253 new property on roi centroid (#277)

* feat: add centroid property

* test: add testing cases for centroid property

close: #253

* refactor: redo the algorithm of centroid

* refactor: add origin only once the point should be returned

* refactor: change names of variables xCoords and yCoords

Author: EscapedGibbon

src/roi/Roi.ts

@@ -33,6 +33,7 @@ interface Computed {
   fillRatio: number;
   internalIDs: number[];
   feret: Feret;
+  centroid: Point;
 }
 export class Roi {
   /**
@@ -328,6 +329,29 @@ export class Roi {
     };
   }
 
+  get centroid() {
+    return this.#getComputed('centroid', () => {
+      const roiMap = this.getMap();
+      const data = roiMap.data;
+      let sumColumn = 0;
+      let sumRow = 0;
+      for (let column = 0; column < this.width; column++) {
+        for (let row = 0; row < this.height; row++) {
+          let target = this.computeIndex(row, column);
+          if (data[target] === this.id) {
+            sumColumn += column;
+            sumRow += row;
+          }
+        }
+      }
+
+      return {
+        column: sumColumn / this.surface + this.origin.column,
+        row: sumRow / this.surface + this.origin.row,
+      };
+    });
+  }
+
   #getComputed<T extends keyof Computed>(
     property: T,
     callback: () => Computed[T],

src/roi/__tests__/centroid.test.ts

@@ -0,0 +1,39 @@
+import { fromMask } from '../..';
+
+test('centroid property 4x4', () => {
+  const mask = testUtils.createMask([
+    [0, 1, 1, 1],
+    [0, 1, 0, 1],
+    [0, 1, 1, 1],
+    [0, 0, 0, 0],
+  ]);
+  const roiMapManager = fromMask(mask);
+  const rois = roiMapManager.getRois();
+  expect(rois[0].centroid).toStrictEqual({ row: 1, column: 2 });
+});
+
+test('border lengths property 5x5', () => {
+  const mask = testUtils.createMask([
+    [1, 0, 0, 1, 0],
+    [1, 1, 1, 1, 0],
+    [1, 0, 0, 0, 0],
+    [1, 1, 1, 1, 0],
+    [1, 1, 1, 0, 0],
+  ]);
+  const roiMapManager = fromMask(mask);
+  const rois = roiMapManager.getRois();
+  expect(rois[0].centroid.row).toBeCloseTo(2.14286);
+  expect(rois[0].centroid.column).toBeCloseTo(1.28571);
+});
+
+test('border lengths property 5x5', () => {
+  const mask = testUtils.createMask([
+    [1, 1, 1],
+    [0, 1, 0],
+    [1, 1, 1],
+  ]);
+  const roiMapManager = fromMask(mask);
+  const rois = roiMapManager.getRois();
+  expect(rois[0].centroid.row).toBeCloseTo(1);
+  expect(rois[0].centroid.column).toBeCloseTo(1);
+});