feat: Support LaTeX and AsciiMath via MathJax on stem.excalidraw.com

src/subtypes.ts

@@ -0,0 +1,417 @@
+import {
+  ExcalidrawElement,
+  ExcalidrawTextElement,
+  NonDeleted,
+} from "./element/types";
+import { getNonDeletedElements } from "./element";
+import { getSelectedElements } from "./scene";
+import { AppState } from "./types";
+import { registerAuxLangData } from "./i18n";
+
+import { Action, ActionName, DisableFn, EnableFn } from "./actions/types";
+import {
+  CustomShortcutName,
+  registerCustomShortcuts,
+} from "./actions/shortcuts";
+import { register } from "./actions/register";
+import { registerDisableFn, registerEnableFn } from "./actions/guards";
+import { hasBoundTextElement } from "./element/typeChecks";
+import { getBoundTextElement } from "./element/textElement";
+
+// Use "let" instead of "const" so we can dynamically add subtypes
+let subtypeNames: readonly Subtype[] = [];
+let parentTypeMap: readonly {
+  subtype: Subtype;
+  parentType: ExcalidrawElement["type"];
+}[] = [];
+let subtypeActionMap: readonly {
+  subtype: Subtype;
+  actions: readonly SubtypeActionName[];
+}[] = [];
+let disabledActionMap: readonly {
+  subtype: Subtype;
+  actions: readonly DisabledActionName[];
+}[] = [];
+let alwaysEnabledMap: readonly {
+  subtype: Subtype;
+  actions: readonly SubtypeActionName[];
+}[] = [];
+
+export type SubtypeRecord = Readonly<{
+  subtype: Subtype;
+  parents: readonly ExcalidrawElement["type"][];
+  actionNames?: readonly SubtypeActionName[];
+  disabledNames?: readonly DisabledActionName[];
+  shortcutMap?: Record<CustomShortcutName, string[]>;
+  alwaysEnabledNames?: readonly SubtypeActionName[];
+}>;
+
+// Subtype Names
+export type Subtype = string;
+export const getSubtypeNames = (): readonly Subtype[] => {
+  return subtypeNames;
+};
+export const isValidSubtype = (s: any, t: any): s is Subtype =>
+  parentTypeMap.find(
+    (val) => val.subtype === (s as string) && val.parentType === (t as string),
+  ) !== undefined;
+const isSubtypeName = (s: any): s is Subtype => subtypeNames.includes(s);
+
+// Subtype Actions
+
+// Used for context menus in the shape chooser
+export const hasAlwaysEnabledActions = (s: any): boolean => {
+  if (!isSubtypeName(s)) {
+    return false;
+  }
+  return alwaysEnabledMap.some((value) => value.subtype === s);
+};
+
+type SubtypeActionName = string;
+
+const isSubtypeActionName = (s: any): s is SubtypeActionName =>
+  subtypeActionMap.some((val) => val.actions.includes(s));
+
+const addSubtypeAction = (action: Action) => {
+  if (isSubtypeActionName(action.name) || isSubtypeName(action.name)) {
+    register(action);
+  }
+};
+
+// Standard actions disabled by subtypes
+type DisabledActionName = ActionName;
+
+const isDisabledActionName = (s: any): s is DisabledActionName =>
+  disabledActionMap.some((val) => val.actions.includes(s));
+
+// Is the `actionName` one of the subtype actions for `subtype`
+// (if `isAdded` is true) or one of the standard actions disabled
+// by `subtype` (if `isAdded` is false)?
+const isForSubtype = (
+  subtype: ExcalidrawElement["subtype"],
+  actionName: ActionName | SubtypeActionName,
+  isAdded: boolean,
+) => {
+  const actions = isAdded ? subtypeActionMap : disabledActionMap;
+  const map = actions.find((value) => value.subtype === subtype);
+  if (map) {
+    return map.actions.includes(actionName);
+  }
+  return false;
+};
+
+const isActionDisabled: DisableFn = function (elements, appState, actionName) {
+  return !isActionEnabled(elements, appState, actionName);
+};
+
+const isActionEnabled: EnableFn = function (elements, appState, actionName) {
+  // We always enable subtype actions.  Also let through standard actions
+  // which no subtypes might have disabled.
+  if (
+    isSubtypeName(actionName) ||
+    (!isSubtypeActionName(actionName) && !isDisabledActionName(actionName))
+  ) {
+    return true;
+  }
+  const selectedElements = getSelectedElements(
+    getNonDeletedElements(elements),
+    appState,
+  );
+  const chosen = appState.editingElement
+    ? [appState.editingElement, ...selectedElements]
+    : selectedElements;
+  // Now handle actions added by subtypes
+  if (isSubtypeActionName(actionName)) {
+    // Has any ExcalidrawElement enabled this actionName through having
+    // its subtype?
+    return (
+      chosen.some((el) => {
+        const e = hasBoundTextElement(el) ? getBoundTextElement(el)! : el;
+        return isForSubtype(e.subtype, actionName, true);
+      }) ||
+      // Or has any active subtype enabled this actionName?
+      (appState.activeSubtypes !== undefined &&
+        appState.activeSubtypes?.some((subtype) => {
+          if (!isValidSubtype(subtype, appState.activeTool.type)) {
+            return false;
+          }
+          return isForSubtype(subtype, actionName, true);
+        })) ||
+      alwaysEnabledMap.some((value) => {
+        return value.actions.includes(actionName);
+      })
+    );
+  }
+  // Now handle standard actions disabled by subtypes
+  if (isDisabledActionName(actionName)) {
+    return (
+      // Has every ExcalidrawElement not disabled this actionName?
+      (chosen.every((el) => {
+        const e = hasBoundTextElement(el) ? getBoundTextElement(el)! : el;
+        return !isForSubtype(e.subtype, actionName, false);
+      }) &&
+        // And has every active subtype not disabled this actionName?
+        (appState.activeSubtypes === undefined ||
+          appState.activeSubtypes?.every((subtype) => {
+            if (!isValidSubtype(subtype, appState.activeTool.type)) {
+              return true;
+            }
+            return !isForSubtype(subtype, actionName, false);
+          }))) ||
+      // Or is there an ExcalidrawElement without a subtype which would
+      // disable this action if it had a subtype?
+      chosen.some((el) => {
+        const e = hasBoundTextElement(el) ? getBoundTextElement(el)! : el;
+        return parentTypeMap.some(
+          (value) =>
+            value.parentType === e.type &&
+            e.subtype === undefined &&
+            disabledActionMap
+              .find((val) => val.subtype === value.subtype)!
+              .actions.includes(actionName),
+        );
+      })
+    );
+  }
+  // Shouldn't happen
+  return true;
+};
+
+// Are any of the parent types of `subtype` shared by any subtype
+// in the array?
+export const subtypeCollides = (subtype: Subtype, subtypeArray: Subtype[]) => {
+  const subtypeParents = parentTypeMap
+    .filter((value) => value.subtype === subtype)
+    .map((value) => value.parentType);
+  const subtypeArrayParents = subtypeArray.flatMap((s) =>
+    parentTypeMap
+      .filter((value) => value.subtype === s)
+      .map((value) => value.parentType),
+  );
+  return subtypeParents.some((t) => subtypeArrayParents.includes(t));
+};
+
+// Subtype Methods
+export type SubtypeMethods = {
+  clean: (
+    updates: Omit<
+      Partial<ExcalidrawElement>,
+      "id" | "version" | "versionNonce"
+    >,
+  ) => Omit<Partial<ExcalidrawElement>, "id" | "version" | "versionNonce">;
+  ensureLoaded: (callback?: () => void) => Promise<void>;
+  measureText: (
+    element: Pick<
+      ExcalidrawTextElement,
+      "subtype" | "customData" | "fontSize" | "fontFamily" | "text"
+    >,
+    next?: {
+      fontSize?: number;
+      text?: string;
+      customData?: ExcalidrawElement["customData"];
+    },
+    maxWidth?: number | null,
+  ) => { width: number; height: number; baseline: number };
+  render: (
+    element: NonDeleted<ExcalidrawElement>,
+    context: CanvasRenderingContext2D,
+    renderCb?: () => void,
+  ) => void;
+  renderSvg: (
+    svgRoot: SVGElement,
+    root: SVGElement,
+    element: NonDeleted<ExcalidrawElement>,
+    opt?: { offsetX?: number; offsetY?: number },
+  ) => void;
+  wrapText: (
+    element: Pick<
+      ExcalidrawTextElement,
+      "subtype" | "customData" | "fontSize" | "fontFamily" | "originalText"
+    >,
+    containerWidth: number,
+    next?: {
+      fontSize?: number;
+      text?: string;
+      customData?: ExcalidrawElement["customData"];
+    },
+  ) => string;
+};
+
+type MethodMap = { subtype: Subtype; methods: Partial<SubtypeMethods> };
+const methodMaps = [] as Array<MethodMap>;
+
+// Use `getSubtypeMethods` to call subtype-specialized methods, like `render`.
+export const getSubtypeMethods = (subtype: Subtype | undefined) => {
+  const map = methodMaps.find((method) => method.subtype === subtype);
+  return map?.methods;
+};
+
+export const addSubtypeMethods = (
+  subtype: Subtype,
+  methods: Partial<SubtypeMethods>,
+) => {
+  if (!methodMaps.find((method) => method.subtype === subtype)) {
+    methodMaps.push({ subtype, methods });
+  }
+};
+
+// For a given `ExcalidrawElement` type, return the active subtype
+// and associated customData (if any) from the AppState.  Assume
+// only one subtype is active for a given `ExcalidrawElement` type
+// at any given time.
+export const selectSubtype = (
+  appState: {
+    activeSubtypes?: AppState["activeSubtypes"];
+    customData?: AppState["customData"];
+  },
+  type: ExcalidrawElement["type"],
+): {
+  subtype?: ExcalidrawElement["subtype"];
+  customData?: ExcalidrawElement["customData"];
+} => {
+  if (appState.activeSubtypes === undefined) {
+    return {};
+  }
+  const subtype = appState.activeSubtypes.find((subtype) =>
+    isValidSubtype(subtype, type),
+  );
+  if (subtype === undefined) {
+    return {};
+  }
+  if (appState.customData === undefined || !(subtype in appState.customData)) {
+    return { subtype };
+  }
+  const customData = appState.customData[subtype];
+  return { subtype, customData };
+};
+
+// Callback to re-render subtyped `ExcalidrawElement`s after completing
+// async loading of the subtype.
+export type SubtypeLoadedCb = (
+  hasSubtype: (element: ExcalidrawElement) => boolean,
+) => void;
+
+// Functions to prepare subtypes for use
+export type SubtypePrepFn = (
+  addSubtypeAction: (action: Action) => void,
+  addLangData: (
+    fallbackLangData: Object,
+    setLanguageAux: (langCode: string) => Promise<Object | undefined>,
+  ) => void,
+  onSubtypeLoaded?: SubtypeLoadedCb,
+) => {
+  actions: Action[];
+  methods: Partial<SubtypeMethods>;
+};
+
+// This is the main method to set up the subtype.  The optional
+// `onSubtypeLoaded` callback may be used to re-render subtyped
+// `ExcalidrawElement`s after the subtype has finished async loading.
+// See the MathJax extension in `@excalidraw/extensions` for example.
+export const prepareSubtype = (
+  record: SubtypeRecord,
+  subtypePrepFn: SubtypePrepFn,
+  onSubtypeLoaded?: SubtypeLoadedCb,
+): { actions: Action[] | null; methods: Partial<SubtypeMethods> } => {
+  const map = getSubtypeMethods(record.subtype);
+  if (map) {
+    return { actions: null, methods: map };
+  }
+
+  // Check for undefined/null subtypes and parentTypes
+  if (
+    record.subtype === undefined ||
+    record.subtype === "" ||
+    record.parents === undefined ||
+    record.parents.length === 0
+  ) {
+    return { actions: null, methods: {} };
+  }
+
+  // Register the types
+  const subtype = record.subtype;
+  subtypeNames = [...subtypeNames, subtype];
+  record.parents.forEach((parentType) => {
+    parentTypeMap = [...parentTypeMap, { subtype, parentType }];
+  });
+  if (record.actionNames) {
+    subtypeActionMap = [
+      ...subtypeActionMap,
+      { subtype, actions: record.actionNames },
+    ];
+  }
+  if (record.disabledNames) {
+    disabledActionMap = [
+      ...disabledActionMap,
+      { subtype, actions: record.disabledNames },
+    ];
+  }
+  if (record.alwaysEnabledNames) {
+    alwaysEnabledMap = [
+      ...alwaysEnabledMap,
+      { subtype, actions: record.alwaysEnabledNames },
+    ];
+  }
+  if (record.shortcutMap) {
+    registerCustomShortcuts(record.shortcutMap);
+  }
+
+  // Prepare the subtype
+  const { actions, methods } = subtypePrepFn(
+    addSubtypeAction,
+    registerAuxLangData,
+    onSubtypeLoaded,
+  );
+
+  record.disabledNames?.forEach((name) => {
+    registerDisableFn(name, isActionDisabled);
+  });
+  record.actionNames?.forEach((name) => {
+    registerEnableFn(name, isActionEnabled);
+  });
+  registerEnableFn(record.subtype, isActionEnabled);
+  // Register the subtype's methods
+  addSubtypeMethods(record.subtype, methods);
+  return { actions, methods };
+};
+
+// Ensure all subtypes are loaded before continuing, eg to
+// render SVG previews of new charts.  Chart-relevant subtypes
+// include math equations in titles or non hand-drawn line styles.
+export const ensureSubtypesLoadedForElements = async (
+  elements: readonly ExcalidrawElement[],
+  callback?: () => void,
+) => {
+  // Only ensure the loading of subtypes which are actually needed.
+  // We don't want to be held up by eg downloading the MathJax SVG fonts
+  // if we don't actually need them yet.
+  const subtypesUsed = [] as Subtype[];
+  elements.forEach((el) => {
+    if (
+      "subtype" in el &&
+      isValidSubtype(el.subtype, el.type) &&
+      !subtypesUsed.includes(el.subtype)
+    ) {
+      subtypesUsed.push(el.subtype);
+    }
+  });
+  await ensureSubtypesLoaded(subtypesUsed, callback);
+};
+
+export const ensureSubtypesLoaded = async (
+  subtypes: Subtype[],
+  callback?: () => void,
+) => {
+  // Use a for loop so we can do `await map.ensureLoaded()`
+  for (let i = 0; i < subtypes.length; i++) {
+    const subtype = subtypes[i];
+    // Should be defined if prepareSubtype() has run
+    const map = getSubtypeMethods(subtype);
+    if (map?.ensureLoaded) {
+      await map.ensureLoaded();
+    }
+  }
+  if (callback) {
+    callback();
+  }
+};