Align.

src/actions/manager.tsx

@@ -2,10 +2,10 @@ import React from "react";
 import {
   Action,
   UpdaterFn,
-  ActionName,
   ActionResult,
   PanelComponentProps,
   ActionSource,
+  ActionPredicateFn,
 } from "./types";
 import { ExcalidrawElement } from "../element/types";
 import { AppClassProperties, AppState } from "../types";
@@ -40,7 +40,8 @@ const trackAction = (
 };
 
 export class ActionManager {
-  actions = {} as Record<ActionName, Action>;
+  actions = {} as Record<Action["name"], Action>;
+  actionPredicates = [] as ActionPredicateFn[];
 
   updater: (actionResult: ActionResult | Promise<ActionResult>) => void;
 
@@ -68,6 +69,12 @@ export class ActionManager {
     this.app = app;
   }
 
+  registerActionPredicate(predicate: ActionPredicateFn) {
+    if (!this.actionPredicates.includes(predicate)) {
+      this.actionPredicates.push(predicate);
+    }
+  }
+
   registerAction(action: Action) {
     this.actions[action.name] = action;
   }
@@ -84,7 +91,7 @@ export class ActionManager {
         (action) =>
           (action.name in canvasActions
             ? canvasActions[action.name as keyof typeof canvasActions]
-            : true) &&
+            : this.isActionEnabled(action, { noPredicates: true })) &&
           action.keyTest &&
           action.keyTest(
             event,
@@ -134,7 +141,7 @@ export class ActionManager {
   /**
    * @param data additional data sent to the PanelComponent
    */
-  renderAction = (name: ActionName, data?: PanelComponentProps["data"]) => {
+  renderAction = (name: Action["name"], data?: PanelComponentProps["data"]) => {
     const canvasActions = this.app.props.UIOptions.canvasActions;
 
     if (
@@ -142,7 +149,7 @@ export class ActionManager {
       "PanelComponent" in this.actions[name] &&
       (name in canvasActions
         ? canvasActions[name as keyof typeof canvasActions]
-        : true)
+        : this.isActionEnabled(this.actions[name], { noPredicates: true }))
     ) {
       const action = this.actions[name];
       const PanelComponent = action.PanelComponent!;
@@ -176,13 +183,31 @@ export class ActionManager {
     return null;
   };
 
-  isActionEnabled = (action: Action) => {
+  isActionEnabled = (
-    const elements = this.getElementsIncludingDeleted();
+    action: Action,
+    opts?: {
+      elements?: readonly ExcalidrawElement[];
+      data?: Record<string, any>;
+      noPredicates?: boolean;
+    },
+  ): boolean => {
+    const elements = opts?.elements ?? this.getElementsIncludingDeleted();
     const appState = this.getAppState();
+    const data = opts?.data;
 
-    return (
+    if (
-      !action.predicate ||
+      !opts?.noPredicates &&
-      action.predicate(elements, appState, this.app.props, this.app)
+      action.predicate &&
-    );
+      !action.predicate(elements, appState, this.app.props, this.app, data)
+    ) {
+      return false;
+    }
+    let enabled = true;
+    this.actionPredicates.forEach((fn) => {
+      if (!fn(action, elements, appState, data)) {
+        enabled = false;
+      }
+    });
+    return enabled;
   };
 }

src/actions/types.ts

@@ -32,6 +32,15 @@ type ActionFn = (
   app: AppClassProperties,
 ) => ActionResult | Promise<ActionResult>;
 
+// Return `true` *unless* `Action` should be disabled
+// given `elements`, `appState`, and optionally `data`.
+export type ActionPredicateFn = (
+  action: Action,
+  elements: readonly ExcalidrawElement[],
+  appState: AppState,
+  data?: Record<string, any>,
+) => boolean;
+
 export type UpdaterFn = (res: ActionResult) => void;
 export type ActionFilterFn = (action: Action) => void;
 
@@ -132,7 +141,7 @@ export type PanelComponentProps = {
 };
 
 export interface Action {
-  name: ActionName;
+  name: string;
   PanelComponent?: React.FC<PanelComponentProps>;
   perform: ActionFn;
   keyPriority?: number;
@@ -152,6 +161,7 @@ export interface Action {
     appState: AppState,
     appProps: ExcalidrawProps,
     app: AppClassProperties,
+    data?: Record<string, any>,
   ) => boolean;
   checked?: (appState: Readonly<AppState>) => boolean;
   trackEvent:

src/components/App.tsx

@@ -479,6 +479,12 @@ class App extends React.Component<AppProps, AppState> {
 
     this.id = nanoid();
     this.library = new Library(this);
+    this.actionManager = new ActionManager(
+      this.syncActionResult,
+      () => this.state,
+      () => this.scene.getElementsIncludingDeleted(),
+      this,
+    );
     if (excalidrawRef) {
       const readyPromise =
         ("current" in excalidrawRef && excalidrawRef.current?.readyPromise) ||
@@ -499,6 +505,7 @@ class App extends React.Component<AppProps, AppState> {
         getSceneElements: this.getSceneElements,
         getAppState: () => this.state,
         getFiles: () => this.files,
+        actionManager: this.actionManager,
         refresh: this.refresh,
         setToast: this.setToast,
         id: this.id,
@@ -527,12 +534,6 @@ class App extends React.Component<AppProps, AppState> {
       onSceneUpdated: this.onSceneUpdated,
     });
     this.history = new History();
-    this.actionManager = new ActionManager(
-      this.syncActionResult,
-      () => this.state,
-      () => this.scene.getElementsIncludingDeleted(),
-      this,
-    );
     this.actionManager.registerAll(actions);
 
     this.actionManager.registerAction(createUndoAction(this.history));

src/tests/customActions.test.tsx

@@ -0,0 +1,71 @@
+import { ExcalidrawElement } from "../element/types";
+import { API } from "./helpers/api";
+import { render } from "./test-utils";
+import ExcalidrawApp from "../excalidraw-app";
+import { Action, ActionPredicateFn, ActionResult } from "../actions/types";
+import {
+  actionChangeFontFamily,
+  actionChangeFontSize,
+} from "../actions/actionProperties";
+import { isTextElement } from "../element";
+
+const { h } = window;
+
+describe("regression tests", () => {
+  it("should apply universal action predicates", async () => {
+    await render(<ExcalidrawApp />);
+    // Create the test elements
+    const el1 = API.createElement({ type: "rectangle", id: "A", y: 0 });
+    const el2 = API.createElement({ type: "rectangle", id: "B", y: 30 });
+    const el3 = API.createElement({ type: "text", id: "C", y: 60 });
+    const el12: ExcalidrawElement[] = [el1, el2];
+    const el13: ExcalidrawElement[] = [el1, el3];
+    const el23: ExcalidrawElement[] = [el2, el3];
+    const el123: ExcalidrawElement[] = [el1, el2, el3];
+    // Set up the custom Action enablers
+    const enableName = "custom" as Action["name"];
+    const enableAction: Action = {
+      name: enableName,
+      perform: (): ActionResult => {
+        return {} as ActionResult;
+      },
+      trackEvent: false,
+    };
+    const enabler: ActionPredicateFn = function (action, elements) {
+      if (action.name !== enableName || elements.some((el) => el.y === 30)) {
+        return true;
+      }
+      return false;
+    };
+    // Set up the standard Action disablers
+    const disabled1 = actionChangeFontFamily;
+    const disabled2 = actionChangeFontSize;
+    const disabler: ActionPredicateFn = function (action, elements) {
+      if (
+        action.name === disabled2.name &&
+        elements.some((el) => el.y === 0 || isTextElement(el))
+      ) {
+        return false;
+      }
+      return true;
+    };
+    // Test the custom Action enablers
+    const am = h.app.actionManager;
+    am.registerActionPredicate(enabler);
+    expect(am.isActionEnabled(enableAction, { elements: el12 })).toBe(true);
+    expect(am.isActionEnabled(enableAction, { elements: el13 })).toBe(false);
+    expect(am.isActionEnabled(enableAction, { elements: el23 })).toBe(true);
+    expect(am.isActionEnabled(disabled1, { elements: el12 })).toBe(true);
+    expect(am.isActionEnabled(disabled1, { elements: el13 })).toBe(true);
+    expect(am.isActionEnabled(disabled1, { elements: el23 })).toBe(true);
+    // Test the standard Action disablers
+    am.registerActionPredicate(disabler);
+    expect(am.isActionEnabled(disabled1, { elements: el123 })).toBe(true);
+    expect(am.isActionEnabled(disabled2, { elements: [el1] })).toBe(false);
+    expect(am.isActionEnabled(disabled2, { elements: [el2] })).toBe(true);
+    expect(am.isActionEnabled(disabled2, { elements: [el3] })).toBe(false);
+    expect(am.isActionEnabled(disabled2, { elements: el12 })).toBe(false);
+    expect(am.isActionEnabled(disabled2, { elements: el23 })).toBe(false);
+    expect(am.isActionEnabled(disabled2, { elements: el13 })).toBe(false);
+  });
+});

src/types.ts

@@ -528,6 +528,7 @@ export type ExcalidrawImperativeAPI = {
   getSceneElements: InstanceType<typeof App>["getSceneElements"];
   getAppState: () => InstanceType<typeof App>["state"];
   getFiles: () => InstanceType<typeof App>["files"];
+  actionManager: InstanceType<typeof App>["actionManager"];
   refresh: InstanceType<typeof App>["refresh"];
   setToast: InstanceType<typeof App>["setToast"];
   addFiles: (data: BinaryFileData[]) => void;