ImageComponent.tsx

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 */

import type {
  BaseSelection,
  LexicalCommand,
  LexicalEditor,
  NodeKey,
} from 'lexical';

import './ImageNode.css';

import {AutoFocusPlugin} from '@lexical/react/LexicalAutoFocusPlugin';
import {useCollaborationContext} from '@lexical/react/LexicalCollaborationContext';
import {CollaborationPlugin} from '@lexical/react/LexicalCollaborationPlugin';
import {useLexicalComposerContext} from '@lexical/react/LexicalComposerContext';
import LexicalErrorBoundary from '@lexical/react/LexicalErrorBoundary';
import {HashtagPlugin} from '@lexical/react/LexicalHashtagPlugin';
import {HistoryPlugin} from '@lexical/react/LexicalHistoryPlugin';
import {LexicalNestedComposer} from '@lexical/react/LexicalNestedComposer';
import {RichTextPlugin} from '@lexical/react/LexicalRichTextPlugin';
import {useLexicalNodeSelection} from '@lexical/react/useLexicalNodeSelection';
import {mergeRegister} from '@lexical/utils';
import {
  $getNodeByKey,
  $getSelection,
  $isNodeSelection,
  $isRangeSelection,
  $setSelection,
  CLICK_COMMAND,
  COMMAND_PRIORITY_LOW,
  createCommand,
  DRAGSTART_COMMAND,
  KEY_BACKSPACE_COMMAND,
  KEY_DELETE_COMMAND,
  KEY_ENTER_COMMAND,
  KEY_ESCAPE_COMMAND,
  SELECTION_CHANGE_COMMAND,
} from 'lexical';
import * as React from 'react';
import {Suspense, useCallback, useEffect, useRef, useState} from 'react';

import {createWebsocketProvider} from '../collaboration';
import {useSettings} from '../context/SettingsContext';
import {useSharedHistoryContext} from '../context/SharedHistoryContext';
import EmojisPlugin from '../plugins/EmojisPlugin';
import KeywordsPlugin from '../plugins/KeywordsPlugin';
import LinkPlugin from '../plugins/LinkPlugin';
import MentionsPlugin from '../plugins/MentionsPlugin';
import TreeViewPlugin from '../plugins/TreeViewPlugin';
import ContentEditable from '../ui/ContentEditable';
import ImageResizer from '../ui/ImageResizer';
import Placeholder from '../ui/Placeholder';
import {$isImageNode} from './ImageNode';

const imageCache = new Set();

export const RIGHT_CLICK_IMAGE_COMMAND: LexicalCommand<MouseEvent> =
  createCommand('RIGHT_CLICK_IMAGE_COMMAND');

function useSuspenseImage(src: string) {
  if (!imageCache.has(src)) {
    throw new Promise((resolve) => {
      const img = new Image();
      img.src = src;
      img.onload = () => {
        imageCache.add(src);
        resolve(null);
      };
    });
  }
}

function LazyImage({
  altText,
  className,
  imageRef,
  src,
  width,
  height,
  maxWidth,
}: {
  altText: string;
  className: string | null;
  height: 'inherit' | number;
  imageRef: {current: null | HTMLImageElement};
  maxWidth: number;
  src: string;
  width: 'inherit' | number;
}): JSX.Element {
  useSuspenseImage(src);
  return (
    <img
      className={className || undefined}
      src={src}
      alt={altText}
      ref={imageRef}
      style={{
        height,
        maxWidth,
        width,
      }}
      draggable="false"
    />
  );
}

export default function ImageComponent({
  src,
  altText,
  nodeKey,
  width,
  height,
  maxWidth,
  resizable,
  showCaption,
  caption,
  captionsEnabled,
}: {
  altText: string;
  caption: LexicalEditor;
  height: 'inherit' | number;
  maxWidth: number;
  nodeKey: NodeKey;
  resizable: boolean;
  showCaption: boolean;
  src: string;
  width: 'inherit' | number;
  captionsEnabled: boolean;
}): JSX.Element {
  const imageRef = useRef<null | HTMLImageElement>(null);
  const buttonRef = useRef<HTMLButtonElement | null>(null);
  const [isSelected, setSelected, clearSelection] =
    useLexicalNodeSelection(nodeKey);
  const [isResizing, setIsResizing] = useState<boolean>(false);
  const {isCollabActive} = useCollaborationContext();
  const [editor] = useLexicalComposerContext();
  const [selection, setSelection] = useState<BaseSelection | null>(null);
  const activeEditorRef = useRef<LexicalEditor | null>(null);

  const onDelete = useCallback(
    (payload: KeyboardEvent) => {
      if (isSelected && $isNodeSelection($getSelection())) {
        const event: KeyboardEvent = payload;
        event.preventDefault();
        const node = $getNodeByKey(nodeKey);
        if ($isImageNode(node)) {
          node.remove();
          return true;
        }
      }
      return false;
    },
    [isSelected, nodeKey],
  );

  const onEnter = useCallback(
    (event: KeyboardEvent) => {
      const latestSelection = $getSelection();
      const buttonElem = buttonRef.current;
      if (
        isSelected &&
        $isNodeSelection(latestSelection) &&
        latestSelection.getNodes().length === 1
      ) {
        if (showCaption) {
          // Move focus into nested editor
          $setSelection(null);
          event.preventDefault();
          caption.focus();
          return true;
        } else if (
          buttonElem !== null &&
          buttonElem !== document.activeElement
        ) {
          event.preventDefault();
          buttonElem.focus();
          return true;
        }
      }
      return false;
    },
    [caption, isSelected, showCaption],
  );

  const onEscape = useCallback(
    (event: KeyboardEvent) => {
      if (
        activeEditorRef.current === caption ||
        buttonRef.current === event.target
      ) {
        $setSelection(null);
        editor.update(() => {
          setSelected(true);
          const parentRootElement = editor.getRootElement();
          if (parentRootElement !== null) {
            parentRootElement.focus();
          }
        });
        return true;
      }
      return false;
    },
    [caption, editor, setSelected],
  );

  const onClick = useCallback(
    (payload: MouseEvent) => {
      const event = payload;

      if (isResizing) {
        return true;
      }
      if (event.target === imageRef.current) {
        if (event.shiftKey) {
          setSelected(!isSelected);
        } else {
          clearSelection();
          setSelected(true);
        }
        return true;
      }

      return false;
    },
    [isResizing, isSelected, setSelected, clearSelection],
  );

  const onRightClick = useCallback(
    (event: MouseEvent): void => {
      editor.getEditorState().read(() => {
        const latestSelection = $getSelection();
        const domElement = event.target as HTMLElement;
        if (
          domElement.tagName === 'IMG' &&
          $isRangeSelection(latestSelection) &&
          latestSelection.getNodes().length === 1
        ) {
          editor.dispatchCommand(
            RIGHT_CLICK_IMAGE_COMMAND,
            event as MouseEvent,
          );
        }
      });
    },
    [editor],
  );

  useEffect(() => {
    let isMounted = true;
    const rootElement = editor.getRootElement();
    const unregister = mergeRegister(
      editor.registerUpdateListener(({editorState}) => {
        if (isMounted) {
          setSelection(editorState.read(() => $getSelection()));
        }
      }),
      editor.registerCommand(
        SELECTION_CHANGE_COMMAND,
        (_, activeEditor) => {
          activeEditorRef.current = activeEditor;
          return false;
        },
        COMMAND_PRIORITY_LOW,
      ),
      editor.registerCommand<MouseEvent>(
        CLICK_COMMAND,
        onClick,
        COMMAND_PRIORITY_LOW,
      ),
      editor.registerCommand<MouseEvent>(
        RIGHT_CLICK_IMAGE_COMMAND,
        onClick,
        COMMAND_PRIORITY_LOW,
      ),
      editor.registerCommand(
        DRAGSTART_COMMAND,
        (event) => {
          if (event.target === imageRef.current) {
            // TODO This is just a temporary workaround for FF to behave like other browsers.
            // Ideally, this handles drag & drop too (and all browsers).
            event.preventDefault();
            return true;
          }
          return false;
        },
        COMMAND_PRIORITY_LOW,
      ),
      editor.registerCommand(
        KEY_DELETE_COMMAND,
        onDelete,
        COMMAND_PRIORITY_LOW,
      ),
      editor.registerCommand(
        KEY_BACKSPACE_COMMAND,
        onDelete,
        COMMAND_PRIORITY_LOW,
      ),
      editor.registerCommand(KEY_ENTER_COMMAND, onEnter, COMMAND_PRIORITY_LOW),
      editor.registerCommand(
        KEY_ESCAPE_COMMAND,
        onEscape,
        COMMAND_PRIORITY_LOW,
      ),
    );

    rootElement?.addEventListener('contextmenu', onRightClick);

    return () => {
      isMounted = false;
      unregister();
      rootElement?.removeEventListener('contextmenu', onRightClick);
    };
  }, [
    clearSelection,
    editor,
    isResizing,
    isSelected,
    nodeKey,
    onDelete,
    onEnter,
    onEscape,
    onClick,
    onRightClick,
    setSelected,
  ]);

  const setShowCaption = () => {
    editor.update(() => {
      const node = $getNodeByKey(nodeKey);
      if ($isImageNode(node)) {
        node.setShowCaption(true);
      }
    });
  };

  const onResizeEnd = (
    nextWidth: 'inherit' | number,
    nextHeight: 'inherit' | number,
  ) => {
    // Delay hiding the resize bars for click case
    setTimeout(() => {
      setIsResizing(false);
    }, 200);

    editor.update(() => {
      const node = $getNodeByKey(nodeKey);
      if ($isImageNode(node)) {
        node.setWidthAndHeight(nextWidth, nextHeight);
      }
    });
  };

  const onResizeStart = () => {
    setIsResizing(true);
  };

  const {historyState} = useSharedHistoryContext();
  const {
    settings: {showNestedEditorTreeView},
  } = useSettings();

  const draggable = isSelected && $isNodeSelection(selection) && !isResizing;
  const isFocused = isSelected || isResizing;
  return (
    <Suspense fallback={null}>
      <>
        <div draggable={draggable}>
          <LazyImage
            className={
              isFocused
                ? `focused ${$isNodeSelection(selection) ? 'draggable' : ''}`
                : null
            }
            src={src}
            altText={altText}
            imageRef={imageRef}
            width={width}
            height={height}
            maxWidth={maxWidth}
          />
        </div>
        {showCaption && (
          <div className="image-caption-container">
            <LexicalNestedComposer initialEditor={caption}>
              <AutoFocusPlugin />
              <MentionsPlugin />
              <LinkPlugin />
              <EmojisPlugin />
              <HashtagPlugin />
              <KeywordsPlugin />
              {isCollabActive ? (
                <CollaborationPlugin
                  id={caption.getKey()}
                  providerFactory={createWebsocketProvider}
                  shouldBootstrap={true}
                />
              ) : (
                <HistoryPlugin externalHistoryState={historyState} />
              )}
              <RichTextPlugin
                contentEditable={
                  <ContentEditable className="ImageNode__contentEditable" />
                }
                placeholder={
                  <Placeholder className="ImageNode__placeholder">
                    Enter a caption...
                  </Placeholder>
                }
                ErrorBoundary={LexicalErrorBoundary}
              />
              {showNestedEditorTreeView === true ? <TreeViewPlugin /> : null}
            </LexicalNestedComposer>
          </div>
        )}
        {resizable && $isNodeSelection(selection) && isFocused && (
          <ImageResizer
            showCaption={showCaption}
            setShowCaption={setShowCaption}
            editor={editor}
            buttonRef={buttonRef}
            imageRef={imageRef}
            maxWidth={maxWidth}
            onResizeStart={onResizeStart}
            onResizeEnd={onResizeEnd}
            captionsEnabled={captionsEnabled}
          />
        )}
      </>
    </Suspense>
  );
}