loader(z, x, y) {
          return new Promise((resolve) => {
            const context = createCanvasContext2D(256, 256);
            context.fillStyle = `rgb(${z}, ${x % 255}, ${y % 255})`;
            context.fillRect(0, 0, 256, 256);
            resolve(context.getImageData(0, 0, 256, 256).data);
          });
        }
@type {import("../../../../../src/ol/renderer/webgl/TileLayer.js").default}