in src/shapes/shapes.ts [172:180]
export function containsPoint(rect: IRect, point: IPoint): boolean {
if ((rect === null) || (point === null)) {
return false;
}
return Double.lessOrEqualWithPrecision(rect.left, point.x) &&
Double.lessOrEqualWithPrecision(point.x, rect.left + rect.width) &&
Double.lessOrEqualWithPrecision(rect.top, point.y) &&
Double.lessOrEqualWithPrecision(point.y, rect.top + rect.height);
}