exportToSvg(elementsToRender, {
      exportBackground: false,
      viewBackgroundColor: "#fff",
      shouldAddWatermark: false,
    });
    for (const child of ref.current!.children) {
      if (child.tagName !== "svg") {
        continue;
      }
      ref.current!.removeChild(child);
    }
    ref.current!.appendChild(svg);

    const current = ref.current!;
    return () => {
      current.removeChild(svg);
    };
  }, [elements, pendingElements]);

  const [isHovered, setIsHovered] = useState(false);
  const isMobile = useIsMobile();

  const adder = (isHovered || isMobile) && pendingElements && (
    <div className="library-unit__adder">{PLUS_ICON}</div>
  );

  return (
    <div
      className={`library-unit ${
        elements || pendingElements ? "library-unit__active" : ""
      }`}
      onMouseEnter={() => setIsHovered(true)}
      onMouseLeave={() => setIsHovered(false)}
    >
      <div
        className={`library-unit__dragger ${
          !!pendingElements ? "library-unit__pulse" : ""
        }`}
        ref={ref}
        draggable={!!elements}
        onClick={!!elements || !!pendingElements ? onClick : undefined}
        onDragStart={(event) => {
          setIsHovered(false);
          event.dataTransfer.setData(
            "application/vnd.excalidrawlib+json",
            JSON.stringify(elements),
          );
        }}
      />
      {adder}
      {elements && (isHovered || isMobile) && (
        <button
          className="library-unit__removeFromLibrary"
          aria-label={t("labels.removeFromLibrary")}
          onClick={onRemoveFromLibrary}
        >
          {close}
        </button>
      )}
    </div>
  );
};