fix: 🐛 cells do not have properly initialized coordinates

Each virtual cell has a default (0, 0) coordinate. When using methods
like eraseScreen() it modifies all the cells, but misses the
coordinates, which remains (0, 0). It leads to unusual behaviour
sometimes and was fixed with this commit. Now, when Canvas initializes
an array of cells it sets its coordinates immediately based on index in
the array.

Author: ghaiklor

src/canvas/Canvas.ts

@@ -53,7 +53,10 @@ export class Canvas implements ICanvasOptions {
       this.height = options.height;
     }
 
-    this.cells = Array.from<Cell>({ length: this.width * this.height }).map(() => new Cell(' '));
+    this.cells = Array
+      .from<Cell>({ length: this.width * this.height })
+      .map((_, index) => new Cell(' ', { x: this.getXYFromPointer(index)[0], y: this.getXYFromPointer(index)[1] }));
+
     this.lastFrame = Array.from<string>({ length: this.width * this.height }).fill('');
   }
 

test/Canvas.spec.ts

@@ -56,6 +56,22 @@ describe('Canvas', () => {
     expect(canvas.height).toEqual(10);
   });
 
+  it('Should properly initialize the coordinates for the cells', () => {
+    const canvas = new Canvas({ width: 2, height: 2 });
+
+    expect(canvas.cells[0].x).toBe(0);
+    expect(canvas.cells[0].y).toBe(0);
+
+    expect(canvas.cells[1].x).toBe(1);
+    expect(canvas.cells[1].y).toBe(0);
+
+    expect(canvas.cells[2].x).toBe(0);
+    expect(canvas.cells[2].y).toBe(1);
+
+    expect(canvas.cells[3].x).toBe(1);
+    expect(canvas.cells[3].y).toBe(1);
+  });
+
   it('Should properly write to the canvas', () => {
     const canvas = new Canvas({ width: 20, height: 10 });
     expect(canvas.cells[0].getChar()).toEqual(' ');