How to get the structure members from a TagDecl with clang

I use clang and an AST Consumer for a little header parser that I am writing.

I Am able to get the TagDecl for unions, structures, classes and enums in the headers file that I parse( with the method HandleTagDeclDefinition).

I am now trying to figure out how to get the structure members like with the TagDecl::dumpColor() method(it just displays the informations that I want to handle).

It seems that I have to get the FieldDecl for each members of the structure but I don't know how to get them
from a TagDecl.

Any idea?