feat: more idiomatic element filters [POC]

packages/common/src/utility-types.ts

@@ -68,3 +68,28 @@ export type MaybePromise<T> = T | Promise<T>;
 
 // get union of all keys from the union of types
 export type AllPossibleKeys<T> = T extends any ? keyof T : never;
+
+// utlity types for filter helper and related data structures
+// -----------------------------------------------------------------------------
+export type ReadonlyArrayOrMap<
+  T,
+  K = T extends { id: string } ? T["id"] : string,
+> = readonly T[] | ReadonlyMap<K, T>;
+
+export type GenericAccumulator<T = unknown> = Set<T> | Map<T, T> | Array<T>;
+export type ArrayAccumulator<T = unknown> = Array<T>;
+export type MapAccumulator<T = unknown, K = unknown> = Map<T, K>;
+export type SetAccumulator<T = unknown> = Set<T>;
+export type OutputAccumulator<
+  Accumulator,
+  OutputType,
+  Attr extends keyof OutputType = never,
+> = Accumulator extends SetAccumulator
+  ? Set<[Attr] extends [never] ? OutputType : Attr>
+  : Accumulator extends MapAccumulator
+  ? Map<
+      OutputType extends { id: string } ? OutputType["id"] : string,
+      OutputType
+    >
+  : Array<OutputType>;
+// -----------------------------------------------------------------------------

packages/element/src/dragElements.ts

@@ -26,6 +26,10 @@ import {
   isTextElement,
 } from "./typeChecks";
 
+import { filterElements } from "./utils";
+
+import { getFrameChildren } from "./frame";
+
 import type Scene from "./Scene";
 
 import type { Bounds } from "./bounds";
@@ -65,23 +69,13 @@ export const dragSelectedElements = (
     return true;
   });
 
-  // we do not want a frame and its elements to be selected at the same time
+  // update frames and their children (use a set to make sure we avoid
-  // but when it happens (due to some bug), we want to avoid updating element
+  // duplicates in case the user already selected the frame's children)
-  // in the frame twice, hence the use of set
+  const elementsToUpdate = getFrameChildren(
-  const elementsToUpdate = new Set<NonDeletedExcalidrawElement>(
+    scene.getNonDeletedElements(),
-    selectedElements,
+    filterElements(selectedElements, isFrameLikeElement, new Set(), "id"),
+    new Set(selectedElements),
   );
-  const frames = selectedElements
-    .filter((e) => isFrameLikeElement(e))
-    .map((f) => f.id);
-
-  if (frames.length > 0) {
-    for (const element of scene.getNonDeletedElements()) {
-      if (element.frameId !== null && frames.includes(element.frameId)) {
-        elementsToUpdate.add(element);
-      }
-    }
-  }
 
   const origElements: ExcalidrawElement[] = [];
 

packages/element/src/frame.ts

@@ -9,7 +9,13 @@ import type {
   StaticCanvasAppState,
 } from "@excalidraw/excalidraw/types";
 
-import type { ReadonlySetLike } from "@excalidraw/common/utility-types";
+import type {
+  ArrayAccumulator,
+  GenericAccumulator,
+  ReadonlyArrayOrMap,
+  ReadonlySetLike,
+  OutputAccumulator,
+} from "@excalidraw/common/utility-types";
 
 import { getElementsWithinSelection, getSelectedElements } from "./selection";
 import { getElementsInGroup, selectGroupsFromGivenElements } from "./groups";
@@ -27,6 +33,8 @@ import {
   isTextElement,
 } from "./typeChecks";
 
+import { filterElements } from "./utils";
+
 import type { ExcalidrawElementsIncludingDeleted } from "./Scene";
 
 import type {
@@ -230,17 +238,30 @@ export const groupByFrameLikes = (elements: readonly ExcalidrawElement[]) => {
   return frameElementsMap;
 };
 
-export const getFrameChildren = (
+export const getFrameChildren = <
-  allElements: ElementsMapOrArray,
+  K extends ExcalidrawElement,
-  frameId: string,
+  O extends GenericAccumulator = ArrayAccumulator,
-) => {
+>(
-  const frameChildren: ExcalidrawElement[] = [];
+  allElements: ReadonlyArrayOrMap<K>,
-  for (const element of allElements.values()) {
+  frameId: K["id"] | Set<string>,
-    if (element.frameId === frameId) {
+  output?: O,
-      frameChildren.push(element);
+): OutputAccumulator<O, K> => {
+  if (frameId instanceof Set && frameId.size === 0) {
+    return (output || []) as any as OutputAccumulator<O, K>;
   }
+
+  return filterElements(
+    allElements,
+    (element): element is K => {
+      if (!element.frameId) {
+        return false;
       }
-  return frameChildren;
+      return typeof frameId === "string"
+        ? element.frameId === frameId
+        : frameId.has(element.frameId);
+    },
+    output || [],
+  ) as any as OutputAccumulator<O, K>;
 };
 
 export const getFrameLikeElements = (

packages/element/src/utils.ts

@@ -10,7 +10,7 @@ import {
   type GlobalPoint,
 } from "@excalidraw/math";
 
-import { elementCenterPoint } from "@excalidraw/common";
+import { elementCenterPoint, isReadonlyArray } from "@excalidraw/common";
 
 import type { Curve, LineSegment } from "@excalidraw/math";
 
@@ -18,8 +18,15 @@ import { getCornerRadius } from "./shapes";
 
 import { getDiamondPoints } from "./bounds";
 
+import type {
+  GenericAccumulator,
+  OutputAccumulator,
+  ReadonlyArrayOrMap,
+} from "../../common/src/utility-types";
+
 import type {
   ExcalidrawDiamondElement,
+  ExcalidrawElement,
   ExcalidrawRectanguloidElement,
 } from "./types";
 
@@ -353,3 +360,35 @@ export function deconstructDiamondElement(
 
   return [sides, corners];
 }
+
+export const filterElements = <
+  InputType extends ExcalidrawElement,
+  PredicateOutputType extends InputType,
+  AccumulatorType extends GenericAccumulator,
+  Attr extends keyof PredicateOutputType = never,
+>(
+  elements: ReadonlyArrayOrMap<InputType>,
+  predicate: (elem: InputType) => elem is PredicateOutputType,
+  accumulator: AccumulatorType,
+  attr?: Attr,
+): OutputAccumulator<AccumulatorType, PredicateOutputType, Attr> => {
+  for (const element of isReadonlyArray(elements)
+    ? elements
+    : elements.values()) {
+    if (predicate(element)) {
+      if (accumulator instanceof Set) {
+        accumulator.add(attr ? element[attr] : element);
+      } else if (accumulator instanceof Map) {
+        accumulator.set(element.id, attr ? element[attr] : element);
+      } else {
+        accumulator.push(element);
+      }
+    }
+  }
+
+  return accumulator as any as OutputAccumulator<
+    AccumulatorType,
+    PredicateOutputType,
+    Attr
+  >;
+};