Embeddable Markdown Renderer

Note

All credits for this snippet go to MgMeyers (maintainer of the Kanban plugin), who originally wrote this code.

If you have ever tried to get an input field where the Markdown syntax is properly rendered, you know that it isn’t as simple as creating a <textarea> or creating the MarkdownView.

The snippet below offers a way to create a view or field, which uses in essence the same editor that Obsidian uses. This means that all markup is rendered, vim is supported, commands can be executed, etc.

Warning

However, any CodeMirror editor extensions provided by other plugins will not be added to this editor instance. You can still re-add your own plugins in the buildLocalExtensions method.

Component

/**
 * All credits go to mgmeyers for figuring out how to grab the proper editor prototype
 *    and making it easily deployable
 * Changes made to the original code:
 *    - Refactored to JS-only syntax (original code made use of React)
 *    - Added blur completion
 *    - Added some comments on how the code functions
 *    - Made editor settings fully optional
 *    - Allow all editor commands to function on this editor
 *    - Added typings for the editor(s) (will be added to obsidian-typings)
 * Make sure to also check out the original source code here: https://github.com/mgmeyers/obsidian-kanban/blob/main/src/components/Editor/MarkdownEditor.tsx
 */

import {
  App, Constructor, Keymap, Scope, ScrollableMarkdownEditor,
  TFile, WidgetEditorView, WorkspaceLeaf,
} from "obsidian";

import {EditorSelection, Extension, Prec} from "@codemirror/state";
import {EditorView, keymap, placeholder, ViewUpdate} from "@codemirror/view";

import {around} from "monkey-around";


function resolveEditorPrototype(app: App) {
  // Create a temporary editor to resolve the prototype of ScrollableMarkdownEditor
  const widgetEditorView = app.embedRegistry.embedByExtension.md(
    { app, containerEl: document.createElement('div') },
    null as unknown as TFile,
    '',
  ) as WidgetEditorView;

  // Mark as editable to instantiate the editor
  widgetEditorView.editable = true;
  widgetEditorView.showEditor();
  const MarkdownEditor = Object.getPrototypeOf(Object.getPrototypeOf(widgetEditorView.editMode!));

  // Unload to remove the temporary editor
  widgetEditorView.unload();

  return MarkdownEditor.constructor as Constructor<ScrollableMarkdownEditor>;
}

interface MarkdownEditorProps {
  cursorLocation?: { anchor: number, head: number };
  value?: string;
  cls?: string;
  placeholder?: string;

  onEnter: (editor: EmbeddableMarkdownEditor, mod: boolean, shift: boolean) => boolean;
  onEscape: (editor: EmbeddableMarkdownEditor) => void;
  onSubmit: (editor: EmbeddableMarkdownEditor) => void;
  onBlur: (editor: EmbeddableMarkdownEditor) => void;
  onPaste: (e: ClipboardEvent, editor: EmbeddableMarkdownEditor) => void;
  onChange: (update: ViewUpdate) => void;
}

const defaultProperties: MarkdownEditorProps = {
  cursorLocation: { anchor: 0, head: 0 },
  value: '',
  cls: '',
  placeholder: '',

  onEnter: () => false,
  onEscape: () => {},
  onSubmit: () => {},
  // NOTE: Blur takes precedence over Escape (this can be changed)
  onBlur: () => {},
  onPaste: () => {},
  onChange: () => {},
}


export class EmbeddableMarkdownEditor extends resolveEditorPrototype(app) implements ScrollableMarkdownEditor {
  options: MarkdownEditorProps;
  initial_value: string;
  scope: Scope;

  /**
   * Construct the editor
   * @remark Takes 5ms to fully construct and attach
   * @param app - Reference to App instance
   * @param container - Container element to add the editor to
   * @param options - Options for controling the initial state of the editor
   */
  constructor(app: App, container: HTMLElement, options: Partial<MarkdownEditorProps>) {
    super(app, container, {
      app,
      // This mocks the MarkdownView functions, which is required for proper functioning of scrolling
      onMarkdownScroll: () => {},
      getMode: () => 'source',
    });
    this.options = {...defaultProperties, ...options};
    this.initial_value = this.options.value!;
    this.scope = new Scope(this.app.scope);
    // NOTE: Hotkeys take precedence over CM keymap, so scope is introduced to allow for specific hotkeys to be overwritten
    //   In this case, since Mod+Enter is linked to the "Open link in new leaf" command, but it is also the default user action for submitting the editor,
    //      the scope is used to prevent the hotkey from executing (by returning `true`)
    // TODO: It is also possible to allow both behaviours to coexist:
    //     1) Fetch the command via hotkeyManager
    //     2) Execute the command callback
    //     3) Return the result of the callback (callback returns false if callback could not execute)
    //         (In this case, if cursor is not on a link token, the callback will return false, and onEnter will be applied)
    this.scope.register(["Mod"], "Enter", (e, ctx) => {
      return true;
    });

    // Since the commands expect that this is a MarkdownView (with editMode as the Editor itself),
    //   we need to mock this by setting both the editMode and editor to this instance and its containing view respectively
    // @ts-expect-error (editMode is normally a MarkdownSubView)
    this.owner.editMode = this;
    this.owner.editor = this.editor;

    this.set(options.value || '');
    this.register(
      around(this.app.workspace, {
        // @ts-expect-error (Incorrectly matches the deprecated setActiveLeaf method)
        setActiveLeaf: (oldMethod: (leaf: WorkspaceLeaf, params?: ({ focus?: boolean })) => void) =>
          (leaf: WorkspaceLeaf, params: { focus?: boolean }) => {
            // If the editor is currently focused, prevent the workspace setting the focus to a workspaceLeaf instead
            if (!this.activeCM.hasFocus)
              oldMethod.call(this.app.workspace, leaf, params);
          },
      }),
    );

    // Execute onBlur when the editor loses focus
    // NOTE: Apparently Chrome does a weird thing where removing an element from the DOM triggers a blur event
    //     (Hence why the ._loaded check is necessary)
    if (this.options.onBlur !== defaultProperties.onBlur) {
      this.editor.cm.contentDOM.addEventListener('blur', () => {
        this.app.keymap.popScope(this.scope);
        if (this._loaded)
          this.options.onBlur(this)
      });
    }

    // Whenever the editor is focused, set the activeEditor to the mocked view (this.owner)
    // This allows for the editorCommands to actually work
    this.editor.cm.contentDOM.addEventListener('focusin', (e) => {
      this.app.keymap.pushScope(this.scope);
      this.app.workspace.activeEditor = this.owner;
    });

    if (options.cls) this.editorEl.classList.add(options.cls);
    if (options.cursorLocation) {
      this.editor.cm.dispatch({
        selection: EditorSelection.range(options.cursorLocation.anchor, options.cursorLocation.head),
      });
    }
  }

  get value() {
    return this.editor.cm.state.doc.toString();
  }

  onUpdate(update: ViewUpdate, changed: boolean) {
    super.onUpdate(update, changed);
    if (changed) this.options.onChange(update);
  }

  /**
   * Loads the CM extensions for rendering Markdown and handling user inputs
   * Note that other plugins will not be able to send updates to these extensions to change configurations
   */
  buildLocalExtensions(): Extension[] {
    const extensions = super.buildLocalExtensions();
    if (this.options.placeholder) extensions.push(placeholder(this.options.placeholder));

    /* Editor extension for handling specific user inputs */
    extensions.push(EditorView.domEventHandlers({ paste: (event) => {
      this.options.onPaste(event, this);
    }}));
    extensions.push(Prec.highest(keymap.of([
      {
        key: 'Enter',
        run: (cm) => this.options.onEnter(this, false, false),
        shift: (cm) => this.options.onEnter(this, false, true)
      },
      {
        key: 'Mod-Enter',
        run: (cm) => this.options.onEnter(this, true, false),
        shift: (cm) => this.options.onEnter(this, true, true)
      },
      {
        key: 'Escape',
        run: (cm) => {
          this.options.onEscape(this);
          return true;
        },
        preventDefault: true
      }
    ])));

    /* Additional Editor extensions (renderers, ...) */


    return extensions;
  }

  /**
   * Ensure that the editor is properly destroyed when the view is closed
   */
  destroy(): void {
    if (this._loaded)
      this.unload();
    this.app.keymap.popScope(this.scope);
    this.app.workspace.activeEditor = null;
    this.containerEl.empty();
    super.destroy();
  }

  /**
   * When removing as a component, destroy will also get invoked
   */
  onunload() {
    super.onunload();
    this.destroy();
  }
}

Example Usage

The code below gives an example of how you might mount this Editor instance to a View, for instance. Do note that you can technically add the Editor anywhere you want.

/**
 * This view provides an example on how you can utilise the EmbeddableMarkdownEditor
 * Note that it is not required for the editor be marked to a leaf or view,
 *   but you do need to be careful in managing the editor lifecycle (via registering it to a component or destroying it manually)
 */

import {EmbeddableMarkdownEditor} from "./embeddable-editor";
import SamplePlugin from "./main";
import {ItemView, Notice, WorkspaceLeaf} from "obsidian";

export const SAMPLE_VIEW_ID = "example-view";
export class SampleView extends ItemView {
  editors: HTMLElement[] = [];

  constructor(private plugin: SamplePlugin, leaf: WorkspaceLeaf) {
    super(leaf);
  }

  getViewType() {
    return SAMPLE_VIEW_ID;
  }

  getDisplayText() {
    return "Sample View";
  }

  createEditor(container: HTMLElement) {
    // The editor can easily be destructed via calling the.removeChild(editor) method (if registered),
    //    or by calling editor.destroy()
    return this.addChild(new EmbeddableMarkdownEditor(this.app, container, {
      onEscape: (editor) => {
        new Notice(`Escaped the editor: (${editor.initial_value})`);
        this.removeChild(editor);
      },
      onEnter: (editor, mod: boolean, shift: boolean) => {
        if (mod) {
          new Notice(`Ctrl+Entered on the editor: (${editor.value})`);
          this.removeChild(editor);
        }
        return false;
      },
      onSubmit: (editor) => {
        new Notice(`Submitted on the editor: (${editor.value})`);
        this.removeChild(editor);
      },
      // onBlur: (editor) => {
      //   new Notice(`Unfocused the editor: (${editor.initial_value})`);
      //   this.removeChild(editor);
      // },
      value: "Interesting text\n[Some link](https://www.google.com/)",
    }));
  }

  async onOpen() {
    const container = this.containerEl.children[1] as HTMLElement;
    container.empty();

    container.style.display = 'flex';
    container.style.flexDirection = 'column';
    container.style.gap = '1%';


    const numEditors = 3;
    for (let i = 0; i < numEditors; i++) {
      const editorContainer = container.createDiv({ cls: 'sample-editor' });
      editorContainer.style.height = Math.floor((100 - numEditors) / numEditors) + "%";
      editorContainer.style.border = "1px solid var(--background-modifier-border)";

      this.editors.push(editorContainer);
      this.createEditor(editorContainer);
    }
  }
}