feat: element alignments - snapping (#6256)

Co-authored-by: Ryan Di <ryan.weihao.di@gmail.com>
Co-authored-by: dwelle <luzar.david@gmail.com>

src/math.test.ts

@@ -1,4 +1,4 @@
-import { rotate } from "./math";
+import { rangeIntersection, rangesOverlap, rotate } from "./math";
 
 describe("rotate", () => {
   it("should rotate over (x2, y2) and return the rotated coordinates for (x1, y1)", () => {
@@ -13,3 +13,43 @@ describe("rotate", () => {
     expect(res2).toEqual([x1, x2]);
   });
 });
+
+describe("range overlap", () => {
+  it("should overlap when range a contains range b", () => {
+    expect(rangesOverlap([1, 4], [2, 3])).toBe(true);
+    expect(rangesOverlap([1, 4], [1, 4])).toBe(true);
+    expect(rangesOverlap([1, 4], [1, 3])).toBe(true);
+    expect(rangesOverlap([1, 4], [2, 4])).toBe(true);
+  });
+
+  it("should overlap when range b contains range a", () => {
+    expect(rangesOverlap([2, 3], [1, 4])).toBe(true);
+    expect(rangesOverlap([1, 3], [1, 4])).toBe(true);
+    expect(rangesOverlap([2, 4], [1, 4])).toBe(true);
+  });
+
+  it("should overlap when range a and b intersect", () => {
+    expect(rangesOverlap([1, 4], [2, 5])).toBe(true);
+  });
+});
+
+describe("range intersection", () => {
+  it("should intersect completely with itself", () => {
+    expect(rangeIntersection([1, 4], [1, 4])).toEqual([1, 4]);
+  });
+
+  it("should intersect irrespective of order", () => {
+    expect(rangeIntersection([1, 4], [2, 3])).toEqual([2, 3]);
+    expect(rangeIntersection([2, 3], [1, 4])).toEqual([2, 3]);
+    expect(rangeIntersection([1, 4], [3, 5])).toEqual([3, 4]);
+    expect(rangeIntersection([3, 5], [1, 4])).toEqual([3, 4]);
+  });
+
+  it("should intersect at the edge", () => {
+    expect(rangeIntersection([1, 4], [4, 5])).toEqual([4, 4]);
+  });
+
+  it("should not intersect", () => {
+    expect(rangeIntersection([1, 4], [5, 7])).toEqual(null);
+  });
+});