[Tex/LaTex] How to specify image position using lower-left point coordinate in TikZ

Question

I am using the following LaTeX code to get a TikZ picture that includes a PDF and then draws two nodes:

\begin{figure}
    \begin{tikzpicture}
      \node (label) at (0,0)[draw=black]{
        \includegraphics[width=\textwidth]{my.pdf}
      };
      \node [draw=red] (A) at (0,0) {1};
      \node [draw=red] (B) at (2,0) {2};
    \end{tikzpicture}
    \caption{Simplest picture.}
\end{figure}

The result looks like this:

+---------------+
|               |
|      1 2      |
|               |
+---------------+
    Figure 1

So, the included PDF is centered, and coordinate (0,0), where "1" is drawn, is now in the center of the picture, instead of on the bottom left of the TikZ picture as usual. How can I change it so that (0,0) is still at the bottom left?

It should look like this:

+---------------+
|               |
|               |
|1 2            |
+---------------+
    Figure 1

I don't want to have to use negative x coordinates to place my points on the picture.

UPDATE: Here is a screenshot of what it actually looks like. As you can see, the two red boxes are centered and not at the lower-left. (The chain with the arrows is the PDF.)

If I replace the \includegraphics just with an "X" I get the following picture, where the "X" and the "1" are drawn on top of each other (since they are both at coordinate (0,0)).

Answer 1

Okay, I figured it out. I had to add anchor=south west to the node that includes the picture:

\node [draw=black, anchor=south west] (label) at (0,0) {\includegraphics{my.pdf}};

It looks like this: