refactor: separate elements logic into a standalone package (#9285)

packages/element/src/distance.ts

@@ -0,0 +1,127 @@
+import {
+  curvePointDistance,
+  distanceToLineSegment,
+  pointFrom,
+  pointRotateRads,
+} from "@excalidraw/math";
+
+import { ellipse, ellipseDistanceFromPoint } from "@excalidraw/math/ellipse";
+
+import type { GlobalPoint, Radians } from "@excalidraw/math";
+
+import {
+  deconstructDiamondElement,
+  deconstructRectanguloidElement,
+} from "./utils";
+
+import type {
+  ExcalidrawBindableElement,
+  ExcalidrawDiamondElement,
+  ExcalidrawEllipseElement,
+  ExcalidrawRectanguloidElement,
+} from "./types";
+
+export const distanceToBindableElement = (
+  element: ExcalidrawBindableElement,
+  p: GlobalPoint,
+): number => {
+  switch (element.type) {
+    case "rectangle":
+    case "image":
+    case "text":
+    case "iframe":
+    case "embeddable":
+    case "frame":
+    case "magicframe":
+      return distanceToRectanguloidElement(element, p);
+    case "diamond":
+      return distanceToDiamondElement(element, p);
+    case "ellipse":
+      return distanceToEllipseElement(element, p);
+  }
+};
+
+/**
+ * Returns the distance of a point and the provided rectangular-shaped element,
+ * accounting for roundness and rotation
+ *
+ * @param element The rectanguloid element
+ * @param p The point to consider
+ * @returns The eucledian distance to the outline of the rectanguloid element
+ */
+const distanceToRectanguloidElement = (
+  element: ExcalidrawRectanguloidElement,
+  p: GlobalPoint,
+) => {
+  const center = pointFrom<GlobalPoint>(
+    element.x + element.width / 2,
+    element.y + element.height / 2,
+  );
+  // To emulate a rotated rectangle we rotate the point in the inverse angle
+  // instead. It's all the same distance-wise.
+  const rotatedPoint = pointRotateRads(p, center, -element.angle as Radians);
+
+  // Get the element's building components we can test against
+  const [sides, corners] = deconstructRectanguloidElement(element);
+
+  return Math.min(
+    ...sides.map((s) => distanceToLineSegment(rotatedPoint, s)),
+    ...corners
+      .map((a) => curvePointDistance(a, rotatedPoint))
+      .filter((d): d is number => d !== null),
+  );
+};
+
+/**
+ * Returns the distance of a point and the provided diamond element, accounting
+ * for roundness and rotation
+ *
+ * @param element The diamond element
+ * @param p The point to consider
+ * @returns The eucledian distance to the outline of the diamond
+ */
+const distanceToDiamondElement = (
+  element: ExcalidrawDiamondElement,
+  p: GlobalPoint,
+): number => {
+  const center = pointFrom<GlobalPoint>(
+    element.x + element.width / 2,
+    element.y + element.height / 2,
+  );
+
+  // Rotate the point to the inverse direction to simulate the rotated diamond
+  // points. It's all the same distance-wise.
+  const rotatedPoint = pointRotateRads(p, center, -element.angle as Radians);
+
+  const [sides, curves] = deconstructDiamondElement(element);
+
+  return Math.min(
+    ...sides.map((s) => distanceToLineSegment(rotatedPoint, s)),
+    ...curves
+      .map((a) => curvePointDistance(a, rotatedPoint))
+      .filter((d): d is number => d !== null),
+  );
+};
+
+/**
+ * Returns the distance of a point and the provided ellipse element, accounting
+ * for roundness and rotation
+ *
+ * @param element The ellipse element
+ * @param p The point to consider
+ * @returns The eucledian distance to the outline of the ellipse
+ */
+const distanceToEllipseElement = (
+  element: ExcalidrawEllipseElement,
+  p: GlobalPoint,
+): number => {
+  const center = pointFrom(
+    element.x + element.width / 2,
+    element.y + element.height / 2,
+  );
+  return ellipseDistanceFromPoint(
+    // Instead of rotating the ellipse, rotate the point to the inverse angle
+    pointRotateRads(p, center, -element.angle as Radians),
+    ellipse(center, element.width / 2, element.height / 2),
+  );
+};